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CONTENTS

NAME

perlapi - autogenerated documentation for the perl public API

DESCRIPTION

This file contains most of the documentation of the perl public API, as generated by embed.pl. Specifically, it is a listing of functions, macros, flags, and variables that may be used by extension writers. Besides perlintern and config.h, some items are listed here as being actually documented in another pod.

At the end is a list of functions which have yet to be documented. Patches welcome! The interfaces of these are subject to change without notice.

Some of the functions documented here are consolidated so that a single entry serves for multiple functions which all do basically the same thing, but have some slight differences. For example, one form might process magic, while another doesn't. The name of each variation is listed at the top of the single entry. But if all have the same signature (arguments and return type) except for their names, only the usage for the base form is shown. If any one of the forms has a different signature (such as returning const or not) every function's signature is explicitly displayed.

Anything not listed here or in the other mentioned pods is not part of the public API, and should not be used by extension writers at all. For these reasons, blindly using functions listed in proto.h is to be avoided when writing extensions.

In Perl, unlike C, a string of characters may generally contain embedded NUL characters. Sometimes in the documentation a Perl string is referred to as a "buffer" to distinguish it from a C string, but sometimes they are both just referred to as strings.

Note that all Perl API global variables must be referenced with the PL_ prefix. Again, those not listed here are not to be used by extension writers, and can be changed or removed without notice; same with macros. Some macros are provided for compatibility with the older, unadorned names, but this support may be disabled in a future release.

Perl was originally written to handle US-ASCII only (that is characters whose ordinal numbers are in the range 0 - 127). And documentation and comments may still use the term ASCII, when sometimes in fact the entire range from 0 - 255 is meant.

The non-ASCII characters below 256 can have various meanings, depending on various things. (See, most notably, perllocale.) But usually the whole range can be referred to as ISO-8859-1. Often, the term "Latin-1" (or "Latin1") is used as an equivalent for ISO-8859-1. But some people treat "Latin1" as referring just to the characters in the range 128 through 255, or sometimes from 160 through 255. This documentation uses "Latin1" and "Latin-1" to refer to all 256 characters.

Note that Perl can be compiled and run under either ASCII or EBCDIC (See perlebcdic). Most of the documentation (and even comments in the code) ignore the EBCDIC possibility. For almost all purposes the differences are transparent. As an example, under EBCDIC, instead of UTF-8, UTF-EBCDIC is used to encode Unicode strings, and so whenever this documentation refers to utf8 (and variants of that name, including in function names), it also (essentially transparently) means UTF-EBCDIC. But the ordinals of characters differ between ASCII, EBCDIC, and the UTF- encodings, and a string encoded in UTF-EBCDIC may occupy a different number of bytes than in UTF-8.

The organization of this document is tentative and subject to change. Suggestions and patches welcome perl5-porters@perl.org.

The sections in this document currently are

"AV Handling"
"Callback Functions"
"Casting"
"Character case changing"
"Character classification"
"Compiler and Preprocessor information"
"Compiler directives"
"Compile-time scope hooks"
"Concurrency"
"COP Hint Hashes"
"Custom Operators"
"CV Handling"
"Debugging"
"Display functions"
"Embedding and Interpreter Cloning"
"Errno"
"Exception Handling (simple) Macros"
"Filesystem configuration values"
"Floating point configuration values"
"Formats"
"General Configuration"
"Global Variables"
"GV Handling"
"Hook manipulation"
"HV Handling"
"Input/Output"
"Integer configuration values"
"Lexer interface"
"Locales"
"Magic"
"Memory Management"
"MRO"
"Multicall Functions"
"Numeric Functions"
"Optree construction"
"Optree Manipulation Functions"
"Pack and Unpack"
"Pad Data Structures"
"Password and Group access"
"Paths to system commands"
"Prototype information"
"REGEXP Functions"
"Signals"
"Site configuration"
"Sockets configuration values"
"Source Filters"
"Stack Manipulation Macros"
"String Handling"
"SV Flags"
"SV Handling"
"Time"
"Typedef names"
"Unicode Support"
"Utility Functions"
"Versioning"
"Warning and Dieing"
"XS"
"Undocumented elements"

The listing below is alphabetical, case insensitive.

AV Handling

AV

Described in perlguts.

AvARRAY

Returns a pointer to the AV's internal SV* array.

This is useful for doing pointer arithmetic on the array. If all you need is to look up an array element, then prefer av_fetch.

    SV**  AvARRAY(AV* av)
av_clear

Frees all the elements of an array, leaving it empty. The XS equivalent of @array = (). See also "av_undef".

Note that it is possible that the actions of a destructor called directly or indirectly by freeing an element of the array could cause the reference count of the array itself to be reduced (e.g. by deleting an entry in the symbol table). So it is a possibility that the AV could have been freed (or even reallocated) on return from the call unless you hold a reference to it.

    void  av_clear(AV *av)
av_count

Returns the number of elements in the array av. This is the true length of the array, including any undefined elements. It is always the same as av_top_index(av) + 1.

    Size_t  av_count(AV *av)
av_create_and_push

NOTE: av_create_and_push is experimental and may change or be removed without notice.

Push an SV onto the end of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

NOTE: av_create_and_push must be explicitly called as Perl_av_create_and_push with an aTHX_ parameter.

    void  Perl_av_create_and_push(pTHX_ AV **const avp,
                                  SV *const val)
av_create_and_unshift_one

NOTE: av_create_and_unshift_one is experimental and may change or be removed without notice.

Unshifts an SV onto the beginning of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

NOTE: av_create_and_unshift_one must be explicitly called as Perl_av_create_and_unshift_one with an aTHX_ parameter.

    SV**  Perl_av_create_and_unshift_one(pTHX_ AV **const avp,
                                         SV *const val)
av_delete

Deletes the element indexed by key from the array, makes the element mortal, and returns it. If flags equals G_DISCARD, the element is freed and NULL is returned. NULL is also returned if key is out of range.

Perl equivalent: splice(@myarray, $key, 1, undef) (with the splice in void context if G_DISCARD is present).

    SV*  av_delete(AV *av, SSize_t key, I32 flags)
av_exists

Returns true if the element indexed by key has been initialized.

This relies on the fact that uninitialized array elements are set to NULL.

Perl equivalent: exists($myarray[$key]).

    bool  av_exists(AV *av, SSize_t key)
av_extend

Pre-extend an array so that it is capable of storing values at indexes 0..key. Thus av_extend(av,99) guarantees that the array can store 100 elements, i.e. that av_store(av, 0, sv) through av_store(av, 99, sv) on a plain array will work without any further memory allocation.

If the av argument is a tied array then will call the EXTEND tied array method with an argument of (key+1).

    void  av_extend(AV *av, SSize_t key)
av_fetch

Returns the SV at the specified index in the array. The key is the index. If lval is true, you are guaranteed to get a real SV back (in case it wasn't real before), which you can then modify. Check that the return value is non-null before dereferencing it to a SV*.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

The rough perl equivalent is $myarray[$key].

    SV**  av_fetch(AV *av, SSize_t key, I32 lval)
AvFILL

Same as "av_top_index" or "av_tindex".

    SSize_t  AvFILL(AV* av)
av_fill

Set the highest index in the array to the given number, equivalent to Perl's $#array = $fill;.

The number of elements in the array will be fill + 1 after av_fill() returns. If the array was previously shorter, then the additional elements appended are set to NULL. If the array was longer, then the excess elements are freed. av_fill(av, -1) is the same as av_clear(av).

    void  av_fill(AV *av, SSize_t fill)
av_len

Same as "av_top_index". Note that, unlike what the name implies, it returns the maximum index in the array. This is unlike "sv_len", which returns what you would expect.

To get the true number of elements in the array, instead use "av_count".

    SSize_t  av_len(AV *av)
av_make

Creates a new AV and populates it with a list of SVs. The SVs are copied into the array, so they may be freed after the call to av_make. The new AV will have a reference count of 1.

Perl equivalent: my @new_array = ($scalar1, $scalar2, $scalar3...);

    AV*  av_make(SSize_t size, SV **strp)
av_pop

Removes one SV from the end of the array, reducing its size by one and returning the SV (transferring control of one reference count) to the caller. Returns &PL_sv_undef if the array is empty.

Perl equivalent: pop(@myarray);

    SV*  av_pop(AV *av)
av_push

Pushes an SV (transferring control of one reference count) onto the end of the array. The array will grow automatically to accommodate the addition.

Perl equivalent: push @myarray, $val;.

    void  av_push(AV *av, SV *val)
av_shift

Removes one SV from the start of the array, reducing its size by one and returning the SV (transferring control of one reference count) to the caller. Returns &PL_sv_undef if the array is empty.

Perl equivalent: shift(@myarray);

    SV*  av_shift(AV *av)
av_store

Stores an SV in an array. The array index is specified as key. The return value will be NULL if the operation failed or if the value did not need to be actually stored within the array (as in the case of tied arrays). Otherwise, it can be dereferenced to get the SV* that was stored there (= val)).

Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL.

Approximate Perl equivalent: splice(@myarray, $key, 1, $val).

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

    SV**  av_store(AV *av, SSize_t key, SV *val)
av_tindex
av_top_index

These behave identically. If the array av is empty, these return -1; otherwise they return the maximum value of the indices of all the array elements which are currently defined in av.

They process 'get' magic.

The Perl equivalent for these is $#av.

Use "av_count" to get the number of elements in an array.

    SSize_t  av_tindex(AV *av)
av_undef

Undefines the array. The XS equivalent of undef(@array).

As well as freeing all the elements of the array (like av_clear()), this also frees the memory used by the av to store its list of scalars.

See "av_clear" for a note about the array possibly being invalid on return.

    void  av_undef(AV *av)
av_unshift

Unshift the given number of undef values onto the beginning of the array. The array will grow automatically to accommodate the addition.

Perl equivalent: unshift @myarray, ((undef) x $num);

    void  av_unshift(AV *av, SSize_t num)
get_av

Returns the AV of the specified Perl global or package array with the given name (so it won't work on lexical variables). flags are passed to gv_fetchpv. If GV_ADD is set and the Perl variable does not exist then it will be created. If flags is zero and the variable does not exist then NULL is returned.

Perl equivalent: @{"$name"}.

NOTE: the perl_get_av() form is deprecated.

    AV*  get_av(const char *name, I32 flags)
newAV

Creates a new AV. The reference count is set to 1.

Perl equivalent: my @array;.

    AV*  newAV()
Nullav

DEPRECATED! It is planned to remove Nullav from a future release of Perl. Do not use it for new code; remove it from existing code.

Null AV pointer.

(deprecated - use (AV *)NULL instead)

Callback Functions

call_argv

Performs a callback to the specified named and package-scoped Perl subroutine with argv (a NULL-terminated array of strings) as arguments. See perlcall.

Approximate Perl equivalent: &{"$sub_name"}(@$argv).

NOTE: the perl_call_argv() form is deprecated.

    I32  call_argv(const char* sub_name, I32 flags, char** argv)
call_method

Performs a callback to the specified Perl method. The blessed object must be on the stack. See perlcall.

NOTE: the perl_call_method() form is deprecated.

    I32  call_method(const char* methname, I32 flags)
call_pv

Performs a callback to the specified Perl sub. See perlcall.

NOTE: the perl_call_pv() form is deprecated.

    I32  call_pv(const char* sub_name, I32 flags)
call_sv

Performs a callback to the Perl sub specified by the SV.

If neither the G_METHOD nor G_METHOD_NAMED flag is supplied, the SV may be any of a CV, a GV, a reference to a CV, a reference to a GV or SvPV(sv) will be used as the name of the sub to call.

If the G_METHOD flag is supplied, the SV may be a reference to a CV or SvPV(sv) will be used as the name of the method to call.

If the G_METHOD_NAMED flag is supplied, SvPV(sv) will be used as the name of the method to call.

Some other values are treated specially for internal use and should not be depended on.

See perlcall.

NOTE: the perl_call_sv() form is deprecated.

    I32  call_sv(SV* sv, volatile I32 flags)
ENTER

Opening bracket on a callback. See "LEAVE" and perlcall.

    ENTER;
ENTER_with_name

Same as "ENTER", but when debugging is enabled it also associates the given literal string with the new scope.

    ENTER_with_name("name");
eval_pv

Tells Perl to eval the given string in scalar context and return an SV* result.

NOTE: the perl_eval_pv() form is deprecated.

    SV*  eval_pv(const char* p, I32 croak_on_error)
eval_sv

Tells Perl to eval the string in the SV. It supports the same flags as call_sv, with the obvious exception of G_EVAL. See perlcall.

The G_RETHROW flag can be used if you only need eval_sv() to execute code specified by a string, but not catch any errors.

NOTE: the perl_eval_sv() form is deprecated.

    I32  eval_sv(SV* sv, I32 flags)
FREETMPS

Closing bracket for temporaries on a callback. See "SAVETMPS" and perlcall.

    FREETMPS;
G_ARRAY

Described in perlcall.

G_DISCARD

Described in perlcall.

G_EVAL

Described in perlcall.

GIMME

DEPRECATED! It is planned to remove GIMME from a future release of Perl. Do not use it for new code; remove it from existing code.

A backward-compatible version of GIMME_V which can only return G_SCALAR or G_ARRAY; in a void context, it returns G_SCALAR. Deprecated. Use GIMME_V instead.

    U32  GIMME
GIMME_V

The XSUB-writer's equivalent to Perl's wantarray. Returns G_VOID, G_SCALAR or G_ARRAY for void, scalar or list context, respectively. See perlcall for a usage example.

    U32  GIMME_V
G_KEEPERR

Described in perlcall.

G_NOARGS

Described in perlcall.

G_SCALAR

Described in perlcall.

G_VOID

Described in perlcall.

LEAVE

Closing bracket on a callback. See "ENTER" and perlcall.

    LEAVE;
LEAVE_with_name

Same as "LEAVE", but when debugging is enabled it first checks that the scope has the given name. name must be a literal string.

    LEAVE_with_name("name");
PL_errgv

Described in perlcall.

SAVETMPS

Opening bracket for temporaries on a callback. See "FREETMPS" and perlcall.

    SAVETMPS;

Casting

cBOOL

Cast-to-bool. A simple (bool) expr cast may not do the right thing: if bool is defined as char, for example, then the cast from int is implementation-defined.

(bool)!!(cbool) in a ternary triggers a bug in xlc on AIX

    bool  cBOOL(bool expr)
I_32

Cast an NV to I32 while avoiding undefined C behavior

    I32  I_32(NV what)
INT2PTR

Described in perlguts.

    type  INT2PTR(type, int value)
I_V

Cast an NV to IV while avoiding undefined C behavior

    IV  I_V(NV what)
Perl_cpeep_t

Described in perlguts.

PTR2IV

Described in perlguts.

    IV  PTR2IV(void * ptr)
PTR2nat

Described in perlguts.

    IV  PTR2nat(void *)
PTR2NV

Described in perlguts.

    NV  PTR2NV(void * ptr)
PTR2ul

Described in perlguts.

    unsigned long  PTR2ul(void *)
PTR2UV

Described in perlguts.

    UV  PTR2UV(void * ptr)
PTRV

Described in perlguts.

U_32

Cast an NV to U32 while avoiding undefined C behavior

    U32  U_32(NV what)
U_V

Cast an NV to UV while avoiding undefined C behavior

    UV  U_V(NV what)
XOP

Described in perlguts.

Character case changing

Perl uses "full" Unicode case mappings. This means that converting a single character to another case may result in a sequence of more than one character. For example, the uppercase of ß (LATIN SMALL LETTER SHARP S) is the two character sequence SS. This presents some complications The lowercase of all characters in the range 0..255 is a single character, and thus "toLOWER_L1" is furnished. But, toUPPER_L1 can't exist, as it couldn't return a valid result for all legal inputs. Instead "toUPPER_uvchr" has an API that does allow every possible legal result to be returned.) Likewise no other function that is crippled by not being able to give the correct results for the full range of possible inputs has been implemented here.

toFOLD

Converts the specified character to foldcase. If the input is anything but an ASCII uppercase character, that input character itself is returned. Variant toFOLD_A is equivalent. (There is no equivalent to_FOLD_L1 for the full Latin1 range, as the full generality of "toFOLD_uvchr" is needed there.)

    U8  toFOLD(U8 ch)
toFOLD_utf8
toFOLD_utf8_safe

Converts the first UTF-8 encoded character in the sequence starting at p and extending no further than e - 1 to its foldcase version, and stores that in UTF-8 in s, and its length in bytes in lenp. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the foldcase version may be longer than the original character.

The first code point of the foldcased version is returned (but note, as explained at the top of this section, that there may be more).

It will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

toFOLD_utf8_safe is now just a different spelling of plain toFOLD_utf8

    UV  toFOLD_utf8(U8* p, U8* e, U8* s, STRLEN* lenp)
toFOLD_uvchr

Converts the code point cp to its foldcase version, and stores that in UTF-8 in s, and its length in bytes in lenp. The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the foldcase version may be longer than the original character.

The first code point of the foldcased version is returned (but note, as explained at the top of this section, that there may be more).

    UV  toFOLD_uvchr(UV cp, U8* s, STRLEN* lenp)
toLOWER
toLOWER_A
toLOWER_L1
toLOWER_LATIN1
toLOWER_LC
toLOWER_uvchr
toLOWER_utf8
toLOWER_utf8_safe

These all return the lowercase of a character. The differences are what domain they operate on, and whether the input is specified as a code point (those forms with a cp parameter) or as a UTF-8 string (the others). In the latter case, the code point to use is the first one in the buffer of UTF-8 encoded code points, delineated by the arguments p .. e - 1.

toLOWER and toLOWER_A are synonyms of each other. They return the lowercase of any uppercase ASCII-range code point. All other inputs are returned unchanged. Since these are macros, the input type may be any integral one, and the output will occupy the same number of bits as the input.

toLOWER_L1 and toLOWER_LATIN1 are synonyms of each other. They behave identically as toLOWER for ASCII-range input. But additionally will return the lowercase of any uppercase code point in the entire 0..255 range, assuming a Latin-1 encoding (or the EBCDIC equivalent on such platforms).

toLOWER_LC returns the lowercase of the input code point according to the rules of the current POSIX locale. Input code points outside the range 0..255 are returned unchanged.

toLOWER_uvchr returns the lowercase of any Unicode code point. The return value is identical to that of toLOWER_L1 for input code points in the 0..255 range. The lowercase of the vast majority of Unicode code points is the same as the code point itself. For these, and for code points above the legal Unicode maximum, this returns the input code point unchanged. It additionally stores the UTF-8 of the result into the buffer beginning at s, and its length in bytes into *lenp. The caller must have made s large enough to contain at least UTF8_MAXBYTES_CASE+1 bytes to avoid possible overflow.

NOTE: the lowercase of a code point may be more than one code point. The return value of this function is only the first of these. The entire lowercase is returned in s. To determine if the result is more than a single code point, you can do something like this:

uc = toLOWER_uvchr(cp, s, &len);
if (len > UTF8SKIP(s)) { is multiple code points }
else { is a single code point }

toLOWER_utf8 and toLOWER_utf8_safe are synonyms of each other. The only difference between these and toLOWER_uvchr is that the source for these is encoded in UTF-8, instead of being a code point. It is passed as a buffer starting at p, with e pointing to one byte beyond its end. The p buffer may certainly contain more than one code point; but only the first one (up through e - 1) is examined. If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

    UV  toLOWER          (UV cp)
    UV  toLOWER_A        (UV cp)
    UV  toLOWER_L1       (UV cp)
    UV  toLOWER_LATIN1   (UV cp)
    UV  toLOWER_LC       (UV cp)
    UV  toLOWER_uvchr    (UV cp, U8* s, STRLEN* lenp)
    UV  toLOWER_utf8     (U8* p, U8* e, U8* s, STRLEN* lenp)
    UV  toLOWER_utf8_safe(U8* p, U8* e, U8* s, STRLEN* lenp)
toTITLE

Converts the specified character to titlecase. If the input is anything but an ASCII lowercase character, that input character itself is returned. Variant toTITLE_A is equivalent. (There is no toTITLE_L1 for the full Latin1 range, as the full generality of "toTITLE_uvchr" is needed there. Titlecase is not a concept used in locale handling, so there is no functionality for that.)

    U8  toTITLE(U8 ch)
toTITLE_utf8
toTITLE_utf8_safe

Convert the first UTF-8 encoded character in the sequence starting at p and extending no further than e - 1 to its titlecase version, and stores that in UTF-8 in s, and its length in bytes in lenp. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the titlecase version may be longer than the original character.

The first code point of the titlecased version is returned (but note, as explained at the top of this section, that there may be more).

It will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

toTITLE_utf8_safe is now just a different spelling of plain toTITLE_utf8

    UV  toTITLE_utf8(U8* p, U8* e, U8* s, STRLEN* lenp)
toTITLE_uvchr

Converts the code point cp to its titlecase version, and stores that in UTF-8 in s, and its length in bytes in lenp. The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the titlecase version may be longer than the original character.

The first code point of the titlecased version is returned (but note, as explained at the top of this section, that there may be more).

    UV  toTITLE_uvchr(UV cp, U8* s, STRLEN* lenp)
toUPPER

Converts the specified character to uppercase. If the input is anything but an ASCII lowercase character, that input character itself is returned. Variant toUPPER_A is equivalent.

    U8  toUPPER(int ch)
toUPPER_utf8
toUPPER_utf8_safe

Converts the first UTF-8 encoded character in the sequence starting at p and extending no further than e - 1 to its uppercase version, and stores that in UTF-8 in s, and its length in bytes in lenp. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the uppercase version may be longer than the original character.

The first code point of the uppercased version is returned (but note, as explained at the top of this section, that there may be more).

It will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return the REPLACEMENT CHARACTER, at the discretion of the implementation, and subject to change in future releases.

toUPPER_utf8_safe is now just a different spelling of plain toUPPER_utf8

    UV  toUPPER_utf8(U8* p, U8* e, U8* s, STRLEN* lenp)
toUPPER_uvchr

Converts the code point cp to its uppercase version, and stores that in UTF-8 in s, and its length in bytes in lenp. The code point is interpreted as native if less than 256; otherwise as Unicode. Note that the buffer pointed to by s needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the uppercase version may be longer than the original character.

The first code point of the uppercased version is returned (but note, as explained at the top of this section, that there may be more.)

    UV  toUPPER_uvchr(UV cp, U8* s, STRLEN* lenp)

Character classification

This section is about functions (really macros) that classify characters into types, such as punctuation versus alphabetic, etc. Most of these are analogous to regular expression character classes. (See "POSIX Character Classes" in perlrecharclass.) There are several variants for each class. (Not all macros have all variants; each item below lists the ones valid for it.) None are affected by use bytes, and only the ones with LC in the name are affected by the current locale.

The base function, e.g., isALPHA(), takes any signed or unsigned value, treating it as a code point, and returns a boolean as to whether or not the character represented by it is (or on non-ASCII platforms, corresponds to) an ASCII character in the named class based on platform, Unicode, and Perl rules. If the input is a number that doesn't fit in an octet, FALSE is returned.

Variant isFOO_A (e.g., isALPHA_A()) is identical to the base function with no suffix "_A". This variant is used to emphasize by its name that only ASCII-range characters can return TRUE.

Variant isFOO_L1 imposes the Latin-1 (or EBCDIC equivalent) character set onto the platform. That is, the code points that are ASCII are unaffected, since ASCII is a subset of Latin-1. But the non-ASCII code points are treated as if they are Latin-1 characters. For example, isWORDCHAR_L1() will return true when called with the code point 0xDF, which is a word character in both ASCII and EBCDIC (though it represents different characters in each). If the input is a number that doesn't fit in an octet, FALSE is returned. (Perl's documentation uses a colloquial definition of Latin-1, to include all code points below 256.)

Variant isFOO_uvchr is exactly like the isFOO_L1 variant, for inputs below 256, but if the code point is larger than 255, Unicode rules are used to determine if it is in the character class. For example, isWORDCHAR_uvchr(0x100) returns TRUE, since 0x100 is LATIN CAPITAL LETTER A WITH MACRON in Unicode, and is a word character.

Variants isFOO_utf8 and isFOO_utf8_safe are like isFOO_uvchr, but are used for UTF-8 encoded strings. The two forms are different names for the same thing. Each call to one of these classifies the first character of the string starting at p. The second parameter, e, points to anywhere in the string beyond the first character, up to one byte past the end of the entire string. Although both variants are identical, the suffix _safe in one name emphasizes that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return FALSE, at the discretion of the implementation, and subject to change in future releases.

Variant isFOO_LC is like the isFOO_A and isFOO_L1 variants, but the result is based on the current locale, which is what LC in the name stands for. If Perl can determine that the current locale is a UTF-8 locale, it uses the published Unicode rules; otherwise, it uses the C library function that gives the named classification. For example, isDIGIT_LC() when not in a UTF-8 locale returns the result of calling isdigit(). FALSE is always returned if the input won't fit into an octet. On some platforms where the C library function is known to be defective, Perl changes its result to follow the POSIX standard's rules.

Variant isFOO_LC_uvchr acts exactly like isFOO_LC for inputs less than 256, but for larger ones it returns the Unicode classification of the code point.

Variants isFOO_LC_utf8 and isFOO_LC_utf8_safe are like isFOO_LC_uvchr, but are used for UTF-8 encoded strings. The two forms are different names for the same thing. Each call to one of these classifies the first character of the string starting at p. The second parameter, e, points to anywhere in the string beyond the first character, up to one byte past the end of the entire string. Although both variants are identical, the suffix _safe in one name emphasizes that it will not attempt to read beyond e - 1, provided that the constraint s < e is true (this is asserted for in -DDEBUGGING builds). If the UTF-8 for the input character is malformed in some way, the program may croak, or the function may return FALSE, at the discretion of the implementation, and subject to change in future releases.

isALPHA
isALPHA_A
isALPHA_L1
isALPHA_uvchr
isALPHA_utf8_safe
isALPHA_utf8
isALPHA_LC
isALPHA_LC_uvchr
isALPHA_LC_utf8_safe

Returns a boolean indicating whether the specified input is one of [A-Za-z], analogous to m/[[:alpha:]]/. See the top of this section for an explanation of the variants.

    bool  isALPHA             (UV ch)
    bool  isALPHA_A           (UV ch)
    bool  isALPHA_L1          (UV ch)
    bool  isALPHA_uvchr       (UV ch)
    bool  isALPHA_utf8_safe   (U8 * s, U8 * end)
    bool  isALPHA_utf8        (U8 * s, U8 * end)
    bool  isALPHA_LC          (UV ch)
    bool  isALPHA_LC_uvchr    (UV ch)
    bool  isALPHA_LC_utf8_safe(U8 * s, U8 *end)
isALPHANUMERIC
isALPHANUMERIC_A
isALPHANUMERIC_L1
isALPHANUMERIC_uvchr
isALPHANUMERIC_utf8_safe
isALPHANUMERIC_utf8
isALPHANUMERIC_LC
isALPHANUMERIC_LC_uvchr
isALPHANUMERIC_LC_utf8_safe
isALNUMC
isALNUMC_A
isALNUMC_L1
isALNUMC_LC
isALNUMC_LC_uvchr

Returns a boolean indicating whether the specified character is one of [A-Za-z0-9], analogous to m/[[:alnum:]]/. See the top of this section for an explanation of the variants.

A (discouraged from use) synonym is isALNUMC (where the C suffix means this corresponds to the C language alphanumeric definition). Also there are the variants isALNUMC_A, isALNUMC_L1 isALNUMC_LC, and isALNUMC_LC_uvchr.

    bool  isALPHANUMERIC             (UV ch)
    bool  isALPHANUMERIC_A           (UV ch)
    bool  isALPHANUMERIC_L1          (UV ch)
    bool  isALPHANUMERIC_uvchr       (UV ch)
    bool  isALPHANUMERIC_utf8_safe   (U8 * s, U8 * end)
    bool  isALPHANUMERIC_utf8        (U8 * s, U8 * end)
    bool  isALPHANUMERIC_LC          (UV ch)
    bool  isALPHANUMERIC_LC_uvchr    (UV ch)
    bool  isALPHANUMERIC_LC_utf8_safe(U8 * s, U8 *end)
    bool  isALNUMC                   (UV ch)
    bool  isALNUMC_A                 (UV ch)
    bool  isALNUMC_L1                (UV ch)
    bool  isALNUMC_LC                (UV ch)
    bool  isALNUMC_LC_uvchr          (UV ch)
isASCII
isASCII_A
isASCII_L1
isASCII_uvchr
isASCII_utf8_safe
isASCII_utf8
isASCII_LC
isASCII_LC_uvchr
isASCII_LC_utf8_safe

Returns a boolean indicating whether the specified character is one of the 128 characters in the ASCII character set, analogous to m/[[:ascii:]]/. On non-ASCII platforms, it returns TRUE iff this character corresponds to an ASCII character. Variants isASCII_A() and isASCII_L1() are identical to isASCII(). See the top of this section for an explanation of the variants. Note, however, that some platforms do not have the C library routine isascii(). In these cases, the variants whose names contain LC are the same as the corresponding ones without.

Also note, that because all ASCII characters are UTF-8 invariant (meaning they have the exact same representation (always a single byte) whether encoded in UTF-8 or not), isASCII will give the correct results when called with any byte in any string encoded or not in UTF-8. And similarly isASCII_utf8 and isASCII_utf8_safe will work properly on any string encoded or not in UTF-8.

    bool  isASCII             (UV ch)
    bool  isASCII_A           (UV ch)
    bool  isASCII_L1          (UV ch)
    bool  isASCII_uvchr       (UV ch)
    bool  isASCII_utf8_safe   (U8 * s, U8 * end)
    bool  isASCII_utf8        (U8 * s, U8 * end)
    bool  isASCII_LC          (UV ch)
    bool  isASCII_LC_uvchr    (UV ch)
    bool  isASCII_LC_utf8_safe(U8 * s, U8 *end)
isBLANK
isBLANK_A
isBLANK_L1
isBLANK_uvchr
isBLANK_utf8_safe
isBLANK_utf8
isBLANK_LC
isBLANK_LC_uvchr
isBLANK_LC_utf8_safe

Returns a boolean indicating whether the specified character is a character considered to be a blank, analogous to m/[[:blank:]]/. See the top of this section for an explanation of the variants. Note, however, that some platforms do not have the C library routine isblank(). In these cases, the variants whose names contain LC are the same as the corresponding ones without.

    bool  isBLANK             (UV ch)
    bool  isBLANK_A           (UV ch)
    bool  isBLANK_L1          (UV ch)
    bool  isBLANK_uvchr       (UV ch)
    bool  isBLANK_utf8_safe   (U8 * s, U8 * end)
    bool  isBLANK_utf8        (U8 * s, U8 * end)
    bool  isBLANK_LC          (UV ch)
    bool  isBLANK_LC_uvchr    (UV ch)
    bool  isBLANK_LC_utf8_safe(U8 * s, U8 *end)
isCNTRL
isCNTRL_A
isCNTRL_L1
isCNTRL_uvchr
isCNTRL_utf8_safe
isCNTRL_utf8
isCNTRL_LC
isCNTRL_LC_uvchr
isCNTRL_LC_utf8_safe

Returns a boolean indicating whether the specified character is a control character, analogous to m/[[:cntrl:]]/. See the top of this section for an explanation of the variants. On EBCDIC platforms, you almost always want to use the isCNTRL_L1 variant.

    bool  isCNTRL             (UV ch)
    bool  isCNTRL_A           (UV ch)
    bool  isCNTRL_L1          (UV ch)
    bool  isCNTRL_uvchr       (UV ch)
    bool  isCNTRL_utf8_safe   (U8 * s, U8 * end)
    bool  isCNTRL_utf8        (U8 * s, U8 * end)
    bool  isCNTRL_LC          (UV ch)
    bool  isCNTRL_LC_uvchr    (UV ch)
    bool  isCNTRL_LC_utf8_safe(U8 * s, U8 *end)
isDIGIT
isDIGIT_A
isDIGIT_L1
isDIGIT_uvchr
isDIGIT_utf8_safe
isDIGIT_utf8
isDIGIT_LC
isDIGIT_LC_uvchr
isDIGIT_LC_utf8_safe

Returns a boolean indicating whether the specified character is a digit, analogous to m/[[:digit:]]/. Variants isDIGIT_A and isDIGIT_L1 are identical to isDIGIT. See the top of this section for an explanation of the variants.

    bool  isDIGIT             (UV ch)
    bool  isDIGIT_A           (UV ch)
    bool  isDIGIT_L1          (UV ch)
    bool  isDIGIT_uvchr       (UV ch)
    bool  isDIGIT_utf8_safe   (U8 * s, U8 * end)
    bool  isDIGIT_utf8        (U8 * s, U8 * end)
    bool  isDIGIT_LC          (UV ch)
    bool  isDIGIT_LC_uvchr    (UV ch)
    bool  isDIGIT_LC_utf8_safe(U8 * s, U8 *end)
isGRAPH
isGRAPH_A
isGRAPH_L1
isGRAPH_uvchr
isGRAPH_utf8_safe
isGRAPH_utf8
isGRAPH_LC
isGRAPH_LC_uvchr
isGRAPH_LC_utf8_safe

Returns a boolean indicating whether the specified character is a graphic character, analogous to m/[[:graph:]]/. See the top of this section for an explanation of the variants.

    bool  isGRAPH             (UV ch)
    bool  isGRAPH_A           (UV ch)
    bool  isGRAPH_L1          (UV ch)
    bool  isGRAPH_uvchr       (UV ch)
    bool  isGRAPH_utf8_safe   (U8 * s, U8 * end)
    bool  isGRAPH_utf8        (U8 * s, U8 * end)
    bool  isGRAPH_LC          (UV ch)
    bool  isGRAPH_LC_uvchr    (UV ch)
    bool  isGRAPH_LC_utf8_safe(U8 * s, U8 *end)
isIDCONT
isIDCONT_A
isIDCONT_L1
isIDCONT_uvchr
isIDCONT_utf8_safe
isIDCONT_utf8
isIDCONT_LC
isIDCONT_LC_uvchr
isIDCONT_LC_utf8_safe

Returns a boolean indicating whether the specified character can be the second or succeeding character of an identifier. This is very close to, but not quite the same as the official Unicode property XID_Continue. The difference is that this returns true only if the input character also matches "isWORDCHAR". See the top of this section for an explanation of the variants.

    bool  isIDCONT             (UV ch)
    bool  isIDCONT_A           (UV ch)
    bool  isIDCONT_L1          (UV ch)
    bool  isIDCONT_uvchr       (UV ch)
    bool  isIDCONT_utf8_safe   (U8 * s, U8 * end)
    bool  isIDCONT_utf8        (U8 * s, U8 * end)
    bool  isIDCONT_LC          (UV ch)
    bool  isIDCONT_LC_uvchr    (UV ch)
    bool  isIDCONT_LC_utf8_safe(U8 * s, U8 *end)
isIDFIRST
isIDFIRST_A
isIDFIRST_L1
isIDFIRST_uvchr
isIDFIRST_utf8_safe
isIDFIRST_utf8
isIDFIRST_LC
isIDFIRST_LC_uvchr
isIDFIRST_LC_utf8_safe

Returns a boolean indicating whether the specified character can be the first character of an identifier. This is very close to, but not quite the same as the official Unicode property XID_Start. The difference is that this returns true only if the input character also matches "isWORDCHAR". See the top of this section for an explanation of the variants.

    bool  isIDFIRST             (UV ch)
    bool  isIDFIRST_A           (UV ch)
    bool  isIDFIRST_L1          (UV ch)
    bool  isIDFIRST_uvchr       (UV ch)
    bool  isIDFIRST_utf8_safe   (U8 * s, U8 * end)
    bool  isIDFIRST_utf8        (U8 * s, U8 * end)
    bool  isIDFIRST_LC          (UV ch)
    bool  isIDFIRST_LC_uvchr    (UV ch)
    bool  isIDFIRST_LC_utf8_safe(U8 * s, U8 *end)
isLOWER
isLOWER_A
isLOWER_L1
isLOWER_uvchr
isLOWER_utf8_safe
isLOWER_utf8
isLOWER_LC
isLOWER_LC_uvchr
isLOWER_LC_utf8_safe

Returns a boolean indicating whether the specified character is a lowercase character, analogous to m/[[:lower:]]/. See the top of this section for an explanation of the variants

    bool  isLOWER             (UV ch)
    bool  isLOWER_A           (UV ch)
    bool  isLOWER_L1          (UV ch)
    bool  isLOWER_uvchr       (UV ch)
    bool  isLOWER_utf8_safe   (U8 * s, U8 * end)
    bool  isLOWER_utf8        (U8 * s, U8 * end)
    bool  isLOWER_LC          (UV ch)
    bool  isLOWER_LC_uvchr    (UV ch)
    bool  isLOWER_LC_utf8_safe(U8 * s, U8 *end)
isOCTAL
isOCTAL_A
isOCTAL_L1

Returns a boolean indicating whether the specified character is an octal digit, [0-7]. The only two variants are isOCTAL_A and isOCTAL_L1; each is identical to isOCTAL.

    bool  isOCTAL(UV ch)
isPRINT
isPRINT_A
isPRINT_L1
isPRINT_uvchr
isPRINT_utf8_safe
isPRINT_utf8
isPRINT_LC
isPRINT_LC_uvchr
isPRINT_LC_utf8_safe

Returns a boolean indicating whether the specified character is a printable character, analogous to m/[[:print:]]/. See the top of this section for an explanation of the variants.

    bool  isPRINT             (UV ch)
    bool  isPRINT_A           (UV ch)
    bool  isPRINT_L1          (UV ch)
    bool  isPRINT_uvchr       (UV ch)
    bool  isPRINT_utf8_safe   (U8 * s, U8 * end)
    bool  isPRINT_utf8        (U8 * s, U8 * end)
    bool  isPRINT_LC          (UV ch)
    bool  isPRINT_LC_uvchr    (UV ch)
    bool  isPRINT_LC_utf8_safe(U8 * s, U8 *end)
isPSXSPC
isPSXSPC_A
isPSXSPC_L1
isPSXSPC_uvchr
isPSXSPC_utf8_safe
isPSXSPC_utf8
isPSXSPC_LC
isPSXSPC_LC_uvchr
isPSXSPC_LC_utf8_safe

(short for Posix Space) Starting in 5.18, this is identical in all its forms to the corresponding isSPACE() macros. The locale forms of this macro are identical to their corresponding isSPACE() forms in all Perl releases. In releases prior to 5.18, the non-locale forms differ from their isSPACE() forms only in that the isSPACE() forms don't match a Vertical Tab, and the isPSXSPC() forms do. Otherwise they are identical. Thus this macro is analogous to what m/[[:space:]]/ matches in a regular expression. See the top of this section for an explanation of the variants.

    bool  isPSXSPC             (UV ch)
    bool  isPSXSPC_A           (UV ch)
    bool  isPSXSPC_L1          (UV ch)
    bool  isPSXSPC_uvchr       (UV ch)
    bool  isPSXSPC_utf8_safe   (U8 * s, U8 * end)
    bool  isPSXSPC_utf8        (U8 * s, U8 * end)
    bool  isPSXSPC_LC          (UV ch)
    bool  isPSXSPC_LC_uvchr    (UV ch)
    bool  isPSXSPC_LC_utf8_safe(U8 * s, U8 *end)
isPUNCT
isPUNCT_A
isPUNCT_L1
isPUNCT_uvchr
isPUNCT_utf8_safe
isPUNCT_utf8
isPUNCT_LC
isPUNCT_LC_uvchr
isPUNCT_LC_utf8_safe

Returns a boolean indicating whether the specified character is a punctuation character, analogous to m/[[:punct:]]/. Note that the definition of what is punctuation isn't as straightforward as one might desire. See "POSIX Character Classes" in perlrecharclass for details. See the top of this section for an explanation of the variants.

    bool  isPUNCT             (UV ch)
    bool  isPUNCT_A           (UV ch)
    bool  isPUNCT_L1          (UV ch)
    bool  isPUNCT_uvchr       (UV ch)
    bool  isPUNCT_utf8_safe   (U8 * s, U8 * end)
    bool  isPUNCT_utf8        (U8 * s, U8 * end)
    bool  isPUNCT_LC          (UV ch)
    bool  isPUNCT_LC_uvchr    (UV ch)
    bool  isPUNCT_LC_utf8_safe(U8 * s, U8 *end)
isSPACE
isSPACE_A
isSPACE_L1
isSPACE_uvchr
isSPACE_utf8_safe
isSPACE_utf8
isSPACE_LC
isSPACE_LC_uvchr
isSPACE_LC_utf8_safe

Returns a boolean indicating whether the specified character is a whitespace character. This is analogous to what m/\s/ matches in a regular expression. Starting in Perl 5.18 this also matches what m/[[:space:]]/ does. Prior to 5.18, only the locale forms of this macro (the ones with LC in their names) matched precisely what m/[[:space:]]/ does. In those releases, the only difference, in the non-locale variants, was that isSPACE() did not match a vertical tab. (See "isPSXSPC" for a macro that matches a vertical tab in all releases.) See the top of this section for an explanation of the variants.

    bool  isSPACE             (UV ch)
    bool  isSPACE_A           (UV ch)
    bool  isSPACE_L1          (UV ch)
    bool  isSPACE_uvchr       (UV ch)
    bool  isSPACE_utf8_safe   (U8 * s, U8 * end)
    bool  isSPACE_utf8        (U8 * s, U8 * end)
    bool  isSPACE_LC          (UV ch)
    bool  isSPACE_LC_uvchr    (UV ch)
    bool  isSPACE_LC_utf8_safe(U8 * s, U8 *end)
isUPPER
isUPPER_A
isUPPER_L1
isUPPER_uvchr
isUPPER_utf8_safe
isUPPER_utf8
isUPPER_LC
isUPPER_LC_uvchr
isUPPER_LC_utf8_safe

Returns a boolean indicating whether the specified character is an uppercase character, analogous to m/[[:upper:]]/. See the top of this section for an explanation of the variants.

    bool  isUPPER             (UV ch)
    bool  isUPPER_A           (UV ch)
    bool  isUPPER_L1          (UV ch)
    bool  isUPPER_uvchr       (UV ch)
    bool  isUPPER_utf8_safe   (U8 * s, U8 * end)
    bool  isUPPER_utf8        (U8 * s, U8 * end)
    bool  isUPPER_LC          (UV ch)
    bool  isUPPER_LC_uvchr    (UV ch)
    bool  isUPPER_LC_utf8_safe(U8 * s, U8 *end)
isWORDCHAR
isWORDCHAR_A
isWORDCHAR_L1
isWORDCHAR_uvchr
isWORDCHAR_utf8_safe
isWORDCHAR_utf8
isWORDCHAR_LC
isWORDCHAR_LC_uvchr
isWORDCHAR_LC_utf8_safe
isALNUM
isALNUM_A
isALNUM_LC
isALNUM_LC_uvchr

Returns a boolean indicating whether the specified character is a character that is a word character, analogous to what m/\w/ and m/[[:word:]]/ match in a regular expression. A word character is an alphabetic character, a decimal digit, a connecting punctuation character (such as an underscore), or a "mark" character that attaches to one of those (like some sort of accent). isALNUM() is a synonym provided for backward compatibility, even though a word character includes more than the standard C language meaning of alphanumeric. See the top of this section for an explanation of the variants. isWORDCHAR_A, isWORDCHAR_L1, isWORDCHAR_uvchr, isWORDCHAR_LC, isWORDCHAR_LC_uvchr, isWORDCHAR_LC_utf8, and isWORDCHAR_LC_utf8_safe are also as described there, but additionally include the platform's native underscore.

    bool  isWORDCHAR             (UV ch)
    bool  isWORDCHAR_A           (UV ch)
    bool  isWORDCHAR_L1          (UV ch)
    bool  isWORDCHAR_uvchr       (UV ch)
    bool  isWORDCHAR_utf8_safe   (U8 * s, U8 * end)
    bool  isWORDCHAR_utf8        (U8 * s, U8 * end)
    bool  isWORDCHAR_LC          (UV ch)
    bool  isWORDCHAR_LC_uvchr    (UV ch)
    bool  isWORDCHAR_LC_utf8_safe(U8 * s, U8 *end)
    bool  isALNUM                (UV ch)
    bool  isALNUM_A              (UV ch)
    bool  isALNUM_LC             (UV ch)
    bool  isALNUM_LC_uvchr       (UV ch)
isXDIGIT
isXDIGIT_A
isXDIGIT_L1
isXDIGIT_uvchr
isXDIGIT_utf8_safe
isXDIGIT_utf8
isXDIGIT_LC
isXDIGIT_LC_uvchr
isXDIGIT_LC_utf8_safe

Returns a boolean indicating whether the specified character is a hexadecimal digit. In the ASCII range these are [0-9A-Fa-f]. Variants isXDIGIT_A() and isXDIGIT_L1() are identical to isXDIGIT(). See the top of this section for an explanation of the variants.

    bool  isXDIGIT             (UV ch)
    bool  isXDIGIT_A           (UV ch)
    bool  isXDIGIT_L1          (UV ch)
    bool  isXDIGIT_uvchr       (UV ch)
    bool  isXDIGIT_utf8_safe   (U8 * s, U8 * end)
    bool  isXDIGIT_utf8        (U8 * s, U8 * end)
    bool  isXDIGIT_LC          (UV ch)
    bool  isXDIGIT_LC_uvchr    (UV ch)
    bool  isXDIGIT_LC_utf8_safe(U8 * s, U8 *end)

Compiler and Preprocessor information

CPPLAST

This symbol is intended to be used along with CPPRUN in the same manner symbol CPPMINUS is used with CPPSTDIN. It contains either "-" or "".

CPPMINUS

This symbol contains the second part of the string which will invoke the C preprocessor on the standard input and produce to standard output. This symbol will have the value "-" if CPPSTDIN needs a minus to specify standard input, otherwise the value is "".

CPPRUN

This symbol contains the string which will invoke a C preprocessor on the standard input and produce to standard output. It needs to end with CPPLAST, after all other preprocessor flags have been specified. The main difference with CPPSTDIN is that this program will never be a pointer to a shell wrapper, i.e. it will be empty if no preprocessor is available directly to the user. Note that it may well be different from the preprocessor used to compile the C program.

CPPSTDIN

This symbol contains the first part of the string which will invoke the C preprocessor on the standard input and produce to standard output. Typical value of "cc -E" or "/lib/cpp", but it can also call a wrapper. See "CPPRUN".

HASATTRIBUTE_ALWAYS_INLINE

Can we handle GCC attribute for functions that should always be inlined.

HASATTRIBUTE_DEPRECATED

Can we handle GCC attribute for marking deprecated APIs

HASATTRIBUTE_FORMAT

Can we handle GCC attribute for checking printf-style formats

HASATTRIBUTE_NONNULL

Can we handle GCC attribute for nonnull function parms.

HASATTRIBUTE_NORETURN

Can we handle GCC attribute for functions that do not return

HASATTRIBUTE_PURE

Can we handle GCC attribute for pure functions

HASATTRIBUTE_UNUSED

Can we handle GCC attribute for unused variables and arguments

HASATTRIBUTE_WARN_UNUSED_RESULT

Can we handle GCC attribute for warning on unused results

HAS_BUILTIN_ADD_OVERFLOW

This symbol, if defined, indicates that the compiler supports __builtin_add_overflow for adding integers with overflow checks.

HAS_BUILTIN_CHOOSE_EXPR

Can we handle GCC builtin for compile-time ternary-like expressions

HAS_BUILTIN_EXPECT

Can we handle GCC builtin for telling that certain values are more likely

HAS_BUILTIN_MUL_OVERFLOW

This symbol, if defined, indicates that the compiler supports __builtin_mul_overflow for multiplying integers with overflow checks.

HAS_BUILTIN_SUB_OVERFLOW

This symbol, if defined, indicates that the compiler supports __builtin_sub_overflow for subtracting integers with overflow checks.

HAS_C99_VARIADIC_MACROS

If defined, the compiler supports C99 variadic macros.

HAS_STATIC_INLINE

This symbol, if defined, indicates that the C compiler supports C99-style static inline. That is, the function can't be called from another translation unit.

MEM_ALIGNBYTES

This symbol contains the number of bytes required to align a double, or a long double when applicable. Usual values are 2, 4 and 8. The default is eight, for safety. For cross-compiling or multiarch support, Configure will set a minimum of 8.

PERL_STATIC_INLINE

This symbol gives the best-guess incantation to use for static inline functions. If HAS_STATIC_INLINE is defined, this will give C99-style inline. If HAS_STATIC_INLINE is not defined, this will give a plain 'static'. It will always be defined to something that gives static linkage. Possibilities include

static inline       (c99)
static __inline__   (gcc -ansi)
static __inline     (MSVC)
static _inline      (older MSVC)
static              (c89 compilers)
U32_ALIGNMENT_REQUIRED

This symbol, if defined, indicates that you must access character data through U32-aligned pointers.

Compiler directives

ASSUME

ASSUME is like assert(), but it has a benefit in a release build. It is a hint to a compiler about a statement of fact in a function call free expression, which allows the compiler to generate better machine code. In a debug build, ASSUME(x) is a synonym for assert(x). ASSUME(0) means the control path is unreachable. In a for loop, ASSUME can be used to hint that a loop will run at least X times. ASSUME is based off MSVC's __assume intrinsic function, see its documents for more details.

    ASSUME(bool expr)
dNOOP

Declare nothing; typically used as a placeholder to replace something that used to declare something. Works on compilers that require declarations before any code.

    dNOOP;
END_EXTERN_C

When not compiling using C++, expands to nothing. Otherwise ends a section of code already begun by a "START_EXTERN_C".

    END_EXTERN_C
EXTERN_C

When not compiling using C++, expands to nothing. Otherwise is used in a declaration of a function to indicate the function should have external C linkage. This is required for things to work for just about all functions with external linkage compiled into perl. Often, you can use "START_EXTERN_C" ... "END_EXTERN_C" blocks surrounding all your code that you need to have this linkage.

Example usage:

EXTERN_C int flock(int fd, int op);
LIKELY

Returns the input unchanged, but at the same time it gives a branch prediction hint to the compiler that this condition is likely to be true.

    LIKELY(bool expr)
NOOP

Do nothing; typically used as a placeholder to replace something that used to do something.

    NOOP;
PERL_UNUSED_ARG

This is used to suppress compiler warnings that a parameter to a function is not used. This situation can arise, for example, when a parameter is needed under some configuration conditions, but not others, so that C preprocessor conditional compilation causes it be used just some times.

    PERL_UNUSED_ARG(void x);
PERL_UNUSED_CONTEXT

This is used to suppress compiler warnings that the thread context parameter to a function is not used. This situation can arise, for example, when a C preprocessor conditional compilation causes it be used just some times.

    PERL_UNUSED_CONTEXT;
PERL_UNUSED_DECL

Tells the compiler that the parameter in the function prototype just before it is not necessarily expected to be used in the function. Not that many compilers understand this, so this should only be used in cases where "PERL_UNUSED_ARG" can't conveniently be used.

Example usage:

    Signal_t
    Perl_perly_sighandler(int sig, Siginfo_t *sip PERL_UNUSED_DECL,
                          void *uap PERL_UNUSED_DECL, bool safe)
PERL_UNUSED_RESULT

This macro indicates to discard the return value of the function call inside it, e.g.,

PERL_UNUSED_RESULT(foo(a, b))

The main reason for this is that the combination of gcc -Wunused-result (part of -Wall) and the __attribute__((warn_unused_result)) cannot be silenced with casting to void. This causes trouble when the system header files use the attribute.

Use PERL_UNUSED_RESULT sparingly, though, since usually the warning is there for a good reason: you might lose success/failure information, or leak resources, or changes in resources.

But sometimes you just want to ignore the return value, e.g., on codepaths soon ending up in abort, or in "best effort" attempts, or in situations where there is no good way to handle failures.

Sometimes PERL_UNUSED_RESULT might not be the most natural way: another possibility is that you can capture the return value and use "PERL_UNUSED_VAR" on that.

    PERL_UNUSED_RESULT(void x)
PERL_UNUSED_VAR

This is used to suppress compiler warnings that the variable x is not used. This situation can arise, for example, when a C preprocessor conditional compilation causes it be used just some times.

    PERL_UNUSED_VAR(void x);
PERL_USE_GCC_BRACE_GROUPS

This C pre-processor value, if defined, indicates that it is permissible to use the GCC brace groups extension. This extension, of the form

({ statement ... })

turns the block consisting of statements ... into an expression with a value, unlike plain C language blocks. This can present optimization possibilities, BUT you generally need to specify an alternative in case this ability doesn't exist or has otherwise been forbidden.

Example usage:

    #ifdef PERL_USE_GCC_BRACE_GROUPS
      ...
    #else
      ...
    #endif
START_EXTERN_C

When not compiling using C++, expands to nothing. Otherwise begins a section of code in which every function will effectively have "EXTERN_C" applied to it, that is to have external C linkage. The section is ended by a "END_EXTERN_C".

    START_EXTERN_C
STATIC

Described in perlguts.

STMT_START
STMT_END

This allows a series of statements in a macro to be used as a single statement, as in

if (x) STMT_START { ... } STMT_END else ...

Note that you can't return a value out of them, which limits their utility. But see "PERL_USE_GCC_BRACE_GROUPS".

UNLIKELY

Returns the input unchanged, but at the same time it gives a branch prediction hint to the compiler that this condition is likely to be false.

    UNLIKELY(bool expr)
__ASSERT_

This is a helper macro to avoid preprocessor issues, replaced by nothing unless under DEBUGGING, where it expands to an assert of its argument, followed by a comma (hence the comma operator). If we just used a straight assert(), we would get a comma with nothing before it when not DEBUGGING.

    __ASSERT_(bool expr)

Compile-time scope hooks

BhkDISABLE

NOTE: BhkDISABLE is experimental and may change or be removed without notice.

Temporarily disable an entry in this BHK structure, by clearing the appropriate flag. which is a preprocessor token indicating which entry to disable.

    void  BhkDISABLE(BHK *hk, which)
BhkENABLE

NOTE: BhkENABLE is experimental and may change or be removed without notice.

Re-enable an entry in this BHK structure, by setting the appropriate flag. which is a preprocessor token indicating which entry to enable. This will assert (under -DDEBUGGING) if the entry doesn't contain a valid pointer.

    void  BhkENABLE(BHK *hk, which)
BhkENTRY_set

NOTE: BhkENTRY_set is experimental and may change or be removed without notice.

Set an entry in the BHK structure, and set the flags to indicate it is valid. which is a preprocessing token indicating which entry to set. The type of ptr depends on the entry.

    void  BhkENTRY_set(BHK *hk, which, void *ptr)
blockhook_register

NOTE: blockhook_register is experimental and may change or be removed without notice.

Register a set of hooks to be called when the Perl lexical scope changes at compile time. See "Compile-time scope hooks" in perlguts.

NOTE: blockhook_register must be explicitly called as Perl_blockhook_register with an aTHX_ parameter.

    void  Perl_blockhook_register(pTHX_ BHK *hk)

Concurrency

aTHX

Described in perlguts.

aTHX_

Described in perlguts.

CPERLscope

DEPRECATED! It is planned to remove CPERLscope from a future release of Perl. Do not use it for new code; remove it from existing code.

Now a no-op.

    void  CPERLscope(void x)
dTHR

Described in perlguts.

dTHX

Described in perlguts.

dTHXa

On threaded perls, set pTHX to a; on unthreaded perls, do nothing

dTHXoa

Now a synonym for "dTHXa".

dVAR

This is now a synonym for dNOOP: declare nothing

GETENV_PRESERVES_OTHER_THREAD

This symbol, if defined, indicates that the getenv system call doesn't zap the static buffer of getenv() in a different thread. The typical getenv() implementation will return a pointer to the proper position in **environ. But some may instead copy them to a static buffer in getenv(). If there is a per-thread instance of that buffer, or the return points to **environ, then a many-reader/1-writer mutex will work; otherwise an exclusive locking mutex is required to prevent races.

HAS_PTHREAD_ATFORK

This symbol, if defined, indicates that the pthread_atfork routine is available to setup fork handlers.

HAS_PTHREAD_ATTR_SETSCOPE

This symbol, if defined, indicates that the pthread_attr_setscope system call is available to set the contention scope attribute of a thread attribute object.

HAS_PTHREAD_YIELD

This symbol, if defined, indicates that the pthread_yield routine is available to yield the execution of the current thread. sched_yield is preferable to pthread_yield.

HAS_SCHED_YIELD

This symbol, if defined, indicates that the sched_yield routine is available to yield the execution of the current thread. sched_yield is preferable to pthread_yield.

I_MACH_CTHREADS

This symbol, if defined, indicates to the C program that it should include mach/cthreads.h.

    #ifdef I_MACH_CTHREADS
        #include <mach_cthreads.h>
    #endif
I_PTHREAD

This symbol, if defined, indicates to the C program that it should include pthread.h.

    #ifdef I_PTHREAD
        #include <pthread.h>
    #endif
MULTIPLICITY

This symbol, if defined, indicates that Perl should be built to use multiplicity.

OLD_PTHREADS_API

This symbol, if defined, indicates that Perl should be built to use the old draft POSIX threads API.

OLD_PTHREAD_CREATE_JOINABLE

This symbol, if defined, indicates how to create pthread in joinable (aka undetached) state. NOTE: not defined if pthread.h already has defined PTHREAD_CREATE_JOINABLE (the new version of the constant). If defined, known values are PTHREAD_CREATE_UNDETACHED and __UNDETACHED.

pTHX

Described in perlguts.

pTHX_

Described in perlguts.

SCHED_YIELD

This symbol defines the way to yield the execution of the current thread. Known ways are sched_yield, pthread_yield, and pthread_yield with NULL.

SVf

Described in perlguts.

SVfARG

Described in perlguts.

    SVfARG(SV *sv)

COP Hint Hashes

cop_fetch_label

NOTE: cop_fetch_label is experimental and may change or be removed without notice.

Returns the label attached to a cop, and stores its length in bytes into *len. Upon return, *flags will be set to either SVf_UTF8 or 0.

Alternatively, use the macro "CopLABEL_len_flags"; or if you don't need to know if the label is UTF-8 or not, the macro "CopLABEL_len"; or if you additionally dont need to know the length, "CopLABEL".

    const char *  cop_fetch_label(COP *const cop, STRLEN *len,
                                  U32 *flags)
CopFILE

Returns the name of the file associated with the COP c

    const char *  CopFILE(const COP * c)
CopFILEAV

Returns the AV associated with the COP c

    AV *  CopFILEAV(const COP * c)
CopFILEGV

Returns the GV associated with the COP c

    GV *  CopFILEGV(const COP * c)
CopFILEGV_set

Available only on unthreaded perls. Makes pv the name of the file associated with the COP c

    void  CopFILEGV_set(COP * c, GV * gv)
CopFILE_set

Makes pv the name of the file associated with the COP c

    void  CopFILE_set(COP * c, const char * pv)
CopFILESV

Returns the SV associated with the COP c

    SV *  CopFILESV(const COP * c)
cophh_2hv

NOTE: cophh_2hv is experimental and may change or be removed without notice.

Generates and returns a standard Perl hash representing the full set of key/value pairs in the cop hints hash cophh. flags is currently unused and must be zero.

    HV *  cophh_2hv(const COPHH *cophh, U32 flags)
cophh_copy

NOTE: cophh_copy is experimental and may change or be removed without notice.

Make and return a complete copy of the cop hints hash cophh.

    COPHH *  cophh_copy(COPHH *cophh)
cophh_delete_pv

NOTE: cophh_delete_pv is experimental and may change or be removed without notice.

Like "cophh_delete_pvn", but takes a nul-terminated string instead of a string/length pair.

    COPHH *  cophh_delete_pv(COPHH *cophh, char *key, U32 hash,
                             U32 flags)
cophh_delete_pvn

NOTE: cophh_delete_pvn is experimental and may change or be removed without notice.

Delete a key and its associated value from the cop hints hash cophh, and returns the modified hash. The returned hash pointer is in general not the same as the hash pointer that was passed in. The input hash is consumed by the function, and the pointer to it must not be subsequently used. Use "cophh_copy" if you need both hashes.

The key is specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed.

    COPHH *  cophh_delete_pvn(COPHH *cophh, const char *keypv,
                              STRLEN keylen, U32 hash, U32 flags)
cophh_delete_pvs

NOTE: cophh_delete_pvs is experimental and may change or be removed without notice.

Like "cophh_delete_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

    COPHH *  cophh_delete_pvs(COPHH *cophh, "key", U32 flags)
cophh_delete_sv

NOTE: cophh_delete_sv is experimental and may change or be removed without notice.

Like "cophh_delete_pvn", but takes a Perl scalar instead of a string/length pair.

    COPHH *  cophh_delete_sv(COPHH *cophh, SV *key, U32 hash,
                             U32 flags)
cophh_exists_pv

NOTE: cophh_exists_pv is experimental and may change or be removed without notice.

Like "cophh_exists_pvn", but takes a nul-terminated string instead of a string/length pair.

    bool  cophh_exists_pv(const COPHH *cophh, const char *key,
                          U32 hash, U32 flags)
cophh_exists_pvn

NOTE: cophh_exists_pvn is experimental and may change or be removed without notice.

Look up the entry in the cop hints hash cophh with the key specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed. Returns true if a value exists, and false otherwise.

    bool  cophh_exists_pvn(const COPHH *cophh, const char *keypv,
                           STRLEN keylen, U32 hash, U32 flags)
cophh_exists_pvs

NOTE: cophh_exists_pvs is experimental and may change or be removed without notice.

Like "cophh_exists_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

    bool  cophh_exists_pvs(const COPHH *cophh, "key", U32 flags)
cophh_exists_sv

NOTE: cophh_exists_sv is experimental and may change or be removed without notice.

Like "cophh_exists_pvn", but takes a Perl scalar instead of a string/length pair.

    bool  cophh_exists_sv(const COPHH *cophh, SV *key, U32 hash,
                          U32 flags)
cophh_fetch_pv

NOTE: cophh_fetch_pv is experimental and may change or be removed without notice.

Like "cophh_fetch_pvn", but takes a nul-terminated string instead of a string/length pair.

    SV *  cophh_fetch_pv(const COPHH *cophh, const char *key,
                         U32 hash, U32 flags)
cophh_fetch_pvn

NOTE: cophh_fetch_pvn is experimental and may change or be removed without notice.

Look up the entry in the cop hints hash cophh with the key specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed. Returns a mortal scalar copy of the value associated with the key, or &PL_sv_placeholder if there is no value associated with the key.

    SV *  cophh_fetch_pvn(const COPHH *cophh, const char *keypv,
                          STRLEN keylen, U32 hash, U32 flags)
cophh_fetch_pvs

NOTE: cophh_fetch_pvs is experimental and may change or be removed without notice.

Like "cophh_fetch_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

    SV *  cophh_fetch_pvs(const COPHH *cophh, "key", U32 flags)
cophh_fetch_sv

NOTE: cophh_fetch_sv is experimental and may change or be removed without notice.

Like "cophh_fetch_pvn", but takes a Perl scalar instead of a string/length pair.

    SV *  cophh_fetch_sv(const COPHH *cophh, SV *key, U32 hash,
                         U32 flags)
cophh_free

NOTE: cophh_free is experimental and may change or be removed without notice.

Discard the cop hints hash cophh, freeing all resources associated with it.

    void  cophh_free(COPHH *cophh)
cophh_new_empty

NOTE: cophh_new_empty is experimental and may change or be removed without notice.

Generate and return a fresh cop hints hash containing no entries.

    COPHH *  cophh_new_empty()
cophh_store_pv

NOTE: cophh_store_pv is experimental and may change or be removed without notice.

Like "cophh_store_pvn", but takes a nul-terminated string instead of a string/length pair.

    COPHH *  cophh_store_pv(COPHH *cophh, const char *key, U32 hash,
                            SV *value, U32 flags)
cophh_store_pvn

NOTE: cophh_store_pvn is experimental and may change or be removed without notice.

Stores a value, associated with a key, in the cop hints hash cophh, and returns the modified hash. The returned hash pointer is in general not the same as the hash pointer that was passed in. The input hash is consumed by the function, and the pointer to it must not be subsequently used. Use "cophh_copy" if you need both hashes.

The key is specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed.

value is the scalar value to store for this key. value is copied by this function, which thus does not take ownership of any reference to it, and later changes to the scalar will not be reflected in the value visible in the cop hints hash. Complex types of scalar will not be stored with referential integrity, but will be coerced to strings.

    COPHH *  cophh_store_pvn(COPHH *cophh, const char *keypv,
                             STRLEN keylen, U32 hash, SV *value,
                             U32 flags)
cophh_store_pvs

NOTE: cophh_store_pvs is experimental and may change or be removed without notice.

Like "cophh_store_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

    COPHH *  cophh_store_pvs(COPHH *cophh, "key", SV *value,
                             U32 flags)
cophh_store_sv

NOTE: cophh_store_sv is experimental and may change or be removed without notice.

Like "cophh_store_pvn", but takes a Perl scalar instead of a string/length pair.

    COPHH *  cophh_store_sv(COPHH *cophh, SV *key, U32 hash,
                            SV *value, U32 flags)
cop_hints_2hv

Generates and returns a standard Perl hash representing the full set of hint entries in the cop cop. flags is currently unused and must be zero.

    HV *  cop_hints_2hv(const COP *cop, U32 flags)
cop_hints_exists_pv

Like "cop_hints_exists_pvn", but takes a nul-terminated string instead of a string/length pair.

    bool  cop_hints_exists_pv(const COP *cop, const char *key,
                              U32 hash, U32 flags)
cop_hints_exists_pvn

Look up the hint entry in the cop cop with the key specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed. Returns true if a value exists, and false otherwise.

    bool  cop_hints_exists_pvn(const COP *cop, const char *keypv,
                               STRLEN keylen, U32 hash, U32 flags)
cop_hints_exists_pvs

Like "cop_hints_exists_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

    bool  cop_hints_exists_pvs(const COP *cop, "key", U32 flags)
cop_hints_exists_sv

Like "cop_hints_exists_pvn", but takes a Perl scalar instead of a string/length pair.

    bool  cop_hints_exists_sv(const COP *cop, SV *key, U32 hash,
                              U32 flags)
cop_hints_fetch_pv

Like "cop_hints_fetch_pvn", but takes a nul-terminated string instead of a string/length pair.

    SV *  cop_hints_fetch_pv(const COP *cop, const char *key,
                             U32 hash, U32 flags)
cop_hints_fetch_pvn

Look up the hint entry in the cop cop with the key specified by keypv and keylen. If flags has the COPHH_KEY_UTF8 bit set, the key octets are interpreted as UTF-8, otherwise they are interpreted as Latin-1. hash is a precomputed hash of the key string, or zero if it has not been precomputed. Returns a mortal scalar copy of the value associated with the key, or &PL_sv_placeholder if there is no value associated with the key.

    SV *  cop_hints_fetch_pvn(const COP *cop, const char *keypv,
                              STRLEN keylen, U32 hash, U32 flags)
cop_hints_fetch_pvs

Like "cop_hints_fetch_pvn", but takes a literal string instead of a string/length pair, and no precomputed hash.

    SV *  cop_hints_fetch_pvs(const COP *cop, "key", U32 flags)
cop_hints_fetch_sv

Like "cop_hints_fetch_pvn", but takes a Perl scalar instead of a string/length pair.

    SV *  cop_hints_fetch_sv(const COP *cop, SV *key, U32 hash,
                             U32 flags)
CopLABEL

Returns the label attached to a cop.

    const char *  CopLABEL(COP *const cop)
CopLABEL_len

Returns the label attached to a cop, and stores its length in bytes into *len.

    const char *  CopLABEL_len(COP *const cop, STRLEN *len)
CopLABEL_len_flags

Returns the label attached to a cop, and stores its length in bytes into *len. Upon return, *flags will be set to either SVf_UTF8 or 0.

    const char *  CopLABEL_len_flags(COP *const cop, STRLEN *len,
                                     U32 *flags)
CopLINE

Returns the line number in the source code associated with the COP c

    STRLEN  CopLINE(const COP * c)
CopSTASH

Returns the stash associated with c.

    HV *  CopSTASH(const COP * c)
CopSTASH_eq

Returns a boolean as to whether or not hv is the stash associated with c.

    bool  CopSTASH_eq(const COP * c, const HV * hv)
CopSTASHPV

Returns the package name of the stash associated with c, or NULL if no associated stash

    char *  CopSTASHPV(const COP * c)
CopSTASHPV_set

Set the package name of the stash associated with c, to the NUL-terminated C string p, creating the package if necessary.

    void  CopSTASHPV_set(COP * c, const char * pv)
CopSTASH_set

Set the stash associated with c to hv.

    bool  CopSTASH_set(COP * c, HV * hv)
cop_store_label

NOTE: cop_store_label is experimental and may change or be removed without notice.

Save a label into a cop_hints_hash. You need to set flags to SVf_UTF8 for a UTF-8 label. Any other flag is ignored.

    void  cop_store_label(COP *const cop, const char *label,
                          STRLEN len, U32 flags)
PERL_SI

Use this typedef to declare variables that are to hold struct stackinfo.

Custom Operators

custom_op_desc

DEPRECATED! It is planned to remove custom_op_desc from a future release of Perl. Do not use it for new code; remove it from existing code.

Return the description of a given custom op. This was once used by the OP_DESC macro, but is no longer: it has only been kept for compatibility, and should not be used.

    const char *  custom_op_desc(const OP *o)
custom_op_name

DEPRECATED! It is planned to remove custom_op_name from a future release of Perl. Do not use it for new code; remove it from existing code.

Return the name for a given custom op. This was once used by the OP_NAME macro, but is no longer: it has only been kept for compatibility, and should not be used.

    const char *  custom_op_name(const OP *o)
custom_op_register

Register a custom op. See "Custom Operators" in perlguts.

NOTE: custom_op_register must be explicitly called as Perl_custom_op_register with an aTHX_ parameter.

    void  Perl_custom_op_register(pTHX_ Perl_ppaddr_t ppaddr,
                                  const XOP *xop)
Perl_custom_op_xop

Return the XOP structure for a given custom op. This macro should be considered internal to OP_NAME and the other access macros: use them instead. This macro does call a function. Prior to 5.19.6, this was implemented as a function.

    const XOP *  Perl_custom_op_xop(pTHX_ const OP *o)
XopDISABLE

Temporarily disable a member of the XOP, by clearing the appropriate flag.

    void  XopDISABLE(XOP *xop, which)
XopENABLE

Reenable a member of the XOP which has been disabled.

    void  XopENABLE(XOP *xop, which)
XopENTRY

Return a member of the XOP structure. which is a cpp token indicating which entry to return. If the member is not set this will return a default value. The return type depends on which. This macro evaluates its arguments more than once. If you are using Perl_custom_op_xop to retrieve a XOP * from a OP *, use the more efficient "XopENTRYCUSTOM" instead.

    XopENTRY(XOP *xop, which)
XopENTRYCUSTOM

Exactly like XopENTRY(XopENTRY(Perl_custom_op_xop(aTHX_ o), which) but more efficient. The which parameter is identical to "XopENTRY".

    XopENTRYCUSTOM(const OP *o, which)
XopENTRY_set

Set a member of the XOP structure. which is a cpp token indicating which entry to set. See "Custom Operators" in perlguts for details about the available members and how they are used. This macro evaluates its argument more than once.

    void  XopENTRY_set(XOP *xop, which, value)
XopFLAGS

Return the XOP's flags.

    U32  XopFLAGS(XOP *xop)

CV Handling

This section documents functions to manipulate CVs which are code-values, meaning subroutines. For more information, see perlguts.

caller_cx

The XSUB-writer's equivalent of caller(). The returned PERL_CONTEXT structure can be interrogated to find all the information returned to Perl by caller. Note that XSUBs don't get a stack frame, so caller_cx(0, NULL) will return information for the immediately-surrounding Perl code.

This function skips over the automatic calls to &DB::sub made on the behalf of the debugger. If the stack frame requested was a sub called by DB::sub, the return value will be the frame for the call to DB::sub, since that has the correct line number/etc. for the call site. If dbcxp is non-NULL, it will be set to a pointer to the frame for the sub call itself.

    const PERL_CONTEXT *  caller_cx(I32 level,
                                    const PERL_CONTEXT **dbcxp)
CvGV

Returns the GV associated with the CV sv, reifying it if necessary.

    GV *  CvGV(CV *sv)
CvSTASH

Returns the stash of the CV. A stash is the symbol table hash, containing the package-scoped variables in the package where the subroutine was defined. For more information, see perlguts.

This also has a special use with XS AUTOLOAD subs. See "Autoloading with XSUBs" in perlguts.

    HV*  CvSTASH(CV* cv)
find_runcv

Locate the CV corresponding to the currently executing sub or eval. If db_seqp is non_null, skip CVs that are in the DB package and populate *db_seqp with the cop sequence number at the point that the DB:: code was entered. (This allows debuggers to eval in the scope of the breakpoint rather than in the scope of the debugger itself.)

    CV*  find_runcv(U32 *db_seqp)
get_cv
get_cvs
get_cvn_flags

These return the CV of the specified Perl subroutine. flags are passed to gv_fetchpvn_flags. If GV_ADD is set and the Perl subroutine does not exist then it will be declared (which has the same effect as saying sub name;). If GV_ADD is not set and the subroutine does not exist, then NULL is returned.

The forms differ only in how the subroutine is specified.. With get_cvs, the name is a literal C string, enclosed in double quotes. With get_cv, the name is given by the name parameter, which must be a NUL-terminated C string. With get_cvn_flags, the name is also given by the name parameter, but it is a Perl string (possibly containing embedded NUL bytes), and its length in bytes is contained in the len parameter.

NOTE: the perl_get_cv() form is deprecated.

NOTE: the perl_get_cvs() form is deprecated.

NOTE: the perl_get_cvn_flags() form is deprecated.

    CV*   get_cv       (const char* name, I32 flags)
    CV *  get_cvs      ("string", I32 flags)
    CV*   get_cvn_flags(const char* name, STRLEN len, I32 flags)
Nullcv

DEPRECATED! It is planned to remove Nullcv from a future release of Perl. Do not use it for new code; remove it from existing code.

Null CV pointer.

(deprecated - use (CV *)NULL instead)

Debugging

dump_all

Dumps the entire optree of the current program starting at PL_main_root to STDERR. Also dumps the optrees for all visible subroutines in PL_defstash.

    void  dump_all()
dump_c_backtrace

Dumps the C backtrace to the given fp.

Returns true if a backtrace could be retrieved, false if not.

    bool  dump_c_backtrace(PerlIO* fp, int max_depth, int skip)
dump_packsubs

Dumps the optrees for all visible subroutines in stash.

    void  dump_packsubs(const HV* stash)
get_c_backtrace_dump

Returns a SV containing a dump of depth frames of the call stack, skipping the skip innermost ones. depth of 20 is usually enough.

The appended output looks like:

...
1   10e004812:0082   Perl_croak   util.c:1716    /usr/bin/perl
2   10df8d6d2:1d72   perl_parse   perl.c:3975    /usr/bin/perl
...

The fields are tab-separated. The first column is the depth (zero being the innermost non-skipped frame). In the hex:offset, the hex is where the program counter was in S_parse_body, and the :offset (might be missing) tells how much inside the S_parse_body the program counter was.

The util.c:1716 is the source code file and line number.

The /usr/bin/perl is obvious (hopefully).

Unknowns are "-". Unknowns can happen unfortunately quite easily: if the platform doesn't support retrieving the information; if the binary is missing the debug information; if the optimizer has transformed the code by for example inlining.

    SV*  get_c_backtrace_dump(int max_depth, int skip)
HAS_BACKTRACE

This symbol, if defined, indicates that the backtrace() routine is available to get a stack trace. The execinfo.h header must be included to use this routine.

op_class

Given an op, determine what type of struct it has been allocated as. Returns one of the OPclass enums, such as OPclass_LISTOP.

    OPclass  op_class(const OP *o)
op_dump

Dumps the optree starting at OP o to STDERR.

    void  op_dump(const OP *o)
sv_dump

Dumps the contents of an SV to the STDERR filehandle.

For an example of its output, see Devel::Peek.

    void  sv_dump(SV* sv)

Display functions

form
form_nocontext

These take a sprintf-style format pattern and conventional (non-SV) arguments and return the formatted string.

(char *) Perl_form(pTHX_ const char* pat, ...)

can be used any place a string (char *) is required:

char * s = Perl_form("%d.%d",major,minor);

They use a single (per-thread) private buffer so if you want to format several strings you must explicitly copy the earlier strings away (and free the copies when you are done).

The two forms differ only in that form_nocontext does not take a thread context (aTHX) parameter, so is used in situations where the caller doesn't already have the thread context.

NOTE: form must be explicitly called as Perl_form with an aTHX_ parameter.

    char*  Perl_form     (pTHX_ const char* pat, ...)
    char*  form_nocontext(const char* pat, ...)
mess
mess_nocontext

These take a sprintf-style format pattern and argument list, which are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

Normally, the resulting message is returned in a new mortal SV. But during global destruction a single SV may be shared between uses of this function.

The two forms differ only in that mess_nocontext does not take a thread context (aTHX) parameter, so is used in situations where the caller doesn't already have the thread context.

NOTE: mess must be explicitly called as Perl_mess with an aTHX_ parameter.

    SV*  Perl_mess     (pTHX_ const char* pat, ...)
    SV*  mess_nocontext(const char* pat, ...)
mess_sv

Expands a message, intended for the user, to include an indication of the current location in the code, if the message does not already appear to be complete.

basemsg is the initial message or object. If it is a reference, it will be used as-is and will be the result of this function. Otherwise it is used as a string, and if it already ends with a newline, it is taken to be complete, and the result of this function will be the same string. If the message does not end with a newline, then a segment such as at foo.pl line 37 will be appended, and possibly other clauses indicating the current state of execution. The resulting message will end with a dot and a newline.

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function. If consume is true, then the function is permitted (but not required) to modify and return basemsg instead of allocating a new SV.

    SV*  mess_sv(SV* basemsg, bool consume)
pv_display

Similar to

pv_escape(dsv,pv,cur,pvlim,PERL_PV_ESCAPE_QUOTE);

except that an additional "\0" will be appended to the string when len > cur and pv[cur] is "\0".

Note that the final string may be up to 7 chars longer than pvlim.

    char*  pv_display(SV *dsv, const char *pv, STRLEN cur, STRLEN len,
                      STRLEN pvlim)
pv_escape

Escapes at most the first count chars of pv and puts the results into dsv such that the size of the escaped string will not exceed max chars and will not contain any incomplete escape sequences. The number of bytes escaped will be returned in the STRLEN *escaped parameter if it is not null. When the dsv parameter is null no escaping actually occurs, but the number of bytes that would be escaped were it not null will be calculated.

If flags contains PERL_PV_ESCAPE_QUOTE then any double quotes in the string will also be escaped.

Normally the SV will be cleared before the escaped string is prepared, but when PERL_PV_ESCAPE_NOCLEAR is set this will not occur.

If PERL_PV_ESCAPE_UNI is set then the input string is treated as UTF-8 if PERL_PV_ESCAPE_UNI_DETECT is set then the input string is scanned using is_utf8_string() to determine if it is UTF-8.

If PERL_PV_ESCAPE_ALL is set then all input chars will be output using \x01F1 style escapes, otherwise if PERL_PV_ESCAPE_NONASCII is set, only non-ASCII chars will be escaped using this style; otherwise, only chars above 255 will be so escaped; other non printable chars will use octal or common escaped patterns like \n. Otherwise, if PERL_PV_ESCAPE_NOBACKSLASH then all chars below 255 will be treated as printable and will be output as literals.

If PERL_PV_ESCAPE_FIRSTCHAR is set then only the first char of the string will be escaped, regardless of max. If the output is to be in hex, then it will be returned as a plain hex sequence. Thus the output will either be a single char, an octal escape sequence, a special escape like \n or a hex value.

If PERL_PV_ESCAPE_RE is set then the escape char used will be a "%" and not a "\\". This is because regexes very often contain backslashed sequences, whereas "%" is not a particularly common character in patterns.

Returns a pointer to the escaped text as held by dsv.

    char*  pv_escape(SV *dsv, char const * const str,
                     const STRLEN count, const STRLEN max,
                     STRLEN * const escaped, const U32 flags)
pv_pretty

Converts a string into something presentable, handling escaping via pv_escape() and supporting quoting and ellipses.

If the PERL_PV_PRETTY_QUOTE flag is set then the result will be double quoted with any double quotes in the string escaped. Otherwise if the PERL_PV_PRETTY_LTGT flag is set then the result be wrapped in angle brackets.

If the PERL_PV_PRETTY_ELLIPSES flag is set and not all characters in string were output then an ellipsis ... will be appended to the string. Note that this happens AFTER it has been quoted.

If start_color is non-null then it will be inserted after the opening quote (if there is one) but before the escaped text. If end_color is non-null then it will be inserted after the escaped text but before any quotes or ellipses.

Returns a pointer to the prettified text as held by dsv.

    char*  pv_pretty(SV *dsv, char const * const str,
                     const STRLEN count, const STRLEN max,
                     char const * const start_color,
                     char const * const end_color, const U32 flags)
vform

Like "form" but but the arguments are an encapsulated argument list.

    char*  vform(const char* pat, va_list* args)
vmess

pat and args are a sprintf-style format pattern and encapsulated argument list, respectively. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

Normally, the resulting message is returned in a new mortal SV. During global destruction a single SV may be shared between uses of this function.

    SV*  vmess(const char* pat, va_list* args)

Embedding and Interpreter Cloning

cv_clone

Clone a CV, making a lexical closure. proto supplies the prototype of the function: its code, pad structure, and other attributes. The prototype is combined with a capture of outer lexicals to which the code refers, which are taken from the currently-executing instance of the immediately surrounding code.

    CV*  cv_clone(CV* proto)
cv_name

Returns an SV containing the name of the CV, mainly for use in error reporting. The CV may actually be a GV instead, in which case the returned SV holds the GV's name. Anything other than a GV or CV is treated as a string already holding the sub name, but this could change in the future.

An SV may be passed as a second argument. If so, the name will be assigned to it and it will be returned. Otherwise the returned SV will be a new mortal.

If flags has the CV_NAME_NOTQUAL bit set, then the package name will not be included. If the first argument is neither a CV nor a GV, this flag is ignored (subject to change).

    SV *  cv_name(CV *cv, SV *sv, U32 flags)
cv_undef

Clear out all the active components of a CV. This can happen either by an explicit undef &foo, or by the reference count going to zero. In the former case, we keep the CvOUTSIDE pointer, so that any anonymous children can still follow the full lexical scope chain.

    void  cv_undef(CV* cv)
find_rundefsv

Returns the global variable $_.

    SV*  find_rundefsv()
find_rundefsvoffset

DEPRECATED! It is planned to remove find_rundefsvoffset from a future release of Perl. Do not use it for new code; remove it from existing code.

Until the lexical $_ feature was removed, this function would find the position of the lexical $_ in the pad of the currently-executing function and return the offset in the current pad, or NOT_IN_PAD.

Now it always returns NOT_IN_PAD.

    PADOFFSET  find_rundefsvoffset()
intro_my

"Introduce" my variables to visible status. This is called during parsing at the end of each statement to make lexical variables visible to subsequent statements.

    U32  intro_my()
load_module

Loads the module whose name is pointed to by the string part of name. Note that the actual module name, not its filename, should be given. Eg, "Foo::Bar" instead of "Foo/Bar.pm". ver, if specified and not NULL, provides version semantics similar to use Foo::Bar VERSION. The optional trailing arguments can be used to specify arguments to the module's import() method, similar to use Foo::Bar VERSION LIST; their precise handling depends on the flags. The flags argument is a bitwise-ORed collection of any of PERL_LOADMOD_DENY, PERL_LOADMOD_NOIMPORT, or PERL_LOADMOD_IMPORT_OPS (or 0 for no flags).

If PERL_LOADMOD_NOIMPORT is set, the module is loaded as if with an empty import list, as in use Foo::Bar (); this is the only circumstance in which the trailing optional arguments may be omitted entirely. Otherwise, if PERL_LOADMOD_IMPORT_OPS is set, the trailing arguments must consist of exactly one OP*, containing the op tree that produces the relevant import arguments. Otherwise, the trailing arguments must all be SV* values that will be used as import arguments; and the list must be terminated with (SV*) NULL. If neither PERL_LOADMOD_NOIMPORT nor PERL_LOADMOD_IMPORT_OPS is set, the trailing NULL pointer is needed even if no import arguments are desired. The reference count for each specified SV* argument is decremented. In addition, the name argument is modified.

If PERL_LOADMOD_DENY is set, the module is loaded as if with no rather than use.

    void  load_module(U32 flags, SV* name, SV* ver, ...)
load_module_nocontext

Like "load_module" but does not take a thread context (aTHX) parameter, so is used in situations where the caller doesn't already have the thread context.

    void  load_module_nocontext(U32 flags, SV* name, SV* ver, ...)
my_exit

A wrapper for the C library exit(3), honoring what "PL_exit_flags" in perlapi say to do.

    void  my_exit(U32 status)
newPADNAMELIST

NOTE: newPADNAMELIST is experimental and may change or be removed without notice.

Creates a new pad name list. max is the highest index for which space is allocated.

    PADNAMELIST *  newPADNAMELIST(size_t max)
newPADNAMEouter

NOTE: newPADNAMEouter is experimental and may change or be removed without notice.

Constructs and returns a new pad name. Only use this function for names that refer to outer lexicals. (See also "newPADNAMEpvn".) outer is the outer pad name that this one mirrors. The returned pad name has the PADNAMEt_OUTER flag already set.

    PADNAME *  newPADNAMEouter(PADNAME *outer)
newPADNAMEpvn

NOTE: newPADNAMEpvn is experimental and may change or be removed without notice.

Constructs and returns a new pad name. s must be a UTF-8 string. Do not use this for pad names that point to outer lexicals. See "newPADNAMEouter".

    PADNAME *  newPADNAMEpvn(const char *s, STRLEN len)
nothreadhook

Stub that provides thread hook for perl_destruct when there are no threads.

    int  nothreadhook()
pad_add_anon

Allocates a place in the currently-compiling pad (via "pad_alloc") for an anonymous function that is lexically scoped inside the currently-compiling function. The function func is linked into the pad, and its CvOUTSIDE link to the outer scope is weakened to avoid a reference loop.

One reference count is stolen, so you may need to do SvREFCNT_inc(func).

optype should be an opcode indicating the type of operation that the pad entry is to support. This doesn't affect operational semantics, but is used for debugging.

    PADOFFSET  pad_add_anon(CV* func, I32 optype)
pad_add_name_pv

Exactly like "pad_add_name_pvn", but takes a nul-terminated string instead of a string/length pair.

    PADOFFSET  pad_add_name_pv(const char *name, const U32 flags,
                               HV *typestash, HV *ourstash)
pad_add_name_pvn

Allocates a place in the currently-compiling pad for a named lexical variable. Stores the name and other metadata in the name part of the pad, and makes preparations to manage the variable's lexical scoping. Returns the offset of the allocated pad slot.

namepv/namelen specify the variable's name, including leading sigil. If typestash is non-null, the name is for a typed lexical, and this identifies the type. If ourstash is non-null, it's a lexical reference to a package variable, and this identifies the package. The following flags can be OR'ed together:

padadd_OUR          redundantly specifies if it's a package var
padadd_STATE        variable will retain value persistently
padadd_NO_DUP_CHECK skip check for lexical shadowing
    PADOFFSET  pad_add_name_pvn(const char *namepv, STRLEN namelen,
                                U32 flags, HV *typestash,
                                HV *ourstash)
pad_add_name_sv

Exactly like "pad_add_name_pvn", but takes the name string in the form of an SV instead of a string/length pair.

    PADOFFSET  pad_add_name_sv(SV *name, U32 flags, HV *typestash,
                               HV *ourstash)
pad_alloc

NOTE: pad_alloc is experimental and may change or be removed without notice.

Allocates a place in the currently-compiling pad, returning the offset of the allocated pad slot. No name is initially attached to the pad slot. tmptype is a set of flags indicating the kind of pad entry required, which will be set in the value SV for the allocated pad entry:

SVs_PADMY    named lexical variable ("my", "our", "state")
SVs_PADTMP   unnamed temporary store
SVf_READONLY constant shared between recursion levels

SVf_READONLY has been supported here only since perl 5.20. To work with earlier versions as well, use SVf_READONLY|SVs_PADTMP. SVf_READONLY does not cause the SV in the pad slot to be marked read-only, but simply tells pad_alloc that it will be made read-only (by the caller), or at least should be treated as such.

optype should be an opcode indicating the type of operation that the pad entry is to support. This doesn't affect operational semantics, but is used for debugging.

    PADOFFSET  pad_alloc(I32 optype, U32 tmptype)
pad_findmy_pv

Exactly like "pad_findmy_pvn", but takes a nul-terminated string instead of a string/length pair.

    PADOFFSET  pad_findmy_pv(const char* name, U32 flags)
pad_findmy_pvn

Given the name of a lexical variable, find its position in the currently-compiling pad. namepv/namelen specify the variable's name, including leading sigil. flags is reserved and must be zero. If it is not in the current pad but appears in the pad of any lexically enclosing scope, then a pseudo-entry for it is added in the current pad. Returns the offset in the current pad, or NOT_IN_PAD if no such lexical is in scope.

    PADOFFSET  pad_findmy_pvn(const char* namepv, STRLEN namelen,
                              U32 flags)
pad_findmy_sv

Exactly like "pad_findmy_pvn", but takes the name string in the form of an SV instead of a string/length pair.

    PADOFFSET  pad_findmy_sv(SV* name, U32 flags)
padnamelist_fetch

NOTE: padnamelist_fetch is experimental and may change or be removed without notice.

Fetches the pad name from the given index.

    PADNAME *  padnamelist_fetch(PADNAMELIST *pnl, SSize_t key)
padnamelist_store

NOTE: padnamelist_store is experimental and may change or be removed without notice.

Stores the pad name (which may be null) at the given index, freeing any existing pad name in that slot.

    PADNAME **  padnamelist_store(PADNAMELIST *pnl, SSize_t key,
                                  PADNAME *val)
pad_tidy

NOTE: pad_tidy is experimental and may change or be removed without notice.

Tidy up a pad at the end of compilation of the code to which it belongs. Jobs performed here are: remove most stuff from the pads of anonsub prototypes; give it a @_; mark temporaries as such. type indicates the kind of subroutine:

padtidy_SUB        ordinary subroutine
padtidy_SUBCLONE   prototype for lexical closure
padtidy_FORMAT     format
    void  pad_tidy(padtidy_type type)
perl_alloc

Allocates a new Perl interpreter. See perlembed.

    PerlInterpreter*  perl_alloc()
PERL_ASYNC_CHECK

Described in perlinterp.

    void  PERL_ASYNC_CHECK()
perl_clone

Create and return a new interpreter by cloning the current one.

perl_clone takes these flags as parameters:

CLONEf_COPY_STACKS - is used to, well, copy the stacks also, without it we only clone the data and zero the stacks, with it we copy the stacks and the new perl interpreter is ready to run at the exact same point as the previous one. The pseudo-fork code uses COPY_STACKS while the threads->create doesn't.

CLONEf_KEEP_PTR_TABLE - perl_clone keeps a ptr_table with the pointer of the old variable as a key and the new variable as a value, this allows it to check if something has been cloned and not clone it again, but rather just use the value and increase the refcount. If KEEP_PTR_TABLE is not set then perl_clone will kill the ptr_table using the function ptr_table_free(PL_ptr_table); PL_ptr_table = NULL;. A reason to keep it around is if you want to dup some of your own variables which are outside the graph that perl scans.

CLONEf_CLONE_HOST - This is a win32 thing, it is ignored on unix, it tells perl's win32host code (which is c++) to clone itself, this is needed on win32 if you want to run two threads at the same time, if you just want to do some stuff in a separate perl interpreter and then throw it away and return to the original one, you don't need to do anything.

    PerlInterpreter*  perl_clone(PerlInterpreter *proto_perl,
                                 UV flags)
perl_construct

Initializes a new Perl interpreter. See perlembed.

    void  perl_construct(PerlInterpreter *my_perl)
perl_destruct

Shuts down a Perl interpreter. See perlembed for a tutorial.

my_perl points to the Perl interpreter. It must have been previously created through the use of "perl_alloc" and "perl_construct". It may have been initialised through "perl_parse", and may have been used through "perl_run" and other means. This function should be called for any Perl interpreter that has been constructed with "perl_construct", even if subsequent operations on it failed, for example if "perl_parse" returned a non-zero value.

If the interpreter's PL_exit_flags word has the PERL_EXIT_DESTRUCT_END flag set, then this function will execute code in END blocks before performing the rest of destruction. If it is desired to make any use of the interpreter between "perl_parse" and "perl_destruct" other than just calling "perl_run", then this flag should be set early on. This matters if "perl_run" will not be called, or if anything else will be done in addition to calling "perl_run".

Returns a value be a suitable value to pass to the C library function exit (or to return from main), to serve as an exit code indicating the nature of the way the interpreter terminated. This takes into account any failure of "perl_parse" and any early exit from "perl_run". The exit code is of the type required by the host operating system, so because of differing exit code conventions it is not portable to interpret specific numeric values as having specific meanings.

    int  perl_destruct(PerlInterpreter *my_perl)
perl_free

Releases a Perl interpreter. See perlembed.

    void  perl_free(PerlInterpreter *my_perl)
perl_parse

Tells a Perl interpreter to parse a Perl script. This performs most of the initialisation of a Perl interpreter. See perlembed for a tutorial.

my_perl points to the Perl interpreter that is to parse the script. It must have been previously created through the use of "perl_alloc" and "perl_construct". xsinit points to a callback function that will be called to set up the ability for this Perl interpreter to load XS extensions, or may be null to perform no such setup.

argc and argv supply a set of command-line arguments to the Perl interpreter, as would normally be passed to the main function of a C program. argv[argc] must be null. These arguments are where the script to parse is specified, either by naming a script file or by providing a script in a -e option. If $0 will be written to in the Perl interpreter, then the argument strings must be in writable memory, and so mustn't just be string constants.

env specifies a set of environment variables that will be used by this Perl interpreter. If non-null, it must point to a null-terminated array of environment strings. If null, the Perl interpreter will use the environment supplied by the environ global variable.

This function initialises the interpreter, and parses and compiles the script specified by the command-line arguments. This includes executing code in BEGIN, UNITCHECK, and CHECK blocks. It does not execute INIT blocks or the main program.

Returns an integer of slightly tricky interpretation. The correct use of the return value is as a truth value indicating whether there was a failure in initialisation. If zero is returned, this indicates that initialisation was successful, and it is safe to proceed to call "perl_run" and make other use of it. If a non-zero value is returned, this indicates some problem that means the interpreter wants to terminate. The interpreter should not be just abandoned upon such failure; the caller should proceed to shut the interpreter down cleanly with "perl_destruct" and free it with "perl_free".

For historical reasons, the non-zero return value also attempts to be a suitable value to pass to the C library function exit (or to return from main), to serve as an exit code indicating the nature of the way initialisation terminated. However, this isn't portable, due to differing exit code conventions. A historical bug is preserved for the time being: if the Perl built-in exit is called during this function's execution, with a type of exit entailing a zero exit code under the host operating system's conventions, then this function returns zero rather than a non-zero value. This bug, [perl #2754], leads to perl_run being called (and therefore INIT blocks and the main program running) despite a call to exit. It has been preserved because a popular module-installing module has come to rely on it and needs time to be fixed. This issue is [perl #132577], and the original bug is due to be fixed in Perl 5.30.

    int  perl_parse(PerlInterpreter *my_perl, XSINIT_t xsinit,
                    int argc, char** argv, char** env)
perl_run

Tells a Perl interpreter to run its main program. See perlembed for a tutorial.

my_perl points to the Perl interpreter. It must have been previously created through the use of "perl_alloc" and "perl_construct", and initialised through "perl_parse". This function should not be called if "perl_parse" returned a non-zero value, indicating a failure in initialisation or compilation.

This function executes code in INIT blocks, and then executes the main program. The code to be executed is that established by the prior call to "perl_parse". If the interpreter's PL_exit_flags word does not have the PERL_EXIT_DESTRUCT_END flag set, then this function will also execute code in END blocks. If it is desired to make any further use of the interpreter after calling this function, then END blocks should be postponed to "perl_destruct" time by setting that flag.

Returns an integer of slightly tricky interpretation. The correct use of the return value is as a truth value indicating whether the program terminated non-locally. If zero is returned, this indicates that the program ran to completion, and it is safe to make other use of the interpreter (provided that the PERL_EXIT_DESTRUCT_END flag was set as described above). If a non-zero value is returned, this indicates that the interpreter wants to terminate early. The interpreter should not be just abandoned because of this desire to terminate; the caller should proceed to shut the interpreter down cleanly with "perl_destruct" and free it with "perl_free".

For historical reasons, the non-zero return value also attempts to be a suitable value to pass to the C library function exit (or to return from main), to serve as an exit code indicating the nature of the way the program terminated. However, this isn't portable, due to differing exit code conventions. An attempt is made to return an exit code of the type required by the host operating system, but because it is constrained to be non-zero, it is not necessarily possible to indicate every type of exit. It is only reliable on Unix, where a zero exit code can be augmented with a set bit that will be ignored. In any case, this function is not the correct place to acquire an exit code: one should get that from "perl_destruct".

    int  perl_run(PerlInterpreter *my_perl)
PERL_SYS_INIT

Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters.

    void  PERL_SYS_INIT(int *argc, char*** argv)
PERL_SYS_INIT3

Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters.

    void  PERL_SYS_INIT3(int *argc, char*** argv, char*** env)
PERL_SYS_TERM

Provides system-specific clean up of the C runtime environment after running Perl interpreters. This should be called only once, after freeing any remaining Perl interpreters.

    void  PERL_SYS_TERM()
PL_exit_flags

Contains flags controlling perl's behaviour on exit():

  • PERL_EXIT_DESTRUCT_END

    If set, END blocks are executed when the interpreter is destroyed. This is normally set by perl itself after the interpreter is constructed.

  • PERL_EXIT_ABORT

    Call abort() on exit. This is used internally by perl itself to abort if exit is called while processing exit.

  • PERL_EXIT_WARN

    Warn on exit.

  • PERL_EXIT_EXPECTED

    Set by the "exit" in perlfunc operator.

    U8  PL_exit_flags
PL_perl_destruct_level

This value may be set when embedding for full cleanup.

Possible values:

  • 0 - none

  • 1 - full

  • 2 or greater - full with checks.

If $ENV{PERL_DESTRUCT_LEVEL} is set to an integer greater than the value of PL_perl_destruct_level its value is used instead.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    signed char  PL_perl_destruct_level
require_pv

Tells Perl to require the file named by the string argument. It is analogous to the Perl code eval "require '$file'". It's even implemented that way; consider using load_module instead.

NOTE: the perl_require_pv() form is deprecated.

    void  require_pv(const char* pv)
UVf

DEPRECATED! It is planned to remove UVf from a future release of Perl. Do not use it for new code; remove it from existing code.

Obsolete form of UVuf, which you should convert to instead use

    const char *  UVf
vload_module

Like "load_module" but the arguments are an encapsulated argument list.

    void  vload_module(U32 flags, SV* name, SV* ver, va_list* args)

Errno

sv_string_from_errnum

Generates the message string describing an OS error and returns it as an SV. errnum must be a value that errno could take, identifying the type of error.

If tgtsv is non-null then the string will be written into that SV (overwriting existing content) and it will be returned. If tgtsv is a null pointer then the string will be written into a new mortal SV which will be returned.

The message will be taken from whatever locale would be used by $!, and will be encoded in the SV in whatever manner would be used by $!. The details of this process are subject to future change. Currently, the message is taken from the C locale by default (usually producing an English message), and from the currently selected locale when in the scope of the use locale pragma. A heuristic attempt is made to decode the message from the locale's character encoding, but it will only be decoded as either UTF-8 or ISO-8859-1. It is always correctly decoded in a UTF-8 locale, usually in an ISO-8859-1 locale, and never in any other locale.

The SV is always returned containing an actual string, and with no other OK bits set. Unlike $!, a message is even yielded for errnum zero (meaning success), and if no useful message is available then a useless string (currently empty) is returned.

    SV*  sv_string_from_errnum(int errnum, SV* tgtsv)

Exception Handling (simple) Macros

dXCPT

Set up necessary local variables for exception handling. See "Exception Handling" in perlguts.

    dXCPT;
JMPENV_JUMP

Described in perlinterp.

    void  JMPENV_JUMP(int v)
JMPENV_PUSH

Described in perlinterp.

    void  JMPENV_PUSH(int v)
PL_restartop

Described in perlinterp.

XCPT_CATCH

Introduces a catch block. See "Exception Handling" in perlguts.

XCPT_RETHROW

Rethrows a previously caught exception. See "Exception Handling" in perlguts.

    XCPT_RETHROW;
XCPT_TRY_END

Ends a try block. See "Exception Handling" in perlguts.

XCPT_TRY_START

Starts a try block. See "Exception Handling" in perlguts.

Filesystem configuration values

Also see "List of capability HAS_foo symbols".

DIRNAMLEN

This symbol, if defined, indicates to the C program that the length of directory entry names is provided by a d_namlen field. Otherwise you need to do strlen() on the d_name field.

DOSUID

This symbol, if defined, indicates that the C program should check the script that it is executing for setuid/setgid bits, and attempt to emulate setuid/setgid on systems that have disabled setuid #! scripts because the kernel can't do it securely. It is up to the package designer to make sure that this emulation is done securely. Among other things, it should do an fstat on the script it just opened to make sure it really is a setuid/setgid script, it should make sure the arguments passed correspond exactly to the argument on the #! line, and it should not trust any subprocesses to which it must pass the filename rather than the file descriptor of the script to be executed.

EOF_NONBLOCK

This symbol, if defined, indicates to the C program that a read() on a non-blocking file descriptor will return 0 on EOF, and not the value held in RD_NODATA (-1 usually, in that case!).

FCNTL_CAN_LOCK

This symbol, if defined, indicates that fcntl() can be used for file locking. Normally on Unix systems this is defined. It may be undefined on VMS.

FFLUSH_ALL

This symbol, if defined, tells that to flush all pending stdio output one must loop through all the stdio file handles stored in an array and fflush them. Note that if fflushNULL is defined, fflushall will not even be probed for and will be left undefined.

FFLUSH_NULL

This symbol, if defined, tells that fflush(NULL) correctly flushes all pending stdio output without side effects. In particular, on some platforms calling fflush(NULL) *still* corrupts STDIN if it is a pipe.

FILE_base

This macro is used to access the _base field (or equivalent) of the FILE structure pointed to by its argument. This macro will always be defined if USE_STDIO_BASE is defined.

    void *  FILE_base(FILE * f)
FILE_bufsiz

This macro is used to determine the number of bytes in the I/O buffer pointed to by _base field (or equivalent) of the FILE structure pointed to its argument. This macro will always be defined if USE_STDIO_BASE is defined.

    Size_t  FILE_bufsiz(FILE *f)
FILE_cnt

This macro is used to access the _cnt field (or equivalent) of the FILE structure pointed to by its argument. This macro will always be defined if USE_STDIO_PTR is defined.

    Size_t  FILE_cnt(FILE * f)
FILE_ptr

This macro is used to access the _ptr field (or equivalent) of the FILE structure pointed to by its argument. This macro will always be defined if USE_STDIO_PTR is defined.

    void *  FILE_ptr(FILE * f)
FLEXFILENAMES

This symbol, if defined, indicates that the system supports filenames longer than 14 characters.

HAS_DIR_DD_FD

This symbol, if defined, indicates that the the DIR* dirstream structure contains a member variable named dd_fd.

HAS_DUP2

This symbol, if defined, indicates that the dup2 routine is available to duplicate file descriptors.

HAS_DUP3

This symbol, if defined, indicates that the dup3 routine is available to duplicate file descriptors.

HAS_FAST_STDIO

This symbol, if defined, indicates that the "fast stdio" is available to manipulate the stdio buffers directly.

HAS_FCHDIR

This symbol, if defined, indicates that the fchdir routine is available to change directory using a file descriptor.

HAS_FCNTL

This symbol, if defined, indicates to the C program that the fcntl() function exists.

HAS_FDCLOSE

This symbol, if defined, indicates that the fdclose routine is available to free a FILE structure without closing the underlying file descriptor. This function appeared in FreeBSD 10.2.

HAS_FPATHCONF

This symbol, if defined, indicates that pathconf() is available to determine file-system related limits and options associated with a given open file descriptor.

HAS_FPOS64_T

This symbol will be defined if the C compiler supports fpos64_t.

HAS_FSTATFS

This symbol, if defined, indicates that the fstatfs routine is available to stat filesystems by file descriptors.

HAS_FSTATVFS

This symbol, if defined, indicates that the fstatvfs routine is available to stat filesystems by file descriptors.

HAS_GETFSSTAT

This symbol, if defined, indicates that the getfsstat routine is available to stat filesystems in bulk.

HAS_GETMNT

This symbol, if defined, indicates that the getmnt routine is available to get filesystem mount info by filename.

HAS_GETMNTENT

This symbol, if defined, indicates that the getmntent routine is available to iterate through mounted file systems to get their info.

HAS_HASMNTOPT

This symbol, if defined, indicates that the hasmntopt routine is available to query the mount options of file systems.

HAS_LSEEK_PROTO

This symbol, if defined, indicates that the system provides a prototype for the lseek() function. Otherwise, it is up to the program to supply one. A good guess is

extern off_t lseek(int, off_t, int);
HAS_MKDIR

This symbol, if defined, indicates that the mkdir routine is available to create directories. Otherwise you should fork off a new process to exec /bin/mkdir.

HAS_OFF64_T

This symbol will be defined if the C compiler supports off64_t.

HAS_OPEN3

This manifest constant lets the C program know that the three argument form of open(2) is available.

HAS_OPENAT

This symbol is defined if the openat() routine is available.

HAS_POLL

This symbol, if defined, indicates that the poll routine is available to poll active file descriptors. Please check I_POLL and I_SYS_POLL to know which header should be included as well.

HAS_READDIR

This symbol, if defined, indicates that the readdir routine is available to read directory entries. You may have to include dirent.h. See "I_DIRENT".

HAS_READDIR64_R

This symbol, if defined, indicates that the readdir64_r routine is available to readdir64 re-entrantly.

HAS_REWINDDIR

This symbol, if defined, indicates that the rewinddir routine is available. You may have to include dirent.h. See "I_DIRENT".

HAS_RMDIR

This symbol, if defined, indicates that the rmdir routine is available to remove directories. Otherwise you should fork off a new process to exec /bin/rmdir.

HAS_SEEKDIR

This symbol, if defined, indicates that the seekdir routine is available. You may have to include dirent.h. See "I_DIRENT".

HAS_SELECT

This symbol, if defined, indicates that the select routine is available to select active file descriptors. If the timeout field is used, sys/time.h may need to be included.

HAS_SETVBUF

This symbol, if defined, indicates that the setvbuf routine is available to change buffering on an open stdio stream. to a line-buffered mode.

HAS_STDIO_STREAM_ARRAY

This symbol, if defined, tells that there is an array holding the stdio streams.

HAS_STRUCT_FS_DATA

This symbol, if defined, indicates that the struct fs_data to do statfs() is supported.

HAS_STRUCT_STATFS

This symbol, if defined, indicates that the struct statfs to do statfs() is supported.

HAS_STRUCT_STATFS_F_FLAGS

This symbol, if defined, indicates that the struct statfs does have the f_flags member containing the mount flags of the filesystem containing the file. This kind of struct statfs is coming from sys/mount.h (BSD 4.3), not from sys/statfs.h (SYSV). Older BSDs (like Ultrix) do not have statfs() and struct statfs, they have ustat() and getmnt() with struct ustat and struct fs_data.

HAS_TELLDIR

This symbol, if defined, indicates that the telldir routine is available. You may have to include dirent.h. See "I_DIRENT".

HAS_USTAT

This symbol, if defined, indicates that the ustat system call is available to query file system statistics by dev_t.

I_FCNTL

This manifest constant tells the C program to include fcntl.h.

    #ifdef I_FCNTL
        #include <fcntl.h>
    #endif
I_SYS_DIR

This symbol, if defined, indicates to the C program that it should include sys/dir.h.

    #ifdef I_SYS_DIR
        #include <sys_dir.h>
    #endif
I_SYS_FILE

This symbol, if defined, indicates to the C program that it should include sys/file.h to get definition of R_OK and friends.

    #ifdef I_SYS_FILE
        #include <sys_file.h>
    #endif
I_SYS_NDIR

This symbol, if defined, indicates to the C program that it should include sys/ndir.h.

    #ifdef I_SYS_NDIR
        #include <sys_ndir.h>
    #endif
I_SYS_STATFS

This symbol, if defined, indicates that sys/statfs.h exists.

    #ifdef I_SYS_STATFS
        #include <sys_statfs.h>
    #endif
LSEEKSIZE

This symbol holds the number of bytes used by the Off_t.

RD_NODATA

This symbol holds the return code from read() when no data is present on the non-blocking file descriptor. Be careful! If EOF_NONBLOCK is not defined, then you can't distinguish between no data and EOF by issuing a read(). You'll have to find another way to tell for sure!

READDIR64_R_PROTO

This symbol encodes the prototype of readdir64_r. It is zero if d_readdir64_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_readdir64_r is defined.

STDCHAR

This symbol is defined to be the type of char used in stdio.h. It has the values "unsigned char" or "char".

STDIO_CNT_LVALUE

This symbol is defined if the FILE_cnt macro can be used as an lvalue.

STDIO_PTR_LVALUE

This symbol is defined if the FILE_ptr macro can be used as an lvalue.

STDIO_PTR_LVAL_NOCHANGE_CNT

This symbol is defined if using the FILE_ptr macro as an lvalue to increase the pointer by n leaves File_cnt(fp) unchanged.

STDIO_PTR_LVAL_SETS_CNT

This symbol is defined if using the FILE_ptr macro as an lvalue to increase the pointer by n has the side effect of decreasing the value of File_cnt(fp) by n.

STDIO_STREAM_ARRAY

This symbol tells the name of the array holding the stdio streams. Usual values include _iob, __iob, and __sF.

ST_INO_SIGN

This symbol holds the signedness of struct stat's st_ino. 1 for unsigned, -1 for signed.

ST_INO_SIZE

This variable contains the size of struct stat's st_ino in bytes.

VAL_EAGAIN

This symbol holds the errno error code set by read() when no data was present on the non-blocking file descriptor.

VAL_O_NONBLOCK

This symbol is to be used during open() or fcntl(F_SETFL) to turn on non-blocking I/O for the file descriptor. Note that there is no way back, i.e. you cannot turn it blocking again this way. If you wish to alternatively switch between blocking and non-blocking, use the ioctl(FIOSNBIO) call instead, but that is not supported by all devices.

VOID_CLOSEDIR

This symbol, if defined, indicates that the closedir() routine does not return a value.

Floating point configuration values

Also "List of capability HAS_foo symbols" lists capabilities that arent in this section. For example HAS_ASINH, for the hyperbolic sine function.

CASTFLAGS

This symbol contains flags that say what difficulties the compiler has casting odd floating values to unsigned long:

0 = ok
1 = couldn't cast < 0
2 = couldn't cast >= 0x80000000
4 = couldn't cast in argument expression list
CASTNEGFLOAT

This symbol is defined if the C compiler can cast negative numbers to unsigned longs, ints and shorts.

DOUBLE_HAS_INF

This symbol, if defined, indicates that the double has the infinity.

DOUBLE_HAS_NAN

This symbol, if defined, indicates that the double has the not-a-number.

DOUBLE_HAS_NEGATIVE_ZERO

This symbol, if defined, indicates that the double has the negative_zero.

DOUBLE_HAS_SUBNORMALS

This symbol, if defined, indicates that the double has the subnormals (denormals).

DOUBLEINFBYTES

This symbol, if defined, is a comma-separated list of hexadecimal bytes for the double precision infinity.

DOUBLEKIND

DOUBLEKIND will be one of DOUBLE_IS_IEEE_754_32_BIT_LITTLE_ENDIAN DOUBLE_IS_IEEE_754_32_BIT_BIG_ENDIAN DOUBLE_IS_IEEE_754_64_BIT_LITTLE_ENDIAN DOUBLE_IS_IEEE_754_64_BIT_BIG_ENDIAN DOUBLE_IS_IEEE_754_128_BIT_LITTLE_ENDIAN DOUBLE_IS_IEEE_754_128_BIT_BIG_ENDIAN DOUBLE_IS_IEEE_754_64_BIT_MIXED_ENDIAN_LE_BE DOUBLE_IS_IEEE_754_64_BIT_MIXED_ENDIAN_BE_LE DOUBLE_IS_VAX_F_FLOAT DOUBLE_IS_VAX_D_FLOAT DOUBLE_IS_VAX_G_FLOAT DOUBLE_IS_IBM_SINGLE_32_BIT DOUBLE_IS_IBM_DOUBLE_64_BIT DOUBLE_IS_CRAY_SINGLE_64_BIT DOUBLE_IS_UNKNOWN_FORMAT

DOUBLEMANTBITS

This symbol, if defined, tells how many mantissa bits there are in double precision floating point format. Note that this is usually DBL_MANT_DIG minus one, since with the standard IEEE 754 formats DBL_MANT_DIG includes the implicit bit, which doesn't really exist.

DOUBLENANBYTES

This symbol, if defined, is a comma-separated list of hexadecimal bytes (0xHH) for the double precision not-a-number.

DOUBLESIZE

This symbol contains the size of a double, so that the C preprocessor can make decisions based on it.

DOUBLE_STYLE_CRAY

This symbol, if defined, indicates that the double is the 64-bit CRAY mainframe format.

DOUBLE_STYLE_IBM

This symbol, if defined, indicates that the double is the 64-bit IBM mainframe format.

DOUBLE_STYLE_IEEE

This symbol, if defined, indicates that the double is the 64-bit IEEE 754.

DOUBLE_STYLE_VAX

This symbol, if defined, indicates that the double is the 64-bit VAX format D or G.

HAS_ATOLF

This symbol, if defined, indicates that the atolf routine is available to convert strings into long doubles.

HAS_CLASS

This symbol, if defined, indicates that the class routine is available to classify doubles. Available for example in AIX. The returned values are defined in float.h and are:

FP_PLUS_NORM    Positive normalized, nonzero
FP_MINUS_NORM   Negative normalized, nonzero
FP_PLUS_DENORM  Positive denormalized, nonzero
FP_MINUS_DENORM Negative denormalized, nonzero
FP_PLUS_ZERO    +0.0
FP_MINUS_ZERO   -0.0
FP_PLUS_INF     +INF
FP_MINUS_INF    -INF
FP_NANS         Signaling Not a Number (NaNS)
FP_NANQ         Quiet Not a Number (NaNQ)
HAS_FINITE

This symbol, if defined, indicates that the finite routine is available to check whether a double is finite (non-infinity non-NaN).

HAS_FINITEL

This symbol, if defined, indicates that the finitel routine is available to check whether a long double is finite (non-infinity non-NaN).

HAS_FPCLASS

This symbol, if defined, indicates that the fpclass routine is available to classify doubles. Available for example in Solaris/SVR4. The returned values are defined in ieeefp.h and are:

FP_SNAN         signaling NaN
FP_QNAN         quiet NaN
FP_NINF         negative infinity
FP_PINF         positive infinity
FP_NDENORM      negative denormalized non-zero
FP_PDENORM      positive denormalized non-zero
FP_NZERO        negative zero
FP_PZERO        positive zero
FP_NNORM        negative normalized non-zero
FP_PNORM        positive normalized non-zero
HAS_FPCLASSIFY

This symbol, if defined, indicates that the fpclassify routine is available to classify doubles. Available for example in HP-UX. The returned values are defined in math.h and are

FP_NORMAL     Normalized
FP_ZERO       Zero
FP_INFINITE   Infinity
FP_SUBNORMAL  Denormalized
FP_NAN        NaN
HAS_FPCLASSL

This symbol, if defined, indicates that the fpclassl routine is available to classify long doubles. Available for example in IRIX. The returned values are defined in ieeefp.h and are:

FP_SNAN         signaling NaN
FP_QNAN         quiet NaN
FP_NINF         negative infinity
FP_PINF         positive infinity
FP_NDENORM      negative denormalized non-zero
FP_PDENORM      positive denormalized non-zero
FP_NZERO        negative zero
FP_PZERO        positive zero
FP_NNORM        negative normalized non-zero
FP_PNORM        positive normalized non-zero
HAS_FPGETROUND

This symbol, if defined, indicates that the fpgetround routine is available to get the floating point rounding mode.

HAS_FP_CLASS

This symbol, if defined, indicates that the fp_class routine is available to classify doubles. Available for example in Digital UNIX. The returned values are defined in math.h and are:

FP_SNAN           Signaling NaN (Not-a-Number)
FP_QNAN           Quiet NaN (Not-a-Number)
FP_POS_INF        +infinity
FP_NEG_INF        -infinity
FP_POS_NORM       Positive normalized
FP_NEG_NORM       Negative normalized
FP_POS_DENORM     Positive denormalized
FP_NEG_DENORM     Negative denormalized
FP_POS_ZERO       +0.0 (positive zero)
FP_NEG_ZERO       -0.0 (negative zero)
HAS_FP_CLASSIFY

This symbol, if defined, indicates that the fp_classify routine is available to classify doubles. The values are defined in math.h

FP_NORMAL     Normalized
FP_ZERO       Zero
FP_INFINITE   Infinity
FP_SUBNORMAL  Denormalized
FP_NAN        NaN
HAS_FP_CLASSL

This symbol, if defined, indicates that the fp_classl routine is available to classify long doubles. Available for example in Digital UNIX. See for possible values HAS_FP_CLASS.

HAS_FREXPL

This symbol, if defined, indicates that the frexpl routine is available to break a long double floating-point number into a normalized fraction and an integral power of 2.

HAS_ILOGB

This symbol, if defined, indicates that the ilogb routine is available to get integer exponent of a floating-point value.

HAS_ISFINITE

This symbol, if defined, indicates that the isfinite routine is available to check whether a double is finite (non-infinity non-NaN).

HAS_ISFINITEL

This symbol, if defined, indicates that the isfinitel routine is available to check whether a long double is finite. (non-infinity non-NaN).

HAS_ISINF

This symbol, if defined, indicates that the isinf routine is available to check whether a double is an infinity.

HAS_ISINFL

This symbol, if defined, indicates that the isinfl routine is available to check whether a long double is an infinity.

HAS_ISNAN

This symbol, if defined, indicates that the isnan routine is available to check whether a double is a NaN.

HAS_ISNANL

This symbol, if defined, indicates that the isnanl routine is available to check whether a long double is a NaN.

HAS_ISNORMAL

This symbol, if defined, indicates that the isnormal routine is available to check whether a double is normal (non-zero normalized).

HAS_J0

This symbol, if defined, indicates to the C program that the j0() function is available for Bessel functions of the first kind of the order zero, for doubles.

HAS_J0L

This symbol, if defined, indicates to the C program that the j0l() function is available for Bessel functions of the first kind of the order zero, for long doubles.

HAS_LDBL_DIG

This symbol, if defined, indicates that this system's float.h or limits.h defines the symbol LDBL_DIG, which is the number of significant digits in a long double precision number. Unlike for DBL_DIG, there's no good guess for LDBL_DIG if it is undefined.

HAS_LDEXPL

This symbol, if defined, indicates that the ldexpl routine is available to shift a long double floating-point number by an integral power of 2.

HAS_LLRINT

This symbol, if defined, indicates that the llrint routine is available to return the long long value closest to a double (according to the current rounding mode).

HAS_LLRINTL

This symbol, if defined, indicates that the llrintl routine is available to return the long long value closest to a long double (according to the current rounding mode).

HAS_LLROUNDL

This symbol, if defined, indicates that the llroundl routine is available to return the nearest long long value away from zero of the long double argument value.

HAS_LONG_DOUBLE

This symbol will be defined if the C compiler supports long doubles.

HAS_LRINT

This symbol, if defined, indicates that the lrint routine is available to return the integral value closest to a double (according to the current rounding mode).

HAS_LRINTL

This symbol, if defined, indicates that the lrintl routine is available to return the integral value closest to a long double (according to the current rounding mode).

HAS_LROUNDL

This symbol, if defined, indicates that the lroundl routine is available to return the nearest integral value away from zero of the long double argument value.

HAS_MODFL

This symbol, if defined, indicates that the modfl routine is available to split a long double x into a fractional part f and an integer part i such that |f| < 1.0 and (f + i) = x.

HAS_NAN

This symbol, if defined, indicates that the nan routine is available to generate NaN.

HAS_NEXTTOWARD

This symbol, if defined, indicates that the nexttoward routine is available to return the next machine representable long double from x in direction y.

HAS_REMAINDER

This symbol, if defined, indicates that the remainder routine is available to return the floating-point remainder.

HAS_SCALBN

This symbol, if defined, indicates that the scalbn routine is available to multiply floating-point number by integral power of radix.

HAS_SIGNBIT

This symbol, if defined, indicates that the signbit routine is available to check if the given number has the sign bit set. This should include correct testing of -0.0. This will only be set if the signbit() routine is safe to use with the NV type used internally in perl. Users should call Perl_signbit(), which will be #defined to the system's signbit() function or macro if this symbol is defined.

HAS_SQRTL

This symbol, if defined, indicates that the sqrtl routine is available to do long double square roots.

HAS_STRTOD_L

This symbol, if defined, indicates that the strtod_l routine is available to convert strings to long doubles.

HAS_STRTOLD

This symbol, if defined, indicates that the strtold routine is available to convert strings to long doubles.

HAS_STRTOLD_L

This symbol, if defined, indicates that the strtold_l routine is available to convert strings to long doubles.

HAS_TRUNC

This symbol, if defined, indicates that the trunc routine is available to round doubles towards zero.

HAS_UNORDERED

This symbol, if defined, indicates that the unordered routine is available to check whether two doubles are unordered (effectively: whether either of them is NaN)

I_FENV

This symbol, if defined, indicates to the C program that it should include fenv.h to get the floating point environment definitions.

    #ifdef I_FENV
        #include <fenv.h>
    #endif
I_QUADMATH

This symbol, if defined, indicates that quadmath.h exists and should be included.

    #ifdef I_QUADMATH
        #include <quadmath.h>
    #endif
LONGDBLINFBYTES

This symbol, if defined, is a comma-separated list of hexadecimal bytes for the long double precision infinity.

LONGDBLMANTBITS

This symbol, if defined, tells how many mantissa bits there are in long double precision floating point format. Note that this can be LDBL_MANT_DIG minus one, since LDBL_MANT_DIG can include the IEEE 754 implicit bit. The common x86-style 80-bit long double does not have an implicit bit.

LONGDBLNANBYTES

This symbol, if defined, is a comma-separated list of hexadecimal bytes (0xHH) for the long double precision not-a-number.

LONG_DOUBLEKIND

LONG_DOUBLEKIND will be one of LONG_DOUBLE_IS_DOUBLE LONG_DOUBLE_IS_IEEE_754_128_BIT_LITTLE_ENDIAN LONG_DOUBLE_IS_IEEE_754_128_BIT_BIG_ENDIAN LONG_DOUBLE_IS_X86_80_BIT_LITTLE_ENDIAN LONG_DOUBLE_IS_X86_80_BIT_BIG_ENDIAN LONG_DOUBLE_IS_DOUBLEDOUBLE_128_BIT_LE_LE LONG_DOUBLE_IS_DOUBLEDOUBLE_128_BIT_BE_BE LONG_DOUBLE_IS_DOUBLEDOUBLE_128_BIT_LE_BE LONG_DOUBLE_IS_DOUBLEDOUBLE_128_BIT_BE_LE LONG_DOUBLE_IS_DOUBLEDOUBLE_128_BIT_LITTLE_ENDIAN LONG_DOUBLE_IS_DOUBLEDOUBLE_128_BIT_BIG_ENDIAN LONG_DOUBLE_IS_VAX_H_FLOAT LONG_DOUBLE_IS_UNKNOWN_FORMAT It is only defined if the system supports long doubles.

LONG_DOUBLESIZE

This symbol contains the size of a long double, so that the C preprocessor can make decisions based on it. It is only defined if the system supports long doubles. Note that this is sizeof(long double), which may include unused bytes.

LONG_DOUBLE_STYLE_IEEE

This symbol, if defined, indicates that the long double is any of the IEEE 754 style long doubles: LONG_DOUBLE_STYLE_IEEE_STD, LONG_DOUBLE_STYLE_IEEE_EXTENDED, LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE.

LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE

This symbol, if defined, indicates that the long double is the 128-bit double-double.

LONG_DOUBLE_STYLE_IEEE_EXTENDED

This symbol, if defined, indicates that the long double is the 80-bit IEEE 754. Note that despite the 'extended' this is less than the 'std', since this is an extension of the double precision.

LONG_DOUBLE_STYLE_IEEE_STD

This symbol, if defined, indicates that the long double is the 128-bit IEEE 754.

LONG_DOUBLE_STYLE_VAX

This symbol, if defined, indicates that the long double is the 128-bit VAX format H.

NVMANTBITS

This symbol, if defined, tells how many mantissa bits (not including implicit bit) there are in a Perl NV. This depends on which floating point type was chosen.

NV_OVERFLOWS_INTEGERS_AT

This symbol gives the largest integer value that NVs can hold. This value + 1.0 cannot be stored accurately. It is expressed as constant floating point expression to reduce the chance of decimal/binary conversion issues. If it can not be determined, the value 0 is given.

NV_PRESERVES_UV

This symbol, if defined, indicates that a variable of type NVTYPE can preserve all the bits of a variable of type UVTYPE.

NV_PRESERVES_UV_BITS

This symbol contains the number of bits a variable of type NVTYPE can preserve of a variable of type UVTYPE.

NVSIZE

This symbol contains the sizeof(NV). Note that some floating point formats have unused bytes. The most notable example is the x86* 80-bit extended precision which comes in byte sizes of 12 and 16 (for 32 and 64 bit platforms, respectively), but which only uses 10 bytes. Perl compiled with -Duselongdouble on x86* is like this.

NVTYPE

This symbol defines the C type used for Perl's NV.

NV_ZERO_IS_ALLBITS_ZERO

This symbol, if defined, indicates that a variable of type NVTYPE stores 0.0 in memory as all bits zero.

Formats

These are used for formatting the corresponding type For example, instead of saying

Perl_newSVpvf(pTHX_ "Create an SV with a %d in it\n", iv);

use

Perl_newSVpvf(pTHX_ "Create an SV with a " IVdf " in it\n", iv);

This keeps you from having to know if, say an IV, needs to be printed as %d, %ld, or something else.

IVdf

This symbol defines the format string used for printing a Perl IV as a signed decimal integer.

NVef

This symbol defines the format string used for printing a Perl NV using %e-ish floating point format.

NVff

This symbol defines the format string used for printing a Perl NV using %f-ish floating point format.

NVgf

This symbol defines the format string used for printing a Perl NV using %g-ish floating point format.

PERL_PRIeldbl

This symbol, if defined, contains the string used by stdio to format long doubles (format 'e') for output.

PERL_PRIfldbl

This symbol, if defined, contains the string used by stdio to format long doubles (format 'f') for output.

PERL_PRIgldbl

This symbol, if defined, contains the string used by stdio to format long doubles (format 'g') for output.

PERL_SCNfldbl

This symbol, if defined, contains the string used by stdio to format long doubles (format 'f') for input.

PRINTF_FORMAT_NULL_OK

Allows __printf__ format to be null when checking printf-style

UTF8f

Described in perlguts.

UTF8fARG

Described in perlguts.

    UTF8fARG(bool is_utf8, Size_t byte_len, char *str)
UVof

This symbol defines the format string used for printing a Perl UV as an unsigned octal integer.

UVuf

This symbol defines the format string used for printing a Perl UV as an unsigned decimal integer.

UVXf

This symbol defines the format string used for printing a Perl UV as an unsigned hexadecimal integer in uppercase ABCDEF.

UVxf

This symbol defines the format string used for printing a Perl UV as an unsigned hexadecimal integer in lowercase abcdef.

General Configuration

This section contains configuration information not otherwise found in the more specialized sections of this document. At the end is a list of #defines whose name should be enough to tell you what they do, and a list of #defines which tell you if you need to #include files to get the corresponding functionality.

BYTEORDER

This symbol holds the hexadecimal constant defined in byteorder, in a UV, i.e. 0x1234 or 0x4321 or 0x12345678, etc... If the compiler supports cross-compiling or multiple-architecture binaries, use compiler-defined macros to determine the byte order.

CHARBITS

This symbol contains the size of a char, so that the C preprocessor can make decisions based on it.

DB_VERSION_MAJOR_CFG

This symbol, if defined, defines the major version number of Berkeley DB found in the db.h header when Perl was configured.

DB_VERSION_MINOR_CFG

This symbol, if defined, defines the minor version number of Berkeley DB found in the db.h header when Perl was configured. For DB version 1 this is always 0.

DB_VERSION_PATCH_CFG

This symbol, if defined, defines the patch version number of Berkeley DB found in the db.h header when Perl was configured. For DB version 1 this is always 0.

DEFAULT_INC_EXCLUDES_DOT

This symbol, if defined, removes the legacy default behavior of including '.' at the end of @INC.

DLSYM_NEEDS_UNDERSCORE

This symbol, if defined, indicates that we need to prepend an underscore to the symbol name before calling dlsym(). This only makes sense if you *have* dlsym, which we will presume is the case if you're using dl_dlopen.xs.

EBCDIC

This symbol, if defined, indicates that this system uses EBCDIC encoding.

HAS_CSH

This symbol, if defined, indicates that the C-shell exists.

HAS_GETHOSTNAME

This symbol, if defined, indicates that the C program may use the gethostname() routine to derive the host name. See also "HAS_UNAME" and "PHOSTNAME".

HAS_GNULIBC

This symbol, if defined, indicates to the C program that the GNU C library is being used. A better check is to use the __GLIBC__ and __GLIBC_MINOR__ symbols supplied with glibc.

HAS_LGAMMA

This symbol, if defined, indicates that the lgamma routine is available to do the log gamma function. See also "HAS_TGAMMA" and "HAS_LGAMMA_R".

HAS_LGAMMA_R

This symbol, if defined, indicates that the lgamma_r routine is available to do the log gamma function without using the global signgam variable.

HAS_PRCTL_SET_NAME

This symbol, if defined, indicates that the prctl routine is available to set process title and supports PR_SET_NAME.

HAS_PROCSELFEXE

This symbol is defined if PROCSELFEXE_PATH is a symlink to the absolute pathname of the executing program.

HAS_PSEUDOFORK

This symbol, if defined, indicates that an emulation of the fork routine is available.

HAS_REGCOMP

This symbol, if defined, indicates that the regcomp() routine is available to do some regular pattern matching (usually on POSIX.2 conforming systems).

HAS_SETPGID

This symbol, if defined, indicates that the setpgid(pid, gpid) routine is available to set process group ID.

HAS_SIGSETJMP

This variable indicates to the C program that the sigsetjmp() routine is available to save the calling process's registers and stack environment for later use by siglongjmp(), and to optionally save the process's signal mask. See "Sigjmp_buf", "Sigsetjmp", and "Siglongjmp".

HAS_STRUCT_CMSGHDR

This symbol, if defined, indicates that the struct cmsghdr is supported.

HAS_STRUCT_MSGHDR

This symbol, if defined, indicates that the struct msghdr is supported.

HAS_TGAMMA

This symbol, if defined, indicates that the tgamma routine is available to do the gamma function. See also "HAS_LGAMMA".

HAS_UNAME

This symbol, if defined, indicates that the C program may use the uname() routine to derive the host name. See also "HAS_GETHOSTNAME" and "PHOSTNAME".

HAS_UNION_SEMUN

This symbol, if defined, indicates that the union semun is defined by including sys/sem.h. If not, the user code probably needs to define it as:

union semun {
int val;
struct semid_ds *buf;
unsigned short *array;
}
I_DIRENT

This symbol, if defined, indicates to the C program that it should include dirent.h. Using this symbol also triggers the definition of the Direntry_t define which ends up being 'struct dirent' or 'struct direct' depending on the availability of dirent.h.

    #ifdef I_DIRENT
        #include <dirent.h>
    #endif
I_POLL

This symbol, if defined, indicates that poll.h exists and should be included. (see also "HAS_POLL")

    #ifdef I_POLL
        #include <poll.h>
    #endif
I_SYS_RESOURCE

This symbol, if defined, indicates to the C program that it should include sys/resource.h.

    #ifdef I_SYS_RESOURCE
        #include <sys_resource.h>
    #endif
LIBM_LIB_VERSION

This symbol, if defined, indicates that libm exports _LIB_VERSION and that math.h defines the enum to manipulate it.

NEED_VA_COPY

This symbol, if defined, indicates that the system stores the variable argument list datatype, va_list, in a format that cannot be copied by simple assignment, so that some other means must be used when copying is required. As such systems vary in their provision (or non-provision) of copying mechanisms, handy.h defines a platform- independent macro, Perl_va_copy(src, dst), to do the job.

OSNAME

This symbol contains the name of the operating system, as determined by Configure. You shouldn't rely on it too much; the specific feature tests from Configure are generally more reliable.

OSVERS

This symbol contains the version of the operating system, as determined by Configure. You shouldn't rely on it too much; the specific feature tests from Configure are generally more reliable.

PHOSTNAME

This symbol, if defined, indicates the command to feed to the popen() routine to derive the host name. See also "HAS_GETHOSTNAME" and "HAS_UNAME". Note that the command uses a fully qualified path, so that it is safe even if used by a process with super-user privileges.

PROCSELFEXE_PATH

If HAS_PROCSELFEXE is defined this symbol is the filename of the symbolic link pointing to the absolute pathname of the executing program.

PTRSIZE

This symbol contains the size of a pointer, so that the C preprocessor can make decisions based on it. It will be sizeof(void *) if the compiler supports (void *); otherwise it will be sizeof(char *).

RANDBITS

This symbol indicates how many bits are produced by the function used to generate normalized random numbers. Values include 15, 16, 31, and 48.

SELECT_MIN_BITS

This symbol holds the minimum number of bits operated by select. That is, if you do select(n, ...), how many bits at least will be cleared in the masks if some activity is detected. Usually this is either n or 32*ceil(n/32), especially many little-endians do the latter. This is only useful if you have select(), naturally.

SETUID_SCRIPTS_ARE_SECURE_NOW

This symbol, if defined, indicates that the bug that prevents setuid scripts from being secure is not present in this kernel.

List of capability HAS_foo symbols

This is a list of those symbols that dont appear elsewhere in ths document that indicate if the current platform has a certain capability. Their names all begin with HAS_. Only those symbols whose capability is directly derived from the name are listed here. All others have their meaning expanded out elsewhere in this document. This (relatively) compact list is because we think that the expansion would add little or no value and take up a lot of space (because there are so many). If you think certain ones should be expanded, send email to perl5-porters@perl.org.

Each symbol here will be #defined if and only if the platform has the capability. If you need more detail, see the corresponding entry in config.h. For convenience, the list is split so that the ones that indicate there is a reentrant version of a capability are listed separately

HAS_ACCEPT4, HAS_ACCESS, HAS_ACCESSX, HAS_ACOSH, HAS_AINTL, HAS_ALARM, HAS_ASINH, HAS_ATANH, HAS_ATOLL, HAS_CBRT, HAS_CHOWN, HAS_CHROOT, HAS_CHSIZE, HAS_CLEARENV, HAS_COPYSIGN, HAS_COPYSIGNL, HAS_CRYPT, HAS_CTERMID, HAS_CUSERID, HAS_DIRFD, HAS_DLADDR, HAS_DLERROR, HAS_EACCESS, HAS_ENDHOSTENT, HAS_ENDNETENT, HAS_ENDPROTOENT, HAS_ENDSERVENT, HAS_ERF, HAS_ERFC, HAS_EXP2, HAS_EXPM1, HAS_FCHMOD, HAS_FCHMODAT, HAS_FCHOWN, HAS_FDIM, HAS_FD_SET, HAS_FEGETROUND, HAS_FGETPOS, HAS_FLOCK, HAS_FMA, HAS_FMAX, HAS_FMIN, HAS_FORK, HAS_FSEEKO, HAS_FSETPOS, HAS_FSYNC, HAS_FTELLO, HAS_GAI_STRERROR, HAS_GETADDRINFO, HAS_GETCWD, HAS_GETESPWNAM, HAS_GETGROUPS, HAS_GETHOSTBYADDR, HAS_GETHOSTBYNAME, HAS_GETHOSTENT, HAS_GETLOGIN, HAS_GETNAMEINFO, HAS_GETNETBYADDR, HAS_GETNETBYNAME, HAS_GETNETENT, HAS_GETPAGESIZE, HAS_GETPGID, HAS_GETPGRP, HAS_GETPGRP2, HAS_GETPPID, HAS_GETPRIORITY, HAS_GETPROTOBYNAME, HAS_GETPROTOBYNUMBER, HAS_GETPROTOENT, HAS_GETPRPWNAM, HAS_GETSERVBYNAME, HAS_GETSERVBYPORT, HAS_GETSERVENT, HAS_GETSPNAM, HAS_HTONL, HAS_HTONS, HAS_HYPOT, HAS_ILOGBL, HAS_INETNTOP, HAS_INETPTON, HAS_INET_ATON, HAS_IPV6_MREQ, HAS_IPV6_MREQ_SOURCE, HAS_IP_MREQ, HAS_IP_MREQ_SOURCE, HAS_ISASCII, HAS_ISBLANK, HAS_ISLESS, HAS_KILLPG, HAS_LCHOWN, HAS_LINK, HAS_LINKAT, HAS_LLROUND, HAS_LOCKF, HAS_LOG1P, HAS_LOG2, HAS_LOGB, HAS_LROUND, HAS_LSTAT, HAS_MADVISE, HAS_MBLEN, HAS_MBRLEN, HAS_MBRTOWC, HAS_MBSTOWCS, HAS_MBTOWC, HAS_MEMMEM, HAS_MEMRCHR, HAS_MKDTEMP, HAS_MKFIFO, HAS_MKOSTEMP, HAS_MKSTEMP, HAS_MKSTEMPS, HAS_MMAP, HAS_MPROTECT, HAS_MSG, HAS_MSYNC, HAS_MUNMAP, HAS_NEARBYINT, HAS_NEXTAFTER, HAS_NICE, HAS_NTOHL, HAS_NTOHS, HAS_PATHCONF, HAS_PAUSE, HAS_PHOSTNAME, HAS_PIPE, HAS_PIPE2, HAS_PRCTL, HAS_PTRDIFF_T, HAS_READLINK, HAS_READV, HAS_RECVMSG, HAS_REMQUO, HAS_RENAME, HAS_RENAMEAT, HAS_RINT, HAS_ROUND, HAS_SCALBNL, HAS_SEM, HAS_SENDMSG, HAS_SETEGID, HAS_SETEUID, HAS_SETGROUPS, HAS_SETHOSTENT, HAS_SETLINEBUF, HAS_SETNETENT, HAS_SETPGRP, HAS_SETPGRP2, HAS_SETPRIORITY, HAS_SETPROCTITLE, HAS_SETPROTOENT, HAS_SETREGID, HAS_SETRESGID, HAS_SETRESUID, HAS_SETREUID, HAS_SETRGID, HAS_SETRUID, HAS_SETSERVENT, HAS_SETSID, HAS_SHM, HAS_SIGACTION, HAS_SIGPROCMASK, HAS_SIN6_SCOPE_ID, HAS_SNPRINTF, HAS_STAT, HAS_STRCOLL, HAS_STRERROR_L, HAS_STRLCAT, HAS_STRLCPY, HAS_STRNLEN, HAS_STRTOD, HAS_STRTOL, HAS_STRTOLL, HAS_STRTOQ, HAS_STRTOUL, HAS_STRTOULL, HAS_STRTOUQ, HAS_STRXFRM, HAS_SYMLINK, HAS_SYSCALL, HAS_SYSCONF, HAS_SYSTEM, HAS_SYS_ERRLIST, HAS_TCGETPGRP, HAS_TCSETPGRP, HAS_TOWLOWER, HAS_TOWUPPER, HAS_TRUNCATE, HAS_TRUNCL, HAS_UALARM, HAS_UMASK, HAS_UNLINKAT, HAS_UNSETENV, HAS_VFORK, HAS_VSNPRINTF, HAS_WAIT4, HAS_WAITPID, HAS_WCRTOMB, HAS_WCSCMP, HAS_WCSTOMBS, HAS_WCSXFRM, HAS_WCTOMB, HAS_WRITEV, HAS__FWALK

And, the reentrant capabilities:

HAS_CRYPT_R, HAS_CTERMID_R, HAS_DRAND48_R, HAS_ENDHOSTENT_R, HAS_ENDNETENT_R, HAS_ENDPROTOENT_R, HAS_ENDSERVENT_R, HAS_GETGRGID_R, HAS_GETGRNAM_R, HAS_GETHOSTBYADDR_R, HAS_GETHOSTBYNAME_R, HAS_GETHOSTENT_R, HAS_GETLOGIN_R, HAS_GETNETBYADDR_R, HAS_GETNETBYNAME_R, HAS_GETNETENT_R, HAS_GETPROTOBYNAME_R, HAS_GETPROTOBYNUMBER_R, HAS_GETPROTOENT_R, HAS_GETPWNAM_R, HAS_GETPWUID_R, HAS_GETSERVBYNAME_R, HAS_GETSERVBYPORT_R, HAS_GETSERVENT_R, HAS_GETSPNAM_R, HAS_RANDOM_R, HAS_READDIR_R, HAS_SETHOSTENT_R, HAS_SETNETENT_R, HAS_SETPROTOENT_R, HAS_SETSERVENT_R, HAS_SRAND48_R, HAS_SRANDOM_R, HAS_STRERROR_R, HAS_TMPNAM_R, HAS_TTYNAME_R

Example usage:

List of #include needed symbols

This list contains symbols that indicate if certain #include files are present on the platform. If your code accesses the functionality that one of these is for, you will need to #include it if the symbol on this list is #defined. For more detail, see the corresponding entry in config.h.

I_ARPA_INET, I_BFD, I_CRYPT, I_DBM, I_DLFCN, I_EXECINFO, I_FP, I_FP_CLASS, I_GDBM, I_GDBMNDBM, I_GDBM_NDBM, I_GRP, I_IEEEFP, I_INTTYPES, I_LIBUTIL, I_MNTENT, I_NDBM, I_NETDB, I_NETINET_IN, I_NETINET_TCP, I_NET_ERRNO, I_PROT, I_PWD, I_RPCSVC_DBM, I_SGTTY, I_SHADOW, I_STDBOOL, I_STDINT, I_SUNMATH, I_SYSLOG, I_SYSMODE, I_SYSUIO, I_SYSUTSNAME, I_SYS_ACCESS, I_SYS_IOCTL, I_SYS_MOUNT, I_SYS_PARAM, I_SYS_POLL, I_SYS_SECURITY, I_SYS_SELECT, I_SYS_STAT, I_SYS_STATVFS, I_SYS_TIME, I_SYS_TIMES, I_SYS_TIME_KERNEL, I_SYS_TYPES, I_SYS_UN, I_SYS_VFS, I_SYS_WAIT, I_TERMIO, I_TERMIOS, I_UNISTD, I_USTAT, I_VFORK, I_WCHAR, I_WCTYPE

Example usage:

Global Variables

These variables are global to an entire process. They are shared between all interpreters and all threads in a process. Any variables not documented here may be changed or removed without notice, so don't use them! If you feel you really do need to use an unlisted variable, first send email to perl5-porters@perl.org. It may be that someone there will point out a way to accomplish what you need without using an internal variable. But if not, you should get a go-ahead to document and then use the variable.

PL_check

Array, indexed by opcode, of functions that will be called for the "check" phase of optree building during compilation of Perl code. For most (but not all) types of op, once the op has been initially built and populated with child ops it will be filtered through the check function referenced by the appropriate element of this array. The new op is passed in as the sole argument to the check function, and the check function returns the completed op. The check function may (as the name suggests) check the op for validity and signal errors. It may also initialise or modify parts of the ops, or perform more radical surgery such as adding or removing child ops, or even throw the op away and return a different op in its place.

This array of function pointers is a convenient place to hook into the compilation process. An XS module can put its own custom check function in place of any of the standard ones, to influence the compilation of a particular type of op. However, a custom check function must never fully replace a standard check function (or even a custom check function from another module). A module modifying checking must instead wrap the preexisting check function. A custom check function must be selective about when to apply its custom behaviour. In the usual case where it decides not to do anything special with an op, it must chain the preexisting op function. Check functions are thus linked in a chain, with the core's base checker at the end.

For thread safety, modules should not write directly to this array. Instead, use the function "wrap_op_checker".

PL_keyword_plugin

NOTE: PL_keyword_plugin is experimental and may change or be removed without notice.

Function pointer, pointing at a function used to handle extended keywords. The function should be declared as

int keyword_plugin_function(pTHX_
        char *keyword_ptr, STRLEN keyword_len,
        OP **op_ptr)

The function is called from the tokeniser, whenever a possible keyword is seen. keyword_ptr points at the word in the parser's input buffer, and keyword_len gives its length; it is not null-terminated. The function is expected to examine the word, and possibly other state such as %^H, to decide whether it wants to handle it as an extended keyword. If it does not, the function should return KEYWORD_PLUGIN_DECLINE, and the normal parser process will continue.

If the function wants to handle the keyword, it first must parse anything following the keyword that is part of the syntax introduced by the keyword. See "Lexer interface" for details.

When a keyword is being handled, the plugin function must build a tree of OP structures, representing the code that was parsed. The root of the tree must be stored in *op_ptr. The function then returns a constant indicating the syntactic role of the construct that it has parsed: KEYWORD_PLUGIN_STMT if it is a complete statement, or KEYWORD_PLUGIN_EXPR if it is an expression. Note that a statement construct cannot be used inside an expression (except via do BLOCK and similar), and an expression is not a complete statement (it requires at least a terminating semicolon).

When a keyword is handled, the plugin function may also have (compile-time) side effects. It may modify %^H, define functions, and so on. Typically, if side effects are the main purpose of a handler, it does not wish to generate any ops to be included in the normal compilation. In this case it is still required to supply an op tree, but it suffices to generate a single null op.

That's how the *PL_keyword_plugin function needs to behave overall. Conventionally, however, one does not completely replace the existing handler function. Instead, take a copy of PL_keyword_plugin before assigning your own function pointer to it. Your handler function should look for keywords that it is interested in and handle those. Where it is not interested, it should call the saved plugin function, passing on the arguments it received. Thus PL_keyword_plugin actually points at a chain of handler functions, all of which have an opportunity to handle keywords, and only the last function in the chain (built into the Perl core) will normally return KEYWORD_PLUGIN_DECLINE.

For thread safety, modules should not set this variable directly. Instead, use the function "wrap_keyword_plugin".

PL_phase

A value that indicates the current Perl interpreter's phase. Possible values include PERL_PHASE_CONSTRUCT, PERL_PHASE_START, PERL_PHASE_CHECK, PERL_PHASE_INIT, PERL_PHASE_RUN, PERL_PHASE_END, and PERL_PHASE_DESTRUCT.

For example, the following determines whether the interpreter is in global destruction:

if (PL_phase == PERL_PHASE_DESTRUCT) {
    // we are in global destruction
}

PL_phase was introduced in Perl 5.14; in prior perls you can use PL_dirty (boolean) to determine whether the interpreter is in global destruction. (Use of PL_dirty is discouraged since 5.14.)

    enum perl_phase  PL_phase

GV Handling

A GV is a structure which corresponds to to a Perl typeglob, ie *foo. It is a structure that holds a pointer to a scalar, an array, a hash etc, corresponding to $foo, @foo, %foo.

GVs are usually found as values in stashes (symbol table hashes) where Perl stores its global variables.

gv_autoload4

Equivalent to "gv_autoload_pvn".

    GV*  gv_autoload4(HV* stash, const char* name, STRLEN len,
                      I32 method)
GvAV

Return the AV from the GV.

    AV*  GvAV(GV* gv)
gv_const_sv

If gv is a typeglob whose subroutine entry is a constant sub eligible for inlining, or gv is a placeholder reference that would be promoted to such a typeglob, then returns the value returned by the sub. Otherwise, returns NULL.

    SV*  gv_const_sv(GV* gv)
GvCV

Return the CV from the GV.

    CV*  GvCV(GV* gv)
gv_fetchfile
gv_fetchfile_flags

These return the debugger glob for the file (compiled by Perl) whose name is given by the name parameter.

There are currently exactly two differences between these functions.

The name parameter to gv_fetchfile is a C string, meaning it is NUL-terminated; whereas the name parameter to gv_fetchfile_flags is a Perl string, whose length (in bytes) is passed in via the namelen parameter This means the name may contain embedded NUL characters. namelen doesn't exist in plain gv_fetchfile).

The other difference is that gv_fetchfile_flags has an extra flags parameter, which is currently completely ignored, but allows for possible future extensions.

    GV*  gv_fetchfile      (const char* name)
    GV*  gv_fetchfile_flags(const char *const name, const STRLEN len,
                            const U32 flags)
gv_fetchmeth

Like "gv_fetchmeth_pvn", but lacks a flags parameter.

    GV*  gv_fetchmeth(HV* stash, const char* name, STRLEN len,
                      I32 level)
gv_fetchmethod

See "gv_fetchmethod_autoload".

    GV*  gv_fetchmethod(HV* stash, const char* name)
gv_fetchmethod_autoload

Returns the glob which contains the subroutine to call to invoke the method on the stash. In fact in the presence of autoloading this may be the glob for "AUTOLOAD". In this case the corresponding variable $AUTOLOAD is already setup.

The third parameter of gv_fetchmethod_autoload determines whether AUTOLOAD lookup is performed if the given method is not present: non-zero means yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling gv_fetchmethod is equivalent to calling gv_fetchmethod_autoload with a non-zero autoload parameter.

These functions grant "SUPER" token as a prefix of the method name. Note that if you want to keep the returned glob for a long time, you need to check for it being "AUTOLOAD", since at the later time the call may load a different subroutine due to $AUTOLOAD changing its value. Use the glob created as a side effect to do this.

These functions have the same side-effects as gv_fetchmeth with level==0. The warning against passing the GV returned by gv_fetchmeth to call_sv applies equally to these functions.

    GV*  gv_fetchmethod_autoload(HV* stash, const char* name,
                                 I32 autoload)
gv_fetchmeth_autoload

This is the old form of "gv_fetchmeth_pvn_autoload", which has no flags parameter.

    GV*  gv_fetchmeth_autoload(HV* stash, const char* name,
                               STRLEN len, I32 level)
gv_fetchmeth_pv

Exactly like "gv_fetchmeth_pvn", but takes a nul-terminated string instead of a string/length pair.

    GV*  gv_fetchmeth_pv(HV* stash, const char* name, I32 level,
                         U32 flags)
gv_fetchmeth_pvn

Returns the glob with the given name and a defined subroutine or NULL. The glob lives in the given stash, or in the stashes accessible via @ISA and UNIVERSAL::.

The argument level should be either 0 or -1. If level==0, as a side-effect creates a glob with the given name in the given stash which in the case of success contains an alias for the subroutine, and sets up caching info for this glob.

The only significant values for flags are GV_SUPER, GV_NOUNIVERSAL, and SVf_UTF8.

GV_SUPER indicates that we want to look up the method in the superclasses of the stash.

GV_NOUNIVERSAL indicates that we do not want to look up the method in the stash accessible by UNIVERSAL::.

The GV returned from gv_fetchmeth may be a method cache entry, which is not visible to Perl code. So when calling call_sv, you should not use the GV directly; instead, you should use the method's CV, which can be obtained from the GV with the GvCV macro.

    GV*  gv_fetchmeth_pvn(HV* stash, const char* name, STRLEN len,
                          I32 level, U32 flags)
gv_fetchmeth_pvn_autoload

Same as gv_fetchmeth_pvn(), but looks for autoloaded subroutines too. Returns a glob for the subroutine.

For an autoloaded subroutine without a GV, will create a GV even if level < 0. For an autoloaded subroutine without a stub, GvCV() of the result may be zero.

Currently, the only significant value for flags is SVf_UTF8.

    GV*  gv_fetchmeth_pvn_autoload(HV* stash, const char* name,
                                   STRLEN len, I32 level, U32 flags)
gv_fetchmeth_pv_autoload

Exactly like "gv_fetchmeth_pvn_autoload", but takes a nul-terminated string instead of a string/length pair.

    GV*  gv_fetchmeth_pv_autoload(HV* stash, const char* name,
                                  I32 level, U32 flags)
gv_fetchmeth_sv

Exactly like "gv_fetchmeth_pvn", but takes the name string in the form of an SV instead of a string/length pair.

    GV*  gv_fetchmeth_sv(HV* stash, SV* namesv, I32 level, U32 flags)
gv_fetchmeth_sv_autoload

Exactly like "gv_fetchmeth_pvn_autoload", but takes the name string in the form of an SV instead of a string/length pair.

    GV*  gv_fetchmeth_sv_autoload(HV* stash, SV* namesv, I32 level,
                                  U32 flags)
gv_fetchpv
gv_fetchpvn
gv_fetchpvn_flags
gv_fetchpvs
gv_fetchsv
gv_fetchsv_nomg

These all return the GV of type sv_type whose name is given by the inputs, or NULL if no GV of that name and type could be found. See "Stashes and Globs" in perlguts.

The only differences are how the input name is specified, and if 'get' magic is normally used in getting that name.

Don't be fooled by the fact that only one form has flags in its name. They all have a flags parameter in fact, and all the flag bits have the same meanings for all

If any of the flags GV_ADD, GV_ADDMG, GV_ADDWARN, GV_ADDMULTI, or GV_NOINIT is set, a GV is created if none already exists for the input name and type. However, GV_ADDMG will only do the creation for magical GV's. For all of these flags except GV_NOINIT, "gv_init_pvn" is called after the addition. GV_ADDWARN is used when the caller expects that adding won't be necessary because the symbol should already exist; but if not, add it anyway, with a warning that it was unexpectedly absent. The GV_ADDMULTI flag means to pretend that the GV has been seen before (i.e., suppress "Used once" warnings).

The flag GV_NOADD_NOINIT causes "gv_init_pvn" not be to called if the GV existed but isn't PVGV.

If the SVf_UTF8 bit is set, the name is treated as being encoded in UTF-8; otherwise the name won't be considered to be UTF-8 in the pv-named forms, and the UTF-8ness of the underlying SVs will be used in the sv forms.

If the flag GV_NOTQUAL is set, the caller warrants that the input name is a plain symbol name, not qualified with a package, otherwise the name is checked for being a qualified one.

In gv_fetchpv, nambeg is a C string, NUL-terminated with no intermediate NULs.

In gv_fetchpvs, name is a literal C string, hence is enclosed in double quotes.

gv_fetchpvn and gv_fetchpvn_flags are identical. In these, <nambeg> is a Perl string whose byte length is given by full_len, and may contain embedded NULs.

In gv_fetchsv and gv_fetchsv_nomg, the name is extracted from the PV of the input name SV. The only difference between these two forms is that 'get' magic is normally done on name in gv_fetchsv, and always skipped with gv_fetchsv_nomg. Including GV_NO_SVGMAGIC in the flags parameter to gv_fetchsv makes it behave identically to gv_fetchsv_nomg.

    GV*   gv_fetchpv       (const char *nambeg, I32 flags,
                            const svtype sv_type)
    GV *  gv_fetchpvn      (const char * nambeg, STRLEN full_len,
                            I32 flags, const svtype sv_type)
    GV*   gv_fetchpvn_flags(const char* name, STRLEN len, I32 flags,
                            const svtype sv_type)
    GV *  gv_fetchpvs      ("name", I32 flags, const svtype sv_type)
    GV*   gv_fetchsv       (SV *name, I32 flags, const svtype sv_type)
    GV *  gv_fetchsv_nomg  (SV *name, I32 flags, const svtype sv_type)
GvHV

Return the HV from the GV.

    HV*  GvHV(GV* gv)
gv_init

The old form of gv_init_pvn(). It does not work with UTF-8 strings, as it has no flags parameter. If the multi parameter is set, the GV_ADDMULTI flag will be passed to gv_init_pvn().

    void  gv_init(GV* gv, HV* stash, const char* name, STRLEN len,
                  int multi)
gv_init_pv

Same as gv_init_pvn(), but takes a nul-terminated string for the name instead of separate char * and length parameters.

    void  gv_init_pv(GV* gv, HV* stash, const char* name, U32 flags)
gv_init_pvn

Converts a scalar into a typeglob. This is an incoercible typeglob; assigning a reference to it will assign to one of its slots, instead of overwriting it as happens with typeglobs created by SvSetSV. Converting any scalar that is SvOK() may produce unpredictable results and is reserved for perl's internal use.

gv is the scalar to be converted.

stash is the parent stash/package, if any.

name and len give the name. The name must be unqualified; that is, it must not include the package name. If gv is a stash element, it is the caller's responsibility to ensure that the name passed to this function matches the name of the element. If it does not match, perl's internal bookkeeping will get out of sync.

flags can be set to SVf_UTF8 if name is a UTF-8 string, or the return value of SvUTF8(sv). It can also take the GV_ADDMULTI flag, which means to pretend that the GV has been seen before (i.e., suppress "Used once" warnings).

    void  gv_init_pvn(GV* gv, HV* stash, const char* name, STRLEN len,
                      U32 flags)
gv_init_sv

Same as gv_init_pvn(), but takes an SV * for the name instead of separate char * and length parameters. flags is currently unused.

    void  gv_init_sv(GV* gv, HV* stash, SV* namesv, U32 flags)
gv_stashpv

Returns a pointer to the stash for a specified package. Uses strlen to determine the length of name, then calls gv_stashpvn().

    HV*  gv_stashpv(const char* name, I32 flags)
gv_stashpvn

Returns a pointer to the stash for a specified package. The namelen parameter indicates the length of the name, in bytes. flags is passed to gv_fetchpvn_flags(), so if set to GV_ADD then the package will be created if it does not already exist. If the package does not exist and flags is 0 (or any other setting that does not create packages) then NULL is returned.

Flags may be one of:

GV_ADD           Create and initialize the package if doesn't
                 already exist
GV_NOADD_NOINIT  Don't create the package,
GV_ADDMG         GV_ADD iff the GV is magical
GV_NOINIT        GV_ADD, but don't initialize
GV_NOEXPAND      Don't expand SvOK() entries to PVGV
SVf_UTF8         The name is in UTF-8

The most important of which are probably GV_ADD and SVf_UTF8.

Note, use of gv_stashsv instead of gv_stashpvn where possible is strongly recommended for performance reasons.

    HV*  gv_stashpvn(const char* name, U32 namelen, I32 flags)
gv_stashpvs

Like gv_stashpvn, but takes a literal string instead of a string/length pair.

    HV*  gv_stashpvs("name", I32 create)
gv_stashsv

Returns a pointer to the stash for a specified package. See "gv_stashpvn".

Note this interface is strongly preferred over gv_stashpvn for performance reasons.

    HV*  gv_stashsv(SV* sv, I32 flags)
GvSV

Return the SV from the GV.

Prior to Perl v5.9.3, this would add a scalar if none existed. Nowadays, use "GvSVn" for that, or compile perl with -DPERL_CREATE_GVSV. See perl5100delta.

    SV*  GvSV(GV* gv)
GvSVn

Like "GvSV", but creates an empty scalar if none already exists.

    SV*  GvSVn(GV* gv)
save_gp

Saves the current GP of gv on the save stack to be restored on scope exit.

If empty is true, replace the GP with a new GP.

If empty is false, mark gv with GVf_INTRO so the next reference assigned is localized, which is how local *foo = $someref; works.

    void  save_gp(GV* gv, I32 empty)
setdefout

Sets PL_defoutgv, the default file handle for output, to the passed in typeglob. As PL_defoutgv "owns" a reference on its typeglob, the reference count of the passed in typeglob is increased by one, and the reference count of the typeglob that PL_defoutgv points to is decreased by one.

    void  setdefout(GV* gv)

Hook manipulation

These functions provide convenient and thread-safe means of manipulating hook variables.

wrap_op_checker

Puts a C function into the chain of check functions for a specified op type. This is the preferred way to manipulate the "PL_check" array. opcode specifies which type of op is to be affected. new_checker is a pointer to the C function that is to be added to that opcode's check chain, and old_checker_p points to the storage location where a pointer to the next function in the chain will be stored. The value of new_checker is written into the "PL_check" array, while the value previously stored there is written to *old_checker_p.

"PL_check" is global to an entire process, and a module wishing to hook op checking may find itself invoked more than once per process, typically in different threads. To handle that situation, this function is idempotent. The location *old_checker_p must initially (once per process) contain a null pointer. A C variable of static duration (declared at file scope, typically also marked static to give it internal linkage) will be implicitly initialised appropriately, if it does not have an explicit initialiser. This function will only actually modify the check chain if it finds *old_checker_p to be null. This function is also thread safe on the small scale. It uses appropriate locking to avoid race conditions in accessing "PL_check".

When this function is called, the function referenced by new_checker must be ready to be called, except for *old_checker_p being unfilled. In a threading situation, new_checker may be called immediately, even before this function has returned. *old_checker_p will always be appropriately set before new_checker is called. If new_checker decides not to do anything special with an op that it is given (which is the usual case for most uses of op check hooking), it must chain the check function referenced by *old_checker_p.

Taken all together, XS code to hook an op checker should typically look something like this:

static Perl_check_t nxck_frob;
static OP *myck_frob(pTHX_ OP *op) {
    ...
    op = nxck_frob(aTHX_ op);
    ...
    return op;
}
BOOT:
    wrap_op_checker(OP_FROB, myck_frob, &nxck_frob);

If you want to influence compilation of calls to a specific subroutine, then use "cv_set_call_checker_flags" rather than hooking checking of all entersub ops.

    void  wrap_op_checker(Optype opcode, Perl_check_t new_checker,
                          Perl_check_t *old_checker_p)

HV Handling

A HV structure represents a Perl hash. It consists mainly of an array of pointers, each of which points to a linked list of HE structures. The array is indexed by the hash function of the key, so each linked list represents all the hash entries with the same hash value. Each HE contains a pointer to the actual value, plus a pointer to a HEK structure which holds the key and hash value.

get_hv

Returns the HV of the specified Perl hash. flags are passed to gv_fetchpv. If GV_ADD is set and the Perl variable does not exist then it will be created. If flags is zero and the variable does not exist then NULL is returned.

NOTE: the perl_get_hv() form is deprecated.

    HV*  get_hv(const char *name, I32 flags)
HEf_SVKEY

This flag, used in the length slot of hash entries and magic structures, specifies the structure contains an SV* pointer where a char* pointer is to be expected. (For information only--not to be used).

HeHASH

Returns the computed hash stored in the hash entry.

    U32  HeHASH(HE* he)
HeKEY

Returns the actual pointer stored in the key slot of the hash entry. The pointer may be either char* or SV*, depending on the value of HeKLEN(). Can be assigned to. The HePV() or HeSVKEY() macros are usually preferable for finding the value of a key.

    void*  HeKEY(HE* he)
HeKLEN

If this is negative, and amounts to HEf_SVKEY, it indicates the entry holds an SV* key. Otherwise, holds the actual length of the key. Can be assigned to. The HePV() macro is usually preferable for finding key lengths.

    STRLEN  HeKLEN(HE* he)
HePV

Returns the key slot of the hash entry as a char* value, doing any necessary dereferencing of possibly SV* keys. The length of the string is placed in len (this is a macro, so do not use &len). If you do not care about what the length of the key is, you may use the global variable PL_na, though this is rather less efficient than using a local variable. Remember though, that hash keys in perl are free to contain embedded nulls, so using strlen() or similar is not a good way to find the length of hash keys. This is very similar to the SvPV() macro described elsewhere in this document. See also "HeUTF8".

If you are using HePV to get values to pass to newSVpvn() to create a new SV, you should consider using newSVhek(HeKEY_hek(he)) as it is more efficient.

    char*  HePV(HE* he, STRLEN len)
HeSVKEY

Returns the key as an SV*, or NULL if the hash entry does not contain an SV* key.

    SV*  HeSVKEY(HE* he)
HeSVKEY_force

Returns the key as an SV*. Will create and return a temporary mortal SV* if the hash entry contains only a char* key.

    SV*  HeSVKEY_force(HE* he)
HeSVKEY_set

Sets the key to a given SV*, taking care to set the appropriate flags to indicate the presence of an SV* key, and returns the same SV*.

    SV*  HeSVKEY_set(HE* he, SV* sv)
HeUTF8

Returns whether the char * value returned by HePV is encoded in UTF-8, doing any necessary dereferencing of possibly SV* keys. The value returned will be 0 or non-0, not necessarily 1 (or even a value with any low bits set), so do not blindly assign this to a bool variable, as bool may be a typedef for char.

    U32  HeUTF8(HE* he)
HeVAL

Returns the value slot (type SV*) stored in the hash entry. Can be assigned to.

SV *foo= HeVAL(hv);
HeVAL(hv)= sv;
    SV*  HeVAL(HE* he)
HV

Described in perlguts.

hv_assert

Check that a hash is in an internally consistent state.

NOTE: hv_assert must be explicitly called as Perl_hv_assert with an aTHX_ parameter.

    void  Perl_hv_assert(pTHX_ HV *hv)
hv_bucket_ratio

NOTE: hv_bucket_ratio is experimental and may change or be removed without notice.

If the hash is tied dispatches through to the SCALAR tied method, otherwise if the hash contains no keys returns 0, otherwise returns a mortal sv containing a string specifying the number of used buckets, followed by a slash, followed by the number of available buckets.

This function is expensive, it must scan all of the buckets to determine which are used, and the count is NOT cached. In a large hash this could be a lot of buckets.

    SV*  hv_bucket_ratio(HV *hv)
hv_clear

Frees all the elements of a hash, leaving it empty. The XS equivalent of %hash = (). See also "hv_undef".

See "av_clear" for a note about the hash possibly being invalid on return.

    void  hv_clear(HV *hv)
hv_clear_placeholders

Clears any placeholders from a hash. If a restricted hash has any of its keys marked as readonly and the key is subsequently deleted, the key is not actually deleted but is marked by assigning it a value of &PL_sv_placeholder. This tags it so it will be ignored by future operations such as iterating over the hash, but will still allow the hash to have a value reassigned to the key at some future point. This function clears any such placeholder keys from the hash. See Hash::Util::lock_keys() for an example of its use.

    void  hv_clear_placeholders(HV *hv)
hv_copy_hints_hv

A specialised version of "newHVhv" for copying %^H. ohv must be a pointer to a hash (which may have %^H magic, but should be generally non-magical), or NULL (interpreted as an empty hash). The content of ohv is copied to a new hash, which has the %^H-specific magic added to it. A pointer to the new hash is returned.

    HV *  hv_copy_hints_hv(HV *const ohv)
hv_delete

Deletes a key/value pair in the hash. The value's SV is removed from the hash, made mortal, and returned to the caller. The absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode. The flags value will normally be zero; if set to G_DISCARD then NULL will be returned. NULL will also be returned if the key is not found.

    SV*  hv_delete(HV *hv, const char *key, I32 klen, I32 flags)
hv_delete_ent

Deletes a key/value pair in the hash. The value SV is removed from the hash, made mortal, and returned to the caller. The flags value will normally be zero; if set to G_DISCARD then NULL will be returned. NULL will also be returned if the key is not found. hash can be a valid precomputed hash value, or 0 to ask for it to be computed.

    SV*  hv_delete_ent(HV *hv, SV *keysv, I32 flags, U32 hash)
HvENAME

Returns the effective name of a stash, or NULL if there is none. The effective name represents a location in the symbol table where this stash resides. It is updated automatically when packages are aliased or deleted. A stash that is no longer in the symbol table has no effective name. This name is preferable to HvNAME for use in MRO linearisations and isa caches.

    char*  HvENAME(HV* stash)
HvENAMELEN

Returns the length of the stash's effective name.

    STRLEN  HvENAMELEN(HV *stash)
HvENAMEUTF8

Returns true if the effective name is in UTF-8 encoding.

    unsigned char  HvENAMEUTF8(HV *stash)
hv_exists

Returns a boolean indicating whether the specified hash key exists. The absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode.

    bool  hv_exists(HV *hv, const char *key, I32 klen)
hv_exists_ent

Returns a boolean indicating whether the specified hash key exists. hash can be a valid precomputed hash value, or 0 to ask for it to be computed.

    bool  hv_exists_ent(HV *hv, SV *keysv, U32 hash)
hv_fetch

Returns the SV which corresponds to the specified key in the hash. The absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode. If lval is set then the fetch will be part of a store. This means that if there is no value in the hash associated with the given key, then one is created and a pointer to it is returned. The SV* it points to can be assigned to. But always check that the return value is non-null before dereferencing it to an SV*.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

    SV**  hv_fetch(HV *hv, const char *key, I32 klen, I32 lval)
hv_fetchs

Like hv_fetch, but takes a literal string instead of a string/length pair.

    SV**  hv_fetchs(HV* tb, "key", I32 lval)
hv_fetch_ent

Returns the hash entry which corresponds to the specified key in the hash. hash must be a valid precomputed hash number for the given key, or 0 if you want the function to compute it. IF lval is set then the fetch will be part of a store. Make sure the return value is non-null before accessing it. The return value when hv is a tied hash is a pointer to a static location, so be sure to make a copy of the structure if you need to store it somewhere.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

    HE*  hv_fetch_ent(HV *hv, SV *keysv, I32 lval, U32 hash)
HvFILL

See "hv_fill".

    STRLEN  HvFILL(HV *const hv)
hv_fill

Returns the number of hash buckets that happen to be in use.

This function is wrapped by the macro HvFILL.

As of perl 5.25 this function is used only for debugging purposes, and the number of used hash buckets is not in any way cached, thus this function can be costly to execute as it must iterate over all the buckets in the hash.

NOTE: hv_fill must be explicitly called as Perl_hv_fill with an aTHX_ parameter.

    STRLEN  Perl_hv_fill(pTHX_ HV *const hv)
hv_iterinit

Prepares a starting point to traverse a hash table. Returns the number of keys in the hash, including placeholders (i.e. the same as HvTOTALKEYS(hv)). The return value is currently only meaningful for hashes without tie magic.

NOTE: Before version 5.004_65, hv_iterinit used to return the number of hash buckets that happen to be in use. If you still need that esoteric value, you can get it through the macro HvFILL(hv).

    I32  hv_iterinit(HV *hv)
hv_iterkey

Returns the key from the current position of the hash iterator. See "hv_iterinit".

    char*  hv_iterkey(HE* entry, I32* retlen)
hv_iterkeysv

Returns the key as an SV* from the current position of the hash iterator. The return value will always be a mortal copy of the key. Also see "hv_iterinit".

    SV*  hv_iterkeysv(HE* entry)
hv_iternext

Returns entries from a hash iterator. See "hv_iterinit".

You may call hv_delete or hv_delete_ent on the hash entry that the iterator currently points to, without losing your place or invalidating your iterator. Note that in this case the current entry is deleted from the hash with your iterator holding the last reference to it. Your iterator is flagged to free the entry on the next call to hv_iternext, so you must not discard your iterator immediately else the entry will leak - call hv_iternext to trigger the resource deallocation.

    HE*  hv_iternext(HV *hv)
hv_iternextsv

Performs an hv_iternext, hv_iterkey, and hv_iterval in one operation.

    SV*  hv_iternextsv(HV *hv, char **key, I32 *retlen)
hv_iternext_flags

NOTE: hv_iternext_flags is experimental and may change or be removed without notice.

Returns entries from a hash iterator. See "hv_iterinit" and "hv_iternext". The flags value will normally be zero; if HV_ITERNEXT_WANTPLACEHOLDERS is set the placeholders keys (for restricted hashes) will be returned in addition to normal keys. By default placeholders are automatically skipped over. Currently a placeholder is implemented with a value that is &PL_sv_placeholder. Note that the implementation of placeholders and restricted hashes may change, and the implementation currently is insufficiently abstracted for any change to be tidy.

    HE*  hv_iternext_flags(HV *hv, I32 flags)
hv_iterval

Returns the value from the current position of the hash iterator. See "hv_iterkey".

    SV*  hv_iterval(HV *hv, HE *entry)
hv_magic

Adds magic to a hash. See "sv_magic".

    void  hv_magic(HV *hv, GV *gv, int how)
HvNAME

Returns the package name of a stash, or NULL if stash isn't a stash. See "SvSTASH", "CvSTASH".

    char*  HvNAME(HV* stash)
HvNAMELEN

Returns the length of the stash's name.

Disfavored forms of HvNAME and HvNAMELEN; suppress mention of them

    STRLEN  HvNAMELEN(HV *stash)
HvNAMEUTF8

Returns true if the name is in UTF-8 encoding.

    unsigned char  HvNAMEUTF8(HV *stash)
hv_scalar

Evaluates the hash in scalar context and returns the result.

When the hash is tied dispatches through to the SCALAR method, otherwise returns a mortal SV containing the number of keys in the hash.

Note, prior to 5.25 this function returned what is now returned by the hv_bucket_ratio() function.

    SV*  hv_scalar(HV *hv)
hv_store

Stores an SV in a hash. The hash key is specified as key and the absolute value of klen is the length of the key. If klen is negative the key is assumed to be in UTF-8-encoded Unicode. The hash parameter is the precomputed hash value; if it is zero then Perl will compute it.

The return value will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise it can be dereferenced to get the original SV*. Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store takes ownership of one reference to val. This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

    SV**  hv_store(HV *hv, const char *key, I32 klen, SV *val,
                   U32 hash)
hv_stores

Like hv_store, but takes a literal string instead of a string/length pair and omits the hash parameter.

    SV**  hv_stores(HV* tb, "key", SV* val)
hv_store_ent

Stores val in a hash. The hash key is specified as key. The hash parameter is the precomputed hash value; if it is zero then Perl will compute it. The return value is the new hash entry so created. It will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise the contents of the return value can be accessed using the He? macros described here. Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store_ent takes ownership of one reference to val. This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. Note that hv_store_ent only reads the key; unlike val it does not take ownership of it, so maintaining the correct reference count on key is entirely the caller's responsibility. The reason it does not take ownership, is that key is not used after this function returns, and so can be freed immediately. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

    HE*  hv_store_ent(HV *hv, SV *key, SV *val, U32 hash)
hv_undef

Undefines the hash. The XS equivalent of undef(%hash).

As well as freeing all the elements of the hash (like hv_clear()), this also frees any auxiliary data and storage associated with the hash.

See "av_clear" for a note about the hash possibly being invalid on return.

    void  hv_undef(HV *hv)
MGVTBL

Described in perlguts.

newHV

Creates a new HV. The reference count is set to 1.

    HV*  newHV()
Nullhv

DEPRECATED! It is planned to remove Nullhv from a future release of Perl. Do not use it for new code; remove it from existing code.

Null HV pointer.

(deprecated - use (HV *)NULL instead)

PERL_HASH

Described in perlguts.

    void  PERL_HASH(U32 hash, char *key, STRLEN klen)
PERL_MAGIC_arylen
PERL_MAGIC_arylen_p
PERL_MAGIC_backref
PERL_MAGIC_bm
PERL_MAGIC_checkcall
PERL_MAGIC_collxfrm
PERL_MAGIC_dbfile
PERL_MAGIC_dbline
PERL_MAGIC_debugvar
PERL_MAGIC_defelem
PERL_MAGIC_env
PERL_MAGIC_envelem
PERL_MAGIC_ext
PERL_MAGIC_fm
PERL_MAGIC_hints
PERL_MAGIC_hintselem
PERL_MAGIC_isa
PERL_MAGIC_isaelem
PERL_MAGIC_lvref
PERL_MAGIC_nkeys
PERL_MAGIC_nonelem
PERL_MAGIC_overload_table
PERL_MAGIC_pos
PERL_MAGIC_qr
PERL_MAGIC_regdata
PERL_MAGIC_regdatum
PERL_MAGIC_regex_global
PERL_MAGIC_rhash
PERL_MAGIC_shared
PERL_MAGIC_shared_scalar
PERL_MAGIC_sig
PERL_MAGIC_sigelem
PERL_MAGIC_substr
PERL_MAGIC_sv
PERL_MAGIC_symtab
PERL_MAGIC_taint
PERL_MAGIC_tied
PERL_MAGIC_tiedelem
PERL_MAGIC_tiedscalar
PERL_MAGIC_utf8
PERL_MAGIC_uvar
PERL_MAGIC_uvar_elem
PERL_MAGIC_vec
PERL_MAGIC_vstring

Described in perlguts.

PL_modglobal

PL_modglobal is a general purpose, interpreter global HV for use by extensions that need to keep information on a per-interpreter basis. In a pinch, it can also be used as a symbol table for extensions to share data among each other. It is a good idea to use keys prefixed by the package name of the extension that owns the data.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    HV*  PL_modglobal

Input/Output

PerlIO_apply_layers

Described in perlapio.

    int  PerlIO_apply_layers(PerlIO *f, const char *mode,
                             const char *layers)
PerlIO_binmode

Described in perlapio.

    int  PerlIO_binmode(PerlIO *f, int ptype, int imode,
                        const char *layers)
PerlIO_canset_cnt

Described in perlapio.

    int  PerlIO_canset_cnt(PerlIO *f)
PerlIO_clearerr

Described in perlapio.

    void  PerlIO_clearerr(PerlIO *f)
PerlIO_close

Described in perlapio.

    int  PerlIO_close(PerlIO *f)
PerlIO_debug

Described in perlapio.

    void  PerlIO_debug(const char *fmt, ...)
PerlIO_eof

Described in perlapio.

    int  PerlIO_eof(PerlIO *f)
PerlIO_error

Described in perlapio.

    int  PerlIO_error(PerlIO *f)
PerlIO_exportFILE

Described in perlapio.

    FILE  *  PerlIO_exportFILE(PerlIO *f, const char *mode)
PerlIO_fast_gets

Described in perlapio.

    int  PerlIO_fast_gets(PerlIO *f)
PerlIO_fdopen

Described in perlapio.

    PerlIO*  PerlIO_fdopen(int fd, const char *mode)
PerlIO_fileno

Described in perlapio.

    int  PerlIO_fileno(PerlIO *f)
PerlIO_findFILE

Described in perlapio.

    FILE  *  PerlIO_findFILE(PerlIO *f)
PerlIO_flush

Described in perlapio.

    int  PerlIO_flush(PerlIO *f)
PERLIO_F_APPEND
PERLIO_F_CANREAD
PERLIO_F_CANWRITE
PERLIO_F_CRLF
PERLIO_F_EOF
PERLIO_F_ERROR
PERLIO_F_FASTGETS
PERLIO_F_LINEBUF
PERLIO_F_OPEN
PERLIO_F_RDBUF
PERLIO_F_TEMP
PERLIO_F_TRUNCATE
PERLIO_F_UNBUF
PERLIO_F_UTF8
PERLIO_F_WRBUF

Described in perliol.

PerlIO_getc

Described in perlapio.

    int  PerlIO_getc(PerlIO *d)
PerlIO_getpos

Described in perlapio.

    int  PerlIO_getpos(PerlIO *f, SV *save)
PerlIO_get_base

Described in perlapio.

    STDCHAR *  PerlIO_get_base(PerlIO *f)
PerlIO_get_bufsiz

Described in perlapio.

    SSize_t  PerlIO_get_bufsiz(PerlIO *f)
PerlIO_get_cnt

Described in perlapio.

    SSize_t  PerlIO_get_cnt(PerlIO *f)
PerlIO_get_ptr

Described in perlapio.

    STDCHAR *  PerlIO_get_ptr(PerlIO *f)
PerlIO_has_base

Described in perlapio.

    int  PerlIO_has_base(PerlIO *f)
PerlIO_has_cntptr

Described in perlapio.

    int  PerlIO_has_cntptr(PerlIO *f)
PerlIO_importFILE

Described in perlapio.

    PerlIO*  PerlIO_importFILE(FILE *stdio, const char *mode)
PERLIO_K_BUFFERED
PERLIO_K_CANCRLF
PERLIO_K_FASTGETS
PERLIO_K_MULTIARG
PERLIO_K_RAW

Described in perliol.

PerlIO_open

Described in perlapio.

    PerlIO*  PerlIO_open(const char *path, const char *mode)
PerlIO_printf

Described in perlapio.

    int  PerlIO_printf(PerlIO *f, const char *fmt, ...)
PerlIO_putc

Described in perlapio.

    int  PerlIO_putc(PerlIO *f, int ch)
PerlIO_puts

Described in perlapio.

    int  PerlIO_puts(PerlIO *f, const char *string)
PerlIO_read

Described in perlapio.

    SSize_t  PerlIO_read(PerlIO *f, void *vbuf, Size_t count)
PerlIO_releaseFILE

Described in perlapio.

    void  PerlIO_releaseFILE(PerlIO *f, FILE *stdio)
PerlIO_reopen

Described in perlapio.

    PerlIO *  PerlIO_reopen(const char *path, const char *mode,
                            PerlIO *old)
PerlIO_rewind

Described in perlapio.

    void  PerlIO_rewind(PerlIO *f)
PerlIO_seek

Described in perlapio.

    int  PerlIO_seek(PerlIO *f, Off_t offset, int whence)
PerlIO_setlinebuf

Described in perlapio.

    void  PerlIO_setlinebuf(PerlIO *f)
PerlIO_setpos

Described in perlapio.

    int  PerlIO_setpos(PerlIO *f, SV *saved)
PerlIO_set_cnt

Described in perlapio.

    void  PerlIO_set_cnt(PerlIO *f, SSize_t cnt)
PerlIO_set_ptrcnt

Described in perlapio.

    void  PerlIO_set_ptrcnt(PerlIO *f, STDCHAR *ptr, SSize_t cnt)
PerlIO_stderr

Described in perlapio.

    PerlIO *  PerlIO_stderr()
PerlIO_stdin

Described in perlapio.

    PerlIO *  PerlIO_stdin()
PerlIO_stdout

Described in perlapio.

    PerlIO *  PerlIO_stdout()
PerlIO_stdoutf

Described in perlapio.

    int  PerlIO_stdoutf(const char *fmt, ...)
PerlIO_tell

Described in perlapio.

    Off_t  PerlIO_tell(PerlIO *f)
PerlIO_ungetc

Described in perlapio.

    int  PerlIO_ungetc(PerlIO *f, int ch)
PerlIO_vprintf

Described in perlapio.

    int  PerlIO_vprintf(PerlIO *f, const char *fmt, va_list args)
PerlIO_write

Described in perlapio.

    SSize_t  PerlIO_write(PerlIO *f, const void *vbuf, Size_t count)
PL_maxsysfd

Described in perliol.

Integer configuration values

CASTI32

This symbol is defined if the C compiler can cast negative or large floating point numbers to 32-bit ints.

HAS_INT64_T

This symbol will defined if the C compiler supports int64_t. Usually the inttypes.h needs to be included, but sometimes sys/types.h is enough.

HAS_LONG_LONG

This symbol will be defined if the C compiler supports long long.

HAS_QUAD

This symbol, if defined, tells that there's a 64-bit integer type, Quad_t, and its unsigned counterpart, Uquad_t. QUADKIND will be one of QUAD_IS_INT, QUAD_IS_LONG, QUAD_IS_LONG_LONG, QUAD_IS_INT64_T, or QUAD_IS___INT64.

HE

Described in perlguts.

I8
I16
I32
I64
IV

Described in perlguts.

I32SIZE

This symbol contains the sizeof(I32).

I32TYPE

This symbol defines the C type used for Perl's I32.

I64SIZE

This symbol contains the sizeof(I64).

I64TYPE

This symbol defines the C type used for Perl's I64.

I16SIZE

This symbol contains the sizeof(I16).

I16TYPE

This symbol defines the C type used for Perl's I16.

INT16_C
INT32_C
INT64_C

Returns a token the C compiler recognizes for the constant number of the corresponding integer type on the machine.

If the machine does not have a 64-bit type, INT64_C is undefined. Use "INTMAX_C" to get the largest type available on the platform.

    I16  INT16_C(number)
    I32  INT32_C(number)
    I64  INT64_C(number)
INTMAX_C

Returns a token the C compiler recognizes for the constant number of the widest integer type on the machine. For example, if the machine has long longs, INTMAX_C(-1) would yield

-1LL

See also, for example, "INT32_C".

Use "IV" to declare variables of the maximum usable size on this platform.

    INTMAX_C(number)
INTSIZE

This symbol contains the value of sizeof(int) so that the C preprocessor can make decisions based on it.

I8SIZE

This symbol contains the sizeof(I8).

I8TYPE

This symbol defines the C type used for Perl's I8.

IV_MAX

The largest signed integer that fits in an IV on this platform.

    IV  IV_MAX
IV_MIN

The negative signed integer furthest away from 0 that fits in an IV on this platform.

    IV  IV_MIN
IVSIZE

This symbol contains the sizeof(IV).

IVTYPE

This symbol defines the C type used for Perl's IV.

line_t

The typedef to use to declare variables that are to hold line numbers.

LONGLONGSIZE

This symbol contains the size of a long long, so that the C preprocessor can make decisions based on it. It is only defined if the system supports long long.

LONGSIZE

This symbol contains the value of sizeof(long) so that the C preprocessor can make decisions based on it.

memzero

Set the l bytes starting at *d to all zeroes.

    void  memzero(void * d, Size_t l)
NV

Described in perlguts.

PERL_INT_FAST8_T
PERL_INT_FAST16_T
PERL_UINT_FAST8_T
PERL_UINT_FAST16_T

These are equivalent to the correspondingly-named C99 typedefs on platforms that have those; they evaluate to int and unsigned int on platforms that don't, so that you can portably take advantage of this C99 feature.

PERL_INT_MAX
PERL_INT_MIN
PERL_LONG_MAX
PERL_LONG_MIN
PERL_SHORT_MAX
PERL_SHORT_MIN
PERL_UCHAR_MAX
PERL_UCHAR_MIN
PERL_UINT_MAX
PERL_UINT_MIN
PERL_ULONG_MAX
PERL_ULONG_MIN
PERL_USHORT_MAX
PERL_USHORT_MIN
PERL_QUAD_MAX
PERL_QUAD_MIN
PERL_UQUAD_MAX
PERL_UQUAD_MIN

These give the largest and smallest number representable in the current platform in variables of the corresponding types.

For signed types, the smallest representable number is the most negative number, the one furthest away from zero.

For C99 and later compilers, these correspond to things like INT_MAX, which are available to the C code. But these constants, furnished by Perl, allow code compiled on earlier compilers to portably have access to the same constants.

SHORTSIZE

This symbol contains the value of sizeof(short) so that the C preprocessor can make decisions based on it.

STRLEN

Described in perlguts.

U8
U16
U32
U64
UV

Described in perlguts.

U32SIZE

This symbol contains the sizeof(U32).

U32TYPE

This symbol defines the C type used for Perl's U32.

U64SIZE

This symbol contains the sizeof(U64).

U64TYPE

This symbol defines the C type used for Perl's U64.

U16SIZE

This symbol contains the sizeof(U16).

U16TYPE

This symbol defines the C type used for Perl's U16.

UINT16_C
UINT32_C
UINT64_C

Returns a token the C compiler recognizes for the constant number of the corresponding unsigned integer type on the machine.

If the machine does not have a 64-bit type, UINT64_C is undefined. Use "UINTMAX_C" to get the largest type available on the platform.

    U16  UINT16_C(number)
    U32  UINT32_C(number)
    U64  UINT64_C(number)
UINTMAX_C

Returns a token the C compiler recognizes for the constant number of the widest unsigned integer type on the machine. For example, if the machine has longs, UINTMAX_C(1) would yield

1UL

See also, for example, "UINT32_C".

Use "UV" to declare variables of the maximum usable size on this platform.

    UINTMAX_C(number)
U8SIZE

This symbol contains the sizeof(U8).

U8TYPE

This symbol defines the C type used for Perl's U8.

UV_MAX

The largest unsigned integer that fits in a UV on this platform.

    UV  UV_MAX
UV_MIN

The smallest unsigned integer that fits in a UV on this platform. It should equal zero.

    UV  UV_MIN
UVSIZE

This symbol contains the sizeof(UV).

UVTYPE

This symbol defines the C type used for Perl's UV.

WIDEST_UTYPE

Yields the widest unsigned integer type on the platform, currently either U32 or U64. This can be used in declarations such as

WIDEST_UTYPE my_uv;

or casts

my_uv = (WIDEST_UTYPE) val;

Lexer interface

This is the lower layer of the Perl parser, managing characters and tokens.

lex_bufutf8

NOTE: lex_bufutf8 is experimental and may change or be removed without notice.

Indicates whether the octets in the lexer buffer ("PL_parser->linestr") should be interpreted as the UTF-8 encoding of Unicode characters. If not, they should be interpreted as Latin-1 characters. This is analogous to the SvUTF8 flag for scalars.

In UTF-8 mode, it is not guaranteed that the lexer buffer actually contains valid UTF-8. Lexing code must be robust in the face of invalid encoding.

The actual SvUTF8 flag of the "PL_parser->linestr" scalar is significant, but not the whole story regarding the input character encoding. Normally, when a file is being read, the scalar contains octets and its SvUTF8 flag is off, but the octets should be interpreted as UTF-8 if the use utf8 pragma is in effect. During a string eval, however, the scalar may have the SvUTF8 flag on, and in this case its octets should be interpreted as UTF-8 unless the use bytes pragma is in effect. This logic may change in the future; use this function instead of implementing the logic yourself.

    bool  lex_bufutf8()
lex_discard_to

NOTE: lex_discard_to is experimental and may change or be removed without notice.

Discards the first part of the "PL_parser->linestr" buffer, up to ptr. The remaining content of the buffer will be moved, and all pointers into the buffer updated appropriately. ptr must not be later in the buffer than the position of "PL_parser->bufptr": it is not permitted to discard text that has yet to be lexed.

Normally it is not necessarily to do this directly, because it suffices to use the implicit discarding behaviour of "lex_next_chunk" and things based on it. However, if a token stretches across multiple lines, and the lexing code has kept multiple lines of text in the buffer for that purpose, then after completion of the token it would be wise to explicitly discard the now-unneeded earlier lines, to avoid future multi-line tokens growing the buffer without bound.

    void  lex_discard_to(char* ptr)
lex_grow_linestr

NOTE: lex_grow_linestr is experimental and may change or be removed without notice.

Reallocates the lexer buffer ("PL_parser->linestr") to accommodate at least len octets (including terminating NUL). Returns a pointer to the reallocated buffer. This is necessary before making any direct modification of the buffer that would increase its length. "lex_stuff_pvn" provides a more convenient way to insert text into the buffer.

Do not use SvGROW or sv_grow directly on PL_parser->linestr; this function updates all of the lexer's variables that point directly into the buffer.

    char*  lex_grow_linestr(STRLEN len)
lex_next_chunk

NOTE: lex_next_chunk is experimental and may change or be removed without notice.

Reads in the next chunk of text to be lexed, appending it to "PL_parser->linestr". This should be called when lexing code has looked to the end of the current chunk and wants to know more. It is usual, but not necessary, for lexing to have consumed the entirety of the current chunk at this time.

If "PL_parser->bufptr" is pointing to the very end of the current chunk (i.e., the current chunk has been entirely consumed), normally the current chunk will be discarded at the same time that the new chunk is read in. If flags has the LEX_KEEP_PREVIOUS bit set, the current chunk will not be discarded. If the current chunk has not been entirely consumed, then it will not be discarded regardless of the flag.

Returns true if some new text was added to the buffer, or false if the buffer has reached the end of the input text.

    bool  lex_next_chunk(U32 flags)
lex_peek_unichar

NOTE: lex_peek_unichar is experimental and may change or be removed without notice.

Looks ahead one (Unicode) character in the text currently being lexed. Returns the codepoint (unsigned integer value) of the next character, or -1 if lexing has reached the end of the input text. To consume the peeked character, use "lex_read_unichar".

If the next character is in (or extends into) the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags has the LEX_KEEP_PREVIOUS bit set, then the current chunk will not be discarded.

If the input is being interpreted as UTF-8 and a UTF-8 encoding error is encountered, an exception is generated.

    I32  lex_peek_unichar(U32 flags)
lex_read_space

NOTE: lex_read_space is experimental and may change or be removed without notice.

Reads optional spaces, in Perl style, in the text currently being lexed. The spaces may include ordinary whitespace characters and Perl-style comments. #line directives are processed if encountered. "PL_parser->bufptr" is moved past the spaces, so that it points at a non-space character (or the end of the input text).

If spaces extend into the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags has the LEX_KEEP_PREVIOUS bit set, then the current chunk will not be discarded.

    void  lex_read_space(U32 flags)
lex_read_to

NOTE: lex_read_to is experimental and may change or be removed without notice.

Consume text in the lexer buffer, from "PL_parser->bufptr" up to ptr. This advances "PL_parser->bufptr" to match ptr, performing the correct bookkeeping whenever a newline character is passed. This is the normal way to consume lexed text.

Interpretation of the buffer's octets can be abstracted out by using the slightly higher-level functions "lex_peek_unichar" and "lex_read_unichar".

    void  lex_read_to(char* ptr)
lex_read_unichar

NOTE: lex_read_unichar is experimental and may change or be removed without notice.

Reads the next (Unicode) character in the text currently being lexed. Returns the codepoint (unsigned integer value) of the character read, and moves "PL_parser->bufptr" past the character, or returns -1 if lexing has reached the end of the input text. To non-destructively examine the next character, use "lex_peek_unichar" instead.

If the next character is in (or extends into) the next chunk of input text, the next chunk will be read in. Normally the current chunk will be discarded at the same time, but if flags has the LEX_KEEP_PREVIOUS bit set, then the current chunk will not be discarded.

If the input is being interpreted as UTF-8 and a UTF-8 encoding error is encountered, an exception is generated.

    I32  lex_read_unichar(U32 flags)
lex_start

NOTE: lex_start is experimental and may change or be removed without notice.

Creates and initialises a new lexer/parser state object, supplying a context in which to lex and parse from a new source of Perl code. A pointer to the new state object is placed in "PL_parser". An entry is made on the save stack so that upon unwinding, the new state object will be destroyed and the former value of "PL_parser" will be restored. Nothing else need be done to clean up the parsing context.

The code to be parsed comes from line and rsfp. line, if non-null, provides a string (in SV form) containing code to be parsed. A copy of the string is made, so subsequent modification of line does not affect parsing. rsfp, if non-null, provides an input stream from which code will be read to be parsed. If both are non-null, the code in line comes first and must consist of complete lines of input, and rsfp supplies the remainder of the source.

The flags parameter is reserved for future use. Currently it is only used by perl internally, so extensions should always pass zero.

    void  lex_start(SV* line, PerlIO *rsfp, U32 flags)
lex_stuff_pv

NOTE: lex_stuff_pv is experimental and may change or be removed without notice.

Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

The string to be inserted is represented by octets starting at pv and continuing to the first nul. These octets are interpreted as either UTF-8 or Latin-1, according to whether the LEX_STUFF_UTF8 flag is set in flags. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If it is not convenient to nul-terminate a string to be inserted, the "lex_stuff_pvn" function is more appropriate.

    void  lex_stuff_pv(const char* pv, U32 flags)
lex_stuff_pvn

NOTE: lex_stuff_pvn is experimental and may change or be removed without notice.

Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

The string to be inserted is represented by len octets starting at pv. These octets are interpreted as either UTF-8 or Latin-1, according to whether the LEX_STUFF_UTF8 flag is set in flags. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If a string to be inserted is available as a Perl scalar, the "lex_stuff_sv" function is more convenient.

    void  lex_stuff_pvn(const char* pv, STRLEN len, U32 flags)
lex_stuff_pvs

NOTE: lex_stuff_pvs is experimental and may change or be removed without notice.

Like "lex_stuff_pvn", but takes a literal string instead of a string/length pair.

    void  lex_stuff_pvs("pv", U32 flags)
lex_stuff_sv

NOTE: lex_stuff_sv is experimental and may change or be removed without notice.

Insert characters into the lexer buffer ("PL_parser->linestr"), immediately after the current lexing point ("PL_parser->bufptr"), reallocating the buffer if necessary. This means that lexing code that runs later will see the characters as if they had appeared in the input. It is not recommended to do this as part of normal parsing, and most uses of this facility run the risk of the inserted characters being interpreted in an unintended manner.

The string to be inserted is the string value of sv. The characters are recoded for the lexer buffer, according to how the buffer is currently being interpreted ("lex_bufutf8"). If a string to be inserted is not already a Perl scalar, the "lex_stuff_pvn" function avoids the need to construct a scalar.

    void  lex_stuff_sv(SV* sv, U32 flags)
lex_unstuff

NOTE: lex_unstuff is experimental and may change or be removed without notice.

Discards text about to be lexed, from "PL_parser->bufptr" up to ptr. Text following ptr will be moved, and the buffer shortened. This hides the discarded text from any lexing code that runs later, as if the text had never appeared.

This is not the normal way to consume lexed text. For that, use "lex_read_to".

    void  lex_unstuff(char* ptr)
parse_arithexpr

NOTE: parse_arithexpr is experimental and may change or be removed without notice.

Parse a Perl arithmetic expression. This may contain operators of precedence down to the bit shift operators. The expression must be followed (and thus terminated) either by a comparison or lower-precedence operator or by something that would normally terminate an expression such as semicolon. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

    OP*  parse_arithexpr(U32 flags)
parse_barestmt

NOTE: parse_barestmt is experimental and may change or be removed without notice.

Parse a single unadorned Perl statement. This may be a normal imperative statement or a declaration that has compile-time effect. It does not include any label or other affixture. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the statement is returned. This may be a null pointer if the statement is null, for example if it was actually a subroutine definition (which has compile-time side effects). If not null, it will be ops directly implementing the statement, suitable to pass to "newSTATEOP". It will not normally include a nextstate or equivalent op (except for those embedded in a scope contained entirely within the statement).

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

    OP*  parse_barestmt(U32 flags)
parse_block

NOTE: parse_block is experimental and may change or be removed without notice.

Parse a single complete Perl code block. This consists of an opening brace, a sequence of statements, and a closing brace. The block constitutes a lexical scope, so my variables and various compile-time effects can be contained within it. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the code block is returned. This is always a real op, never a null pointer. It will normally be a lineseq list, including nextstate or equivalent ops. No ops to construct any kind of runtime scope are included by virtue of it being a block.

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

    OP*  parse_block(U32 flags)
parse_fullexpr

NOTE: parse_fullexpr is experimental and may change or be removed without notice.

Parse a single complete Perl expression. This allows the full expression grammar, including the lowest-precedence operators such as or. The expression must be followed (and thus terminated) by a token that an expression would normally be terminated by: end-of-file, closing bracketing punctuation, semicolon, or one of the keywords that signals a postfix expression-statement modifier. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

    OP*  parse_fullexpr(U32 flags)
parse_fullstmt

NOTE: parse_fullstmt is experimental and may change or be removed without notice.

Parse a single complete Perl statement. This may be a normal imperative statement or a declaration that has compile-time effect, and may include optional labels. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statement.

The op tree representing the statement is returned. This may be a null pointer if the statement is null, for example if it was actually a subroutine definition (which has compile-time side effects). If not null, it will be the result of a "newSTATEOP" call, normally including a nextstate or equivalent op.

If an error occurs in parsing or compilation, in most cases a valid op tree (most likely null) is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

    OP*  parse_fullstmt(U32 flags)
parse_label

NOTE: parse_label is experimental and may change or be removed without notice.

Parse a single label, possibly optional, of the type that may prefix a Perl statement. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed. If flags has the PARSE_OPTIONAL bit set, then the label is optional, otherwise it is mandatory.

The name of the label is returned in the form of a fresh scalar. If an optional label is absent, a null pointer is returned.

If an error occurs in parsing, which can only occur if the label is mandatory, a valid label is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred.

    SV*  parse_label(U32 flags)
parse_listexpr

NOTE: parse_listexpr is experimental and may change or be removed without notice.

Parse a Perl list expression. This may contain operators of precedence down to the comma operator. The expression must be followed (and thus terminated) either by a low-precedence logic operator such as or or by something that would normally terminate an expression such as semicolon. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

    OP*  parse_listexpr(U32 flags)
parse_stmtseq

NOTE: parse_stmtseq is experimental and may change or be removed without notice.

Parse a sequence of zero or more Perl statements. These may be normal imperative statements, including optional labels, or declarations that have compile-time effect, or any mixture thereof. The statement sequence ends when a closing brace or end-of-file is encountered in a place where a new statement could have validly started. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the statements.

The op tree representing the statement sequence is returned. This may be a null pointer if the statements were all null, for example if there were no statements or if there were only subroutine definitions (which have compile-time side effects). If not null, it will be a lineseq list, normally including nextstate or equivalent ops.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

The flags parameter is reserved for future use, and must always be zero.

    OP*  parse_stmtseq(U32 flags)
parse_subsignature

NOTE: parse_subsignature is experimental and may change or be removed without notice.

Parse a subroutine signature declaration. This is the contents of the parentheses following a named or anonymous subroutine declaration when the signatures feature is enabled. Note that this function neither expects nor consumes the opening and closing parentheses around the signature; it is the caller's job to handle these.

This function must only be called during parsing of a subroutine; after "start_subparse" has been called. It might allocate lexical variables on the pad for the current subroutine.

The op tree to unpack the arguments from the stack at runtime is returned. This op tree should appear at the beginning of the compiled function. The caller may wish to use "op_append_list" to build their function body after it, or splice it together with the body before calling "newATTRSUB".

The flags parameter is reserved for future use, and must always be zero.

    OP*  parse_subsignature(U32 flags)
parse_termexpr

NOTE: parse_termexpr is experimental and may change or be removed without notice.

Parse a Perl term expression. This may contain operators of precedence down to the assignment operators. The expression must be followed (and thus terminated) either by a comma or lower-precedence operator or by something that would normally terminate an expression such as semicolon. If flags has the PARSE_OPTIONAL bit set, then the expression is optional, otherwise it is mandatory. It is up to the caller to ensure that the dynamic parser state ("PL_parser" et al) is correctly set to reflect the source of the code to be parsed and the lexical context for the expression.

The op tree representing the expression is returned. If an optional expression is absent, a null pointer is returned, otherwise the pointer will be non-null.

If an error occurs in parsing or compilation, in most cases a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. Some compilation errors, however, will throw an exception immediately.

    OP*  parse_termexpr(U32 flags)
PL_parser

Pointer to a structure encapsulating the state of the parsing operation currently in progress. The pointer can be locally changed to perform a nested parse without interfering with the state of an outer parse. Individual members of PL_parser have their own documentation.

PL_parser->bufend

NOTE: PL_parser->bufend is experimental and may change or be removed without notice.

Direct pointer to the end of the chunk of text currently being lexed, the end of the lexer buffer. This is equal to SvPVX(PL_parser->linestr) + SvCUR(PL_parser->linestr). A NUL character (zero octet) is always located at the end of the buffer, and does not count as part of the buffer's contents.

PL_parser->bufptr

NOTE: PL_parser->bufptr is experimental and may change or be removed without notice.

Points to the current position of lexing inside the lexer buffer. Characters around this point may be freely examined, within the range delimited by SvPVX("PL_parser->linestr") and "PL_parser->bufend". The octets of the buffer may be intended to be interpreted as either UTF-8 or Latin-1, as indicated by "lex_bufutf8".

Lexing code (whether in the Perl core or not) moves this pointer past the characters that it consumes. It is also expected to perform some bookkeeping whenever a newline character is consumed. This movement can be more conveniently performed by the function "lex_read_to", which handles newlines appropriately.

Interpretation of the buffer's octets can be abstracted out by using the slightly higher-level functions "lex_peek_unichar" and "lex_read_unichar".

PL_parser->linestart

NOTE: PL_parser->linestart is experimental and may change or be removed without notice.

Points to the start of the current line inside the lexer buffer. This is useful for indicating at which column an error occurred, and not much else. This must be updated by any lexing code that consumes a newline; the function "lex_read_to" handles this detail.

PL_parser->linestr

NOTE: PL_parser->linestr is experimental and may change or be removed without notice.

Buffer scalar containing the chunk currently under consideration of the text currently being lexed. This is always a plain string scalar (for which SvPOK is true). It is not intended to be used as a scalar by normal scalar means; instead refer to the buffer directly by the pointer variables described below.

The lexer maintains various char* pointers to things in the PL_parser->linestr buffer. If PL_parser->linestr is ever reallocated, all of these pointers must be updated. Don't attempt to do this manually, but rather use "lex_grow_linestr" if you need to reallocate the buffer.

The content of the text chunk in the buffer is commonly exactly one complete line of input, up to and including a newline terminator, but there are situations where it is otherwise. The octets of the buffer may be intended to be interpreted as either UTF-8 or Latin-1. The function "lex_bufutf8" tells you which. Do not use the SvUTF8 flag on this scalar, which may disagree with it.

For direct examination of the buffer, the variable "PL_parser->bufend" points to the end of the buffer. The current lexing position is pointed to by "PL_parser->bufptr". Direct use of these pointers is usually preferable to examination of the scalar through normal scalar means.

wrap_keyword_plugin

NOTE: wrap_keyword_plugin is experimental and may change or be removed without notice.

Puts a C function into the chain of keyword plugins. This is the preferred way to manipulate the "PL_keyword_plugin" variable. new_plugin is a pointer to the C function that is to be added to the keyword plugin chain, and old_plugin_p points to the storage location where a pointer to the next function in the chain will be stored. The value of new_plugin is written into the "PL_keyword_plugin" variable, while the value previously stored there is written to *old_plugin_p.

"PL_keyword_plugin" is global to an entire process, and a module wishing to hook keyword parsing may find itself invoked more than once per process, typically in different threads. To handle that situation, this function is idempotent. The location *old_plugin_p must initially (once per process) contain a null pointer. A C variable of static duration (declared at file scope, typically also marked static to give it internal linkage) will be implicitly initialised appropriately, if it does not have an explicit initialiser. This function will only actually modify the plugin chain if it finds *old_plugin_p to be null. This function is also thread safe on the small scale. It uses appropriate locking to avoid race conditions in accessing "PL_keyword_plugin".

When this function is called, the function referenced by new_plugin must be ready to be called, except for *old_plugin_p being unfilled. In a threading situation, new_plugin may be called immediately, even before this function has returned. *old_plugin_p will always be appropriately set before new_plugin is called. If new_plugin decides not to do anything special with the identifier that it is given (which is the usual case for most calls to a keyword plugin), it must chain the plugin function referenced by *old_plugin_p.

Taken all together, XS code to install a keyword plugin should typically look something like this:

static Perl_keyword_plugin_t next_keyword_plugin;
static OP *my_keyword_plugin(pTHX_
    char *keyword_ptr, STRLEN keyword_len, OP **op_ptr)
{
    if (memEQs(keyword_ptr, keyword_len,
               "my_new_keyword")) {
        ...
    } else {
        return next_keyword_plugin(aTHX_
            keyword_ptr, keyword_len, op_ptr);
    }
}
BOOT:
    wrap_keyword_plugin(my_keyword_plugin,
                        &next_keyword_plugin);

Direct access to "PL_keyword_plugin" should be avoided.

    void  wrap_keyword_plugin(Perl_keyword_plugin_t new_plugin,
                              Perl_keyword_plugin_t *old_plugin_p)

Locales

DECLARATION_FOR_LC_NUMERIC_MANIPULATION

This macro should be used as a statement. It declares a private variable (whose name begins with an underscore) that is needed by the other macros in this section. Failing to include this correctly should lead to a syntax error. For compatibility with C89 C compilers it should be placed in a block before any executable statements.

    void  DECLARATION_FOR_LC_NUMERIC_MANIPULATION
foldEQ_locale

Returns true if the leading len bytes of the strings s1 and s2 are the same case-insensitively in the current locale; false otherwise.

    I32  foldEQ_locale(const char* a, const char* b, I32 len)
HAS_DUPLOCALE

This symbol, if defined, indicates that the duplocale routine is available to duplicate a locale object.

HAS_FREELOCALE

This symbol, if defined, indicates that the freelocale routine is available to deallocates the resources associated with a locale object.

HAS_LC_MONETARY_2008

This symbol, if defined, indicates that the localeconv routine is available and has the additional members added in POSIX 1003.1-2008.

HAS_LOCALECONV

This symbol, if defined, indicates that the localeconv routine is available for numeric and monetary formatting conventions.

HAS_LOCALECONV_L

This symbol, if defined, indicates that the localeconv_l routine is available to query certain information about a locale.

HAS_NEWLOCALE

This symbol, if defined, indicates that the newlocale routine is available to return a new locale object or modify an existing locale object.

HAS_NL_LANGINFO

This symbol, if defined, indicates that the nl_langinfo routine is available to return local data. You will also need langinfo.h and therefore I_LANGINFO.

HAS_QUERYLOCALE

This symbol, if defined, indicates that the querylocale routine is available to return the name of the locale for a category mask.

HAS_SETLOCALE

This symbol, if defined, indicates that the setlocale routine is available to handle locale-specific ctype implementations.

HAS_SETLOCALE_R

This symbol, if defined, indicates that the setlocale_r routine is available to setlocale re-entrantly.

HAS_THREAD_SAFE_NL_LANGINFO_L

This symbol, when defined, indicates presence of the nl_langinfo_l() function, and that it is thread-safe.

HAS_USELOCALE

This symbol, if defined, indicates that the uselocale routine is available to set the current locale for the calling thread.

I_LANGINFO

This symbol, if defined, indicates that langinfo.h exists and should be included.

    #ifdef I_LANGINFO
        #include <langinfo.h>
    #endif
I_LOCALE

This symbol, if defined, indicates to the C program that it should include locale.h.

    #ifdef I_LOCALE
        #include <locale.h>
    #endif
IN_LOCALE

Evaluates to TRUE if the plain locale pragma without a parameter (use locale) is in effect.

    bool  IN_LOCALE
IN_LOCALE_COMPILETIME

Evaluates to TRUE if, when compiling a perl program (including an eval) if the plain locale pragma without a parameter (use locale) is in effect.

    bool  IN_LOCALE_COMPILETIME
IN_LOCALE_RUNTIME

Evaluates to TRUE if, when executing a perl program (including an eval) if the plain locale pragma without a parameter (use locale) is in effect.

    bool  IN_LOCALE_RUNTIME
I_XLOCALE

This symbol, if defined, indicates to the C program that it should include xlocale.h to get uselocale() and its friends.

    #ifdef I_XLOCALE
        #include <xlocale.h>
    #endif
Perl_langinfo

This is an (almost) drop-in replacement for the system nl_langinfo(3), taking the same item parameter values, and returning the same information. But it is more thread-safe than regular nl_langinfo(), and hides the quirks of Perl's locale handling from your code, and can be used on systems that lack a native nl_langinfo.

Expanding on these:

  • The reason it isn't quite a drop-in replacement is actually an advantage. The only difference is that it returns const char *, whereas plain nl_langinfo() returns char *, but you are (only by documentation) forbidden to write into the buffer. By declaring this const, the compiler enforces this restriction, so if it is violated, you know at compilation time, rather than getting segfaults at runtime.

  • It delivers the correct results for the RADIXCHAR and THOUSEP items, without you having to write extra code. The reason for the extra code would be because these are from the LC_NUMERIC locale category, which is normally kept set by Perl so that the radix is a dot, and the separator is the empty string, no matter what the underlying locale is supposed to be, and so to get the expected results, you have to temporarily toggle into the underlying locale, and later toggle back. (You could use plain nl_langinfo and "STORE_LC_NUMERIC_FORCE_TO_UNDERLYING" for this but then you wouldn't get the other advantages of Perl_langinfo(); not keeping LC_NUMERIC in the C (or equivalent) locale would break a lot of CPAN, which is expecting the radix (decimal point) character to be a dot.)

  • The system function it replaces can have its static return buffer trashed, not only by a subsequent call to that function, but by a freelocale, setlocale, or other locale change. The returned buffer of this function is not changed until the next call to it, so the buffer is never in a trashed state.

  • Its return buffer is per-thread, so it also is never overwritten by a call to this function from another thread; unlike the function it replaces.

  • But most importantly, it works on systems that don't have nl_langinfo, such as Windows, hence makes your code more portable. Of the fifty-some possible items specified by the POSIX 2008 standard, http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/langinfo.h.html, only one is completely unimplemented, though on non-Windows platforms, another significant one is also not implemented). It uses various techniques to recover the other items, including calling localeconv(3), and strftime(3), both of which are specified in C89, so should be always be available. Later strftime() versions have additional capabilities; "" is returned for those not available on your system.

    It is important to note that when called with an item that is recovered by using localeconv, the buffer from any previous explicit call to localeconv will be overwritten. This means you must save that buffer's contents if you need to access them after a call to this function. (But note that you might not want to be using localeconv() directly anyway, because of issues like the ones listed in the second item of this list (above) for RADIXCHAR and THOUSEP. You can use the methods given in perlcall to call "localeconv" in POSIX and avoid all the issues, but then you have a hash to unpack).

    The details for those items which may deviate from what this emulation returns and what a native nl_langinfo() would return are specified in I18N::Langinfo.

When using Perl_langinfo on systems that don't have a native nl_langinfo(), you must

#include "perl_langinfo.h"

before the perl.h #include. You can replace your langinfo.h #include with this one. (Doing it this way keeps out the symbols that plain langinfo.h would try to import into the namespace for code that doesn't need it.)

The original impetus for Perl_langinfo() was so that code that needs to find out the current currency symbol, floating point radix character, or digit grouping separator can use, on all systems, the simpler and more thread-friendly nl_langinfo API instead of localeconv(3) which is a pain to make thread-friendly. For other fields returned by localeconv, it is better to use the methods given in perlcall to call POSIX::localeconv(), which is thread-friendly.

    const char*  Perl_langinfo(const nl_item item)
Perl_setlocale

This is an (almost) drop-in replacement for the system setlocale(3), taking the same parameters, and returning the same information, except that it returns the correct underlying LC_NUMERIC locale. Regular setlocale will instead return C if the underlying locale has a non-dot decimal point character, or a non-empty thousands separator for displaying floating point numbers. This is because perl keeps that locale category such that it has a dot and empty separator, changing the locale briefly during the operations where the underlying one is required. Perl_setlocale knows about this, and compensates; regular setlocale doesn't.

Another reason it isn't completely a drop-in replacement is that it is declared to return const char *, whereas the system setlocale omits the const (presumably because its API was specified long ago, and can't be updated; it is illegal to change the information setlocale returns; doing so leads to segfaults.)

Finally, Perl_setlocale works under all circumstances, whereas plain setlocale can be completely ineffective on some platforms under some configurations.

Perl_setlocale should not be used to change the locale except on systems where the predefined variable ${^SAFE_LOCALES} is 1. On some such systems, the system setlocale() is ineffective, returning the wrong information, and failing to actually change the locale. Perl_setlocale, however works properly in all circumstances.

The return points to a per-thread static buffer, which is overwritten the next time Perl_setlocale is called from the same thread.

    const char*  Perl_setlocale(const int category,
                                const char* locale)
RESTORE_LC_NUMERIC

This is used in conjunction with one of the macros "STORE_LC_NUMERIC_SET_TO_NEEDED" and "STORE_LC_NUMERIC_FORCE_TO_UNDERLYING" to properly restore the LC_NUMERIC state.

A call to "DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro and the two STORE ones. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

{
   DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    ...
   RESTORE_LC_NUMERIC();
    ...
}
    void  RESTORE_LC_NUMERIC()
SETLOCALE_ACCEPTS_ANY_LOCALE_NAME

This symbol, if defined, indicates that the setlocale routine is available and it accepts any input locale name as valid.

STORE_LC_NUMERIC_FORCE_TO_UNDERLYING

This is used by XS code that is LC_NUMERIC locale-aware to force the locale for category LC_NUMERIC to be what perl thinks is the current underlying locale. (The perl interpreter could be wrong about what the underlying locale actually is if some C or XS code has called the C library function setlocale(3) behind its back; calling "sync_locale" before calling this macro will update perl's records.)

A call to "DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

{
   DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    ...
   STORE_LC_NUMERIC_FORCE_TO_UNDERLYING();
    ...
   RESTORE_LC_NUMERIC();
    ...
}

The private variable is used to save the current locale state, so that the requisite matching call to "RESTORE_LC_NUMERIC" can restore it.

On threaded perls not operating with thread-safe functionality, this macro uses a mutex to force a critical section. Therefore the matching RESTORE should be close by, and guaranteed to be called.

    void  STORE_LC_NUMERIC_FORCE_TO_UNDERLYING()
STORE_LC_NUMERIC_SET_TO_NEEDED

This is used to help wrap XS or C code that is LC_NUMERIC locale-aware. This locale category is generally kept set to a locale where the decimal radix character is a dot, and the separator between groups of digits is empty. This is because most XS code that reads floating point numbers is expecting them to have this syntax.

This macro makes sure the current LC_NUMERIC state is set properly, to be aware of locale if the call to the XS or C code from the Perl program is from within the scope of a use locale; or to ignore locale if the call is instead from outside such scope.

This macro is the start of wrapping the C or XS code; the wrap ending is done by calling the "RESTORE_LC_NUMERIC" macro after the operation. Otherwise the state can be changed that will adversely affect other XS code.

A call to "DECLARATION_FOR_LC_NUMERIC_MANIPULATION" must have been made to declare at compile time a private variable used by this macro. This macro should be called as a single statement, not an expression, but with an empty argument list, like this:

{
   DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    ...
   STORE_LC_NUMERIC_SET_TO_NEEDED();
    ...
   RESTORE_LC_NUMERIC();
    ...
}

On threaded perls not operating with thread-safe functionality, this macro uses a mutex to force a critical section. Therefore the matching RESTORE should be close by, and guaranteed to be called; see "WITH_LC_NUMERIC_SET_TO_NEEDED" for a more contained way to ensure that.

    void  STORE_LC_NUMERIC_SET_TO_NEEDED()
STORE_LC_NUMERIC_SET_TO_NEEDED_IN

Same as "STORE_LC_NUMERIC_SET_TO_NEEDED" with in_lc_numeric provided as the precalculated value of IN_LC(LC_NUMERIC). It is the caller's responsibility to ensure that the status of PL_compiling and PL_hints cannot have changed since the precalculation.

    void  STORE_LC_NUMERIC_SET_TO_NEEDED_IN(bool in_lc_numeric)
switch_to_global_locale

On systems without locale support, or on typical single-threaded builds, or on platforms that do not support per-thread locale operations, this function does nothing. On such systems that do have locale support, only a locale global to the whole program is available.

On multi-threaded builds on systems that do have per-thread locale operations, this function converts the thread it is running in to use the global locale. This is for code that has not yet or cannot be updated to handle multi-threaded locale operation. As long as only a single thread is so-converted, everything works fine, as all the other threads continue to ignore the global one, so only this thread looks at it.

However, on Windows systems this isn't quite true prior to Visual Studio 15, at which point Microsoft fixed a bug. A race can occur if you use the following operations on earlier Windows platforms:

POSIX::localeconv
I18N::Langinfo, items CRNCYSTR and THOUSEP
"Perl_langinfo" in perlapi, items CRNCYSTR and THOUSEP

The first item is not fixable (except by upgrading to a later Visual Studio release), but it would be possible to work around the latter two items by using the Windows API functions GetNumberFormat and GetCurrencyFormat; patches welcome.

Without this function call, threads that use the setlocale(3) system function will not work properly, as all the locale-sensitive functions will look at the per-thread locale, and setlocale will have no effect on this thread.

Perl code should convert to either call Perl_setlocale (which is a drop-in for the system setlocale) or use the methods given in perlcall to call POSIX::setlocale. Either one will transparently properly handle all cases of single- vs multi-thread, POSIX 2008-supported or not.

Non-Perl libraries, such as gtk, that call the system setlocale can continue to work if this function is called before transferring control to the library.

Upon return from the code that needs to use the global locale, sync_locale() should be called to restore the safe multi-thread operation.

    void  switch_to_global_locale()
sync_locale

Perl_setlocale can be used at any time to query or change the locale (though changing the locale is antisocial and dangerous on multi-threaded systems that don't have multi-thread safe locale operations. (See "Multi-threaded operation" in perllocale). Using the system setlocale(3) should be avoided. Nevertheless, certain non-Perl libraries called from XS, such as Gtk do so, and this can't be changed. When the locale is changed by XS code that didn't use Perl_setlocale, Perl needs to be told that the locale has changed. Use this function to do so, before returning to Perl.

The return value is a boolean: TRUE if the global locale at the time of call was in effect; and FALSE if a per-thread locale was in effect. This can be used by the caller that needs to restore things as-they-were to decide whether or not to call Perl_switch_to_global_locale.

    bool  sync_locale()
WITH_LC_NUMERIC_SET_TO_NEEDED

This macro invokes the supplied statement or block within the context of a "STORE_LC_NUMERIC_SET_TO_NEEDED" .. "RESTORE_LC_NUMERIC" pair if required, so eg:

WITH_LC_NUMERIC_SET_TO_NEEDED(
  SNPRINTF_G(fv, ebuf, sizeof(ebuf), precis)
);

is equivalent to:

  {
#ifdef USE_LOCALE_NUMERIC
    DECLARATION_FOR_LC_NUMERIC_MANIPULATION;
    STORE_LC_NUMERIC_SET_TO_NEEDED();
#endif
    SNPRINTF_G(fv, ebuf, sizeof(ebuf), precis);
#ifdef USE_LOCALE_NUMERIC
    RESTORE_LC_NUMERIC();
#endif
  }
    void  WITH_LC_NUMERIC_SET_TO_NEEDED(block)
WITH_LC_NUMERIC_SET_TO_NEEDED_IN

Same as "WITH_LC_NUMERIC_SET_TO_NEEDED" with in_lc_numeric provided as the precalculated value of IN_LC(LC_NUMERIC). It is the caller's responsibility to ensure that the status of PL_compiling and PL_hints cannot have changed since the precalculation.

    void  WITH_LC_NUMERIC_SET_TO_NEEDED_IN(bool in_lc_numeric, block)

Magic

"Magic" is special data attached to SV structures in order to give them "magical" properties. When any Perl code tries to read from, or assign to, an SV marked as magical, it calls the 'get' or 'set' function associated with that SV's magic. A get is called prior to reading an SV, in order to give it a chance to update its internal value (get on $. writes the line number of the last read filehandle into the SV's IV slot), while set is called after an SV has been written to, in order to allow it to make use of its changed value (set on $/ copies the SV's new value to the PL_rs global variable).

Magic is implemented as a linked list of MAGIC structures attached to the SV. Each MAGIC struct holds the type of the magic, a pointer to an array of functions that implement the get(), set(), length() etc functions, plus space for some flags and pointers. For example, a tied variable has a MAGIC structure that contains a pointer to the object associated with the tie.

mg_clear

Clear something magical that the SV represents. See "sv_magic".

    int  mg_clear(SV* sv)
mg_copy

Copies the magic from one SV to another. See "sv_magic".

    int  mg_copy(SV *sv, SV *nsv, const char *key, I32 klen)
mg_find

Finds the magic pointer for type matching the SV. See "sv_magic".

    MAGIC*  mg_find(const SV* sv, int type)
mg_findext

Finds the magic pointer of type with the given vtbl for the SV. See "sv_magicext".

    MAGIC*  mg_findext(const SV* sv, int type, const MGVTBL *vtbl)
mg_free

Free any magic storage used by the SV. See "sv_magic".

    int  mg_free(SV* sv)
mg_freeext

Remove any magic of type how using virtual table vtbl from the SV sv. See "sv_magic".

mg_freeext(sv, how, NULL) is equivalent to mg_free_type(sv, how).

    void  mg_freeext(SV* sv, int how, const MGVTBL *vtbl)
mg_free_type

Remove any magic of type how from the SV sv. See "sv_magic".

    void  mg_free_type(SV* sv, int how)
mg_get

Do magic before a value is retrieved from the SV. The type of SV must be >= SVt_PVMG. See "sv_magic".

    int  mg_get(SV* sv)
mg_length

DEPRECATED! It is planned to remove mg_length from a future release of Perl. Do not use it for new code; remove it from existing code.

Reports on the SV's length in bytes, calling length magic if available, but does not set the UTF8 flag on sv. It will fall back to 'get' magic if there is no 'length' magic, but with no indication as to whether it called 'get' magic. It assumes sv is a PVMG or higher. Use sv_len() instead.

    U32  mg_length(SV* sv)
mg_magical

Turns on the magical status of an SV. See "sv_magic".

    void  mg_magical(SV* sv)
mg_set

Do magic after a value is assigned to the SV. See "sv_magic".

    int  mg_set(SV* sv)
SvTIED_obj

Described in perlinterp.

    SvTIED_obj(SV *sv, MAGIC *mg)

Memory Management

HASATTRIBUTE_MALLOC

Can we handle GCC attribute for malloc-style functions.

HAS_MALLOC_GOOD_SIZE

This symbol, if defined, indicates that the malloc_good_size routine is available for use.

HAS_MALLOC_SIZE

This symbol, if defined, indicates that the malloc_size routine is available for use.

I_MALLOCMALLOC

This symbol, if defined, indicates to the C program that it should include malloc/malloc.h.

    #ifdef I_MALLOCMALLOC
        #include <mallocmalloc.h>
    #endif
MYMALLOC

This symbol, if defined, indicates that we're using our own malloc.

Newx

The XSUB-writer's interface to the C malloc function.

Memory obtained by this should ONLY be freed with "Safefree".

In 5.9.3, Newx() and friends replace the older New() API, and drops the first parameter, x, a debug aid which allowed callers to identify themselves. This aid has been superseded by a new build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in perlhacktips). The older API is still there for use in XS modules supporting older perls.

    void  Newx(void* ptr, int nitems, type)
Newxc

The XSUB-writer's interface to the C malloc function, with cast. See also "Newx".

Memory obtained by this should ONLY be freed with "Safefree".

    void  Newxc(void* ptr, int nitems, type, cast)
Newxz

The XSUB-writer's interface to the C malloc function. The allocated memory is zeroed with memzero. See also "Newx".

Memory obtained by this should ONLY be freed with "Safefree".

    void  Newxz(void* ptr, int nitems, type)
PERL_MALLOC_WRAP

This symbol, if defined, indicates that we'd like malloc wrap checks.

Renew

The XSUB-writer's interface to the C realloc function.

Memory obtained by this should ONLY be freed with "Safefree".

    void  Renew(void* ptr, int nitems, type)
Renewc

The XSUB-writer's interface to the C realloc function, with cast.

Memory obtained by this should ONLY be freed with "Safefree".

    void  Renewc(void* ptr, int nitems, type, cast)
Safefree

The XSUB-writer's interface to the C free function.

This should ONLY be used on memory obtained using "Newx" and friends.

    void  Safefree(void* ptr)
safesyscalloc

Safe version of system's calloc()

    Malloc_t  safesyscalloc(MEM_SIZE elements, MEM_SIZE size)
safesysfree

Safe version of system's free()

    Free_t  safesysfree(Malloc_t where)
safesysmalloc

Paranoid version of system's malloc()

    Malloc_t  safesysmalloc(MEM_SIZE nbytes)
safesysrealloc

Paranoid version of system's realloc()

    Malloc_t  safesysrealloc(Malloc_t where, MEM_SIZE nbytes)

MRO

These functions are related to the method resolution order of perl classes Also see perlmroapi.

HvMROMETA

Described in perlmroapi.

    struct mro_meta *  HvMROMETA(HV *hv)
mro_get_linear_isa

Returns the mro linearisation for the given stash. By default, this will be whatever mro_get_linear_isa_dfs returns unless some other MRO is in effect for the stash. The return value is a read-only AV*.

You are responsible for SvREFCNT_inc() on the return value if you plan to store it anywhere semi-permanently (otherwise it might be deleted out from under you the next time the cache is invalidated).

    AV*  mro_get_linear_isa(HV* stash)
MRO_GET_PRIVATE_DATA

Described in perlmroapi.

    SV*  MRO_GET_PRIVATE_DATA(struct mro_meta *const smeta,
                              const struct mro_alg *const which)
mro_method_changed_in

Invalidates method caching on any child classes of the given stash, so that they might notice the changes in this one.

Ideally, all instances of PL_sub_generation++ in perl source outside of mro.c should be replaced by calls to this.

Perl automatically handles most of the common ways a method might be redefined. However, there are a few ways you could change a method in a stash without the cache code noticing, in which case you need to call this method afterwards:

1) Directly manipulating the stash HV entries from XS code.

2) Assigning a reference to a readonly scalar constant into a stash entry in order to create a constant subroutine (like constant.pm does).

This same method is available from pure perl via, mro::method_changed_in(classname).

    void  mro_method_changed_in(HV* stash)
mro_register

Registers a custom mro plugin. See perlmroapi for details on this and other mro functions.

NOTE: mro_register must be explicitly called as Perl_mro_register with an aTHX_ parameter.

    void  Perl_mro_register(pTHX_ const struct mro_alg *mro)
mro_set_private_data

Described in perlmroapi.

NOTE: mro_set_private_data must be explicitly called as Perl_mro_set_private_data with an aTHX_ parameter.

    SV*  Perl_mro_set_private_data(pTHX_
                                   struct mro_meta *const smeta,
                                   const struct mro_alg *const which,
                                   SV *const data)

Multicall Functions

dMULTICALL

Declare local variables for a multicall. See "LIGHTWEIGHT CALLBACKS" in perlcall.

    dMULTICALL;
MULTICALL

Make a lightweight callback. See "LIGHTWEIGHT CALLBACKS" in perlcall.

    MULTICALL;
POP_MULTICALL

Closing bracket for a lightweight callback. See "LIGHTWEIGHT CALLBACKS" in perlcall.

    POP_MULTICALL;
PUSH_MULTICALL

Opening bracket for a lightweight callback. See "LIGHTWEIGHT CALLBACKS" in perlcall.

    PUSH_MULTICALL(CV* the_cv);

Numeric Functions

Drand01

This macro is to be used to generate uniformly distributed random numbers over the range [0., 1.[. You may have to supply an 'extern double drand48();' in your program since SunOS 4.1.3 doesn't provide you with anything relevant in its headers. See "HAS_DRAND48_PROTO".

    double  Drand01()
Gconvert

This preprocessor macro is defined to convert a floating point number to a string without a trailing decimal point. This emulates the behavior of sprintf("%g"), but is sometimes much more efficient. If gconvert() is not available, but gcvt() drops the trailing decimal point, then gcvt() is used. If all else fails, a macro using sprintf("%g") is used. Arguments for the Gconvert macro are: value, number of digits, whether trailing zeros should be retained, and the output buffer. The usual values are:

d_Gconvert='gconvert((x),(n),(t),(b))'
d_Gconvert='gcvt((x),(n),(b))'
d_Gconvert='sprintf((b),"%.*g",(n),(x))'

The last two assume trailing zeros should not be kept.

    char *  Gconvert(double x, Size_t n, bool t, char * b)
grok_bin

converts a string representing a binary number to numeric form.

On entry start and *len_p give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or at just before the first invalid character. Unless PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character (except NUL) will also trigger a warning. On return *len_p is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX, grok_bin returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes an approximation of the correct value into *result (which is an NV; or the approximation is discarded if result is NULL).

The binary number may optionally be prefixed with "0b" or "b" unless PERL_SCAN_DISALLOW_PREFIX is set in *flags on entry.

If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then any or all pairs of digits may be separated from each other by a single underscore; also a single leading underscore is accepted.

    UV  grok_bin(const char* start, STRLEN* len_p, I32* flags,
                 NV *result)
grok_hex

converts a string representing a hex number to numeric form.

On entry start and *len_p give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or at just before the first invalid character. Unless PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character (except NUL) will also trigger a warning. On return *len_p is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX, grok_hex returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes an approximation of the correct value into *result (which is an NV; or the approximation is discarded if result is NULL).

The hex number may optionally be prefixed with "0x" or "x" unless PERL_SCAN_DISALLOW_PREFIX is set in *flags on entry.

If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then any or all pairs of digits may be separated from each other by a single underscore; also a single leading underscore is accepted.

    UV  grok_hex(const char* start, STRLEN* len_p, I32* flags,
                 NV *result)
grok_infnan

Helper for grok_number(), accepts various ways of spelling "infinity" or "not a number", and returns one of the following flag combinations:

IS_NUMBER_INFINITY
IS_NUMBER_NAN
IS_NUMBER_INFINITY | IS_NUMBER_NEG
IS_NUMBER_NAN | IS_NUMBER_NEG
0

possibly |-ed with IS_NUMBER_TRAILING.

If an infinity or a not-a-number is recognized, *sp will point to one byte past the end of the recognized string. If the recognition fails, zero is returned, and *sp will not move.

    int  grok_infnan(const char** sp, const char *send)
grok_number

Identical to grok_number_flags() with flags set to zero.

    int  grok_number(const char *pv, STRLEN len, UV *valuep)
grok_number_flags

Recognise (or not) a number. The type of the number is returned (0 if unrecognised), otherwise it is a bit-ORed combination of IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT, IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).

If the value of the number can fit in a UV, it is returned in *valuep. IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV will never be set unless *valuep is valid, but *valuep may have been assigned to during processing even though IS_NUMBER_IN_UV is not set on return. If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when valuep is non-NULL, but no actual assignment (or SEGV) will occur.

IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were seen (in which case *valuep gives the true value truncated to an integer), and IS_NUMBER_NEG if the number is negative (in which case *valuep holds the absolute value). IS_NUMBER_IN_UV is not set if e notation was used or the number is larger than a UV.

flags allows only PERL_SCAN_TRAILING, which allows for trailing non-numeric text on an otherwise successful grok, setting IS_NUMBER_TRAILING on the result.

    int  grok_number_flags(const char *pv, STRLEN len, UV *valuep,
                           U32 flags)
GROK_NUMERIC_RADIX

A synonym for "grok_numeric_radix"

    bool  GROK_NUMERIC_RADIX(NN const char **sp, NN const char *send)
grok_numeric_radix

Scan and skip for a numeric decimal separator (radix).

    bool  grok_numeric_radix(const char **sp, const char *send)
grok_oct

converts a string representing an octal number to numeric form.

On entry start and *len_p give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or at just before the first invalid character. Unless PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character (except NUL) will also trigger a warning. On return *len_p is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX, grok_oct returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes an approximation of the correct value into *result (which is an NV; or the approximation is discarded if result is NULL).

If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then any or all pairs of digits may be separated from each other by a single underscore; also a single leading underscore is accepted.

The PERL_SCAN_DISALLOW_PREFIX flag is always treated as being set for this function.

    UV  grok_oct(const char* start, STRLEN* len_p, I32* flags,
                 NV *result)
isinfnan

Perl_isinfnan() is a utility function that returns true if the NV argument is either an infinity or a NaN, false otherwise. To test in more detail, use Perl_isinf() and Perl_isnan().

This is also the logical inverse of Perl_isfinite().

    bool  isinfnan(NV nv)
my_atof

atof(3), but properly works with Perl locale handling, accepting a dot radix character always, but also the current locale's radix character if and only if called from within the lexical scope of a Perl use locale statement.

N.B. s must be NUL terminated.

    NV  my_atof(const char *s)
my_strtod

This function is equivalent to the libc strtod() function, and is available even on platforms that lack plain strtod(). Its return value is the best available precision depending on platform capabilities and Configure options.

It properly handles the locale radix character, meaning it expects a dot except when called from within the scope of use locale, in which case the radix character should be that specified by the current locale.

The synonym Strtod() may be used instead.

    NV  my_strtod(const char * const s, char ** e)
PERL_ABS

Typeless abs or fabs, etc. (The usage below indicates it is for integers, but it works for any type.) Use instead of these, since the C library ones force their argument to be what it is expecting, potentially leading to disaster. But also beware that this evaluates its argument twice, so no x++.

    int  PERL_ABS(int x)
Perl_acos
Perl_asin
Perl_atan
Perl_atan2
Perl_ceil
Perl_cos
Perl_cosh
Perl_exp
Perl_floor
Perl_fmod
Perl_frexp
Perl_isfinite
Perl_isinf
Perl_isnan
Perl_ldexp
Perl_log
Perl_log10
Perl_modf
Perl_pow
Perl_sin
Perl_sinh
Perl_sqrt
Perl_tan
Perl_tanh

These perform the corresponding mathematical operation on the operand(s), using the libc function designed for the task that has just enough precision for an NV on this platform. If no such function with sufficient precision exists, the highest precision one available is used.

    NV  Perl_acos    (NV x)
    NV  Perl_asin    (NV x)
    NV  Perl_atan    (NV x)
    NV  Perl_atan2   (NV x, NV y)
    NV  Perl_ceil    (NV x)
    NV  Perl_cos     (NV x)
    NV  Perl_cosh    (NV x)
    NV  Perl_exp     (NV x)
    NV  Perl_floor   (NV x)
    NV  Perl_fmod    (NV x, NV y)
    NV  Perl_frexp   (NV x, int *exp)
    IV  Perl_isfinite(NV x)
    IV  Perl_isinf   (NV x)
    IV  Perl_isnan   (NV x)
    NV  Perl_ldexp   (NV x, int exp)
    NV  Perl_log     (NV x)
    NV  Perl_log10   (NV x)
    NV  Perl_modf    (NV x, NV *iptr)
    NV  Perl_pow     (NV x, NV y)
    NV  Perl_sin     (NV x)
    NV  Perl_sinh    (NV x)
    NV  Perl_sqrt    (NV x)
    NV  Perl_tan     (NV x)
    NV  Perl_tanh    (NV x)
Perl_signbit

NOTE: Perl_signbit is experimental and may change or be removed without notice.

Return a non-zero integer if the sign bit on an NV is set, and 0 if it is not.

If Configure detects this system has a signbit() that will work with our NVs, then we just use it via the #define in perl.h. Otherwise, fall back on this implementation. The main use of this function is catching -0.0.

Configure notes: This function is called 'Perl_signbit' instead of a plain 'signbit' because it is easy to imagine a system having a signbit() function or macro that doesn't happen to work with our particular choice of NVs. We shouldn't just re-#define signbit as Perl_signbit and expect the standard system headers to be happy. Also, this is a no-context function (no pTHX_) because Perl_signbit() is usually re-#defined in perl.h as a simple macro call to the system's signbit(). Users should just always call Perl_signbit().

    int  Perl_signbit(NV f)
PL_hexdigit

This array, indexed by an integer, converts that value into the character that represents it. For example, if the input is 8, the return will be a string whose first character is '8'. What is actually returned is a pointer into a string. All you are interested in is the first character of that string. To get uppercase letters (for the values 10..15), add 16 to the index. Hence, PL_hexdigit[11] is 'b', and PL_hexdigit[11+16] is 'B'. Adding 16 to an index whose representation is '0'..'9' yields the same as not adding 16. Indices outside the range 0..31 result in (bad) undedefined behavior.

READ_XDIGIT

Returns the value of an ASCII-range hex digit and advances the string pointer. Behaviour is only well defined when isXDIGIT(*str) is true.

    U8  READ_XDIGIT(char str*)
scan_bin

For backwards compatibility. Use grok_bin instead.

    NV  scan_bin(const char* start, STRLEN len, STRLEN* retlen)
scan_hex

For backwards compatibility. Use grok_hex instead.

    NV  scan_hex(const char* start, STRLEN len, STRLEN* retlen)
scan_oct

For backwards compatibility. Use grok_oct instead.

    NV  scan_oct(const char* start, STRLEN len, STRLEN* retlen)
seedDrand01

This symbol defines the macro to be used in seeding the random number generator (see "Drand01").

    void  seedDrand01(Rand_seed_t x)
Strtod

This is a synonym for "my_strtod".

    NV  Strtod(NN const char * const s, NULLOK char ** e)
Strtol

Platform and configuration independent strtol. This expands to the appropriate strotol-like function based on the platform and Configure options>. For example it could expand to strtoll or strtoq instead of strtol.

    NV  Strtol(NN const char * const s, NULLOK char ** e, int base)
Strtoul

Platform and configuration independent strtoul. This expands to the appropriate strotoul-like function based on the platform and Configure options>. For example it could expand to strtoull or strtouq instead of strtoul.

    NV  Strtoul(NN const char * const s, NULLOK char ** e, int base)

Optree construction

newASSIGNOP

Constructs, checks, and returns an assignment op. left and right supply the parameters of the assignment; they are consumed by this function and become part of the constructed op tree.

If optype is OP_ANDASSIGN, OP_ORASSIGN, or OP_DORASSIGN, then a suitable conditional optree is constructed. If optype is the opcode of a binary operator, such as OP_BIT_OR, then an op is constructed that performs the binary operation and assigns the result to the left argument. Either way, if optype is non-zero then flags has no effect.

If optype is zero, then a plain scalar or list assignment is constructed. Which type of assignment it is is automatically determined. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 or 2 is automatically set as required.

    OP*  newASSIGNOP(I32 flags, OP* left, I32 optype, OP* right)
newBINOP

Constructs, checks, and returns an op of any binary type. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 or 2 is automatically set as required. first and last supply up to two ops to be the direct children of the binary op; they are consumed by this function and become part of the constructed op tree.

    OP*  newBINOP(I32 type, I32 flags, OP* first, OP* last)
newCONDOP

Constructs, checks, and returns a conditional-expression (cond_expr) op. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. first supplies the expression selecting between the two branches, and trueop and falseop supply the branches; they are consumed by this function and become part of the constructed op tree.

    OP*  newCONDOP(I32 flags, OP* first, OP* trueop, OP* falseop)
newDEFSVOP

Constructs and returns an op to access $_.

    OP*  newDEFSVOP()
newFOROP

Constructs, checks, and returns an op tree expressing a foreach loop (iteration through a list of values). This is a heavyweight loop, with structure that allows exiting the loop by last and suchlike.

sv optionally supplies the variable that will be aliased to each item in turn; if null, it defaults to $_. expr supplies the list of values to iterate over. block supplies the main body of the loop, and cont optionally supplies a continue block that operates as a second half of the body. All of these optree inputs are consumed by this function and become part of the constructed op tree.

flags gives the eight bits of op_flags for the leaveloop op and, shifted up eight bits, the eight bits of op_private for the leaveloop op, except that (in both cases) some bits will be set automatically.

    OP*  newFOROP(I32 flags, OP* sv, OP* expr, OP* block, OP* cont)
newGIVENOP

Constructs, checks, and returns an op tree expressing a given block. cond supplies the expression to whose value $_ will be locally aliased, and block supplies the body of the given construct; they are consumed by this function and become part of the constructed op tree. defsv_off must be zero (it used to identity the pad slot of lexical $_).

    OP*  newGIVENOP(OP* cond, OP* block, PADOFFSET defsv_off)
newGVOP

Constructs, checks, and returns an op of any type that involves an embedded reference to a GV. type is the opcode. flags gives the eight bits of op_flags. gv identifies the GV that the op should reference; calling this function does not transfer ownership of any reference to it.

    OP*  newGVOP(I32 type, I32 flags, GV* gv)
newLISTOP

Constructs, checks, and returns an op of any list type. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically if required. first and last supply up to two ops to be direct children of the list op; they are consumed by this function and become part of the constructed op tree.

For most list operators, the check function expects all the kid ops to be present already, so calling newLISTOP(OP_JOIN, ...) (e.g.) is not appropriate. What you want to do in that case is create an op of type OP_LIST, append more children to it, and then call "op_convert_list". See "op_convert_list" for more information.

    OP*  newLISTOP(I32 type, I32 flags, OP* first, OP* last)
newLOGOP

Constructs, checks, and returns a logical (flow control) op. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. first supplies the expression controlling the flow, and other supplies the side (alternate) chain of ops; they are consumed by this function and become part of the constructed op tree.

    OP*  newLOGOP(I32 optype, I32 flags, OP *first, OP *other)
newLOOPEX

Constructs, checks, and returns a loop-exiting op (such as goto or last). type is the opcode. label supplies the parameter determining the target of the op; it is consumed by this function and becomes part of the constructed op tree.

    OP*  newLOOPEX(I32 type, OP* label)
newLOOPOP

Constructs, checks, and returns an op tree expressing a loop. This is only a loop in the control flow through the op tree; it does not have the heavyweight loop structure that allows exiting the loop by last and suchlike. flags gives the eight bits of op_flags for the top-level op, except that some bits will be set automatically as required. expr supplies the expression controlling loop iteration, and block supplies the body of the loop; they are consumed by this function and become part of the constructed op tree. debuggable is currently unused and should always be 1.

    OP*  newLOOPOP(I32 flags, I32 debuggable, OP* expr, OP* block)
newMETHOP

Constructs, checks, and returns an op of method type with a method name evaluated at runtime. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. dynamic_meth supplies an op which evaluates method name; it is consumed by this function and become part of the constructed op tree. Supported optypes: OP_METHOD.

    OP*  newMETHOP(I32 type, I32 flags, OP* dynamic_meth)
newMETHOP_named

Constructs, checks, and returns an op of method type with a constant method name. type is the opcode. flags gives the eight bits of op_flags, and, shifted up eight bits, the eight bits of op_private. const_meth supplies a constant method name; it must be a shared COW string. Supported optypes: OP_METHOD_NAMED.

    OP*  newMETHOP_named(I32 type, I32 flags, SV* const_meth)
newNULLLIST

Constructs, checks, and returns a new stub op, which represents an empty list expression.

    OP*  newNULLLIST()
newOP

Constructs, checks, and returns an op of any base type (any type that has no extra fields). type is the opcode. flags gives the eight bits of op_flags, and, shifted up eight bits, the eight bits of op_private.

    OP*  newOP(I32 optype, I32 flags)
newPADOP

Constructs, checks, and returns an op of any type that involves a reference to a pad element. type is the opcode. flags gives the eight bits of op_flags. A pad slot is automatically allocated, and is populated with sv; this function takes ownership of one reference to it.

This function only exists if Perl has been compiled to use ithreads.

    OP*  newPADOP(I32 type, I32 flags, SV* sv)
newPMOP

Constructs, checks, and returns an op of any pattern matching type. type is the opcode. flags gives the eight bits of op_flags and, shifted up eight bits, the eight bits of op_private.

    OP*  newPMOP(I32 type, I32 flags)
newPVOP

Constructs, checks, and returns an op of any type that involves an embedded C-level pointer (PV). type is the opcode. flags gives the eight bits of op_flags. pv supplies the C-level pointer. Depending on the op type, the memory referenced by pv may be freed when the op is destroyed. If the op is of a freeing type, pv must have been allocated using PerlMemShared_malloc.

    OP*  newPVOP(I32 type, I32 flags, char* pv)
newRANGE

Constructs and returns a range op, with subordinate flip and flop ops. flags gives the eight bits of op_flags for the flip op and, shifted up eight bits, the eight bits of op_private for both the flip and range ops, except that the bit with value 1 is automatically set. left and right supply the expressions controlling the endpoints of the range; they are consumed by this function and become part of the constructed op tree.

    OP*  newRANGE(I32 flags, OP* left, OP* right)
newSLICEOP

Constructs, checks, and returns an lslice (list slice) op. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 or 2 is automatically set as required. listval and subscript supply the parameters of the slice; they are consumed by this function and become part of the constructed op tree.

    OP*  newSLICEOP(I32 flags, OP* subscript, OP* listop)
newSTATEOP

Constructs a state op (COP). The state op is normally a nextstate op, but will be a dbstate op if debugging is enabled for currently-compiled code. The state op is populated from PL_curcop (or PL_compiling). If label is non-null, it supplies the name of a label to attach to the state op; this function takes ownership of the memory pointed at by label, and will free it. flags gives the eight bits of op_flags for the state op.

If o is null, the state op is returned. Otherwise the state op is combined with o into a lineseq list op, which is returned. o is consumed by this function and becomes part of the returned op tree.

    OP*  newSTATEOP(I32 flags, char* label, OP* o)
newSVOP

Constructs, checks, and returns an op of any type that involves an embedded SV. type is the opcode. flags gives the eight bits of op_flags. sv gives the SV to embed in the op; this function takes ownership of one reference to it.

    OP*  newSVOP(I32 type, I32 flags, SV* sv)
newTRYCATCHOP

NOTE: newTRYCATCHOP is experimental and may change or be removed without notice.

Constructs and returns a conditional execution statement that implements the try/catch semantics. First the op tree in tryblock is executed, inside a context that traps exceptions. If an exception occurs then the optree in catchblock is executed, with the trapped exception set into the lexical variable given by catchvar (which must be an op of type OP_PADSV). All the optrees are consumed by this function and become part of the returned op tree.

The flags argument is currently ignored.

    OP*  newTRYCATCHOP(I32 flags, OP* tryblock, OP *catchvar,
                       OP* catchblock)
newUNOP

Constructs, checks, and returns an op of any unary type. type is the opcode. flags gives the eight bits of op_flags, except that OPf_KIDS will be set automatically if required, and, shifted up eight bits, the eight bits of op_private, except that the bit with value 1 is automatically set. first supplies an optional op to be the direct child of the unary op; it is consumed by this function and become part of the constructed op tree.

    OP*  newUNOP(I32 type, I32 flags, OP* first)
newUNOP_AUX

Similar to newUNOP, but creates an UNOP_AUX struct instead, with op_aux initialised to aux

    OP*  newUNOP_AUX(I32 type, I32 flags, OP* first,
                     UNOP_AUX_item *aux)
newWHENOP

Constructs, checks, and returns an op tree expressing a when block. cond supplies the test expression, and block supplies the block that will be executed if the test evaluates to true; they are consumed by this function and become part of the constructed op tree. cond will be interpreted DWIMically, often as a comparison against $_, and may be null to generate a default block.

    OP*  newWHENOP(OP* cond, OP* block)
newWHILEOP

Constructs, checks, and returns an op tree expressing a while loop. This is a heavyweight loop, with structure that allows exiting the loop by last and suchlike.

loop is an optional preconstructed enterloop op to use in the loop; if it is null then a suitable op will be constructed automatically. expr supplies the loop's controlling expression. block supplies the main body of the loop, and cont optionally supplies a continue block that operates as a second half of the body. All of these optree inputs are consumed by this function and become part of the constructed op tree.

flags gives the eight bits of op_flags for the leaveloop op and, shifted up eight bits, the eight bits of op_private for the leaveloop op, except that (in both cases) some bits will be set automatically. debuggable is currently unused and should always be 1. has_my can be supplied as true to force the loop body to be enclosed in its own scope.

    OP*  newWHILEOP(I32 flags, I32 debuggable, LOOP* loop, OP* expr,
                    OP* block, OP* cont, I32 has_my)
PL_opfreehook

When non-NULL, the function pointed by this variable will be called each time an OP is freed with the corresponding OP as the argument. This allows extensions to free any extra attribute they have locally attached to an OP. It is also assured to first fire for the parent OP and then for its kids.

When you replace this variable, it is considered a good practice to store the possibly previously installed hook and that you recall it inside your own.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    Perl_ophook_t  PL_opfreehook
PL_peepp

Pointer to the per-subroutine peephole optimiser. This is a function that gets called at the end of compilation of a Perl subroutine (or equivalently independent piece of Perl code) to perform fixups of some ops and to perform small-scale optimisations. The function is called once for each subroutine that is compiled, and is passed, as sole parameter, a pointer to the op that is the entry point to the subroutine. It modifies the op tree in place.

The peephole optimiser should never be completely replaced. Rather, add code to it by wrapping the existing optimiser. The basic way to do this can be seen in "Compile pass 3: peephole optimization" in perlguts. If the new code wishes to operate on ops throughout the subroutine's structure, rather than just at the top level, it is likely to be more convenient to wrap the "PL_rpeepp" hook.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    peep_t  PL_peepp
PL_rpeepp

Pointer to the recursive peephole optimiser. This is a function that gets called at the end of compilation of a Perl subroutine (or equivalently independent piece of Perl code) to perform fixups of some ops and to perform small-scale optimisations. The function is called once for each chain of ops linked through their op_next fields; it is recursively called to handle each side chain. It is passed, as sole parameter, a pointer to the op that is at the head of the chain. It modifies the op tree in place.

The peephole optimiser should never be completely replaced. Rather, add code to it by wrapping the existing optimiser. The basic way to do this can be seen in "Compile pass 3: peephole optimization" in perlguts. If the new code wishes to operate only on ops at a subroutine's top level, rather than throughout the structure, it is likely to be more convenient to wrap the "PL_peepp" hook.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    peep_t  PL_rpeepp

Optree Manipulation Functions

alloccopstash

NOTE: alloccopstash is experimental and may change or be removed without notice.

Available only under threaded builds, this function allocates an entry in PL_stashpad for the stash passed to it.

    PADOFFSET  alloccopstash(HV *hv)
block_end

Handles compile-time scope exit. floor is the savestack index returned by block_start, and seq is the body of the block. Returns the block, possibly modified.

    OP*  block_end(I32 floor, OP* seq)
block_start

Handles compile-time scope entry. Arranges for hints to be restored on block exit and also handles pad sequence numbers to make lexical variables scope right. Returns a savestack index for use with block_end.

    int  block_start(int full)
ck_entersub_args_list

Performs the default fixup of the arguments part of an entersub op tree. This consists of applying list context to each of the argument ops. This is the standard treatment used on a call marked with &, or a method call, or a call through a subroutine reference, or any other call where the callee can't be identified at compile time, or a call where the callee has no prototype.

    OP*  ck_entersub_args_list(OP *entersubop)
ck_entersub_args_proto

Performs the fixup of the arguments part of an entersub op tree based on a subroutine prototype. This makes various modifications to the argument ops, from applying context up to inserting refgen ops, and checking the number and syntactic types of arguments, as directed by the prototype. This is the standard treatment used on a subroutine call, not marked with &, where the callee can be identified at compile time and has a prototype.

protosv supplies the subroutine prototype to be applied to the call. It may be a normal defined scalar, of which the string value will be used. Alternatively, for convenience, it may be a subroutine object (a CV* that has been cast to SV*) which has a prototype. The prototype supplied, in whichever form, does not need to match the actual callee referenced by the op tree.

If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the namegv parameter.

    OP*  ck_entersub_args_proto(OP *entersubop, GV *namegv,
                                SV *protosv)
ck_entersub_args_proto_or_list

Performs the fixup of the arguments part of an entersub op tree either based on a subroutine prototype or using default list-context processing. This is the standard treatment used on a subroutine call, not marked with &, where the callee can be identified at compile time.

protosv supplies the subroutine prototype to be applied to the call, or indicates that there is no prototype. It may be a normal scalar, in which case if it is defined then the string value will be used as a prototype, and if it is undefined then there is no prototype. Alternatively, for convenience, it may be a subroutine object (a CV* that has been cast to SV*), of which the prototype will be used if it has one. The prototype (or lack thereof) supplied, in whichever form, does not need to match the actual callee referenced by the op tree.

If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the namegv parameter.

    OP*  ck_entersub_args_proto_or_list(OP *entersubop, GV *namegv,
                                        SV *protosv)
cv_const_sv

If cv is a constant sub eligible for inlining, returns the constant value returned by the sub. Otherwise, returns NULL.

Constant subs can be created with newCONSTSUB or as described in "Constant Functions" in perlsub.

    SV*  cv_const_sv(const CV *const cv)
cv_get_call_checker

The original form of "cv_get_call_checker_flags", which does not return checker flags. When using a checker function returned by this function, it is only safe to call it with a genuine GV as its namegv argument.

    void  cv_get_call_checker(CV *cv, Perl_call_checker *ckfun_p,
                              SV **ckobj_p)
cv_get_call_checker_flags

Retrieves the function that will be used to fix up a call to cv. Specifically, the function is applied to an entersub op tree for a subroutine call, not marked with &, where the callee can be identified at compile time as cv.

The C-level function pointer is returned in *ckfun_p, an SV argument for it is returned in *ckobj_p, and control flags are returned in *ckflags_p. The function is intended to be called in this manner:

entersubop = (*ckfun_p)(aTHX_ entersubop, namegv, (*ckobj_p));

In this call, entersubop is a pointer to the entersub op, which may be replaced by the check function, and namegv supplies the name that should be used by the check function to refer to the callee of the entersub op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.

namegv may not actually be a GV. If the CALL_CHECKER_REQUIRE_GV bit is clear in *ckflags_p, it is permitted to pass a CV or other SV instead, anything that can be used as the first argument to "cv_name". If the CALL_CHECKER_REQUIRE_GV bit is set in *ckflags_p then the check function requires namegv to be a genuine GV.

By default, the check function is Perl_ck_entersub_args_proto_or_list, the SV parameter is cv itself, and the CALL_CHECKER_REQUIRE_GV flag is clear. This implements standard prototype processing. It can be changed, for a particular subroutine, by "cv_set_call_checker_flags".

If the CALL_CHECKER_REQUIRE_GV bit is set in gflags then it indicates that the caller only knows about the genuine GV version of namegv, and accordingly the corresponding bit will always be set in *ckflags_p, regardless of the check function's recorded requirements. If the CALL_CHECKER_REQUIRE_GV bit is clear in gflags then it indicates the caller knows about the possibility of passing something other than a GV as namegv, and accordingly the corresponding bit may be either set or clear in *ckflags_p, indicating the check function's recorded requirements.

gflags is a bitset passed into cv_get_call_checker_flags, in which only the CALL_CHECKER_REQUIRE_GV bit currently has a defined meaning (for which see above). All other bits should be clear.

    void  cv_get_call_checker_flags(CV *cv, U32 gflags,
                                    Perl_call_checker *ckfun_p,
                                    SV **ckobj_p, U32 *ckflags_p)
cv_set_call_checker

The original form of "cv_set_call_checker_flags", which passes it the CALL_CHECKER_REQUIRE_GV flag for backward-compatibility. The effect of that flag setting is that the check function is guaranteed to get a genuine GV as its namegv argument.

    void  cv_set_call_checker(CV *cv, Perl_call_checker ckfun,
                              SV *ckobj)
cv_set_call_checker_flags

Sets the function that will be used to fix up a call to cv. Specifically, the function is applied to an entersub op tree for a subroutine call, not marked with &, where the callee can be identified at compile time as cv.

The C-level function pointer is supplied in ckfun, an SV argument for it is supplied in ckobj, and control flags are supplied in ckflags. The function should be defined like this:

STATIC OP * ckfun(pTHX_ OP *op, GV *namegv, SV *ckobj)

It is intended to be called in this manner:

entersubop = ckfun(aTHX_ entersubop, namegv, ckobj);

In this call, entersubop is a pointer to the entersub op, which may be replaced by the check function, and namegv supplies the name that should be used by the check function to refer to the callee of the entersub op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.

namegv may not actually be a GV. For efficiency, perl may pass a CV or other SV instead. Whatever is passed can be used as the first argument to "cv_name". You can force perl to pass a GV by including CALL_CHECKER_REQUIRE_GV in the ckflags.

ckflags is a bitset, in which only the CALL_CHECKER_REQUIRE_GV bit currently has a defined meaning (for which see above). All other bits should be clear.

The current setting for a particular CV can be retrieved by "cv_get_call_checker_flags".

    void  cv_set_call_checker_flags(CV *cv, Perl_call_checker ckfun,
                                    SV *ckobj, U32 ckflags)

Given the root of an optree, link the tree in execution order using the op_next pointers and return the first op executed. If this has already been done, it will not be redone, and o->op_next will be returned. If o->op_next is not already set, o should be at least an UNOP.

    OP*  LINKLIST(OP *o)
newATTRSUB

Construct a Perl subroutine, also performing some surrounding jobs.

This is the same as "newATTRSUB_x" in perlintern with its o_is_gv parameter set to FALSE. This means that if o is null, the new sub will be anonymous; otherwise the name will be derived from o in the way described (as with all other details) in "newATTRSUB_x" in perlintern.

    CV*  newATTRSUB(I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
newCONSTSUB

Behaves like "newCONSTSUB_flags", except that name is nul-terminated rather than of counted length, and no flags are set. (This means that name is always interpreted as Latin-1.)

    CV*  newCONSTSUB(HV* stash, const char* name, SV* sv)
newCONSTSUB_flags

Construct a constant subroutine, also performing some surrounding jobs. A scalar constant-valued subroutine is eligible for inlining at compile-time, and in Perl code can be created by sub FOO () { 123 }. Other kinds of constant subroutine have other treatment.

The subroutine will have an empty prototype and will ignore any arguments when called. Its constant behaviour is determined by sv. If sv is null, the subroutine will yield an empty list. If sv points to a scalar, the subroutine will always yield that scalar. If sv points to an array, the subroutine will always yield a list of the elements of that array in list context, or the number of elements in the array in scalar context. This function takes ownership of one counted reference to the scalar or array, and will arrange for the object to live as long as the subroutine does. If sv points to a scalar then the inlining assumes that the value of the scalar will never change, so the caller must ensure that the scalar is not subsequently written to. If sv points to an array then no such assumption is made, so it is ostensibly safe to mutate the array or its elements, but whether this is really supported has not been determined.

The subroutine will have CvFILE set according to PL_curcop. Other aspects of the subroutine will be left in their default state. The caller is free to mutate the subroutine beyond its initial state after this function has returned.

If name is null then the subroutine will be anonymous, with its CvGV referring to an __ANON__ glob. If name is non-null then the subroutine will be named accordingly, referenced by the appropriate glob. name is a string of length len bytes giving a sigilless symbol name, in UTF-8 if flags has the SVf_UTF8 bit set and in Latin-1 otherwise. The name may be either qualified or unqualified. If the name is unqualified then it defaults to being in the stash specified by stash if that is non-null, or to PL_curstash if stash is null. The symbol is always added to the stash if necessary, with GV_ADDMULTI semantics.

flags should not have bits set other than SVf_UTF8.

If there is already a subroutine of the specified name, then the new sub will replace the existing one in the glob. A warning may be generated about the redefinition.

If the subroutine has one of a few special names, such as BEGIN or END, then it will be claimed by the appropriate queue for automatic running of phase-related subroutines. In this case the relevant glob will be left not containing any subroutine, even if it did contain one before. Execution of the subroutine will likely be a no-op, unless sv was a tied array or the caller modified the subroutine in some interesting way before it was executed. In the case of BEGIN, the treatment is buggy: the sub will be executed when only half built, and may be deleted prematurely, possibly causing a crash.

The function returns a pointer to the constructed subroutine. If the sub is anonymous then ownership of one counted reference to the subroutine is transferred to the caller. If the sub is named then the caller does not get ownership of a reference. In most such cases, where the sub has a non-phase name, the sub will be alive at the point it is returned by virtue of being contained in the glob that names it. A phase-named subroutine will usually be alive by virtue of the reference owned by the phase's automatic run queue. A BEGIN subroutine may have been destroyed already by the time this function returns, but currently bugs occur in that case before the caller gets control. It is the caller's responsibility to ensure that it knows which of these situations applies.

    CV*  newCONSTSUB_flags(HV* stash, const char* name, STRLEN len,
                           U32 flags, SV* sv)
newSUB

Like "newATTRSUB", but without attributes.

    CV*  newSUB(I32 floor, OP* o, OP* proto, OP* block)
newXS

Used by xsubpp to hook up XSUBs as Perl subs. filename needs to be static storage, as it is used directly as CvFILE(), without a copy being made.

op_append_elem

Append an item to the list of ops contained directly within a list-type op, returning the lengthened list. first is the list-type op, and last is the op to append to the list. optype specifies the intended opcode for the list. If first is not already a list of the right type, it will be upgraded into one. If either first or last is null, the other is returned unchanged.

    OP*  op_append_elem(I32 optype, OP* first, OP* last)
op_append_list

Concatenate the lists of ops contained directly within two list-type ops, returning the combined list. first and last are the list-type ops to concatenate. optype specifies the intended opcode for the list. If either first or last is not already a list of the right type, it will be upgraded into one. If either first or last is null, the other is returned unchanged.

    OP*  op_append_list(I32 optype, OP* first, OP* last)
OP_CLASS

Return the class of the provided OP: that is, which of the *OP structures it uses. For core ops this currently gets the information out of PL_opargs, which does not always accurately reflect the type used; in v5.26 onwards, see also the function "op_class" which can do a better job of determining the used type.

For custom ops the type is returned from the registration, and it is up to the registree to ensure it is accurate. The value returned will be one of the OA_* constants from op.h.

    U32  OP_CLASS(OP *o)
op_contextualize

Applies a syntactic context to an op tree representing an expression. o is the op tree, and context must be G_SCALAR, G_ARRAY, or G_VOID to specify the context to apply. The modified op tree is returned.

    OP*  op_contextualize(OP* o, I32 context)
op_convert_list

Converts o into a list op if it is not one already, and then converts it into the specified type, calling its check function, allocating a target if it needs one, and folding constants.

A list-type op is usually constructed one kid at a time via newLISTOP, op_prepend_elem and op_append_elem. Then finally it is passed to op_convert_list to make it the right type.

    OP*  op_convert_list(I32 optype, I32 flags, OP* o)
OP_DESC

Return a short description of the provided OP.

    const char *  OP_DESC(OP *o)
op_free

Free an op and its children. Only use this when an op is no longer linked to from any optree.

    void  op_free(OP* arg)
OpHAS_SIBLING

Returns true if o has a sibling

    bool  OpHAS_SIBLING(OP *o)
OpLASTSIB_set

Marks o as having no further siblings and marks o as having the specified parent. See also "OpMORESIB_set" and OpMAYBESIB_set. For a higher-level interface, see "op_sibling_splice".

    void  OpLASTSIB_set(OP *o, OP *parent)

This function is the implementation of the "LINKLIST" macro. It should not be called directly.

    OP*  op_linklist(OP *o)
op_lvalue

NOTE: op_lvalue is experimental and may change or be removed without notice.

Propagate lvalue ("modifiable") context to an op and its children. type represents the context type, roughly based on the type of op that would do the modifying, although local() is represented by OP_NULL, because it has no op type of its own (it is signalled by a flag on the lvalue op).

This function detects things that can't be modified, such as $x+1, and generates errors for them. For example, $x+1 = 2 would cause it to be called with an op of type OP_ADD and a type argument of OP_SASSIGN.

It also flags things that need to behave specially in an lvalue context, such as $$x = 5 which might have to vivify a reference in $x.

    OP*  op_lvalue(OP* o, I32 type)
OpMAYBESIB_set

Conditionally does OpMORESIB_set or OpLASTSIB_set depending on whether sib is non-null. For a higher-level interface, see "op_sibling_splice".

    void  OpMAYBESIB_set(OP *o, OP *sib, OP *parent)
OpMORESIB_set

Sets the sibling of o to the non-zero value sib. See also "OpLASTSIB_set" and "OpMAYBESIB_set". For a higher-level interface, see "op_sibling_splice".

    void  OpMORESIB_set(OP *o, OP *sib)
OP_NAME

Return the name of the provided OP. For core ops this looks up the name from the op_type; for custom ops from the op_ppaddr.

    const char *  OP_NAME(OP *o)
op_null

Neutralizes an op when it is no longer needed, but is still linked to from other ops.

    void  op_null(OP* o)
op_parent

Returns the parent OP of o, if it has a parent. Returns NULL otherwise.

    OP*  op_parent(OP *o)
op_prepend_elem

Prepend an item to the list of ops contained directly within a list-type op, returning the lengthened list. first is the op to prepend to the list, and last is the list-type op. optype specifies the intended opcode for the list. If last is not already a list of the right type, it will be upgraded into one. If either first or last is null, the other is returned unchanged.

    OP*  op_prepend_elem(I32 optype, OP* first, OP* last)
op_scope

NOTE: op_scope is experimental and may change or be removed without notice.

Wraps up an op tree with some additional ops so that at runtime a dynamic scope will be created. The original ops run in the new dynamic scope, and then, provided that they exit normally, the scope will be unwound. The additional ops used to create and unwind the dynamic scope will normally be an enter/leave pair, but a scope op may be used instead if the ops are simple enough to not need the full dynamic scope structure.

    OP*  op_scope(OP* o)
OpSIBLING

Returns the sibling of o, or NULL if there is no sibling

    OP*  OpSIBLING(OP *o)
op_sibling_splice

A general function for editing the structure of an existing chain of op_sibling nodes. By analogy with the perl-level splice() function, allows you to delete zero or more sequential nodes, replacing them with zero or more different nodes. Performs the necessary op_first/op_last housekeeping on the parent node and op_sibling manipulation on the children. The last deleted node will be marked as the last node by updating the op_sibling/op_sibparent or op_moresib field as appropriate.

Note that op_next is not manipulated, and nodes are not freed; that is the responsibility of the caller. It also won't create a new list op for an empty list etc; use higher-level functions like op_append_elem() for that.

parent is the parent node of the sibling chain. It may passed as NULL if the splicing doesn't affect the first or last op in the chain.

start is the node preceding the first node to be spliced. Node(s) following it will be deleted, and ops will be inserted after it. If it is NULL, the first node onwards is deleted, and nodes are inserted at the beginning.

del_count is the number of nodes to delete. If zero, no nodes are deleted. If -1 or greater than or equal to the number of remaining kids, all remaining kids are deleted.

insert is the first of a chain of nodes to be inserted in place of the nodes. If NULL, no nodes are inserted.

The head of the chain of deleted ops is returned, or NULL if no ops were deleted.

For example:

action                    before      after         returns
------                    -----       -----         -------

                          P           P
splice(P, A, 2, X-Y-Z)    |           |             B-C
                          A-B-C-D     A-X-Y-Z-D

                          P           P
splice(P, NULL, 1, X-Y)   |           |             A
                          A-B-C-D     X-Y-B-C-D

                          P           P
splice(P, NULL, 3, NULL)  |           |             A-B-C
                          A-B-C-D     D

                          P           P
splice(P, B, 0, X-Y)      |           |             NULL
                          A-B-C-D     A-B-X-Y-C-D

For lower-level direct manipulation of op_sibparent and op_moresib, see "OpMORESIB_set", "OpLASTSIB_set", "OpMAYBESIB_set".

    OP*  op_sibling_splice(OP *parent, OP *start, int del_count,
                           OP* insert)
OP_TYPE_IS

Returns true if the given OP is not a NULL pointer and if it is of the given type.

The negation of this macro, OP_TYPE_ISNT is also available as well as OP_TYPE_IS_NN and OP_TYPE_ISNT_NN which elide the NULL pointer check.

    bool  OP_TYPE_IS(OP *o, Optype type)
OP_TYPE_IS_OR_WAS

Returns true if the given OP is not a NULL pointer and if it is of the given type or used to be before being replaced by an OP of type OP_NULL.

The negation of this macro, OP_TYPE_ISNT_AND_WASNT is also available as well as OP_TYPE_IS_OR_WAS_NN and OP_TYPE_ISNT_AND_WASNT_NN which elide the NULL pointer check.

    bool  OP_TYPE_IS_OR_WAS(OP *o, Optype type)
rv2cv_op_cv

Examines an op, which is expected to identify a subroutine at runtime, and attempts to determine at compile time which subroutine it identifies. This is normally used during Perl compilation to determine whether a prototype can be applied to a function call. cvop is the op being considered, normally an rv2cv op. A pointer to the identified subroutine is returned, if it could be determined statically, and a null pointer is returned if it was not possible to determine statically.

Currently, the subroutine can be identified statically if the RV that the rv2cv is to operate on is provided by a suitable gv or const op. A gv op is suitable if the GV's CV slot is populated. A const op is suitable if the constant value must be an RV pointing to a CV. Details of this process may change in future versions of Perl. If the rv2cv op has the OPpENTERSUB_AMPER flag set then no attempt is made to identify the subroutine statically: this flag is used to suppress compile-time magic on a subroutine call, forcing it to use default runtime behaviour.

If flags has the bit RV2CVOPCV_MARK_EARLY set, then the handling of a GV reference is modified. If a GV was examined and its CV slot was found to be empty, then the gv op has the OPpEARLY_CV flag set. If the op is not optimised away, and the CV slot is later populated with a subroutine having a prototype, that flag eventually triggers the warning "called too early to check prototype".

If flags has the bit RV2CVOPCV_RETURN_NAME_GV set, then instead of returning a pointer to the subroutine it returns a pointer to the GV giving the most appropriate name for the subroutine in this context. Normally this is just the CvGV of the subroutine, but for an anonymous (CvANON) subroutine that is referenced through a GV it will be the referencing GV. The resulting GV* is cast to CV* to be returned. A null pointer is returned as usual if there is no statically-determinable subroutine.

    CV*  rv2cv_op_cv(OP *cvop, U32 flags)

Pack and Unpack

pack_cat

DEPRECATED! It is planned to remove pack_cat from a future release of Perl. Do not use it for new code; remove it from existing code.

The engine implementing pack() Perl function. Note: parameters next_in_list and flags are not used. This call should not be used; use "packlist" instead.

    void  pack_cat(SV *cat, const char *pat, const char *patend,
                   SV **beglist, SV **endlist, SV ***next_in_list,
                   U32 flags)
packlist

The engine implementing pack() Perl function.

    void  packlist(SV *cat, const char *pat, const char *patend,
                   SV **beglist, SV **endlist)
unpack_str

DEPRECATED! It is planned to remove unpack_str from a future release of Perl. Do not use it for new code; remove it from existing code.

The engine implementing unpack() Perl function. Note: parameters strbeg, new_s and ocnt are not used. This call should not be used, use unpackstring instead.

    SSize_t  unpack_str(const char *pat, const char *patend,
                        const char *s, const char *strbeg,
                        const char *strend, char **new_s, I32 ocnt,
                        U32 flags)
unpackstring

The engine implementing the unpack() Perl function.

Using the template pat..patend, this function unpacks the string s..strend into a number of mortal SVs, which it pushes onto the perl argument (@_) stack (so you will need to issue a PUTBACK before and SPAGAIN after the call to this function). It returns the number of pushed elements.

The strend and patend pointers should point to the byte following the last character of each string.

Although this function returns its values on the perl argument stack, it doesn't take any parameters from that stack (and thus in particular there's no need to do a PUSHMARK before calling it, unlike "call_pv" for example).

    SSize_t  unpackstring(const char *pat, const char *patend,
                          const char *s, const char *strend,
                          U32 flags)

Pad Data Structures

CvPADLIST

NOTE: CvPADLIST is experimental and may change or be removed without notice.

CV's can have CvPADLIST(cv) set to point to a PADLIST. This is the CV's scratchpad, which stores lexical variables and opcode temporary and per-thread values.

For these purposes "formats" are a kind-of CV; eval""s are too (except they're not callable at will and are always thrown away after the eval"" is done executing). Require'd files are simply evals without any outer lexical scope.

XSUBs do not have a CvPADLIST. dXSTARG fetches values from PL_curpad, but that is really the callers pad (a slot of which is allocated by every entersub). Do not get or set CvPADLIST if a CV is an XSUB (as determined by CvISXSUB()), CvPADLIST slot is reused for a different internal purpose in XSUBs.

The PADLIST has a C array where pads are stored.

The 0th entry of the PADLIST is a PADNAMELIST which represents the "names" or rather the "static type information" for lexicals. The individual elements of a PADNAMELIST are PADNAMEs. Future refactorings might stop the PADNAMELIST from being stored in the PADLIST's array, so don't rely on it. See "PadlistNAMES".

The CvDEPTH'th entry of a PADLIST is a PAD (an AV) which is the stack frame at that depth of recursion into the CV. The 0th slot of a frame AV is an AV which is @_. Other entries are storage for variables and op targets.

Iterating over the PADNAMELIST iterates over all possible pad items. Pad slots for targets (SVs_PADTMP) and GVs end up having &PL_padname_undef "names", while slots for constants have &PL_padname_const "names" (see "pad_alloc"). That &PL_padname_undef and &PL_padname_const are used is an implementation detail subject to change. To test for them, use !PadnamePV(name) and PadnamePV(name) && !PadnameLEN(name), respectively.

Only my/our variable slots get valid names. The rest are op targets/GVs/constants which are statically allocated or resolved at compile time. These don't have names by which they can be looked up from Perl code at run time through eval"" the way my/our variables can be. Since they can't be looked up by "name" but only by their index allocated at compile time (which is usually in PL_op->op_targ), wasting a name SV for them doesn't make sense.

The pad names in the PADNAMELIST have their PV holding the name of the variable. The COP_SEQ_RANGE_LOW and _HIGH fields form a range (low+1..high inclusive) of cop_seq numbers for which the name is valid. During compilation, these fields may hold the special value PERL_PADSEQ_INTRO to indicate various stages:

COP_SEQ_RANGE_LOW        _HIGH
-----------------        -----
PERL_PADSEQ_INTRO            0   variable not yet introduced:
                                 { my ($x
valid-seq#   PERL_PADSEQ_INTRO   variable in scope:
                                 { my ($x);
valid-seq#          valid-seq#   compilation of scope complete:
                                 { my ($x); .... }

When a lexical var hasn't yet been introduced, it already exists from the perspective of duplicate declarations, but not for variable lookups, e.g.

my ($x, $x); # '"my" variable $x masks earlier declaration'
my $x = $x;  # equal to my $x = $::x;

For typed lexicals PadnameTYPE points at the type stash. For our lexicals, PadnameOURSTASH points at the stash of the associated global (so that duplicate our declarations in the same package can be detected). PadnameGEN is sometimes used to store the generation number during compilation.

If PadnameOUTER is set on the pad name, then that slot in the frame AV is a REFCNT'ed reference to a lexical from "outside". Such entries are sometimes referred to as 'fake'. In this case, the name does not use 'low' and 'high' to store a cop_seq range, since it is in scope throughout. Instead 'high' stores some flags containing info about the real lexical (is it declared in an anon, and is it capable of being instantiated multiple times?), and for fake ANONs, 'low' contains the index within the parent's pad where the lexical's value is stored, to make cloning quicker.

If the 'name' is & the corresponding entry in the PAD is a CV representing a possible closure.

Note that formats are treated as anon subs, and are cloned each time write is called (if necessary).

The flag SVs_PADSTALE is cleared on lexicals each time the my() is executed, and set on scope exit. This allows the "Variable $x is not available" warning to be generated in evals, such as

{ my $x = 1; sub f { eval '$x'} } f();

For state vars, SVs_PADSTALE is overloaded to mean 'not yet initialised', but this internal state is stored in a separate pad entry.

    PADLIST *  CvPADLIST(CV *cv)
pad_add_name_pvs

Exactly like "pad_add_name_pvn", but takes a literal string instead of a string/length pair.

    PADOFFSET  pad_add_name_pvs("name", U32 flags, HV *typestash,
                                HV *ourstash)
PadARRAY

NOTE: PadARRAY is experimental and may change or be removed without notice.

The C array of pad entries.

    SV **  PadARRAY(PAD * pad)
pad_findmy_pvs

Exactly like "pad_findmy_pvn", but takes a literal string instead of a string/length pair.

    PADOFFSET  pad_findmy_pvs("name", U32 flags)
PadlistARRAY

NOTE: PadlistARRAY is experimental and may change or be removed without notice.

The C array of a padlist, containing the pads. Only subscript it with numbers >= 1, as the 0th entry is not guaranteed to remain usable.

    PAD **  PadlistARRAY(PADLIST * padlist)
PadlistMAX

NOTE: PadlistMAX is experimental and may change or be removed without notice.

The index of the last allocated space in the padlist. Note that the last pad may be in an earlier slot. Any entries following it will be NULL in that case.

    SSize_t  PadlistMAX(PADLIST * padlist)
PadlistNAMES

NOTE: PadlistNAMES is experimental and may change or be removed without notice.

The names associated with pad entries.

    PADNAMELIST *  PadlistNAMES(PADLIST * padlist)
PadlistNAMESARRAY

NOTE: PadlistNAMESARRAY is experimental and may change or be removed without notice.

The C array of pad names.

    PADNAME **  PadlistNAMESARRAY(PADLIST * padlist)
PadlistNAMESMAX

NOTE: PadlistNAMESMAX is experimental and may change or be removed without notice.

The index of the last pad name.

    SSize_t  PadlistNAMESMAX(PADLIST * padlist)
PadlistREFCNT

NOTE: PadlistREFCNT is experimental and may change or be removed without notice.

The reference count of the padlist. Currently this is always 1.

    U32  PadlistREFCNT(PADLIST * padlist)
PadMAX

NOTE: PadMAX is experimental and may change or be removed without notice.

The index of the last pad entry.

    SSize_t  PadMAX(PAD * pad)
PadnameLEN

NOTE: PadnameLEN is experimental and may change or be removed without notice.

The length of the name.

    STRLEN  PadnameLEN(PADNAME * pn)
PadnamelistARRAY

NOTE: PadnamelistARRAY is experimental and may change or be removed without notice.

The C array of pad names.

    PADNAME **  PadnamelistARRAY(PADNAMELIST * pnl)
PadnamelistMAX

NOTE: PadnamelistMAX is experimental and may change or be removed without notice.

The index of the last pad name.

    SSize_t  PadnamelistMAX(PADNAMELIST * pnl)
PadnamelistREFCNT

NOTE: PadnamelistREFCNT is experimental and may change or be removed without notice.

The reference count of the pad name list.

    SSize_t  PadnamelistREFCNT(PADNAMELIST * pnl)
PadnamelistREFCNT_dec

NOTE: PadnamelistREFCNT_dec is experimental and may change or be removed without notice.

Lowers the reference count of the pad name list.

    void  PadnamelistREFCNT_dec(PADNAMELIST * pnl)
PadnamePV

NOTE: PadnamePV is experimental and may change or be removed without notice.

The name stored in the pad name struct. This returns NULL for a target slot.

    char *  PadnamePV(PADNAME * pn)
PadnameREFCNT

NOTE: PadnameREFCNT is experimental and may change or be removed without notice.

The reference count of the pad name.

    SSize_t  PadnameREFCNT(PADNAME * pn)
PadnameREFCNT_dec

NOTE: PadnameREFCNT_dec is experimental and may change or be removed without notice.

Lowers the reference count of the pad name.

    void  PadnameREFCNT_dec(PADNAME * pn)
PadnameSV

NOTE: PadnameSV is experimental and may change or be removed without notice.

Returns the pad name as a mortal SV.

    SV *  PadnameSV(PADNAME * pn)
PadnameUTF8

NOTE: PadnameUTF8 is experimental and may change or be removed without notice.

Whether PadnamePV is in UTF-8. Currently, this is always true.

    bool  PadnameUTF8(PADNAME * pn)
pad_new

Create a new padlist, updating the global variables for the currently-compiling padlist to point to the new padlist. The following flags can be OR'ed together:

padnew_CLONE        this pad is for a cloned CV
padnew_SAVE         save old globals on the save stack
padnew_SAVESUB      also save extra stuff for start of sub
    PADLIST*  pad_new(int flags)
PL_comppad

NOTE: PL_comppad is experimental and may change or be removed without notice.

During compilation, this points to the array containing the values part of the pad for the currently-compiling code. (At runtime a CV may have many such value arrays; at compile time just one is constructed.) At runtime, this points to the array containing the currently-relevant values for the pad for the currently-executing code.

PL_comppad_name

NOTE: PL_comppad_name is experimental and may change or be removed without notice.

During compilation, this points to the array containing the names part of the pad for the currently-compiling code.

PL_curpad

NOTE: PL_curpad is experimental and may change or be removed without notice.

Points directly to the body of the "PL_comppad" array. (I.e., this is PadARRAY(PL_comppad).)

Password and Group access

GRPASSWD

This symbol, if defined, indicates to the C program that struct group in grp.h contains gr_passwd.

HAS_ENDGRENT

This symbol, if defined, indicates that the getgrent routine is available for finalizing sequential access of the group database.

HAS_ENDGRENT_R

This symbol, if defined, indicates that the endgrent_r routine is available to endgrent re-entrantly.

HAS_ENDPWENT

This symbol, if defined, indicates that the getgrent routine is available for finalizing sequential access of the passwd database.

HAS_ENDPWENT_R

This symbol, if defined, indicates that the endpwent_r routine is available to endpwent re-entrantly.

HAS_GETGRENT

This symbol, if defined, indicates that the getgrent routine is available for sequential access of the group database.

HAS_GETGRENT_R

This symbol, if defined, indicates that the getgrent_r routine is available to getgrent re-entrantly.

HAS_GETPWENT

This symbol, if defined, indicates that the getpwent routine is available for sequential access of the passwd database. If this is not available, the older getpw() function may be available.

HAS_GETPWENT_R

This symbol, if defined, indicates that the getpwent_r routine is available to getpwent re-entrantly.

HAS_SETGRENT

This symbol, if defined, indicates that the setgrent routine is available for initializing sequential access of the group database.

HAS_SETGRENT_R

This symbol, if defined, indicates that the setgrent_r routine is available to setgrent re-entrantly.

HAS_SETPWENT

This symbol, if defined, indicates that the setpwent routine is available for initializing sequential access of the passwd database.

HAS_SETPWENT_R

This symbol, if defined, indicates that the setpwent_r routine is available to setpwent re-entrantly.

PWAGE

This symbol, if defined, indicates to the C program that struct passwd contains pw_age.

PWCHANGE

This symbol, if defined, indicates to the C program that struct passwd contains pw_change.

PWCLASS

This symbol, if defined, indicates to the C program that struct passwd contains pw_class.

PWCOMMENT

This symbol, if defined, indicates to the C program that struct passwd contains pw_comment.

PWEXPIRE

This symbol, if defined, indicates to the C program that struct passwd contains pw_expire.

PWGECOS

This symbol, if defined, indicates to the C program that struct passwd contains pw_gecos.

PWPASSWD

This symbol, if defined, indicates to the C program that struct passwd contains pw_passwd.

PWQUOTA

This symbol, if defined, indicates to the C program that struct passwd contains pw_quota.

Paths to system commands

CSH

This symbol, if defined, contains the full pathname of csh.

LOC_SED

This symbol holds the complete pathname to the sed program.

SH_PATH

This symbol contains the full pathname to the shell used on this on this system to execute Bourne shell scripts. Usually, this will be /bin/sh, though it's possible that some systems will have /bin/ksh, /bin/pdksh, /bin/ash, /bin/bash, or even something such as D:/bin/sh.exe.

Prototype information

CRYPT_R_PROTO

This symbol encodes the prototype of crypt_r. It is zero if d_crypt_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_crypt_r is defined.

CTERMID_R_PROTO

This symbol encodes the prototype of ctermid_r. It is zero if d_ctermid_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_ctermid_r is defined.

DRAND48_R_PROTO

This symbol encodes the prototype of drand48_r. It is zero if d_drand48_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_drand48_r is defined.

ENDGRENT_R_PROTO

This symbol encodes the prototype of endgrent_r. It is zero if d_endgrent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_endgrent_r is defined.

ENDHOSTENT_R_PROTO

This symbol encodes the prototype of endhostent_r. It is zero if d_endhostent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_endhostent_r is defined.

ENDNETENT_R_PROTO

This symbol encodes the prototype of endnetent_r. It is zero if d_endnetent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_endnetent_r is defined.

ENDPROTOENT_R_PROTO

This symbol encodes the prototype of endprotoent_r. It is zero if d_endprotoent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_endprotoent_r is defined.

ENDPWENT_R_PROTO

This symbol encodes the prototype of endpwent_r. It is zero if d_endpwent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_endpwent_r is defined.

ENDSERVENT_R_PROTO

This symbol encodes the prototype of endservent_r. It is zero if d_endservent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_endservent_r is defined.

GDBMNDBM_H_USES_PROTOTYPES

This symbol, if defined, indicates that gdbm/ndbm.h uses real ANSI C prototypes instead of K&R style function declarations without any parameter information. While ANSI C prototypes are supported in C++, K&R style function declarations will yield errors.

GDBM_NDBM_H_USES_PROTOTYPES

This symbol, if defined, indicates that <gdbm-ndbm.h> uses real ANSI C prototypes instead of K&R style function declarations without any parameter information. While ANSI C prototypes are supported in C++, K&R style function declarations will yield errors.

GETGRENT_R_PROTO

This symbol encodes the prototype of getgrent_r. It is zero if d_getgrent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getgrent_r is defined.

GETGRGID_R_PROTO

This symbol encodes the prototype of getgrgid_r. It is zero if d_getgrgid_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getgrgid_r is defined.

GETGRNAM_R_PROTO

This symbol encodes the prototype of getgrnam_r. It is zero if d_getgrnam_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getgrnam_r is defined.

GETHOSTBYADDR_R_PROTO

This symbol encodes the prototype of gethostbyaddr_r. It is zero if d_gethostbyaddr_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_gethostbyaddr_r is defined.

GETHOSTBYNAME_R_PROTO

This symbol encodes the prototype of gethostbyname_r. It is zero if d_gethostbyname_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_gethostbyname_r is defined.

GETHOSTENT_R_PROTO

This symbol encodes the prototype of gethostent_r. It is zero if d_gethostent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_gethostent_r is defined.

GETLOGIN_R_PROTO

This symbol encodes the prototype of getlogin_r. It is zero if d_getlogin_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getlogin_r is defined.

GETNETBYADDR_R_PROTO

This symbol encodes the prototype of getnetbyaddr_r. It is zero if d_getnetbyaddr_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getnetbyaddr_r is defined.

GETNETBYNAME_R_PROTO

This symbol encodes the prototype of getnetbyname_r. It is zero if d_getnetbyname_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getnetbyname_r is defined.

GETNETENT_R_PROTO

This symbol encodes the prototype of getnetent_r. It is zero if d_getnetent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getnetent_r is defined.

GETPROTOBYNAME_R_PROTO

This symbol encodes the prototype of getprotobyname_r. It is zero if d_getprotobyname_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getprotobyname_r is defined.

GETPROTOBYNUMBER_R_PROTO

This symbol encodes the prototype of getprotobynumber_r. It is zero if d_getprotobynumber_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getprotobynumber_r is defined.

GETPROTOENT_R_PROTO

This symbol encodes the prototype of getprotoent_r. It is zero if d_getprotoent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getprotoent_r is defined.

GETPWENT_R_PROTO

This symbol encodes the prototype of getpwent_r. It is zero if d_getpwent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getpwent_r is defined.

GETPWNAM_R_PROTO

This symbol encodes the prototype of getpwnam_r. It is zero if d_getpwnam_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getpwnam_r is defined.

GETPWUID_R_PROTO

This symbol encodes the prototype of getpwuid_r. It is zero if d_getpwuid_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getpwuid_r is defined.

GETSERVBYNAME_R_PROTO

This symbol encodes the prototype of getservbyname_r. It is zero if d_getservbyname_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getservbyname_r is defined.

GETSERVBYPORT_R_PROTO

This symbol encodes the prototype of getservbyport_r. It is zero if d_getservbyport_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getservbyport_r is defined.

GETSERVENT_R_PROTO

This symbol encodes the prototype of getservent_r. It is zero if d_getservent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getservent_r is defined.

GETSPNAM_R_PROTO

This symbol encodes the prototype of getspnam_r. It is zero if d_getspnam_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_getspnam_r is defined.

HAS_DBMINIT_PROTO

This symbol, if defined, indicates that the system provides a prototype for the dbminit() function. Otherwise, it is up to the program to supply one. A good guess is

extern int dbminit(char *);
HAS_DRAND48_PROTO

This symbol, if defined, indicates that the system provides a prototype for the drand48() function. Otherwise, it is up to the program to supply one. A good guess is

extern double drand48(void);
HAS_FLOCK_PROTO

This symbol, if defined, indicates that the system provides a prototype for the flock() function. Otherwise, it is up to the program to supply one. A good guess is

extern int flock(int, int);
HAS_GETHOST_PROTOS

This symbol, if defined, indicates that netdb.h includes prototypes for gethostent(), gethostbyname(), and gethostbyaddr(). Otherwise, it is up to the program to guess them. See netdbtype.U (part of metaconfig) for probing for various Netdb_xxx_t types.

HAS_GETNET_PROTOS

This symbol, if defined, indicates that netdb.h includes prototypes for getnetent(), getnetbyname(), and getnetbyaddr(). Otherwise, it is up to the program to guess them. See netdbtype.U (part of metaconfig) for probing for various Netdb_xxx_t types.

HAS_GETPROTO_PROTOS

This symbol, if defined, indicates that netdb.h includes prototypes for getprotoent(), getprotobyname(), and getprotobyaddr(). Otherwise, it is up to the program to guess them. See netdbtype.U (part of metaconfig) for probing for various Netdb_xxx_t types.

HAS_GETSERV_PROTOS

This symbol, if defined, indicates that netdb.h includes prototypes for getservent(), getservbyname(), and getservbyaddr(). Otherwise, it is up to the program to guess them. See netdbtype.U (part of metaconfig) for probing for various Netdb_xxx_t types.

HAS_MODFL_PROTO

This symbol, if defined, indicates that the system provides a prototype for the modfl() function. Otherwise, it is up to the program to supply one.

HAS_SBRK_PROTO

This symbol, if defined, indicates that the system provides a prototype for the sbrk() function. Otherwise, it is up to the program to supply one. Good guesses are

extern void* sbrk(int);
extern void* sbrk(size_t);
HAS_SETRESGID_PROTO

This symbol, if defined, indicates that the system provides a prototype for the setresgid() function. Otherwise, it is up to the program to supply one. Good guesses are

extern int setresgid(uid_t ruid, uid_t euid, uid_t suid);
HAS_SETRESUID_PROTO

This symbol, if defined, indicates that the system provides a prototype for the setresuid() function. Otherwise, it is up to the program to supply one. Good guesses are

extern int setresuid(uid_t ruid, uid_t euid, uid_t suid);
HAS_SHMAT_PROTOTYPE

This symbol, if defined, indicates that the sys/shm.h includes a prototype for shmat(). Otherwise, it is up to the program to guess one. Shmat_t shmat(int, Shmat_t, int) is a good guess, but not always right so it should be emitted by the program only when HAS_SHMAT_PROTOTYPE is not defined to avoid conflicting defs.

HAS_SOCKATMARK_PROTO

This symbol, if defined, indicates that the system provides a prototype for the sockatmark() function. Otherwise, it is up to the program to supply one. A good guess is

extern int sockatmark(int);
HAS_SYSCALL_PROTO

This symbol, if defined, indicates that the system provides a prototype for the syscall() function. Otherwise, it is up to the program to supply one. Good guesses are

extern int syscall(int,  ...);
extern int syscall(long, ...);
HAS_TELLDIR_PROTO

This symbol, if defined, indicates that the system provides a prototype for the telldir() function. Otherwise, it is up to the program to supply one. A good guess is

extern long telldir(DIR*);
NDBM_H_USES_PROTOTYPES

This symbol, if defined, indicates that ndbm.h uses real ANSI C prototypes instead of K&R style function declarations without any parameter information. While ANSI C prototypes are supported in C++, K&R style function declarations will yield errors.

RANDOM_R_PROTO

This symbol encodes the prototype of random_r. It is zero if d_random_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_random_r is defined.

READDIR_R_PROTO

This symbol encodes the prototype of readdir_r. It is zero if d_readdir_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_readdir_r is defined.

SETGRENT_R_PROTO

This symbol encodes the prototype of setgrent_r. It is zero if d_setgrent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_setgrent_r is defined.

SETHOSTENT_R_PROTO

This symbol encodes the prototype of sethostent_r. It is zero if d_sethostent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_sethostent_r is defined.

SETLOCALE_R_PROTO

This symbol encodes the prototype of setlocale_r. It is zero if d_setlocale_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_setlocale_r is defined.

SETNETENT_R_PROTO

This symbol encodes the prototype of setnetent_r. It is zero if d_setnetent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_setnetent_r is defined.

SETPROTOENT_R_PROTO

This symbol encodes the prototype of setprotoent_r. It is zero if d_setprotoent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_setprotoent_r is defined.

SETPWENT_R_PROTO

This symbol encodes the prototype of setpwent_r. It is zero if d_setpwent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_setpwent_r is defined.

SETSERVENT_R_PROTO

This symbol encodes the prototype of setservent_r. It is zero if d_setservent_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_setservent_r is defined.

SRAND48_R_PROTO

This symbol encodes the prototype of srand48_r. It is zero if d_srand48_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_srand48_r is defined.

SRANDOM_R_PROTO

This symbol encodes the prototype of srandom_r. It is zero if d_srandom_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_srandom_r is defined.

STRERROR_R_PROTO

This symbol encodes the prototype of strerror_r. It is zero if d_strerror_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_strerror_r is defined.

TMPNAM_R_PROTO

This symbol encodes the prototype of tmpnam_r. It is zero if d_tmpnam_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_tmpnam_r is defined.

TTYNAME_R_PROTO

This symbol encodes the prototype of ttyname_r. It is zero if d_ttyname_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_ttyname_r is defined.

REGEXP Functions

pregcomp

Described in perlreguts.

    REGEXP*  pregcomp(SV * const pattern, const U32 flags)
pregexec

Described in perlreguts.

    I32  pregexec(REGEXP * const prog, char* stringarg, char* strend,
                  char* strbeg, SSize_t minend, SV* screamer,
                  U32 nosave)
re_dup_guts

Duplicate a regexp.

This routine is expected to clone a given regexp structure. It is only compiled under USE_ITHREADS.

After all of the core data stored in struct regexp is duplicated the regexp_engine.dupe method is used to copy any private data stored in the *pprivate pointer. This allows extensions to handle any duplication they need to do.

    void  re_dup_guts(const REGEXP *sstr, REGEXP *dstr,
                      CLONE_PARAMS* param)
regmatch_info

Some basic information about the current match that is created by Perl_regexec_flags and then passed to regtry(), regmatch() etc. It is allocated as a local var on the stack, so nothing should be stored in it that needs preserving or clearing up on croak(). For that, see the aux_info and aux_info_eval members of the regmatch_state union.

SvRX

Convenience macro to get the REGEXP from a SV. This is approximately equivalent to the following snippet:

if (SvMAGICAL(sv))
    mg_get(sv);
if (SvROK(sv))
    sv = MUTABLE_SV(SvRV(sv));
if (SvTYPE(sv) == SVt_REGEXP)
    return (REGEXP*) sv;

NULL will be returned if a REGEXP* is not found.

    REGEXP *  SvRX(SV *sv)
SvRXOK

Returns a boolean indicating whether the SV (or the one it references) is a REGEXP.

If you want to do something with the REGEXP* later use SvRX instead and check for NULL.

    bool  SvRXOK(SV* sv)

Signals

HAS_SIGINFO_SI_ADDR

This symbol, if defined, indicates that siginfo_t has the si_addr member

HAS_SIGINFO_SI_BAND

This symbol, if defined, indicates that siginfo_t has the si_band member

HAS_SIGINFO_SI_ERRNO

This symbol, if defined, indicates that siginfo_t has the si_errno member

HAS_SIGINFO_SI_PID

This symbol, if defined, indicates that siginfo_t has the si_pid member

HAS_SIGINFO_SI_STATUS

This symbol, if defined, indicates that siginfo_t has the si_status member

HAS_SIGINFO_SI_UID

This symbol, if defined, indicates that siginfo_t has the si_uid member

HAS_SIGINFO_SI_VALUE

This symbol, if defined, indicates that siginfo_t has the si_value member

PERL_SIGNALS_UNSAFE_FLAG

If this bit in PL_signals is set, the system is uing the pre-Perl 5.8 unsafe signals. See "PERL_SIGNALS" in perlrun and "Deferred Signals (Safe Signals)" in perlipc.

    U32  PERL_SIGNALS_UNSAFE_FLAG
rsignal

A wrapper for the C library signal(2). Don't use the latter, as the Perl version knows things that interact with the rest of the perl interpreter.

    Sighandler_t  rsignal(int i, Sighandler_t t)
Sigjmp_buf

This is the buffer type to be used with Sigsetjmp and Siglongjmp.

Siglongjmp

This macro is used in the same way as siglongjmp(), but will invoke traditional longjmp() if siglongjmp isn't available. See "HAS_SIGSETJMP".

    void  Siglongjmp(jmp_buf env, int val)
SIG_NAME

This symbol contains a list of signal names in order of signal number. This is intended to be used as a static array initialization, like this:

char *sig_name[] = { SIG_NAME };

The signals in the list are separated with commas, and each signal is surrounded by double quotes. There is no leading SIG in the signal name, i.e. SIGQUIT is known as "QUIT". Gaps in the signal numbers (up to NSIG) are filled in with NUMnn, etc., where nn is the actual signal number (e.g. NUM37). The signal number for sig_name[i] is stored in sig_num[i]. The last element is 0 to terminate the list with a NULL. This corresponds to the 0 at the end of the sig_name_init list. Note that this variable is initialized from the sig_name_init, not from sig_name (which is unused).

SIG_NUM

This symbol contains a list of signal numbers, in the same order as the SIG_NAME list. It is suitable for static array initialization, as in:

int sig_num[] = { SIG_NUM };

The signals in the list are separated with commas, and the indices within that list and the SIG_NAME list match, so it's easy to compute the signal name from a number or vice versa at the price of a small dynamic linear lookup. Duplicates are allowed, but are moved to the end of the list. The signal number corresponding to sig_name[i] is sig_number[i]. if (i < NSIG) then sig_number[i] == i. The last element is 0, corresponding to the 0 at the end of the sig_name_init list. Note that this variable is initialized from the sig_num_init, not from sig_num (which is unused).

Sigsetjmp

This macro is used in the same way as sigsetjmp(), but will invoke traditional setjmp() if sigsetjmp isn't available. See "HAS_SIGSETJMP".

    int  Sigsetjmp(jmp_buf env, int savesigs)
SIG_SIZE

This variable contains the number of elements of the SIG_NAME and SIG_NUM arrays, excluding the final NULL entry.

whichsig
whichsig_pv
whichsig_pvn
whichsig_sv

These all convert a signal name into its corresponding signal number; returning -1 if no corresponding number was found.

They differ only in the source of the signal name:

whichsig_pv takes the name from the NUL-terminated string starting at sig.

whichsig is merely a different spelling, a synonym, of whichsig_pv.

whichsig_pvn takes the name from the string starting at sig, with length len bytes.

whichsig_sv takes the name from the PV stored in the SV sigsv.

    I32  whichsig    (const char* sig)
    I32  whichsig_pv (const char* sig)
    I32  whichsig_pvn(const char* sig, STRLEN len)
    I32  whichsig_sv (SV* sigsv)

Site configuration

These variables give details as to where various libraries, installation destinations, etc., go, as well as what various installation options were selected

ARCHLIB

This variable, if defined, holds the name of the directory in which the user wants to put architecture-dependent public library files for perl5. It is most often a local directory such as /usr/local/lib. Programs using this variable must be prepared to deal with filename expansion. If ARCHLIB is the same as PRIVLIB, it is not defined, since presumably the program already searches PRIVLIB.

ARCHLIB_EXP

This symbol contains the ~name expanded version of ARCHLIB, to be used in programs that are not prepared to deal with ~ expansion at run-time.

ARCHNAME

This symbol holds a string representing the architecture name. It may be used to construct an architecture-dependant pathname where library files may be held under a private library, for instance.

BIN

This symbol holds the path of the bin directory where the package will be installed. Program must be prepared to deal with ~name substitution.

BIN_EXP

This symbol is the filename expanded version of the BIN symbol, for programs that do not want to deal with that at run-time.

INSTALL_USR_BIN_PERL

This symbol, if defined, indicates that Perl is to be installed also as /usr/bin/perl.

MULTIARCH

This symbol, if defined, signifies that the build process will produce some binary files that are going to be used in a cross-platform environment. This is the case for example with the NeXT "fat" binaries that contain executables for several CPUs.

PERL_INC_VERSION_LIST

This variable specifies the list of subdirectories in over which perl.c:incpush() and lib/lib.pm will automatically search when adding directories to @INC, in a format suitable for a C initialization string. See the inc_version_list entry in Porting/Glossary for more details.

PERL_OTHERLIBDIRS

This variable contains a colon-separated set of paths for the perl binary to search for additional library files or modules. These directories will be tacked to the end of @INC. Perl will automatically search below each path for version- and architecture-specific directories. See "PERL_INC_VERSION_LIST" for more details.

PERL_RELOCATABLE_INC

This symbol, if defined, indicates that we'd like to relocate entries in @INC at run time based on the location of the perl binary.

PERL_TARGETARCH

This symbol, if defined, indicates the target architecture Perl has been cross-compiled to. Undefined if not a cross-compile.

PERL_USE_DEVEL

This symbol, if defined, indicates that Perl was configured with -Dusedevel, to enable development features. This should not be done for production builds.

PERL_VENDORARCH

If defined, this symbol contains the name of a private library. The library is private in the sense that it needn't be in anyone's execution path, but it should be accessible by the world. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place their own architecture-dependent modules and extensions in this directory with

MakeMaker Makefile.PL INSTALLDIRS=vendor

or equivalent. See INSTALL for details.

PERL_VENDORARCH_EXP

This symbol contains the ~name expanded version of PERL_VENDORARCH, to be used in programs that are not prepared to deal with ~ expansion at run-time.

PERL_VENDORLIB_EXP

This symbol contains the ~name expanded version of VENDORLIB, to be used in programs that are not prepared to deal with ~ expansion at run-time.

PERL_VENDORLIB_STEM

This define is PERL_VENDORLIB_EXP with any trailing version-specific component removed. The elements in inc_version_list (inc_version_list.U (part of metaconfig)) can be tacked onto this variable to generate a list of directories to search.

PRIVLIB

This symbol contains the name of the private library for this package. The library is private in the sense that it needn't be in anyone's execution path, but it should be accessible by the world. The program should be prepared to do ~ expansion.

PRIVLIB_EXP

This symbol contains the ~name expanded version of PRIVLIB, to be used in programs that are not prepared to deal with ~ expansion at run-time.

SITEARCH

This symbol contains the name of the private library for this package. The library is private in the sense that it needn't be in anyone's execution path, but it should be accessible by the world. The program should be prepared to do ~ expansion. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local architecture-dependent modules in this directory with

MakeMaker Makefile.PL

or equivalent. See INSTALL for details.

SITEARCH_EXP

This symbol contains the ~name expanded version of SITEARCH, to be used in programs that are not prepared to deal with ~ expansion at run-time.

SITELIB

This symbol contains the name of the private library for this package. The library is private in the sense that it needn't be in anyone's execution path, but it should be accessible by the world. The program should be prepared to do ~ expansion. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local architecture-independent modules in this directory with

MakeMaker Makefile.PL

or equivalent. See INSTALL for details.

SITELIB_EXP

This symbol contains the ~name expanded version of SITELIB, to be used in programs that are not prepared to deal with ~ expansion at run-time.

SITELIB_STEM

This define is SITELIB_EXP with any trailing version-specific component removed. The elements in inc_version_list (inc_version_list.U (part of metaconfig)) can be tacked onto this variable to generate a list of directories to search.

STARTPERL

This variable contains the string to put in front of a perl script to make sure (one hopes) that it runs with perl and not some shell.

USE_64_BIT_ALL

This symbol, if defined, indicates that 64-bit integers should be used when available. If not defined, the native integers will be used (be they 32 or 64 bits). The maximal possible 64-bitness is employed: LP64 or ILP64, meaning that you will be able to use more than 2 gigabytes of memory. This mode is even more binary incompatible than USE_64_BIT_INT. You may not be able to run the resulting executable in a 32-bit CPU at all or you may need at least to reboot your OS to 64-bit mode.

USE_64_BIT_INT

This symbol, if defined, indicates that 64-bit integers should be used when available. If not defined, the native integers will be employed (be they 32 or 64 bits). The minimal possible 64-bitness is used, just enough to get 64-bit integers into Perl. This may mean using for example "long longs", while your memory may still be limited to 2 gigabytes.

USE_BSD_GETPGRP

This symbol, if defined, indicates that getpgrp needs one arguments whereas USG one needs none.

USE_BSD_SETPGRP

This symbol, if defined, indicates that setpgrp needs two arguments whereas USG one needs none. See also "HAS_SETPGID" for a POSIX interface.

USE_CPLUSPLUS

This symbol, if defined, indicates that a C++ compiler was used to compiled Perl and will be used to compile extensions.

USE_CROSS_COMPILE

This symbol, if defined, indicates that Perl is being cross-compiled.

USE_C_BACKTRACE

This symbol, if defined, indicates that Perl should be built with support for backtrace.

USE_DTRACE

This symbol, if defined, indicates that Perl should be built with support for DTrace.

USE_DYNAMIC_LOADING

This symbol, if defined, indicates that dynamic loading of some sort is available.

USE_FAST_STDIO

This symbol, if defined, indicates that Perl should be built to use 'fast stdio'. Defaults to define in Perls 5.8 and earlier, to undef later.

USE_ITHREADS

This symbol, if defined, indicates that Perl should be built to use the interpreter-based threading implementation.

USE_KERN_PROC_PATHNAME

This symbol, if defined, indicates that we can use sysctl with KERN_PROC_PATHNAME to get a full path for the executable, and hence convert $^X to an absolute path.

USE_LARGE_FILES

This symbol, if defined, indicates that large file support should be used when available.

USE_LONG_DOUBLE

This symbol, if defined, indicates that long doubles should be used when available.

USE_MORE_BITS

This symbol, if defined, indicates that 64-bit interfaces and long doubles should be used when available.

USE_NSGETEXECUTABLEPATH

This symbol, if defined, indicates that we can use _NSGetExecutablePath and realpath to get a full path for the executable, and hence convert $^X to an absolute path.

USE_PERLIO

This symbol, if defined, indicates that the PerlIO abstraction should be used throughout. If not defined, stdio should be used in a fully backward compatible manner.

USE_QUADMATH

This symbol, if defined, indicates that the quadmath library should be used when available.

USE_REENTRANT_API

This symbol, if defined, indicates that Perl should try to use the various _r versions of library functions. This is extremely experimental.

USE_SEMCTL_SEMID_DS

This symbol, if defined, indicates that struct semid_ds * is used for semctl IPC_STAT.

USE_SEMCTL_SEMUN

This symbol, if defined, indicates that union semun is used for semctl IPC_STAT.

USE_SITECUSTOMIZE

This symbol, if defined, indicates that sitecustomize should be used.

USE_SOCKS

This symbol, if defined, indicates that Perl should be built to use socks.

USE_STAT_BLOCKS

This symbol is defined if this system has a stat structure declaring st_blksize and st_blocks.

USE_STDIO_BASE

This symbol is defined if the _base field (or similar) of the stdio FILE structure can be used to access the stdio buffer for a file handle. If this is defined, then the FILE_base(fp) macro will also be defined and should be used to access this field. Also, the FILE_bufsiz(fp) macro will be defined and should be used to determine the number of bytes in the buffer. USE_STDIO_BASE will never be defined unless USE_STDIO_PTR is.

USE_STDIO_PTR

This symbol is defined if the _ptr and _cnt fields (or similar) of the stdio FILE structure can be used to access the stdio buffer for a file handle. If this is defined, then the FILE_ptr(fp) and FILE_cnt(fp) macros will also be defined and should be used to access these fields.

USE_STRICT_BY_DEFAULT

This symbol, if defined, enables additional defaults. At this time it only enables implicit strict by default.

USE_THREADS

This symbol, if defined, indicates that Perl should be built to use threads. At present, it is a synonym for and USE_ITHREADS, but eventually the source ought to be changed to use this to mean _any_ threading implementation.

Sockets configuration values

HAS_SOCKADDR_IN6

This symbol, if defined, indicates the availability of struct sockaddr_in6;

HAS_SOCKADDR_SA_LEN

This symbol, if defined, indicates that the struct sockaddr structure has a member called sa_len, indicating the length of the structure.

HAS_SOCKADDR_STORAGE

This symbol, if defined, indicates the availability of struct sockaddr_storage;

HAS_SOCKATMARK

This symbol, if defined, indicates that the sockatmark routine is available to test whether a socket is at the out-of-band mark.

HAS_SOCKET

This symbol, if defined, indicates that the BSD socket interface is supported.

HAS_SOCKETPAIR

This symbol, if defined, indicates that the BSD socketpair() call is supported.

HAS_SOCKS5_INIT

This symbol, if defined, indicates that the socks5_init routine is available to initialize SOCKS 5.

I_SOCKS

This symbol, if defined, indicates that socks.h exists and should be included.

    #ifdef I_SOCKS
        #include <socks.h>
    #endif
I_SYS_SOCKIO

This symbol, if defined, indicates the sys/sockio.h should be included to get socket ioctl options, like SIOCATMARK.

    #ifdef I_SYS_SOCKIO
        #include <sys_sockio.h>
    #endif

Source Filters

filter_add

Described in perlfilter.

    SV*  filter_add(filter_t funcp, SV* datasv)
filter_read

Described in perlfilter.

    I32  filter_read(int idx, SV *buf_sv, int maxlen)

Stack Manipulation Macros

BHK

Described in perlguts.

BINOP

Described in perlguts.

DESTRUCTORFUNC_NOCONTEXT_t

Described in perlguts.

DESTRUCTORFUNC_t

Described in perlguts.

dMARK

Declare a stack marker variable, mark, for the XSUB. See "MARK" and "dORIGMARK".

    dMARK;
dORIGMARK

Saves the original stack mark for the XSUB. See "ORIGMARK".

    dORIGMARK;
dSP

Declares a local copy of perl's stack pointer for the XSUB, available via the SP macro. See "SP".

    dSP;
dTARGET

Declare that this function uses TARG

    dTARGET;
EXTEND

Used to extend the argument stack for an XSUB's return values. Once used, guarantees that there is room for at least nitems to be pushed onto the stack.

    void  EXTEND(SP, SSize_t nitems)
LISTOP

Described in perlguts.

LOGOP

Described in perlguts.

LOOP

Described in perlguts.

MARK

Stack marker variable for the XSUB. See "dMARK".

mPUSHi

Push an integer onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHi", "mXPUSHi" and "XPUSHi".

    void  mPUSHi(IV iv)
mPUSHn

Push a double onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHn", "mXPUSHn" and "XPUSHn".

    void  mPUSHn(NV nv)
mPUSHp

Push a string onto the stack. The stack must have room for this element. The len indicates the length of the string. Does not use TARG. See also "PUSHp", "mXPUSHp" and "XPUSHp".

    void  mPUSHp(char* str, STRLEN len)
mPUSHs

Push an SV onto the stack and mortalizes the SV. The stack must have room for this element. Does not use TARG. See also "PUSHs" and "mXPUSHs".

    void  mPUSHs(SV* sv)
mPUSHu

Push an unsigned integer onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHu", "mXPUSHu" and "XPUSHu".

    void  mPUSHu(UV uv)
mXPUSHi

Push an integer onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHi", "mPUSHi" and "PUSHi".

    void  mXPUSHi(IV iv)
mXPUSHn

Push a double onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHn", "mPUSHn" and "PUSHn".

    void  mXPUSHn(NV nv)
mXPUSHp

Push a string onto the stack, extending the stack if necessary. The len indicates the length of the string. Does not use TARG. See also "XPUSHp", mPUSHp and PUSHp.

    void  mXPUSHp(char* str, STRLEN len)
mXPUSHs

Push an SV onto the stack, extending the stack if necessary and mortalizes the SV. Does not use TARG. See also "XPUSHs" and "mPUSHs".

    void  mXPUSHs(SV* sv)
mXPUSHu

Push an unsigned integer onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHu", "mPUSHu" and "PUSHu".

    void  mXPUSHu(UV uv)
newXSproto

Used by xsubpp to hook up XSUBs as Perl subs. Adds Perl prototypes to the subs.

OP

Described in perlguts.

ORIGMARK

The original stack mark for the XSUB. See "dORIGMARK".

peep_t

Described in perlguts.

PL_runops

Described in perlguts.

PMOP

Described in perlguts.

POPi

Pops an integer off the stack.

    IV  POPi
POPl

Pops a long off the stack.

    long  POPl
POPn

Pops a double off the stack.

    NV  POPn
POPp

Pops a string off the stack.

    char*  POPp
POPpbytex

Pops a string off the stack which must consist of bytes i.e. characters < 256.

    char*  POPpbytex
POPpx

Pops a string off the stack. Identical to POPp. There are two names for historical reasons.

    char*  POPpx
POPs

Pops an SV off the stack.

    SV*  POPs
POPu

Pops an unsigned integer off the stack.

    UV  POPu
POPul

Pops an unsigned long off the stack.

    long  POPul
PUSHi

Push an integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHi" instead. See also "XPUSHi" and "mXPUSHi".

    void  PUSHi(IV iv)
PUSHMARK

Opening bracket for arguments on a callback. See "PUTBACK" and perlcall.

    void  PUSHMARK(SP)
PUSHmortal

Push a new mortal SV onto the stack. The stack must have room for this element. Does not use TARG. See also "PUSHs", "XPUSHmortal" and "XPUSHs".

    void  PUSHmortal
PUSHn

Push a double onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHn" instead. See also "XPUSHn" and "mXPUSHn".

    void  PUSHn(NV nv)
PUSHp

Push a string onto the stack. The stack must have room for this element. The len indicates the length of the string. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHp" instead. See also "XPUSHp" and "mXPUSHp".

    void  PUSHp(char* str, STRLEN len)
PUSHs

Push an SV onto the stack. The stack must have room for this element. Does not handle 'set' magic. Does not use TARG. See also "PUSHmortal", "XPUSHs", and "XPUSHmortal".

    void  PUSHs(SV* sv)
PUSHu

Push an unsigned integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mPUSHu" instead. See also "XPUSHu" and "mXPUSHu".

    void  PUSHu(UV uv)
PUTBACK

Closing bracket for XSUB arguments. This is usually handled by xsubpp. See "PUSHMARK" and perlcall for other uses.

    PUTBACK;
save_aptr

Described in perlguts.

    void  save_aptr(AV** aptr)
save_ary

Described in perlguts.

    AV*  save_ary(GV* gv)
SAVEBOOL

Described in perlguts.

    SAVEBOOL(bool i)
SAVEDELETE

Described in perlguts.

    SAVEDELETE(HV * hv, char * key, I32 length)
SAVEDESTRUCTOR

Described in perlguts.

    SAVEDESTRUCTOR(DESTRUCTORFUNC_NOCONTEXT_t f, void *p)
SAVEDESTRUCTOR_X

Described in perlguts.

    SAVEDESTRUCTOR_X(DESTRUCTORFUNC_t f, void *p)
SAVEFREEOP

Described in perlguts.

    SAVEFREEOP(OP *op)
SAVEFREEPV

Described in perlguts.

    SAVEFREEPV(void * p)
SAVEFREESV

Described in perlguts.

    SAVEFREESV(SV* sv)
save_hash

Described in perlguts.

    HV*  save_hash(GV* gv)
save_hptr

Described in perlguts.

    void  save_hptr(HV** hptr)
SAVEI8

Described in perlguts.

    SAVEI8(I8 i)
SAVEI32

Described in perlguts.

    SAVEI32(I32 i)
SAVEI16

Described in perlguts.

    SAVEI16(I16 i)
SAVEINT

Described in perlguts.

    SAVEINT(int i)
save_item

Described in perlguts.

    void  save_item(SV* item)
SAVEIV

Described in perlguts.

    SAVEIV(IV i)
save_list

DEPRECATED! It is planned to remove save_list from a future release of Perl. Do not use it for new code; remove it from existing code.

Described in perlguts.

    void  save_list(SV** sarg, I32 maxsarg)
SAVELONG

Described in perlguts.

    SAVELONG(long i)
SAVEMORTALIZESV

Described in perlguts.

    SAVEMORTALIZESV(SV* sv)
SAVEPPTR

Described in perlguts.

    SAVEPPTR(char * p)
save_scalar

Described in perlguts.

    SV*  save_scalar(GV* gv)
SAVESPTR

Described in perlguts.

    SAVESPTR(SV * s)
SAVESTACK_POS

Described in perlguts.

    SAVESTACK_POS()
save_svref

Described in perlguts.

    SV*  save_svref(SV** sptr)
SP

Stack pointer. This is usually handled by xsubpp. See "dSP" and SPAGAIN.

SPAGAIN

Refetch the stack pointer. Used after a callback. See perlcall.

    SPAGAIN;
TARG

TARG is short for "target". It is an entry in the pad that an OPs op_targ refers to. It is scratchpad space, often used as a return value for the OP, but some use it for other purposes.

    TARG;
UNOP

Described in perlguts.

XPUSHi

Push an integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHi" instead. See also "PUSHi" and "mPUSHi".

    void  XPUSHi(IV iv)
XPUSHmortal

Push a new mortal SV onto the stack, extending the stack if necessary. Does not use TARG. See also "XPUSHs", "PUSHmortal" and "PUSHs".

    void  XPUSHmortal
XPUSHn

Push a double onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHn" instead. See also "PUSHn" and "mPUSHn".

    void  XPUSHn(NV nv)
XPUSHp

Push a string onto the stack, extending the stack if necessary. The len indicates the length of the string. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHp" instead. See also "PUSHp" and "mPUSHp".

    void  XPUSHp(char* str, STRLEN len)
XPUSHs

Push an SV onto the stack, extending the stack if necessary. Does not handle 'set' magic. Does not use TARG. See also "XPUSHmortal", PUSHs and PUSHmortal.

    void  XPUSHs(SV* sv)
XPUSHu

Push an unsigned integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG, so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG-oriented macros to return lists from XSUB's - see "mXPUSHu" instead. See also "PUSHu" and "mPUSHu".

    void  XPUSHu(UV uv)
XS_APIVERSION_BOOTCHECK

Macro to verify that the perl api version an XS module has been compiled against matches the api version of the perl interpreter it's being loaded into.

    XS_APIVERSION_BOOTCHECK;
XSRETURN

Return from XSUB, indicating number of items on the stack. This is usually handled by xsubpp.

    void  XSRETURN(int nitems)
XSRETURN_EMPTY

Return an empty list from an XSUB immediately.

    XSRETURN_EMPTY;
XSRETURN_IV

Return an integer from an XSUB immediately. Uses XST_mIV.

    void  XSRETURN_IV(IV iv)
XSRETURN_NO

Return &PL_sv_no from an XSUB immediately. Uses XST_mNO.

    XSRETURN_NO;
XSRETURN_NV

Return a double from an XSUB immediately. Uses XST_mNV.

    void  XSRETURN_NV(NV nv)
XSRETURN_PV

Return a copy of a string from an XSUB immediately. Uses XST_mPV.

    void  XSRETURN_PV(char* str)
XSRETURN_UNDEF

Return &PL_sv_undef from an XSUB immediately. Uses XST_mUNDEF.

    XSRETURN_UNDEF;
XSRETURN_UV

Return an integer from an XSUB immediately. Uses XST_mUV.

    void  XSRETURN_UV(IV uv)
XSRETURN_YES

Return &PL_sv_yes from an XSUB immediately. Uses XST_mYES.

    XSRETURN_YES;
XST_mIV

Place an integer into the specified position pos on the stack. The value is stored in a new mortal SV.

    void  XST_mIV(int pos, IV iv)
XST_mNO

Place &PL_sv_no into the specified position pos on the stack.

    void  XST_mNO(int pos)
XST_mNV

Place a double into the specified position pos on the stack. The value is stored in a new mortal SV.

    void  XST_mNV(int pos, NV nv)
XST_mPV

Place a copy of a string into the specified position pos on the stack. The value is stored in a new mortal SV.

    void  XST_mPV(int pos, char* str)
XST_mUNDEF

Place &PL_sv_undef into the specified position pos on the stack.

    void  XST_mUNDEF(int pos)
XST_mUV

Place an unsigned integer into the specified position pos on the stack. The value is stored in a new mortal SV.

    void  XST_mUV(int pos, UV uv)
XST_mYES

Place &PL_sv_yes into the specified position pos on the stack.

    void  XST_mYES(int pos)
XS_VERSION

The version identifier for an XS module. This is usually handled automatically by ExtUtils::MakeMaker. See "XS_VERSION_BOOTCHECK".

XS_VERSION_BOOTCHECK

Macro to verify that a PM module's $VERSION variable matches the XS module's XS_VERSION variable. This is usually handled automatically by xsubpp. See "The VERSIONCHECK: Keyword" in perlxs.

    XS_VERSION_BOOTCHECK;

String Handling

See also "Unicode Support".

CAT2

This macro concatenates 2 tokens together.

    token  CAT2(token x, token y)
Copy

The XSUB-writer's interface to the C memcpy function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. May fail on overlapping copies. See also "Move".

    void  Copy(void* src, void* dest, int nitems, type)
CopyD

Like Copy but returns dest. Useful for encouraging compilers to tail-call optimise.

    void *  CopyD(void* src, void* dest, int nitems, type)
delimcpy

Copy a source buffer to a destination buffer, stopping at (but not including) the first occurrence in the source of an unescaped (defined below) delimiter byte, delim. The source is the bytes between from and from_end - 1. Similarly, the dest is to up to to_end.

The number of bytes copied is written to *retlen.

Returns the position of the first uncopied delim in the from buffer, but if there is no such occurrence before from_end, then from_end is returned, and the entire buffer from .. from_end - 1 is copied.

If there is room in the destination available after the copy, an extra terminating safety NUL byte is appended (not included in the returned length).

The error case is if the destination buffer is not large enough to accommodate everything that should be copied. In this situation, a value larger than to_end - to is written to *retlen, and as much of the source as fits will be written to the destination. Not having room for the safety NUL is not considered an error.

In the following examples, let x be the delimiter, and 0 represent a NUL byte (NOT the digit 0). Then we would have

 Source     Destination
abcxdef        abc0

provided the destination buffer is at least 4 bytes long.

An escaped delimiter is one which is immediately preceded by a single backslash. Escaped delimiters are copied, and the copy continues past the delimiter; the backslash is not copied:

 Source       Destination
abc\xdef       abcxdef0

(provided the destination buffer is at least 8 bytes long).

It's actually somewhat more complicated than that. A sequence of any odd number of backslashes escapes the following delimiter, and the copy continues with exactly one of the backslashes stripped.

    Source         Destination
    abc\xdef          abcxdef0
  abc\\\xdef        abc\\xdef0
abc\\\\\xdef      abc\\\\xdef0

(as always, if the destination is large enough)

An even number of preceding backslashes does not escape the delimiter, so that the copy stops just before it, and includes all the backslashes (no stripping; zero is considered even):

    Source         Destination
    abcxdef          abc0
  abc\\xdef          abc\\0
abc\\\\xdef          abc\\\\0
    char*  delimcpy(char* to, const char* to_end, const char* from,
                    const char* from_end, const int delim,
                    I32* retlen)
fbm_compile

Analyzes the string in order to make fast searches on it using fbm_instr() -- the Boyer-Moore algorithm.

    void  fbm_compile(SV* sv, U32 flags)
fbm_instr

Returns the location of the SV in the string delimited by big and bigend (bigend) is the char following the last char). It returns NULL if the string can't be found. The sv does not have to be fbm_compiled, but the search will not be as fast then.

    char*  fbm_instr(unsigned char* big, unsigned char* bigend,
                     SV* littlestr, U32 flags)
foldEQ

Returns true if the leading len bytes of the strings s1 and s2 are the same case-insensitively; false otherwise. Uppercase and lowercase ASCII range bytes match themselves and their opposite case counterparts. Non-cased and non-ASCII range bytes match only themselves.

    I32  foldEQ(const char* a, const char* b, I32 len)
ibcmp

This is a synonym for (! foldEQ())

    I32  ibcmp(const char* a, const char* b, I32 len)
ibcmp_locale

This is a synonym for (! foldEQ_locale())

    I32  ibcmp_locale(const char* a, const char* b, I32 len)
ibcmp_utf8

This is a synonym for (! foldEQ_utf8())

    I32  ibcmp_utf8(const char *s1, char **pe1, UV l1, bool u1,
                    const char *s2, char **pe2, UV l2, bool u2)
instr

Same as strstr(3), which finds and returns a pointer to the first occurrence of the NUL-terminated substring little in the NUL-terminated string big, returning NULL if not found. The terminating NUL bytes are not compared.

    char*  instr(const char* big, const char* little)
memCHRs

Returns the position of the first occurence of the byte c in the literal string "list", or NULL if c doesn't appear in "list". All bytes are treated as unsigned char. Thus this macro can be used to determine if c is in a set of particular characters. Unlike strchr(3), it works even if c is NUL (and the set doesn't include NUL).

    bool  memCHRs("list", char c)
memEQ

Test two buffers (which may contain embedded NUL characters, to see if they are equal. The len parameter indicates the number of bytes to compare. Returns true or false. It is undefined behavior if either of the buffers doesn't contain at least len bytes.

    bool  memEQ(char* s1, char* s2, STRLEN len)
memEQs

Like "memEQ", but the second string is a literal enclosed in double quotes, l1 gives the number of bytes in s1. Returns true or false.

    bool  memEQs(char* s1, STRLEN l1, "s2")
memNE

Test two buffers (which may contain embedded NUL characters, to see if they are not equal. The len parameter indicates the number of bytes to compare. Returns true or false. It is undefined behavior if either of the buffers doesn't contain at least len bytes.

    bool  memNE(char* s1, char* s2, STRLEN len)
memNEs

Like "memNE", but the second string is a literal enclosed in double quotes, l1 gives the number of bytes in s1. Returns true or false.

    bool  memNEs(char* s1, STRLEN l1, "s2")
Move

The XSUB-writer's interface to the C memmove function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. Can do overlapping moves. See also "Copy".

    void  Move(void* src, void* dest, int nitems, type)
MoveD

Like Move but returns dest. Useful for encouraging compilers to tail-call optimise.

    void *  MoveD(void* src, void* dest, int nitems, type)
my_snprintf

The C library snprintf functionality, if available and standards-compliant (uses vsnprintf, actually). However, if the vsnprintf is not available, will unfortunately use the unsafe vsprintf which can overrun the buffer (there is an overrun check, but that may be too late). Consider using sv_vcatpvf instead, or getting vsnprintf.

    int  my_snprintf(char *buffer, const Size_t len,
                     const char *format, ...)
my_sprintf

DEPRECATED! It is planned to remove my_sprintf from a future release of Perl. Do not use it for new code; remove it from existing code.

Do NOT use this due to the possibility of overflowing buffer. Instead use my_snprintf()

    int  my_sprintf(NN char *buffer, NN const char *pat, ...)
my_strlcat

The C library strlcat if available, or a Perl implementation of it. This operates on C NUL-terminated strings.

my_strlcat() appends string src to the end of dst. It will append at most size - strlen(dst) - 1 characters. It will then NUL-terminate, unless size is 0 or the original dst string was longer than size (in practice this should not happen as it means that either size is incorrect or that dst is not a proper NUL-terminated string).

Note that size is the full size of the destination buffer and the result is guaranteed to be NUL-terminated if there is room. Note that room for the NUL should be included in size.

The return value is the total length that dst would have if size is sufficiently large. Thus it is the initial length of dst plus the length of src. If size is smaller than the return, the excess was not appended.

    Size_t  my_strlcat(char *dst, const char *src, Size_t size)
my_strlcpy

The C library strlcpy if available, or a Perl implementation of it. This operates on C NUL-terminated strings.

my_strlcpy() copies up to size - 1 characters from the string src to dst, NUL-terminating the result if size is not 0.

The return value is the total length src would be if the copy completely succeeded. If it is larger than size, the excess was not copied.

    Size_t  my_strlcpy(char *dst, const char *src, Size_t size)
my_strnlen

The C library strnlen if available, or a Perl implementation of it.

my_strnlen() computes the length of the string, up to maxlen characters. It will never attempt to address more than maxlen characters, making it suitable for use with strings that are not guaranteed to be NUL-terminated.

    Size_t  my_strnlen(const char *str, Size_t maxlen)
my_vsnprintf

The C library vsnprintf if available and standards-compliant. However, if the vsnprintf is not available, will unfortunately use the unsafe vsprintf which can overrun the buffer (there is an overrun check, but that may be too late). Consider using sv_vcatpvf instead, or getting vsnprintf.

    int  my_vsnprintf(char *buffer, const Size_t len,
                      const char *format, va_list ap)
ninstr

Find the first (leftmost) occurrence of a sequence of bytes within another sequence. This is the Perl version of strstr(), extended to handle arbitrary sequences, potentially containing embedded NUL characters (NUL is what the initial n in the function name stands for; some systems have an equivalent, memmem(), but with a somewhat different API).

Another way of thinking about this function is finding a needle in a haystack. big points to the first byte in the haystack. big_end points to one byte beyond the final byte in the haystack. little points to the first byte in the needle. little_end points to one byte beyond the final byte in the needle. All the parameters must be non-NULL.

The function returns NULL if there is no occurrence of little within big. If little is the empty string, big is returned.

Because this function operates at the byte level, and because of the inherent characteristics of UTF-8 (or UTF-EBCDIC), it will work properly if both the needle and the haystack are strings with the same UTF-8ness, but not if the UTF-8ness differs.

    char*  ninstr(const char* big, const char* bigend,
                  const char* little, const char* lend)
Nullch

Null character pointer. (No longer available when PERL_CORE is defined.)

rninstr

Like "ninstr", but instead finds the final (rightmost) occurrence of a sequence of bytes within another sequence, returning NULL if there is no such occurrence.

    char*  rninstr(const char* big, const char* bigend,
                   const char* little, const char* lend)
savepv

Perl's version of strdup(). Returns a pointer to a newly allocated string which is a duplicate of pv. The size of the string is determined by strlen(), which means it may not contain embedded NUL characters and must have a trailing NUL. To prevent memory leaks, the memory allocated for the new string needs to be freed when no longer needed. This can be done with the "Safefree" function, or SAVEFREEPV.

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedpv".

    char*  savepv(const char* pv)
savepvn

Perl's version of what strndup() would be if it existed. Returns a pointer to a newly allocated string which is a duplicate of the first len bytes from pv, plus a trailing NUL byte. The memory allocated for the new string can be freed with the Safefree() function.

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedpvn".

    char*  savepvn(const char* pv, Size_t len)
savepvs

Like savepvn, but takes a literal string instead of a string/length pair.

    char*  savepvs("literal string")
savesharedpv

A version of savepv() which allocates the duplicate string in memory which is shared between threads.

    char*  savesharedpv(const char* pv)
savesharedpvn

A version of savepvn() which allocates the duplicate string in memory which is shared between threads. (With the specific difference that a NULL pointer is not acceptable)

    char*  savesharedpvn(const char *const pv, const STRLEN len)
savesharedpvs

A version of savepvs() which allocates the duplicate string in memory which is shared between threads.

    char*  savesharedpvs("literal string")
savesharedsvpv

A version of savesharedpv() which allocates the duplicate string in memory which is shared between threads.

    char*  savesharedsvpv(SV *sv)
savesvpv

A version of savepv()/savepvn() which gets the string to duplicate from the passed in SV using SvPV()

On some platforms, Windows for example, all allocated memory owned by a thread is deallocated when that thread ends. So if you need that not to happen, you need to use the shared memory functions, such as "savesharedsvpv".

    char*  savesvpv(SV* sv)
strEQ

Test two NUL-terminated strings to see if they are equal. Returns true or false.

    bool  strEQ(char* s1, char* s2)
strGE

Test two NUL-terminated strings to see if the first, s1, is greater than or equal to the second, s2. Returns true or false.

    bool  strGE(char* s1, char* s2)
strGT

Test two NUL-terminated strings to see if the first, s1, is greater than the second, s2. Returns true or false.

    bool  strGT(char* s1, char* s2)
STRINGIFY

This macro surrounds its token with double quotes.

    string  STRINGIFY(token x)
strLE

Test two NUL-terminated strings to see if the first, s1, is less than or equal to the second, s2. Returns true or false.

    bool  strLE(char* s1, char* s2)
strLT

Test two NUL-terminated strings to see if the first, s1, is less than the second, s2. Returns true or false.

    bool  strLT(char* s1, char* s2)
strNE

Test two NUL-terminated strings to see if they are different. Returns true or false.

    bool  strNE(char* s1, char* s2)
strnEQ

Test two NUL-terminated strings to see if they are equal. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp).

    bool  strnEQ(char* s1, char* s2, STRLEN len)
strnNE

Test two NUL-terminated strings to see if they are different. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp).

    bool  strnNE(char* s1, char* s2, STRLEN len)
STR_WITH_LEN

Returns two comma separated tokens of the input literal string, and its length. This is convenience macro which helps out in some API calls. Note that it can't be used as an argument to macros or functions that under some configurations might be macros, which means that it requires the full Perl_xxx(aTHX_ ...) form for any API calls where it's used.

    pair  STR_WITH_LEN("literal string")
Zero

The XSUB-writer's interface to the C memzero function. The dest is the destination, nitems is the number of items, and type is the type.

    void  Zero(void* dest, int nitems, type)
ZeroD

Like Zero but returns dest. Useful for encouraging compilers to tail-call optimise.

    void *  ZeroD(void* dest, int nitems, type)

SV Flags

SVt_IV

Type flag for scalars. See "svtype".

SVt_NULL

Type flag for scalars. See "svtype".

SVt_NV

Type flag for scalars. See "svtype".

SVt_PV

Type flag for scalars. See "svtype".

SVt_PVAV

Type flag for arrays. See "svtype".

SVt_PVCV

Type flag for subroutines. See "svtype".

SVt_PVFM

Type flag for formats. See "svtype".

SVt_PVGV

Type flag for typeglobs. See "svtype".

SVt_PVHV

Type flag for hashes. See "svtype".

SVt_PVIO

Type flag for I/O objects. See "svtype".

SVt_PVIV

Type flag for scalars. See "svtype".

SVt_PVLV

Type flag for scalars. See "svtype".

SVt_PVMG

Type flag for scalars. See "svtype".

SVt_PVNV

Type flag for scalars. See "svtype".

SVt_REGEXP

Type flag for regular expressions. See "svtype".

svtype

An enum of flags for Perl types. These are found in the file sv.h in the svtype enum. Test these flags with the SvTYPE macro.

The types are:

SVt_NULL
SVt_IV
SVt_NV
SVt_RV
SVt_PV
SVt_PVIV
SVt_PVNV
SVt_PVMG
SVt_INVLIST
SVt_REGEXP
SVt_PVGV
SVt_PVLV
SVt_PVAV
SVt_PVHV
SVt_PVCV
SVt_PVFM
SVt_PVIO

These are most easily explained from the bottom up.

SVt_PVIO is for I/O objects, SVt_PVFM for formats, SVt_PVCV for subroutines, SVt_PVHV for hashes and SVt_PVAV for arrays.

All the others are scalar types, that is, things that can be bound to a $ variable. For these, the internal types are mostly orthogonal to types in the Perl language.

Hence, checking SvTYPE(sv) < SVt_PVAV is the best way to see whether something is a scalar.

SVt_PVGV represents a typeglob. If !SvFAKE(sv), then it is a real, incoercible typeglob. If SvFAKE(sv), then it is a scalar to which a typeglob has been assigned. Assigning to it again will stop it from being a typeglob. SVt_PVLV represents a scalar that delegates to another scalar behind the scenes. It is used, e.g., for the return value of substr and for tied hash and array elements. It can hold any scalar value, including a typeglob. SVt_REGEXP is for regular expressions. SVt_INVLIST is for Perl core internal use only.

SVt_PVMG represents a "normal" scalar (not a typeglob, regular expression, or delegate). Since most scalars do not need all the internal fields of a PVMG, we save memory by allocating smaller structs when possible. All the other types are just simpler forms of SVt_PVMG, with fewer internal fields. SVt_NULL can only hold undef. SVt_IV can hold undef, an integer, or a reference. (SVt_RV is an alias for SVt_IV, which exists for backward compatibility.) SVt_NV can hold any of those or a double. SVt_PV can only hold undef or a string. SVt_PVIV is a superset of SVt_PV and SVt_IV. SVt_PVNV is similar. SVt_PVMG can hold anything SVt_PVNV can hold, but it can, but does not have to, be blessed or magical.

SV Handling

An SV (or AV, HV, etc.) is allocated in two parts: the head (struct sv, av, hv...) contains type and reference count information, and for many types, a pointer to the body (struct xrv, xpv, xpviv...), which contains fields specific to each type. Some types store all they need in the head, so don't have a body.

In all but the most memory-paranoid configurations (ex: PURIFY), heads and bodies are allocated out of arenas, which by default are approximately 4K chunks of memory parcelled up into N heads or bodies. Sv-bodies are allocated by their sv-type, guaranteeing size consistency needed to allocate safely from arrays.

For SV-heads, the first slot in each arena is reserved, and holds a link to the next arena, some flags, and a note of the number of slots. Snaked through each arena chain is a linked list of free items; when this becomes empty, an extra arena is allocated and divided up into N items which are threaded into the free list.

SV-bodies are similar, but they use arena-sets by default, which separate the link and info from the arena itself, and reclaim the 1st slot in the arena. SV-bodies are further described later.

The following global variables are associated with arenas:

PL_sv_arenaroot     pointer to list of SV arenas
PL_sv_root          pointer to list of free SV structures

PL_body_arenas      head of linked-list of body arenas
PL_body_roots[]     array of pointers to list of free bodies of svtype
                    arrays are indexed by the svtype needed

A few special SV heads are not allocated from an arena, but are instead directly created in the interpreter structure, eg PL_sv_undef. The size of arenas can be changed from the default by setting PERL_ARENA_SIZE appropriately at compile time.

The SV arena serves the secondary purpose of allowing still-live SVs to be located and destroyed during final cleanup.

At the lowest level, the macros new_SV() and del_SV() grab and free an SV head. (If debugging with -DD, del_SV() calls the function S_del_sv() to return the SV to the free list with error checking.) new_SV() calls more_sv() / sv_add_arena() to add an extra arena if the free list is empty. SVs in the free list have their SvTYPE field set to all ones.

At the time of very final cleanup, sv_free_arenas() is called from perl_destruct() to physically free all the arenas allocated since the start of the interpreter.

The internal function visit() scans the SV arenas list, and calls a specified function for each SV it finds which is still live, i.e. which has an SvTYPE other than all 1's, and a non-zero SvREFCNT. visit() is used by the following functions (specified as [function that calls visit()] / [function called by visit() for each SV]):

sv_report_used() / do_report_used()
                    dump all remaining SVs (debugging aid)

sv_clean_objs() / do_clean_objs(),do_clean_named_objs(),
                  do_clean_named_io_objs(),do_curse()
                    Attempt to free all objects pointed to by RVs,
                    try to do the same for all objects indir-
                    ectly referenced by typeglobs too, and
                    then do a final sweep, cursing any
                    objects that remain.  Called once from
                    perl_destruct(), prior to calling sv_clean_all()
                    below.

sv_clean_all() / do_clean_all()
                    SvREFCNT_dec(sv) each remaining SV, possibly
                    triggering an sv_free(). It also sets the
                    SVf_BREAK flag on the SV to indicate that the
                    refcnt has been artificially lowered, and thus
                    stopping sv_free() from giving spurious warnings
                    about SVs which unexpectedly have a refcnt
                    of zero.  called repeatedly from perl_destruct()
                    until there are no SVs left.

Arena allocator API Summary

Private API to rest of sv.c

new_SV(),  del_SV(),

new_XPVNV(), del_XPVGV(),
etc

Public API:

sv_report_used(), sv_clean_objs(), sv_clean_all(), sv_free_arenas()
boolSV

Returns a true SV if b is a true value, or a false SV if b is 0.

See also "PL_sv_yes" and "PL_sv_no".

    SV *  boolSV(bool b)
croak_xs_usage

A specialised variant of croak() for emitting the usage message for xsubs

croak_xs_usage(cv, "eee_yow");

works out the package name and subroutine name from cv, and then calls croak(). Hence if cv is &ouch::awk, it would call croak as:

Perl_croak(aTHX_ "Usage: %" SVf "::%" SVf "(%s)", "ouch" "awk",
                                                    "eee_yow");
    void  croak_xs_usage(const CV *const cv, const char *const params)
DEFSV

Returns the SV associated with $_

    SV *  DEFSV
DEFSV_set

Associate sv with $_

    void  DEFSV_set(SV * sv)
get_sv

Returns the SV of the specified Perl scalar. flags are passed to gv_fetchpv. If GV_ADD is set and the Perl variable does not exist then it will be created. If flags is zero and the variable does not exist then NULL is returned.

NOTE: the perl_get_sv() form is deprecated.

    SV*  get_sv(const char *name, I32 flags)
isGV_with_GP

Returns a boolean as to whether or not sv is a GV with a pointer to a GP (glob pointer).

    bool  isGV_with_GP(SV * sv)
looks_like_number

Test if the content of an SV looks like a number (or is a number). Inf and Infinity are treated as numbers (so will not issue a non-numeric warning), even if your atof() doesn't grok them. Get-magic is ignored.

    I32  looks_like_number(SV *const sv)
MUTABLE_PTR
MUTABLE_AV
MUTABLE_CV
MUTABLE_GV
MUTABLE_HV
MUTABLE_IO
MUTABLE_SV

The MUTABLE_*() macros cast pointers to the types shown, in such a way (compiler permitting) that casting away const-ness will give a warning; e.g.:

const SV *sv = ...;
AV *av1 = (AV*)sv;        <== BAD:  the const has been silently
                                    cast away
AV *av2 = MUTABLE_AV(sv); <== GOOD: it may warn

MUTABLE_PTR is the base macro used to derive new casts. The other already-built-in ones return pointers to what their names indicate.

    void *  MUTABLE_PTR(void * p)
    AV *    MUTABLE_AV (AV * p)
    CV *    MUTABLE_CV (CV * p)
    GV *    MUTABLE_GV (GV * p)
    HV *    MUTABLE_HV (HV * p)
    IO *    MUTABLE_IO (IO * p)
    SV *    MUTABLE_SV (SV * p)
newRV
newRV_inc

These are identical. They create an RV wrapper for an SV. The reference count for the original SV is incremented.

    SV*  newRV(SV *const sv)
newRV_noinc

Creates an RV wrapper for an SV. The reference count for the original SV is not incremented.

    SV*  newRV_noinc(SV *const tmpRef)
newSV

Creates a new SV. A non-zero len parameter indicates the number of bytes of preallocated string space the SV should have. An extra byte for a trailing NUL is also reserved. (SvPOK is not set for the SV even if string space is allocated.) The reference count for the new SV is set to 1.

In 5.9.3, newSV() replaces the older NEWSV() API, and drops the first parameter, x, a debug aid which allowed callers to identify themselves. This aid has been superseded by a new build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in perlhacktips). The older API is still there for use in XS modules supporting older perls.

    SV*  newSV(const STRLEN len)
newSVhek

Creates a new SV from the hash key structure. It will generate scalars that point to the shared string table where possible. Returns a new (undefined) SV if hek is NULL.

    SV*  newSVhek(const HEK *const hek)
newSViv

Creates a new SV and copies an integer into it. The reference count for the SV is set to 1.

    SV*  newSViv(const IV i)
newSVnv

Creates a new SV and copies a floating point value into it. The reference count for the SV is set to 1.

    SV*  newSVnv(const NV n)
newSVpadname

NOTE: newSVpadname is experimental and may change or be removed without notice.

Creates a new SV containing the pad name.

    SV*  newSVpadname(PADNAME *pn)
newSVpv

Creates a new SV and copies a string (which may contain NUL (\0) characters) into it. The reference count for the SV is set to 1. If len is zero, Perl will compute the length using strlen(), (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte).

This function can cause reliability issues if you are likely to pass in empty strings that are not null terminated, because it will run strlen on the string and potentially run past valid memory.

Using "newSVpvn" is a safer alternative for non NUL terminated strings. For string literals use "newSVpvs" instead. This function will work fine for NUL terminated strings, but if you want to avoid the if statement on whether to call strlen use newSVpvn instead (calling strlen yourself).

    SV*  newSVpv(const char *const s, const STRLEN len)
newSVpvf

Creates a new SV and initializes it with the string formatted like sv_catpvf.

NOTE: newSVpvf must be explicitly called as Perl_newSVpvf with an aTHX_ parameter.

    SV*  Perl_newSVpvf(pTHX_ const char *const pat, ...)
newSVpvf_nocontext

Like "newSVpvf" but does not take a thread context (aTHX) parameter, so is used in situations where the caller doesn't already have the thread context.

    SV*  newSVpvf_nocontext(const char *const pat, ...)
newSVpvn

Creates a new SV and copies a string into it, which may contain NUL characters (\0) and other binary data. The reference count for the SV is set to 1. Note that if len is zero, Perl will create a zero length (Perl) string. You are responsible for ensuring that the source buffer is at least len bytes long. If the buffer argument is NULL the new SV will be undefined.

    SV*  newSVpvn(const char *const buffer, const STRLEN len)
newSVpvn_flags

Creates a new SV and copies a string (which may contain NUL (\0) characters) into it. The reference count for the SV is set to 1. Note that if len is zero, Perl will create a zero length string. You are responsible for ensuring that the source string is at least len bytes long. If the s argument is NULL the new SV will be undefined. Currently the only flag bits accepted are SVf_UTF8 and SVs_TEMP. If SVs_TEMP is set, then sv_2mortal() is called on the result before returning. If SVf_UTF8 is set, s is considered to be in UTF-8 and the SVf_UTF8 flag will be set on the new SV. newSVpvn_utf8() is a convenience wrapper for this function, defined as

#define newSVpvn_utf8(s, len, u)                    \
    newSVpvn_flags((s), (len), (u) ? SVf_UTF8 : 0)
    SV*  newSVpvn_flags(const char *const s, const STRLEN len,
                        const U32 flags)
newSVpvn_share

Creates a new SV with its SvPVX_const pointing to a shared string in the string table. If the string does not already exist in the table, it is created first. Turns on the SvIsCOW flag (or READONLY and FAKE in 5.16 and earlier). If the hash parameter is non-zero, that value is used; otherwise the hash is computed. The string's hash can later be retrieved from the SV with the "SvSHARED_HASH" macro. The idea here is that as the string table is used for shared hash keys these strings will have SvPVX_const == HeKEY and hash lookup will avoid string compare.

    SV*  newSVpvn_share(const char* s, I32 len, U32 hash)
newSVpvn_utf8

Creates a new SV and copies a string (which may contain NUL (\0) characters) into it. If utf8 is true, calls SvUTF8_on on the new SV. Implemented as a wrapper around newSVpvn_flags.

    SV*  newSVpvn_utf8(const char* s, STRLEN len, U32 utf8)
newSVpvs

Like newSVpvn, but takes a literal string instead of a string/length pair.

    SV*  newSVpvs("literal string")
newSVpvs_flags

Like newSVpvn_flags, but takes a literal string instead of a string/length pair.

    SV*  newSVpvs_flags("literal string", U32 flags)
newSVpv_share

Like newSVpvn_share, but takes a NUL-terminated string instead of a string/length pair.

    SV*  newSVpv_share(const char* s, U32 hash)
newSVpvs_share

Like newSVpvn_share, but takes a literal string instead of a string/length pair and omits the hash parameter.

    SV*  newSVpvs_share("literal string")
newSVrv

Creates a new SV for the existing RV, rv, to point to. If rv is not an RV then it will be upgraded to one. If classname is non-null then the new SV will be blessed in the specified package. The new SV is returned and its reference count is 1. The reference count 1 is owned by rv. See also newRV_inc() and newRV_noinc() for creating a new RV properly.

    SV*  newSVrv(SV *const rv, const char *const classname)
newSVsv
newSVsv_nomg
newSVsv_flags

These create a new SV which is an exact duplicate of the original SV (using sv_setsv.)

They differ only in that newSVsv performs 'get' magic; newSVsv_nomg skips any magic; and newSVsv_flags allows you to explicitly set a flags parameter.

    SV*  newSVsv      (SV *const old)
    SV*  newSVsv_nomg (SV *const old)
    SV*  newSVsv_flags(SV *const old, I32 flags)
newSV_type

Creates a new SV, of the type specified. The reference count for the new SV is set to 1.

    SV*  newSV_type(const svtype type)
newSVuv

Creates a new SV and copies an unsigned integer into it. The reference count for the SV is set to 1.

    SV*  newSVuv(const UV u)
Nullsv

Null SV pointer. (No longer available when PERL_CORE is defined.)

PL_na

A convenience variable which is typically used with SvPV when one doesn't care about the length of the string. It is usually more efficient to either declare a local variable and use that instead or to use the SvPV_nolen macro.

    STRLEN  PL_na
PL_sv_no

This is the false SV. It is readonly. See "PL_sv_yes". Always refer to this as &PL_sv_no.

    SV  PL_sv_no
PL_sv_undef

This is the undef SV. It is readonly. Always refer to this as &PL_sv_undef.

    SV  PL_sv_undef
PL_sv_yes

This is the true SV. It is readonly. See "PL_sv_no". Always refer to this as &PL_sv_yes.

    SV  PL_sv_yes
PL_sv_zero

This readonly SV has a zero numeric value and a "0" string value. It's similar to "PL_sv_no" except for its string value. Can be used as a cheap alternative to mXPUSHi(0) for example. Always refer to this as &PL_sv_zero. Introduced in 5.28.

    SV  PL_sv_zero
SAVE_DEFSV

Localize $_. See "Localizing changes" in perlguts.

    void  SAVE_DEFSV
sortsv

In-place sort an array of SV pointers with the given comparison routine.

Currently this always uses mergesort. See "sortsv_flags" for a more flexible routine.

    void  sortsv(SV** array, size_t num_elts, SVCOMPARE_t cmp)
sortsv_flags

In-place sort an array of SV pointers with the given comparison routine, with various SORTf_* flag options.

    void  sortsv_flags(SV** array, size_t num_elts, SVCOMPARE_t cmp,
                       U32 flags)
SV

Described in perlguts.

sv_2cv

Using various gambits, try to get a CV from an SV; in addition, try if possible to set *st and *gvp to the stash and GV associated with it. The flags in lref are passed to gv_fetchsv.

    CV*  sv_2cv(SV* sv, HV **const st, GV **const gvp, const I32 lref)
sv_2io

Using various gambits, try to get an IO from an SV: the IO slot if its a GV; or the recursive result if we're an RV; or the IO slot of the symbol named after the PV if we're a string.

'Get' magic is ignored on the sv passed in, but will be called on SvRV(sv) if sv is an RV.

    IO*  sv_2io(SV *const sv)
sv_2iv_flags

Return the integer value of an SV, doing any necessary string conversion. If flags has the SV_GMAGIC bit set, does an mg_get() first. Normally used via the SvIV(sv) and SvIVx(sv) macros.

    IV  sv_2iv_flags(SV *const sv, const I32 flags)
sv_2mortal

Marks an existing SV as mortal. The SV will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. SvTEMP() is turned on which means that the SV's string buffer can be "stolen" if this SV is copied. See also "sv_newmortal" and "sv_mortalcopy".

    SV*  sv_2mortal(SV *const sv)
sv_2nv_flags

Return the num value of an SV, doing any necessary string or integer conversion. If flags has the SV_GMAGIC bit set, does an mg_get() first. Normally used via the SvNV(sv) and SvNVx(sv) macros.

    NV  sv_2nv_flags(SV *const sv, const I32 flags)
sv_2pvbyte

Returns a pointer to the byte-encoded representation of the SV, and set *lp to its length. If the SV is marked as being encoded as UTF-8, it will downgrade it to a byte string as a side-effect, if possible. If the SV cannot be downgraded, this croaks.

Processes 'get' magic.

Usually accessed via the SvPVbyte macro.

    char*  sv_2pvbyte(SV *sv, STRLEN *const lp)
sv_2pvutf8

Return a pointer to the UTF-8-encoded representation of the SV, and set *lp to its length. May cause the SV to be upgraded to UTF-8 as a side-effect.

Usually accessed via the SvPVutf8 macro.

    char*  sv_2pvutf8(SV *sv, STRLEN *const lp)
sv_2uv_flags

Return the unsigned integer value of an SV, doing any necessary string conversion. If flags has the SV_GMAGIC bit set, does an mg_get() first. Normally used via the SvUV(sv) and SvUVx(sv) macros.

    UV  sv_2uv_flags(SV *const sv, const I32 flags)
sv_backoff

Remove any string offset. You should normally use the SvOOK_off macro wrapper instead.

    void  sv_backoff(SV *const sv)
sv_bless

Blesses an SV into a specified package. The SV must be an RV. The package must be designated by its stash (see "gv_stashpv"). The reference count of the SV is unaffected.

    SV*  sv_bless(SV *const sv, HV *const stash)
sv_catpv
sv_catpv_flags
sv_catpv_mg
sv_catpv_nomg

These concatenate the NUL-terminated string sstr onto the end of the string which is in the SV. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8.

They differ only in how they handle magic:

sv_catpv_mg performs both 'get' and 'set' magic.

sv_catpv performs only 'get' magic.

sv_catpv_nomg skips all magic.

sv_catpv_flags has an extra flags parameter which allows you to specify any combination of magic handling (using SV_GMAGIC and/or SV_SMAGIC), and to also override the UTF-8 handling. By supplying the SV_CATUTF8 flag, the appended string is forced to be interpreted as UTF-8; by supplying instead the SV_CATBYTES flag, it will be interpreted as just bytes. Either the SV or the string appended will be upgraded to UTF-8 if necessary.

    void  sv_catpv      (SV *const dsv, const char* sstr)
    void  sv_catpv_flags(SV *dsv, const char *sstr, const I32 flags)
    void  sv_catpv_mg   (SV *const dsv, const char *const sstr)
    void  sv_catpv_nomg (SV *const dsv, const char* sstr)
sv_catpvf
sv_catpvf_nocontext
sv_catpvf_mg
sv_catpvf_mg_nocontext

These process their arguments like sprintf, and append the formatted output to an SV. As with sv_vcatpvfn, argument reordering is not supporte when called with a non-null C-style variable argument list.

If the appended data contains "wide" characters (including, but not limited to, SVs with a UTF-8 PV formatted with %s, and characters >255 formatted with %c), the original SV might get upgraded to UTF-8.

If the original SV was UTF-8, the pattern should be valid UTF-8; if the original SV was bytes, the pattern should be too.

All perform 'get' magic, but only sv_catpvf_mg and sv_catpvf_mg_nocontext perform 'set' magic.

sv_catpvf_nocontext and sv_catpvf_mg_nocontext do not take a thread context (aTHX) parameter, so are used in situations where the caller doesn't already have the thread context.

NOTE: sv_catpvf must be explicitly called as Perl_sv_catpvf with an aTHX_ parameter.

NOTE: sv_catpvf_mg must be explicitly called as Perl_sv_catpvf_mg with an aTHX_ parameter.

    void  Perl_sv_catpvf        (pTHX_ SV *const sv,
                                 const char *const pat, ...)
    void  sv_catpvf_nocontext   (SV *const sv, const char *const pat,
                                 ...)
    void  Perl_sv_catpvf_mg     (pTHX_ SV *const sv,
                                 const char *const pat, ...)
    void  sv_catpvf_mg_nocontext(SV *const sv, const char *const pat,
                                 ...)
sv_catpvn
sv_catpvn_flags
sv_catpvn_mg
sv_catpvn_nomg

These concatenate the len bytes of the string beginning at ptr onto the end of the string which is in dsv. The caller must make sure ptr contains at least len bytes.

For all but sv_catpvn_flags, the string appended is assumed to be valid UTF-8 if the SV has the UTF-8 status set, and a string of bytes otherwise.

They differ in that:

sv_catpvn_mg performs both 'get' and 'set' magic on dsv.

sv_catpvn performs only 'get' magic.

sv_catpvn_nomg skips all magic.

sv_catpvn_flags has an extra flags parameter which allows you to specify any combination of magic handling (using SV_GMAGIC and/or SV_SMAGIC) and to also override the UTF-8 handling. By supplying the SV_CATBYTES flag, the appended string is interpreted as plain bytes; by supplying instead the SV_CATUTF8 flag, it will be interpreted as UTF-8, and the dsv will be upgraded to UTF-8 if necessary.

sv_catpvn, sv_catpvn_mg, and sv_catpvn_nomg are implemented in terms of sv_catpvn_flags.

    void  sv_catpvn      (SV *dsv, const char *sstr, STRLEN len)
    void  sv_catpvn_flags(SV *const dsv, const char *sstr,
                          const STRLEN len, const I32 flags)
    void  sv_catpvn_mg   (SV *dsv, const char *sstr, STRLEN len)
    void  sv_catpvn_nomg (SV *dsv, const char *sstr, STRLEN len)
sv_catpvs

Like sv_catpvn, but takes a literal string instead of a string/length pair.

    void  sv_catpvs(SV* sv, "literal string")
sv_catpvs_flags

Like sv_catpvn_flags, but takes a literal string instead of a string/length pair.

    void  sv_catpvs_flags(SV* sv, "literal string", I32 flags)
sv_catpvs_mg

Like sv_catpvn_mg, but takes a literal string instead of a string/length pair.

    void  sv_catpvs_mg(SV* sv, "literal string")
sv_catpvs_nomg

Like sv_catpvn_nomg, but takes a literal string instead of a string/length pair.

    void  sv_catpvs_nomg(SV* sv, "literal string")
sv_catsv
sv_catsv_flags
sv_catsv_mg
sv_catsv_nomg

These concatenate the string from SV sstr onto the end of the string in SV dsv. If sstr is null, these are no-ops; otherwise only dsv is modified.

They differ only in what magic they perform:

sv_catsv_mg performs 'get' magic on both SVs before the copy, and 'set' magic on dsv afterwards.

sv_catsv performs just 'get' magic, on both SVs.

sv_catsv_nomg skips all magic.

sv_catsv_flags has an extra flags parameter which allows you to use SV_GMAGIC and/or SV_SMAGIC to specify any combination of magic handling (although either both or neither SV will have 'get' magic applied to it.)

sv_catsv, sv_catsv_mg, and sv_catsv_nomg are implemented in terms of sv_catsv_flags.

    void  sv_catsv      (SV *dsv, SV *sstr)
    void  sv_catsv_flags(SV *const dsv, SV *const sstr,
                         const I32 flags)
    void  sv_catsv_mg   (SV *dsv, SV *sstr)
    void  sv_catsv_nomg (SV *dsv, SV *sstr)
sv_chop

Efficient removal of characters from the beginning of the string buffer. SvPOK(sv), or at least SvPOKp(sv), must be true and ptr must be a pointer to somewhere inside the string buffer. ptr becomes the first character of the adjusted string. Uses the OOK hack. On return, only SvPOK(sv) and SvPOKp(sv) among the OK flags will be true.

Beware: after this function returns, ptr and SvPVX_const(sv) may no longer refer to the same chunk of data.

The unfortunate similarity of this function's name to that of Perl's chop operator is strictly coincidental. This function works from the left; chop works from the right.

    void  sv_chop(SV *const sv, const char *const ptr)
sv_clear

Clear an SV: call any destructors, free up any memory used by the body, and free the body itself. The SV's head is not freed, although its type is set to all 1's so that it won't inadvertently be assumed to be live during global destruction etc. This function should only be called when REFCNT is zero. Most of the time you'll want to call sv_free() (or its macro wrapper SvREFCNT_dec) instead.

    void  sv_clear(SV *const orig_sv)
sv_cmp

Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the string in sv1 is less than, equal to, or greater than the string in sv2. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp_locale".

    I32  sv_cmp(SV *const sv1, SV *const sv2)
sv_cmp_flags

Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the string in sv1 is less than, equal to, or greater than the string in sv2. Is UTF-8 and 'use bytes' aware and will coerce its args to strings if necessary. If the flags has the SV_GMAGIC bit set, it handles get magic. See also "sv_cmp_locale_flags".

    I32  sv_cmp_flags(SV *const sv1, SV *const sv2, const U32 flags)
sv_cmp_locale

Compares the strings in two SVs in a locale-aware manner. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp".

    I32  sv_cmp_locale(SV *const sv1, SV *const sv2)
sv_cmp_locale_flags

Compares the strings in two SVs in a locale-aware manner. Is UTF-8 and 'use bytes' aware and will coerce its args to strings if necessary. If the flags contain SV_GMAGIC, it handles get magic. See also "sv_cmp_flags".

    I32  sv_cmp_locale_flags(SV *const sv1, SV *const sv2,
                             const U32 flags)
sv_collxfrm

This calls sv_collxfrm_flags with the SV_GMAGIC flag. See "sv_collxfrm_flags".

    char*  sv_collxfrm(SV *const sv, STRLEN *const nxp)
sv_collxfrm_flags

Add Collate Transform magic to an SV if it doesn't already have it. If the flags contain SV_GMAGIC, it handles get-magic.

Any scalar variable may carry PERL_MAGIC_collxfrm magic that contains the scalar data of the variable, but transformed to such a format that a normal memory comparison can be used to compare the data according to the locale settings.

    char*  sv_collxfrm_flags(SV *const sv, STRLEN *const nxp,
                             I32 const flags)
sv_copypv
sv_copypv_nomg
sv_copypv_flags

These copy a stringified representation of the source SV into the destination SV. They automatically perform coercion of numeric values into strings. Guaranteed to preserve the UTF8 flag even from overloaded objects. Similar in nature to sv_2pv[_flags] but they operate directly on an SV instead of just the string. Mostly they use "sv_2pv_flags" in perlintern to do the work, except when that would lose the UTF-8'ness of the PV.

The three forms differ only in whether or not they perform 'get magic' on sv. sv_copypv_nomg skips 'get magic'; sv_copypv performs it; and sv_copypv_flags either performs it (if the SV_GMAGIC bit is set in flags) or doesn't (if that bit is cleared).

    void  sv_copypv      (SV *const dsv, SV *const ssv)
    void  sv_copypv_nomg (SV *const dsv, SV *const ssv)
    void  sv_copypv_flags(SV *const dsv, SV *const ssv,
                          const I32 flags)
SvCUR

Returns the length, in bytes, of the PV inside the SV. Note that this may not match Perl's length; for that, use sv_len_utf8(sv). See "SvLEN" also.

    STRLEN  SvCUR(SV* sv)
SvCUR_set

Sets the current length, in bytes, of the C string which is in the SV. See "SvCUR" and SvIV_set>.

    void  SvCUR_set(SV* sv, STRLEN len)
sv_dec
sv_dec_nomg

These auto-decrement the value in the SV, doing string to numeric conversion if necessary. They both handle operator overloading.

They differ only in that:

sv_dec handles 'get' magic; sv_dec_nomg skips 'get' magic.

    void  sv_dec(SV *const sv)
sv_derived_from

Exactly like "sv_derived_from_pv", but doesn't take a flags parameter.

    bool  sv_derived_from(SV* sv, const char *const name)
sv_derived_from_pv

Exactly like "sv_derived_from_pvn", but takes a nul-terminated string instead of a string/length pair.

    bool  sv_derived_from_pv(SV* sv, const char *const name,
                             U32 flags)
sv_derived_from_pvn

Returns a boolean indicating whether the SV is derived from the specified class at the C level. To check derivation at the Perl level, call isa() as a normal Perl method.

Currently, the only significant value for flags is SVf_UTF8.

    bool  sv_derived_from_pvn(SV* sv, const char *const name,
                              const STRLEN len, U32 flags)
sv_derived_from_sv

Exactly like "sv_derived_from_pvn", but takes the name string in the form of an SV instead of a string/length pair. This is the advised form.

    bool  sv_derived_from_sv(SV* sv, SV *namesv, U32 flags)
sv_does

Like "sv_does_pv", but doesn't take a flags parameter.

    bool  sv_does(SV* sv, const char *const name)
sv_does_pv

Like "sv_does_sv", but takes a nul-terminated string instead of an SV.

    bool  sv_does_pv(SV* sv, const char *const name, U32 flags)
sv_does_pvn

Like "sv_does_sv", but takes a string/length pair instead of an SV.

    bool  sv_does_pvn(SV* sv, const char *const name,
                      const STRLEN len, U32 flags)
sv_does_sv

Returns a boolean indicating whether the SV performs a specific, named role. The SV can be a Perl object or the name of a Perl class.

    bool  sv_does_sv(SV* sv, SV* namesv, U32 flags)
SvEND

Returns a pointer to the spot just after the last character in the string which is in the SV, where there is usually a trailing NUL character (even though Perl scalars do not strictly require it). See "SvCUR". Access the character as *(SvEND(sv)).

Warning: If SvCUR is equal to SvLEN, then SvEND points to unallocated memory.

    char*  SvEND(SV* sv)
sv_eq

Returns a boolean indicating whether the strings in the two SVs are identical. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary.

    I32  sv_eq(SV* sv1, SV* sv2)
sv_eq_flags

Returns a boolean indicating whether the strings in the two SVs are identical. Is UTF-8 and 'use bytes' aware and coerces its args to strings if necessary. If the flags has the SV_GMAGIC bit set, it handles get-magic, too.

    I32  sv_eq_flags(SV* sv1, SV* sv2, const U32 flags)
sv_force_normal

Undo various types of fakery on an SV: if the PV is a shared string, make a private copy; if we're a ref, stop refing; if we're a glob, downgrade to an xpvmg. See also "sv_force_normal_flags".

    void  sv_force_normal(SV *sv)
sv_force_normal_flags

Undo various types of fakery on an SV, where fakery means "more than" a string: if the PV is a shared string, make a private copy; if we're a ref, stop refing; if we're a glob, downgrade to an xpvmg; if we're a copy-on-write scalar, this is the on-write time when we do the copy, and is also used locally; if this is a vstring, drop the vstring magic. If SV_COW_DROP_PV is set then a copy-on-write scalar drops its PV buffer (if any) and becomes SvPOK_off rather than making a copy. (Used where this scalar is about to be set to some other value.) In addition, the flags parameter gets passed to sv_unref_flags() when unreffing. sv_force_normal calls this function with flags set to 0.

This function is expected to be used to signal to perl that this SV is about to be written to, and any extra book-keeping needs to be taken care of. Hence, it croaks on read-only values.

    void  sv_force_normal_flags(SV *const sv, const U32 flags)
sv_free

Decrement an SV's reference count, and if it drops to zero, call sv_clear to invoke destructors and free up any memory used by the body; finally, deallocating the SV's head itself. Normally called via a wrapper macro SvREFCNT_dec.

    void  sv_free(SV *const sv)
SvGAMAGIC

Returns true if the SV has get magic or overloading. If either is true then the scalar is active data, and has the potential to return a new value every time it is accessed. Hence you must be careful to only read it once per user logical operation and work with that returned value. If neither is true then the scalar's value cannot change unless written to.

    U32  SvGAMAGIC(SV* sv)
SvGETMAGIC

Invokes "mg_get" on an SV if it has 'get' magic. For example, this will call FETCH on a tied variable. This macro evaluates its argument more than once.

    void  SvGETMAGIC(SV* sv)
sv_gets

Get a line from the filehandle and store it into the SV, optionally appending to the currently-stored string. If append is not 0, the line is appended to the SV instead of overwriting it. append should be set to the byte offset that the appended string should start at in the SV (typically, SvCUR(sv) is a suitable choice).

    char*  sv_gets(SV *const sv, PerlIO *const fp, I32 append)
sv_get_backrefs

NOTE: sv_get_backrefs is experimental and may change or be removed without notice.

If sv is the target of a weak reference then it returns the back references structure associated with the sv; otherwise return NULL.

When returning a non-null result the type of the return is relevant. If it is an AV then the elements of the AV are the weak reference RVs which point at this item. If it is any other type then the item itself is the weak reference.

See also Perl_sv_add_backref(), Perl_sv_del_backref(), Perl_sv_kill_backrefs()

    SV*  sv_get_backrefs(SV *const sv)
SvGROW

Expands the character buffer in the SV so that it has room for the indicated number of bytes (remember to reserve space for an extra trailing NUL character). Calls sv_grow to perform the expansion if necessary. Returns a pointer to the character buffer. SV must be of type >= SVt_PV. One alternative is to call sv_grow if you are not sure of the type of SV.

You might mistakenly think that len is the number of bytes to add to the existing size, but instead it is the total size sv should be.

    char *  SvGROW(SV* sv, STRLEN len)
sv_inc
sv_inc_nomg

These auto-increment the value in the SV, doing string to numeric conversion if necessary. They both handle operator overloading.

They differ only in that sv_inc performs 'get' magic; sv_inc_nomg skips any magic.

    void  sv_inc(SV *const sv)
sv_insert

Inserts and/or replaces a string at the specified offset/length within the SV. Similar to the Perl substr() function, with littlelen bytes starting at little replacing len bytes of the string in bigstr starting at offset. Handles get magic.

    void  sv_insert(SV *const bigstr, const STRLEN offset,
                    const STRLEN len, const char *const little,
                    const STRLEN littlelen)
sv_insert_flags

Same as sv_insert, but the extra flags are passed to the SvPV_force_flags that applies to bigstr.

    void  sv_insert_flags(SV *const bigstr, const STRLEN offset,
                          const STRLEN len, const char *little,
                          const STRLEN littlelen, const U32 flags)
SvIOK

Returns a U32 value indicating whether the SV contains an integer.

    U32  SvIOK(SV* sv)
SvIOK_notUV

Returns a boolean indicating whether the SV contains a signed integer.

    bool  SvIOK_notUV(SV* sv)
SvIOK_off

Unsets the IV status of an SV.

    void  SvIOK_off(SV* sv)
SvIOK_on

Tells an SV that it is an integer.

    void  SvIOK_on(SV* sv)
SvIOK_only

Tells an SV that it is an integer and disables all other OK bits.

    void  SvIOK_only(SV* sv)
SvIOK_only_UV

Tells an SV that it is an unsigned integer and disables all other OK bits.

    void  SvIOK_only_UV(SV* sv)
SvIOKp

Returns a U32 value indicating whether the SV contains an integer. Checks the private setting. Use SvIOK instead.

    U32  SvIOKp(SV* sv)
SvIOK_UV

Returns a boolean indicating whether the SV contains an integer that must be interpreted as unsigned. A non-negative integer whose value is within the range of both an IV and a UV may be flagged as either SvUOK or SvIOK.

    bool  SvIOK_UV(SV* sv)
sv_isa

Returns a boolean indicating whether the SV is blessed into the specified class.

This does not check for subtypes or method overloading. Use sv_isa_sv to verify an inheritance relationship in the same way as the isa operator by respecting any isa() method overloading; or sv_derived_from_sv to test directly on the actual object type.

    int  sv_isa(SV* sv, const char *const name)
sv_isa_sv

NOTE: sv_isa_sv is experimental and may change or be removed without notice.

Returns a boolean indicating whether the SV is an object reference and is derived from the specified class, respecting any isa() method overloading it may have. Returns false if sv is not a reference to an object, or is not derived from the specified class.

This is the function used to implement the behaviour of the isa operator.

Does not invoke magic on sv.

Not to be confused with the older sv_isa function, which does not use an overloaded isa() method, nor will check subclassing.

    bool  sv_isa_sv(SV* sv, SV* namesv)
SvIsCOW

Returns a U32 value indicating whether the SV is Copy-On-Write (either shared hash key scalars, or full Copy On Write scalars if 5.9.0 is configured for COW).

    U32  SvIsCOW(SV* sv)
SvIsCOW_shared_hash

Returns a boolean indicating whether the SV is Copy-On-Write shared hash key scalar.

    bool  SvIsCOW_shared_hash(SV* sv)
sv_isobject

Returns a boolean indicating whether the SV is an RV pointing to a blessed object. If the SV is not an RV, or if the object is not blessed, then this will return false.

    int  sv_isobject(SV* sv)
SvIV
SvIVx
SvIV_nomg

These coerce the given SV to IV and return it. The returned value in many circumstances will get stored in sv's IV slot, but not in all cases. (Use "sv_setiv" to make sure it does).

SvIVx is different from the others in that it is guaranteed to evaluate sv exactly once; the others may evaluate it multiple times. Only use this form if sv is an expression with side effects, otherwise use the more efficient SvIV.

SvIV_nomg is the same as SvIV, but does not perform 'get' magic.

    IV  SvIV(SV* sv)
SvIV_set

Set the value of the IV pointer in sv to val. It is possible to perform the same function of this macro with an lvalue assignment to SvIVX. With future Perls, however, it will be more efficient to use SvIV_set instead of the lvalue assignment to SvIVX.

    void  SvIV_set(SV* sv, IV val)
SvIVX

Returns the raw value in the SV's IV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvIV".

    IV  SvIVX(SV* sv)
SvLEN

Returns the size of the string buffer in the SV, not including any part attributable to SvOOK. See "SvCUR".

    STRLEN  SvLEN(SV* sv)
sv_len

Returns the length of the string in the SV. Handles magic and type coercion and sets the UTF8 flag appropriately. See also "SvCUR", which gives raw access to the xpv_cur slot.

    STRLEN  sv_len(SV *const sv)
SvLEN_set

Set the size of the string buffer for the SV. See "SvLEN".

    void  SvLEN_set(SV* sv, STRLEN len)
sv_len_utf8

Returns the number of characters in the string in an SV, counting wide UTF-8 bytes as a single character. Handles magic and type coercion.

    STRLEN  sv_len_utf8(SV *const sv)
SvLOCK

Arranges for a mutual exclusion lock to be obtained on sv if a suitable module has been loaded.

    void  SvLOCK(SV* sv)
sv_magic

Adds magic to an SV. First upgrades sv to type SVt_PVMG if necessary, then adds a new magic item of type how to the head of the magic list.

See "sv_magicext" (which sv_magic now calls) for a description of the handling of the name and namlen arguments.

You need to use sv_magicext to add magic to SvREADONLY SVs and also to add more than one instance of the same how.

    void  sv_magic(SV *const sv, SV *const obj, const int how,
                   const char *const name, const I32 namlen)
sv_magicext

Adds magic to an SV, upgrading it if necessary. Applies the supplied vtable and returns a pointer to the magic added.

Note that sv_magicext will allow things that sv_magic will not. In particular, you can add magic to SvREADONLY SVs, and add more than one instance of the same how.

If namlen is greater than zero then a savepvn copy of name is stored, if namlen is zero then name is stored as-is and - as another special case - if (name && namlen == HEf_SVKEY) then name is assumed to contain an SV* and is stored as-is with its REFCNT incremented.

(This is now used as a subroutine by sv_magic.)

    MAGIC *  sv_magicext(SV *const sv, SV *const obj, const int how,
                         const MGVTBL *const vtbl,
                         const char *const name, const I32 namlen)
SvMAGIC_set

Set the value of the MAGIC pointer in sv to val. See "SvIV_set".

    void  SvMAGIC_set(SV* sv, MAGIC* val)
sv_mortalcopy

Creates a new SV which is a copy of the original SV (using sv_setsv). The new SV is marked as mortal. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_newmortal" and "sv_2mortal".

    SV*  sv_mortalcopy(SV *const oldsv)
sv_mortalcopy_flags

Like sv_mortalcopy, but the extra flags are passed to the sv_setsv_flags.

    SV*  sv_mortalcopy_flags(SV *const oldsv, U32 flags)
sv_newmortal

Creates a new null SV which is mortal. The reference count of the SV is set to 1. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_mortalcopy" and "sv_2mortal".

    SV*  sv_newmortal()
SvNIOK

Returns a U32 value indicating whether the SV contains a number, integer or double.

    U32  SvNIOK(SV* sv)
SvNIOK_off

Unsets the NV/IV status of an SV.

    void  SvNIOK_off(SV* sv)
SvNIOKp

Returns a U32 value indicating whether the SV contains a number, integer or double. Checks the private setting. Use SvNIOK instead.

    U32  SvNIOKp(SV* sv)
SvNOK

Returns a U32 value indicating whether the SV contains a double.

    U32  SvNOK(SV* sv)
SvNOK_off

Unsets the NV status of an SV.

    void  SvNOK_off(SV* sv)
SvNOK_on

Tells an SV that it is a double.

    void  SvNOK_on(SV* sv)
SvNOK_only

Tells an SV that it is a double and disables all other OK bits.

    void  SvNOK_only(SV* sv)
SvNOKp

Returns a U32 value indicating whether the SV contains a double. Checks the private setting. Use SvNOK instead.

    U32  SvNOKp(SV* sv)
sv_nolocking

DEPRECATED! It is planned to remove sv_nolocking from a future release of Perl. Do not use it for new code; remove it from existing code.

Dummy routine which "locks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

"Superseded" by sv_nosharing().

    void  sv_nolocking(SV *sv)
sv_nounlocking

DEPRECATED! It is planned to remove sv_nounlocking from a future release of Perl. Do not use it for new code; remove it from existing code.

Dummy routine which "unlocks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

"Superseded" by sv_nosharing().

    void  sv_nounlocking(SV *sv)
SvNV
SvNVx
SvNV_nomg

These coerce the given SV to NV and return it. The returned value in many circumstances will get stored in sv's NV slot, but not in all cases. (Use "sv_setnv" to make sure it does).

SvNVx is different from the others in that it is guaranteed to evaluate sv exactly once; the others may evaluate it multiple times. Only use this form if sv is an expression with side effects, otherwise use the more efficient SvNV.

SvNV_nomg is the same as SvNV, but does not perform 'get' magic.

    NV  SvNV(SV* sv)
SvNV_set

Set the value of the NV pointer in sv to val. See "SvIV_set".

    void  SvNV_set(SV* sv, NV val)
SvNVX

Returns the raw value in the SV's NV slot, without checks or conversions. Only use when you are sure SvNOK is true. See also "SvNV".

    NV  SvNVX(SV* sv)
SvOK

Returns a U32 value indicating whether the value is defined. This is only meaningful for scalars.

    U32  SvOK(SV* sv)
SvOOK

Returns a U32 indicating whether the pointer to the string buffer is offset. This hack is used internally to speed up removal of characters from the beginning of a "SvPV". When SvOOK is true, then the start of the allocated string buffer is actually SvOOK_offset() bytes before SvPVX. This offset used to be stored in SvIVX, but is now stored within the spare part of the buffer.

    U32  SvOOK(SV* sv)
SvOOK_off

Remove any string offset.

    void  SvOOK_off(SV * sv)
SvOOK_offset

Reads into len the offset from SvPVX back to the true start of the allocated buffer, which will be non-zero if sv_chop has been used to efficiently remove characters from start of the buffer. Implemented as a macro, which takes the address of len, which must be of type STRLEN. Evaluates sv more than once. Sets len to 0 if SvOOK(sv) is false.

    void  SvOOK_offset(SV*sv, STRLEN len)
SvPOK

Returns a U32 value indicating whether the SV contains a character string.

    U32  SvPOK(SV* sv)
SvPOK_off

Unsets the PV status of an SV.

    void  SvPOK_off(SV* sv)
SvPOK_on

Tells an SV that it is a string.

    void  SvPOK_on(SV* sv)
SvPOK_only

Tells an SV that it is a string and disables all other OK bits. Will also turn off the UTF-8 status.

    void  SvPOK_only(SV* sv)
SvPOK_only_UTF8

Tells an SV that it is a string and disables all other OK bits, and leaves the UTF-8 status as it was.

    void  SvPOK_only_UTF8(SV* sv)
SvPOKp

Returns a U32 value indicating whether the SV contains a character string. Checks the private setting. Use SvPOK instead.

    U32  SvPOKp(SV* sv)
sv_pos_b2u

Converts the value pointed to by offsetp from a count of bytes from the start of the string, to a count of the equivalent number of UTF-8 chars. Handles magic and type coercion.

Use sv_pos_b2u_flags in preference, which correctly handles strings longer than 2Gb.

    void  sv_pos_b2u(SV *const sv, I32 *const offsetp)
sv_pos_b2u_flags

Converts offset from a count of bytes from the start of the string, to a count of the equivalent number of UTF-8 chars. Handles type coercion. flags is passed to SvPV_flags, and usually should be SV_GMAGIC|SV_CONST_RETURN to handle magic.

    STRLEN  sv_pos_b2u_flags(SV *const sv, STRLEN const offset,
                             U32 flags)
sv_pos_u2b

Converts the value pointed to by offsetp from a count of UTF-8 chars from the start of the string, to a count of the equivalent number of bytes; if lenp is non-zero, it does the same to lenp, but this time starting from the offset, rather than from the start of the string. Handles magic and type coercion.

Use sv_pos_u2b_flags in preference, which correctly handles strings longer than 2Gb.

    void  sv_pos_u2b(SV *const sv, I32 *const offsetp,
                     I32 *const lenp)
sv_pos_u2b_flags

Converts the offset from a count of UTF-8 chars from the start of the string, to a count of the equivalent number of bytes; if lenp is non-zero, it does the same to lenp, but this time starting from offset, rather than from the start of the string. Handles type coercion. flags is passed to SvPV_flags, and usually should be SV_GMAGIC|SV_CONST_RETURN to handle magic.

    STRLEN  sv_pos_u2b_flags(SV *const sv, STRLEN uoffset,
                             STRLEN *const lenp, U32 flags)
SvPV
SvPVx
SvPV_nomg
SvPV_nolen
SvPVx_nolen
SvPV_nomg_nolen
SvPV_mutable
SvPV_const
SvPVx_const
SvPV_nolen_const
SvPVx_nolen_const
SvPV_nomg_const
SvPV_nomg_const_nolen
SvPV_flags
SvPV_flags_const
SvPV_flags_mutable
SvPVbyte
SvPVbyte_nomg
SvPVbyte_nolen
SvPVbytex_nolen
SvPVbytex
SvPVbyte_or_null
SvPVbyte_or_null_nomg
SvPVutf8
SvPVutf8x
SvPVutf8_nomg
SvPVutf8_nolen
SvPVutf8_or_null
SvPVutf8_or_null_nomg

All these return a pointer to the string in sv, or a stringified form of sv if it does not contain a string. The SV may cache the stringified version becoming SvPOK.

This is a very basic and common operation, so there are lots of slightly different versions of it.

Note that there is no guarantee that the return value of SvPV(sv), for example, is equal to SvPVX(sv), or that SvPVX(sv) contains valid data, or that successive calls to SvPV(sv) (or another of these forms) will return the same pointer value each time. This is due to the way that things like overloading and Copy-On-Write are handled. In these cases, the return value may point to a temporary buffer or similar. If you absolutely need the SvPVX field to be valid (for example, if you intend to write to it), then see "SvPV_force".

The differences between the forms are:

The forms with neither byte nor utf8 in their names (e.g., SvPV or SvPV_nolen) can expose the SV's internal string buffer. If that buffer consists entirely of bytes 0-255 and includes any bytes above 127, then you MUST consult SvUTF8 to determine the actual code points the string is meant to contain. Generally speaking, it is probably safer to prefer SvPVbyte, SvPVutf8, and the like. See "How do I pass a Perl string to a C library?" in perlguts for more details.

The forms with flags in their names allow you to use the flags parameter to specify to process 'get' magic (by setting the SV_GMAGIC flag) or to skip 'get' magic (by clearing it). The other forms process 'get' magic, except for the ones with nomg in their names, which skip 'get' magic.

The forms that take a len parameter will set that variable to the byte length of the resultant string (these are macros, so don't use &len).

The forms with nolen in their names indicate they don't have a len parameter. They should be used only when it is known that the PV is a C string, terminated by a NUL byte, and without intermediate NUL characters; or when you don't care about its length.

The forms with const in their names return const char * so that the compiler will hopefully complain if you were to try to modify the contents of the string (unless you cast away const yourself).

The other forms return a mutable pointer so that the string is modifiable by the caller; this is emphasized for the ones with mutable in their names.

The forms whose name ends in x are the same as the corresponding form without the x, but the x form is guaranteed to evaluate sv exactly once, with a slight loss of efficiency. Use this if sv is an expression with side effects.

SvPVutf8 is like SvPV, but converts sv to UTF-8 first if not already UTF-8. Similiarly, the other forms with utf8 in their names correspond to their respective forms without.

SvPVutf8_or_null and SvPVutf8_or_null_nomg don't have corresponding non-utf8 forms. Instead they are like SvPVutf8_nomg, but when sv is undef, they return NULL.

SvPVbyte is like SvPV, but converts sv to byte representation first if currently encoded as UTF-8. If sv cannot be downgraded from UTF-8, it croaks. Similiarly, the other forms with byte in their names correspond to their respective forms without.

SvPVbyte_or_null doesn't have a corresponding non-byte form. Instead it is like SvPVbyte, but when sv is undef, it returns NULL.

    char*         SvPV                 (SV* sv, STRLEN len)
    char*         SvPVx                (SV* sv, STRLEN len)
    char*         SvPV_nomg            (SV* sv, STRLEN len)
    char*         SvPV_nolen           (SV* sv)
    char*         SvPVx_nolen          (SV* sv)
    char*         SvPV_nomg_nolen      (SV* sv)
    char*         SvPV_mutable         (SV* sv, STRLEN len)
    const char*   SvPV_const           (SV* sv, STRLEN len)
    const char*   SvPVx_const          (SV* sv, STRLEN len)
    const char*   SvPV_nolen_const     (SV* sv)
    const char*   SvPVx_nolen_const    (SV* sv)
    const char*   SvPV_nomg_const      (SV* sv, STRLEN len)
    const char*   SvPV_nomg_const_nolen(SV* sv)
    char *        SvPV_flags           (SV * sv, STRLEN len,
                                        U32 flags)
    const char *  SvPV_flags_const     (SV * sv, STRLEN len,
                                        U32 flags)
    char *        SvPV_flags_mutable   (SV * sv, STRLEN len,
                                        U32 flags)
    char*         SvPVbyte             (SV* sv, STRLEN len)
    char*         SvPVbyte_nomg        (SV* sv, STRLEN len)
    char*         SvPVbyte_nolen       (SV* sv)
    char*         SvPVbytex_nolen      (SV* sv)
    char*         SvPVbytex            (SV* sv, STRLEN len)
    char*         SvPVbyte_or_null     (SV* sv, STRLEN len)
    char*         SvPVbyte_or_null_nomg(SV* sv, STRLEN len)
    char*         SvPVutf8             (SV* sv, STRLEN len)
    char*         SvPVutf8x            (SV* sv, STRLEN len)
    char*         SvPVutf8_nomg        (SV* sv, STRLEN len)
    char*         SvPVutf8_nolen       (SV* sv)
    char*         SvPVutf8_or_null     (SV* sv, STRLEN len)
    char*         SvPVutf8_or_null_nomg(SV* sv, STRLEN len)
SvPVbyte

Like SvPV, but converts sv to byte representation first if necessary. If the SV cannot be downgraded from UTF-8, this croaks.

    char*  SvPVbyte(SV* sv, STRLEN len)
SvPVbyte_force

Like SvPV_force, but converts sv to byte representation first if necessary. If the SV cannot be downgraded from UTF-8, this croaks.

    char*  SvPVbyte_force(SV* sv, STRLEN len)
SvPVbyte_nolen

Like SvPV_nolen, but converts sv to byte representation first if necessary. If the SV cannot be downgraded from UTF-8, this croaks.

    char*  SvPVbyte_nolen(SV* sv)
SvPVbyte_nomg

Like SvPVbyte, but does not process get magic.

    char*  SvPVbyte_nomg(SV* sv, STRLEN len)
SvPVbyte_or_null

Like SvPVbyte, but when sv is undef, returns NULL.

    char*  SvPVbyte_or_null(SV* sv, STRLEN len)
SvPVbyte_or_null_nomg

Like SvPVbyte_or_null, but does not process get magic.

    char*  SvPVbyte_or_null_nomg(SV* sv, STRLEN len)
SvPVCLEAR

Ensures that sv is a SVt_PV and that its SvCUR is 0, and that it is properly null terminated. Equivalent to sv_setpvs(""), but more efficient.

    char *  SvPVCLEAR(SV* sv)
SvPV_force
SvPV_force_nolen
SvPVx_force
SvPV_force_nomg
SvPV_force_nomg_nolen
SvPV_force_mutable
SvPV_force_flags
SvPV_force_flags_nolen
SvPV_force_flags_mutable
SvPVbyte_force
SvPVbytex_force
SvPVutf8_force
SvPVutf8x_force

These are like "SvPV", returning the string in the SV, but will force the SV into containing a string ("SvPOK"), and only a string ("SvPOK_only"), by hook or by crook. You need to use one of these force routines if you are going to update the "SvPVX" directly.

Note that coercing an arbitrary scalar into a plain PV will potentially strip useful data from it. For example if the SV was SvROK, then the referent will have its reference count decremented, and the SV itself may be converted to an SvPOK scalar with a string buffer containing a value such as "ARRAY(0x1234)".

The differences between the forms are:

The forms with flags in their names allow you to use the flags parameter to specify to perform 'get' magic (by setting the SV_GMAGIC flag) or to skip 'get' magic (by clearing it). The other forms do perform 'get' magic, except for the ones with nomg in their names, which skip 'get' magic.

The forms that take a len parameter will set that variable to the byte length of the resultant string (these are macros, so don't use &len).

The forms with nolen in their names indicate they don't have a len parameter. They should be used only when it is known that the PV is a C string, terminated by a NUL byte, and without intermediate NUL characters; or when you don't care about its length.

The forms with mutable in their names are effectively the same as those without, but the name emphasizes that the string is modifiable by the caller, which it is in all the forms.

SvPVutf8_force is like SvPV_force, but converts sv to UTF-8 first if not already UTF-8.

SvPVutf8x_force is like SvPVutf8_force, but guarantees to evaluate sv only once; use the more efficient SvPVutf8_force otherwise.

SvPVbyte_force is like SvPV_force, but converts sv to byte representation first if currently encoded as UTF-8. If the SV cannot be downgraded from UTF-8, this croaks.

SvPVbytex_force is like SvPVbyte_force, but guarantees to evaluate sv only once; use the more efficient SvPVbyte_force otherwise.

    char*  SvPV_force              (SV* sv, STRLEN len)
    char*  SvPV_force_nolen        (SV* sv)
    char*  SvPVx_force             (SV* sv, STRLEN len)
    char*  SvPV_force_nomg         (SV* sv, STRLEN len)
    char*  SvPV_force_nomg_nolen   (SV * sv)
    char*  SvPV_force_mutable      (SV * sv, STRLEN len)
    char*  SvPV_force_flags        (SV * sv, STRLEN len, U32 flags)
    char*  SvPV_force_flags_nolen  (SV * sv, U32 flags)
    char*  SvPV_force_flags_mutable(SV * sv, STRLEN len, U32 flags)
    char*  SvPVbyte_force          (SV* sv, STRLEN len)
    char*  SvPVbytex_force         (SV* sv, STRLEN len)
    char*  SvPVutf8_force          (SV* sv, STRLEN len)
    char*  SvPVutf8x_force         (SV* sv, STRLEN len)
SvPV_free

Frees the PV buffer in sv, leaving things in a precarious state, so should only be used as part of a larger operation

    void  SvPV_free(SV * sv)
sv_pvn_force_flags

Get a sensible string out of the SV somehow. If flags has the SV_GMAGIC bit set, will "mg_get" on sv if appropriate, else not. sv_pvn_force and sv_pvn_force_nomg are implemented in terms of this function. You normally want to use the various wrapper macros instead: see "SvPV_force" and "SvPV_force_nomg".

    char*  sv_pvn_force_flags(SV *const sv, STRLEN *const lp,
                              const U32 flags)
SvPV_renew

Low level micro optimization of "SvGROW". It is generally better to use SvGROW instead. This is because SvPV_renew ignores potential issues that SvGROW handles. sv needs to have a real PV that is unencombered by things like COW. Using SV_CHECK_THINKFIRST or SV_CHECK_THINKFIRST_COW_DROP before calling this should clean it up, but why not just use SvGROW if you're not sure about the provenance?

    void  SvPV_renew(SV* sv, STRLEN len)
SvPV_set

This is probably not what you want to use, you probably wanted "sv_usepvn_flags" or "sv_setpvn" or "sv_setpvs".

Set the value of the PV pointer in sv to the Perl allocated NUL-terminated string val. See also "SvIV_set".

Remember to free the previous PV buffer. There are many things to check. Beware that the existing pointer may be involved in copy-on-write or other mischief, so do SvOOK_off(sv) and use sv_force_normal or SvPV_force (or check the SvIsCOW flag) first to make sure this modification is safe. Then finally, if it is not a COW, call "SvPV_free" to free the previous PV buffer.

    void  SvPV_set(SV* sv, char* val)
SvPVutf8

Like SvPV, but converts sv to UTF-8 first if necessary.

    char*  SvPVutf8(SV* sv, STRLEN len)
SvPVutf8_force

Like SvPV_force, but converts sv to UTF-8 first if necessary.

    char*  SvPVutf8_force(SV* sv, STRLEN len)
SvPVutf8_nolen

Like SvPV_nolen, but converts sv to UTF-8 first if necessary.

    char*  SvPVutf8_nolen(SV* sv)
SvPVutf8_nomg

Like SvPVutf8, but does not process get magic.

    char*  SvPVutf8_nomg(SV* sv, STRLEN len)
SvPVutf8_or_null

Like SvPVutf8, but when sv is undef, returns NULL.

    char*  SvPVutf8_or_null(SV* sv, STRLEN len)
SvPVutf8_or_null_nomg

Like SvPVutf8_or_null, but does not process get magic.

    char*  SvPVutf8_or_null_nomg(SV* sv, STRLEN len)
SvPVX
SvPVXx
SvPVX_const
SvPVX_mutable

These return a pointer to the physical string in the SV. The SV must contain a string. Prior to 5.9.3 it is not safe to execute these unless the SV's type >= SVt_PV.

These are also used to store the name of an autoloaded subroutine in an XS AUTOLOAD routine. See "Autoloading with XSUBs" in perlguts.

SvPVXx is identical to SvPVX.

SvPVX_mutable is merely a synonym for SvPVX, but its name emphasizes that the string is modifiable by the caller.

SvPVX_const differs in that the return value has been cast so that the compiler will complain if you were to try to modify the contents of the string, (unless you cast away const yourself).

    char*        SvPVX        (SV* sv)
    char*        SvPVXx       (SV* sv)
    const char*  SvPVX_const  (SV* sv)
    char*        SvPVX_mutable(SV* sv)
SvREADONLY

Returns true if the argument is readonly, otherwise returns false. Exposed to perl code via Internals::SvREADONLY().

    U32  SvREADONLY(SV* sv)
SvREADONLY_off

Mark an object as not-readonly. Exactly what this mean depends on the object type. Exposed to perl code via Internals::SvREADONLY().

    U32  SvREADONLY_off(SV* sv)
SvREADONLY_on

Mark an object as readonly. Exactly what this means depends on the object type. Exposed to perl code via Internals::SvREADONLY().

    U32  SvREADONLY_on(SV* sv)
sv_ref

Returns a SV describing what the SV passed in is a reference to.

dst can be a SV to be set to the description or NULL, in which case a mortal SV is returned.

If ob is true and the SV is blessed, the description is the class name, otherwise it is the type of the SV, "SCALAR", "ARRAY" etc.

    SV*  sv_ref(SV *dst, const SV *const sv, const int ob)
SvREFCNT

Returns the value of the object's reference count. Exposed to perl code via Internals::SvREFCNT().

    U32  SvREFCNT(SV* sv)
SvREFCNT_dec
SvREFCNT_dec_NN

These decrement the reference count of the given SV.

SvREFCNT_dec_NN may only be used when sv is known to not be NULL.

    void  SvREFCNT_dec(SV *sv)
SvREFCNT_inc
SvREFCNT_inc_NN
SvREFCNT_inc_void
SvREFCNT_inc_void_NN
SvREFCNT_inc_simple
SvREFCNT_inc_simple_NN
SvREFCNT_inc_simple_void
SvREFCNT_inc_simple_void_NN

These all increment the reference count of the given SV. The ones without void in their names return the SV.

SvREFCNT_inc is the base operation; the rest are optimizations if various input constraints are known to be true; hence, all can be replaced with SvREFCNT_inc.

SvREFCNT_inc_NN can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller.

SvREFCNT_inc_void can only be used if you don't need the return value. The macro doesn't need to return a meaningful value.

SvREFCNT_inc_void_NN can only be used if you both don't need the return value, and you know that sv is not NULL. The macro doesn't need to return a meaningful value, or check for NULLness, so it's smaller and faster.

SvREFCNT_inc_simple can only be used with expressions without side effects. Since we don't have to store a temporary value, it's faster.

SvREFCNT_inc_simple_NN can only be used with expressions without side effects and you know sv is not NULL. Since we don't have to store a temporary value, nor check for NULLness, it's faster and smaller.

SvREFCNT_inc_simple_void can only be used with expressions without side effects and you don't need the return value.

SvREFCNT_inc_simple_void_NN can only be used with expressions without side effects, you don't need the return value, and you know sv is not NULL.

    SV *  SvREFCNT_inc               (SV *sv)
    SV *  SvREFCNT_inc_NN            (SV *sv)
    void  SvREFCNT_inc_void          (SV *sv)
    void  SvREFCNT_inc_void_NN       (SV* sv)
    SV*   SvREFCNT_inc_simple        (SV* sv)
    SV*   SvREFCNT_inc_simple_NN     (SV* sv)
    void  SvREFCNT_inc_simple_void   (SV* sv)
    void  SvREFCNT_inc_simple_void_NN(SV* sv)
sv_reftype

Returns a string describing what the SV is a reference to.

If ob is true and the SV is blessed, the string is the class name, otherwise it is the type of the SV, "SCALAR", "ARRAY" etc.

    const char*  sv_reftype(const SV *const sv, const int ob)
sv_replace

Make the first argument a copy of the second, then delete the original. The target SV physically takes over ownership of the body of the source SV and inherits its flags; however, the target keeps any magic it owns, and any magic in the source is discarded. Note that this is a rather specialist SV copying operation; most of the time you'll want to use sv_setsv or one of its many macro front-ends.

    void  sv_replace(SV *const sv, SV *const nsv)
sv_report_used

Dump the contents of all SVs not yet freed (debugging aid).

    void  sv_report_used()
sv_reset

Underlying implementation for the reset Perl function. Note that the perl-level function is vaguely deprecated.

    void  sv_reset(const char* s, HV *const stash)
SvROK

Tests if the SV is an RV.

    U32  SvROK(SV* sv)
SvROK_off

Unsets the RV status of an SV.

    void  SvROK_off(SV* sv)
SvROK_on

Tells an SV that it is an RV.

    void  SvROK_on(SV* sv)
SvRV

Dereferences an RV to return the SV.

    SV*  SvRV(SV* sv)
SvRV_set

Set the value of the RV pointer in sv to val. See "SvIV_set".

    void  SvRV_set(SV* sv, SV* val)
sv_rvunweaken

Unweaken a reference: Clear the SvWEAKREF flag on this RV; remove the backreference to this RV from the array of backreferences associated with the target SV, increment the refcount of the target. Silently ignores undef and warns on non-weak references.

    SV*  sv_rvunweaken(SV *const sv)
sv_rvweaken

Weaken a reference: set the SvWEAKREF flag on this RV; give the referred-to SV PERL_MAGIC_backref magic if it hasn't already; and push a back-reference to this RV onto the array of backreferences associated with that magic. If the RV is magical, set magic will be called after the RV is cleared. Silently ignores undef and warns on already-weak references.

    SV*  sv_rvweaken(SV *const sv)
sv_setiv
sv_setiv_mg

These copy an integer into the given SV, upgrading first if necessary.

They differ only in that sv_setiv_mg handles 'set' magic; sv_setiv does not.

    void  sv_setiv   (SV *const sv, const IV num)
    void  sv_setiv_mg(SV *const sv, const IV i)
SvSETMAGIC

Invokes "mg_set" on an SV if it has 'set' magic. This is necessary after modifying a scalar, in case it is a magical variable like $| or a tied variable (it calls STORE). This macro evaluates its argument more than once.

    void  SvSETMAGIC(SV* sv)
sv_setnv
sv_setnv_mg

These copy a double into the given SV, upgrading first if necessary.

They differ only in that sv_setnv_mg handles 'set' magic; sv_setnv does not.

    void  sv_setnv(SV *const sv, const NV num)
sv_setpv
sv_setpv_mg

These copy a string into an SV. The string must be terminated with a NUL character, and not contain embeded NUL's.

They differ only in that:

sv_setpv does not handle 'set' magic; sv_setpv_mg does.

    void  sv_setpv(SV *const sv, const char *const ptr)
sv_setpvf
sv_setpvf_nocontext
sv_setpvf_mg
sv_setpvf_mg_nocontext

These work like "sv_catpvf" but copy the text into the SV instead of appending it.

The differences between these are:

sv_setpvf and sv_setpvf_nocontext do not handle 'set' magic; sv_setpvf_mg and sv_setpvf_mg_nocontext do.

sv_setpvf_nocontext and sv_setpvf_mg_nocontext do not take a thread context (aTHX) parameter, so are used in situations where the caller doesn't already have the thread context.

NOTE: sv_setpvf must be explicitly called as Perl_sv_setpvf with an aTHX_ parameter.

NOTE: sv_setpvf_mg must be explicitly called as Perl_sv_setpvf_mg with an aTHX_ parameter.

    void  Perl_sv_setpvf        (pTHX_ SV *const sv,
                                 const char *const pat, ...)
    void  sv_setpvf_nocontext   (SV *const sv, const char *const pat,
                                 ...)
    void  Perl_sv_setpvf_mg     (pTHX_ SV *const sv,
                                 const char *const pat, ...)
    void  sv_setpvf_mg_nocontext(SV *const sv, const char *const pat,
                                 ...)
sv_setpviv
sv_setpviv_mg

DEPRECATED! It is planned to remove sv_setpviv from a future release of Perl. Do not use it for new code; remove it from existing code.

DEPRECATED! It is planned to remove sv_setpviv_mg from a future release of Perl. Do not use it for new code; remove it from existing code.

These copy an integer into the given SV, also updating its string value.

They differ only in that sv_setpviv_mg performs 'set' magic; sv_setpviv skips any magic.

    void  sv_setpviv   (SV *const sv, const IV num)
    void  sv_setpviv_mg(SV *const sv, const IV iv)
sv_setpvn
sv_setpvn_mg

These copy a string (possibly containing embedded NUL characters) into an SV. The len parameter indicates the number of bytes to be copied. If the ptr argument is NULL the SV will become undefined.

The UTF-8 flag is not changed by these functions. A terminating NUL byte is guaranteed.

They differ only in that:

sv_setpvn does not handle 'set' magic; sv_setpvn_mg does.

    void  sv_setpvn(SV *const sv, const char *const ptr,
                    const STRLEN len)
sv_setpvs

Like sv_setpvn, but takes a literal string instead of a string/length pair.

    void  sv_setpvs(SV* sv, "literal string")
sv_setpvs_mg

Like sv_setpvn_mg, but takes a literal string instead of a string/length pair.

    void  sv_setpvs_mg(SV* sv, "literal string")
sv_setpv_bufsize

Sets the SV to be a string of cur bytes length, with at least len bytes available. Ensures that there is a null byte at SvEND. Returns a char * pointer to the SvPV buffer.

    char  *  sv_setpv_bufsize(SV *const sv, const STRLEN cur,
                              const STRLEN len)
sv_setref_iv

Copies an integer into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

    SV*  sv_setref_iv(SV *const rv, const char *const classname,
                      const IV iv)
sv_setref_nv

Copies a double into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

    SV*  sv_setref_nv(SV *const rv, const char *const classname,
                      const NV nv)
sv_setref_pv

Copies a pointer into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. If the pv argument is NULL, then PL_sv_undef will be placed into the SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

Do not use with other Perl types such as HV, AV, SV, CV, because those objects will become corrupted by the pointer copy process.

Note that sv_setref_pvn copies the string while this copies the pointer.

    SV*  sv_setref_pv(SV *const rv, const char *const classname,
                      void *const pv)
sv_setref_pvn

Copies a string into a new SV, optionally blessing the SV. The length of the string must be specified with n. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

Note that sv_setref_pv copies the pointer while this copies the string.

    SV*  sv_setref_pvn(SV *const rv, const char *const classname,
                       const char *const pv, const STRLEN n)
sv_setref_pvs

Like sv_setref_pvn, but takes a literal string instead of a string/length pair.

    SV *  sv_setref_pvs(SV *const rv, const char *const classname,
                        "literal string")
sv_setref_uv

Copies an unsigned integer into a new SV, optionally blessing the SV. The rv argument will be upgraded to an RV. That RV will be modified to point to the new SV. The classname argument indicates the package for the blessing. Set classname to NULL to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

    SV*  sv_setref_uv(SV *const rv, const char *const classname,
                      const UV uv)
SvSetSV
SvSetMagicSV
SvSetSV_nosteal
SvSetMagicSV_nosteal

if dsv is the same as ssv, these do nothing. Otherwise they all call some form of "sv_setsv". They may evaluate their arguments more than once.

The only differences are:

SvSetMagicSV and SvSetMagicSV_nosteal perform any required 'set' magic afterwards on the destination SV; SvSetSV and SvSetSV_nosteal do not.

SvSetSV_nosteal SvSetMagicSV_nosteal call a non-destructive version of sv_setsv.

    void  SvSetSV(SV* dsv, SV* ssv)
sv_setsv
sv_setsv_flags
sv_setsv_mg
sv_setsv_nomg

These copy the contents of the source SV ssv into the destination SV dsv. ssv may be destroyed if it is mortal, so don't use these functions if the source SV needs to be reused. Loosely speaking, they perform a copy-by-value, obliterating any previous content of the destination.

They differ only in that:

sv_setsv calls 'get' magic on ssv, but skips 'set' magic on dsv.

sv_setsv_mg calls both 'get' magic on ssv and 'set' magic on dsv.

sv_setsv_nomg skips all magic.

sv_setsv_flags has a flags parameter which you can use to specify any combination of magic handling, and also you can specify SV_NOSTEAL so that the buffers of temps will not be stolen.

You probably want to instead use one of the assortment of wrappers, such as "SvSetSV", "SvSetSV_nosteal", "SvSetMagicSV" and "SvSetMagicSV_nosteal".

sv_setsv_flags is the primary function for copying scalars, and most other copy-ish functions and macros use it underneath.

    void  sv_setsv      (SV *dsv, SV *ssv)
    void  sv_setsv_flags(SV *dsv, SV *ssv, const I32 flags)
    void  sv_setsv_mg   (SV *const dsv, SV *const ssv)
    void  sv_setsv_nomg (SV *dsv, SV *ssv)
sv_setuv
sv_setuv_mg

These copy an unsigned integer into the given SV, upgrading first if necessary.

They differ only in that sv_setuv_mg handles 'set' magic; sv_setuv does not.

    void  sv_setuv   (SV *const sv, const UV num)
    void  sv_setuv_mg(SV *const sv, const UV u)
sv_set_undef

Equivalent to sv_setsv(sv, &PL_sv_undef), but more efficient. Doesn't handle set magic.

The perl equivalent is $sv = undef;. Note that it doesn't free any string buffer, unlike undef $sv.

Introduced in perl 5.25.12.

    void  sv_set_undef(SV *sv)
SvSHARE

Arranges for sv to be shared between threads if a suitable module has been loaded.

    void  SvSHARE(SV* sv)
SvSHARED_HASH

Returns the hash for sv created by "newSVpvn_share".

    struct hek*  SvSHARED_HASH(SV * sv)
SvSTASH

Returns the stash of the SV.

    HV*  SvSTASH(SV* sv)
SvSTASH_set

Set the value of the STASH pointer in sv to val. See "SvIV_set".

    void  SvSTASH_set(SV* sv, HV* val)
SvTAINT

Taints an SV if tainting is enabled, and if some input to the current expression is tainted--usually a variable, but possibly also implicit inputs such as locale settings. SvTAINT propagates that taintedness to the outputs of an expression in a pessimistic fashion; i.e., without paying attention to precisely which outputs are influenced by which inputs.

    void  SvTAINT(SV* sv)
SvTAINTED

Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if not.

    bool  SvTAINTED(SV* sv)
SvTAINTED_off

Untaints an SV. Be very careful with this routine, as it short-circuits some of Perl's fundamental security features. XS module authors should not use this function unless they fully understand all the implications of unconditionally untainting the value. Untainting should be done in the standard perl fashion, via a carefully crafted regexp, rather than directly untainting variables.

    void  SvTAINTED_off(SV* sv)
SvTAINTED_on

Marks an SV as tainted if tainting is enabled.

    void  SvTAINTED_on(SV* sv)
SvTRUE
SvTRUEx
SvTRUE_nomg
SvTRUE_NN
SvTRUE_nomg_NN

These return a boolean indicating whether Perl would evaluate the SV as true or false. See "SvOK" for a defined/undefined test.

As of Perl 5.32, all are guaranteed to evaluate sv only once. Prior to that release, only SvTRUEx guaranteed single evaluation; now SvTRUEx is identical to SvTRUE.

SvTRUE_nomg and TRUE_nomg_NN do not perform 'get' magic; the others do unless the scalar is already SvPOK, SvIOK, or SvNOK (the public, not the private flags).

SvTRUE_NN is like "SvTRUE", but sv is assumed to be non-null (NN). If there is a possibility that it is NULL, use plain SvTRUE.

SvTRUE_nomg_NN is like "SvTRUE_nomg", but sv is assumed to be non-null (NN). If there is a possibility that it is NULL, use plain SvTRUE_nomg.

    bool  SvTRUE(SV *sv)
SvTYPE

Returns the type of the SV. See "svtype".

    svtype  SvTYPE(SV* sv)
SvUNLOCK

Releases a mutual exclusion lock on sv if a suitable module has been loaded.

    void  SvUNLOCK(SV* sv)
sv_unmagic

Removes all magic of type type from an SV.

    int  sv_unmagic(SV *const sv, const int type)
sv_unmagicext

Removes all magic of type type with the specified vtbl from an SV.

    int  sv_unmagicext(SV *const sv, const int type, MGVTBL *vtbl)
sv_unref

Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of newSVrv. This is sv_unref_flags with the flag being zero. See "SvROK_off".

    void  sv_unref(SV* sv)
sv_unref_flags

Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of newSVrv. The cflags argument can contain SV_IMMEDIATE_UNREF to force the reference count to be decremented (otherwise the decrementing is conditional on the reference count being different from one or the reference being a readonly SV). See "SvROK_off".

    void  sv_unref_flags(SV *const ref, const U32 flags)
SvUOK

Returns a boolean indicating whether the SV contains an integer that must be interpreted as unsigned. A non-negative integer whose value is within the range of both an IV and a UV may be flagged as either SvUOK or SvIOK.

    bool  SvUOK(SV* sv)
SvUPGRADE

Used to upgrade an SV to a more complex form. Uses sv_upgrade to perform the upgrade if necessary. See "svtype".

    void  SvUPGRADE(SV* sv, svtype type)
sv_upgrade

Upgrade an SV to a more complex form. Generally adds a new body type to the SV, then copies across as much information as possible from the old body. It croaks if the SV is already in a more complex form than requested. You generally want to use the SvUPGRADE macro wrapper, which checks the type before calling sv_upgrade, and hence does not croak. See also "svtype".

    void  sv_upgrade(SV *const sv, svtype new_type)
sv_usepvn

Tells an SV to use ptr to find its string value. Implemented by calling sv_usepvn_flags with flags of 0, hence does not handle 'set' magic. See "sv_usepvn_flags".

    void  sv_usepvn(SV* sv, char* ptr, STRLEN len)
sv_usepvn_flags

Tells an SV to use ptr to find its string value. Normally the string is stored inside the SV, but sv_usepvn allows the SV to use an outside string. ptr should point to memory that was allocated by Newx. It must be the start of a Newx-ed block of memory, and not a pointer to the middle of it (beware of OOK and copy-on-write), and not be from a non-Newx memory allocator like malloc. The string length, len, must be supplied. By default this function will Renew (i.e. realloc, move) the memory pointed to by ptr, so that pointer should not be freed or used by the programmer after giving it to sv_usepvn, and neither should any pointers from "behind" that pointer (e.g. ptr + 1) be used.

If flags & SV_SMAGIC is true, will call SvSETMAGIC. If flags & SV_HAS_TRAILING_NUL is true, then ptr[len] must be NUL, and the realloc will be skipped (i.e. the buffer is actually at least 1 byte longer than len, and already meets the requirements for storing in SvPVX).

    void  sv_usepvn_flags(SV *const sv, char* ptr, const STRLEN len,
                          const U32 flags)
sv_usepvn_mg

Like sv_usepvn, but also handles 'set' magic.

    void  sv_usepvn_mg(SV *sv, char *ptr, STRLEN len)
SvUTF8

Returns a U32 value indicating the UTF-8 status of an SV. If things are set-up properly, this indicates whether or not the SV contains UTF-8 encoded data. You should use this after a call to "SvPV" or one of its variants, in case any call to string overloading updates the internal flag.

If you want to take into account the bytes pragma, use "DO_UTF8" instead.

    U32  SvUTF8(SV* sv)
sv_utf8_decode

If the PV of the SV is an octet sequence in Perl's extended UTF-8 and contains a multiple-byte character, the SvUTF8 flag is turned on so that it looks like a character. If the PV contains only single-byte characters, the SvUTF8 flag stays off. Scans PV for validity and returns FALSE if the PV is invalid UTF-8.

    bool  sv_utf8_decode(SV *const sv)
sv_utf8_downgrade
sv_utf8_downgrade_flags
sv_utf8_downgrade_nomg

These attempt to convert the PV of an SV from characters to bytes. If the PV contains a character that cannot fit in a byte, this conversion will fail; in this case, FALSE is returned if fail_ok is true; otherwise they croak.

They are not a general purpose Unicode to byte encoding interface: use the Encode extension for that.

They differ only in that:

sv_utf8_downgrade processes 'get' magic on sv.

sv_utf8_downgrade_nomg does not.

sv_utf8_downgrade_flags has an additional flags parameter in which you can specify SV_GMAGIC to process 'get' magic, or leave it cleared to not proccess 'get' magic.

    bool  sv_utf8_downgrade      (SV *const sv, const bool fail_ok)
    bool  sv_utf8_downgrade_flags(SV *const sv, const bool fail_ok,
                                  const U32 flags)
    bool  sv_utf8_downgrade_nomg (SV *const sv, const bool fail_ok)
sv_utf8_encode

Converts the PV of an SV to UTF-8, but then turns the SvUTF8 flag off so that it looks like octets again.

    void  sv_utf8_encode(SV *const sv)
sv_utf8_upgrade
sv_utf8_upgrade_nomg
sv_utf8_upgrade_flags
sv_utf8_upgrade_flags_grow

These convert the PV of an SV to its UTF-8-encoded form. The SV is forced to string form if it is not already. They always set the SvUTF8 flag to avoid future validity checks even if the whole string is the same in UTF-8 as not. They return the number of bytes in the converted string

The forms differ in just two ways. The main difference is whether or not they perform 'get magic' on sv. sv_utf8_upgrade_nomg skips 'get magic'; sv_utf8_upgrade performs it; and sv_utf8_upgrade_flags and sv_utf8_upgrade_flags_grow either perform it (if the SV_GMAGIC bit is set in flags) or don't (if that bit is cleared).

The other difference is that sv_utf8_upgrade_flags_grow has an additional parameter, extra, which allows the caller to specify an amount of space to be reserved as spare beyond what is needed for the actual conversion. This is used when the caller knows it will soon be needing yet more space, and it is more efficient to request space from the system in a single call. This form is otherwise identical to sv_utf8_upgrade_flags.

These are not a general purpose byte encoding to Unicode interface: use the Encode extension for that.

The SV_FORCE_UTF8_UPGRADE flag is now ignored.

    STRLEN  sv_utf8_upgrade           (SV *sv)
    STRLEN  sv_utf8_upgrade_nomg      (SV *sv)
    STRLEN  sv_utf8_upgrade_flags     (SV *const sv, const I32 flags)
    STRLEN  sv_utf8_upgrade_flags_grow(SV *const sv, const I32 flags,
                                       STRLEN extra)
SvUTF8_off

Unsets the UTF-8 status of an SV (the data is not changed, just the flag). Do not use frivolously.

    void  SvUTF8_off(SV *sv)
SvUTF8_on

Turn on the UTF-8 status of an SV (the data is not changed, just the flag). Do not use frivolously.

    void  SvUTF8_on(SV *sv)
SvUV
SvUVx
SvUV_nomg

These coerce the given SV to UV and return it. The returned value in many circumstances will get stored in sv's UV slot, but not in all cases. (Use "sv_setuv" to make sure it does).

SvUVx is different from the others in that it is guaranteed to evaluate sv exactly once; the others may evaluate it multiple times. Only use this form if sv is an expression with side effects, otherwise use the more efficient SvUV.

SvUV_nomg is the same as SvUV, but does not perform 'get' magic.

    UV  SvUV(SV* sv)
SvUV_set

Set the value of the UV pointer in sv to val. See "SvIV_set".

    void  SvUV_set(SV* sv, UV val)
SvUVX

Returns the raw value in the SV's UV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvUV".

    UV  SvUVX(SV* sv)
SvUVXx

DEPRECATED! It is planned to remove SvUVXx from a future release of Perl. Do not use it for new code; remove it from existing code.

This is an unnecessary synonym for "SvUVX"

    UV  SvUVXx(SV* sv)
sv_vcatpvf
sv_vcatpvf_mg

These process their arguments like sv_vcatpvfn called with a non-null C-style variable argument list, and append the formatted output to sv.

They differ only in that sv_vcatpvf_mg performs 'set' magic; sv_vcatpvf skips 'set' magic.

Both perform 'get' magic.

They are usually accessed via their frontends "sv_catpvf" and "sv_catpvf_mg".

    void  sv_vcatpvf(SV *const sv, const char *const pat,
                     va_list *const args)
sv_vcatpvfn
sv_vcatpvfn_flags

These process their arguments like vsprintf(3) and append the formatted output to an SV. They use an array of SVs if the C-style variable argument list is missing (NULL). Argument reordering (using format specifiers like %2$d or %*2$d) is supported only when using an array of SVs; using a C-style va_list argument list with a format string that uses argument reordering will yield an exception.

When running with taint checks enabled, they indicate via maybe_tainted if results are untrustworthy (often due to the use of locales).

They assume that pat has the same utf8-ness as sv. It's the caller's responsibility to ensure that this is so.

They differ in that sv_vcatpvfn_flags has a flags parameter in which you can set or clear the SV_GMAGIC and/or SV_SMAGIC flags, to specify which magic to handle or not handle; whereas plain sv_vcatpvfn always specifies both 'get' and 'set' magic.

They are usually used via one of the frontends sv_vcatpvf and sv_vcatpvf_mg.

    void  sv_vcatpvfn      (SV *const sv, const char *const pat,
                            const STRLEN patlen, va_list *const args,
                            SV **const svargs, const Size_t sv_count,
                            bool *const maybe_tainted)
    void  sv_vcatpvfn_flags(SV *const sv, const char *const pat,
                            const STRLEN patlen, va_list *const args,
                            SV **const svargs, const Size_t sv_count,
                            bool *const maybe_tainted,
                            const U32 flags)
SvVOK

Returns a boolean indicating whether the SV contains a v-string.

    bool  SvVOK(SV* sv)
sv_vsetpvf
sv_vsetpvf_mg

These work like "sv_vcatpvf" but copy the text into the SV instead of appending it.

They differ only in that sv_vsetpvf_mg performs 'set' magic; sv_vsetpvf skips all magic.

They are usually used via their frontends, "sv_setpvf" and "sv_setpvf_mg".

    void  sv_vsetpvf(SV *const sv, const char *const pat,
                     va_list *const args)
sv_vsetpvfn

Works like sv_vcatpvfn but copies the text into the SV instead of appending it.

Usually used via one of its frontends sv_vsetpvf and sv_vsetpvf_mg.

    void  sv_vsetpvfn(SV *const sv, const char *const pat,
                      const STRLEN patlen, va_list *const args,
                      SV **const svargs, const Size_t sv_count,
                      bool *const maybe_tainted)
SvVSTRING_mg

Returns the vstring magic, or NULL if none

    MAGIC*  SvVSTRING_mg(SV * sv)
vnewSVpvf

Like "newSVpvf" but but the arguments are an encapsulated argument list.

    SV*  vnewSVpvf(const char *const pat, va_list *const args)

Time

ASCTIME_R_PROTO

This symbol encodes the prototype of asctime_r. It is zero if d_asctime_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_asctime_r is defined.

CTIME_R_PROTO

This symbol encodes the prototype of ctime_r. It is zero if d_ctime_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_ctime_r is defined.

GMTIME_MAX

This symbol contains the maximum value for the time_t offset that the system function gmtime () accepts, and defaults to 0

GMTIME_MIN

This symbol contains the minimum value for the time_t offset that the system function gmtime () accepts, and defaults to 0

GMTIME_R_PROTO

This symbol encodes the prototype of gmtime_r. It is zero if d_gmtime_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_gmtime_r is defined.

HAS_ASCTIME64

This symbol, if defined, indicates that the asctime64 () routine is available to do the 64bit variant of asctime ()

HAS_ASCTIME_R

This symbol, if defined, indicates that the asctime_r routine is available to asctime re-entrantly.

HAS_CTIME64

This symbol, if defined, indicates that the ctime64 () routine is available to do the 64bit variant of ctime ()

HAS_CTIME_R

This symbol, if defined, indicates that the ctime_r routine is available to ctime re-entrantly.

HAS_DIFFTIME

This symbol, if defined, indicates that the difftime routine is available.

HAS_DIFFTIME64

This symbol, if defined, indicates that the difftime64 () routine is available to do the 64bit variant of difftime ()

HAS_FUTIMES

This symbol, if defined, indicates that the futimes routine is available to change file descriptor time stamps with struct timevals.

HAS_GETITIMER

This symbol, if defined, indicates that the getitimer routine is available to return interval timers.

HAS_GETTIMEOFDAY

This symbol, if defined, indicates that the gettimeofday() system call is available for a sub-second accuracy clock. Usually, the file sys/resource.h needs to be included (see "I_SYS_RESOURCE"). The type "Timeval" should be used to refer to "struct timeval".

HAS_GMTIME64

This symbol, if defined, indicates that the gmtime64 () routine is available to do the 64bit variant of gmtime ()

HAS_GMTIME_R

This symbol, if defined, indicates that the gmtime_r routine is available to gmtime re-entrantly.

HAS_LOCALTIME64

This symbol, if defined, indicates that the localtime64 () routine is available to do the 64bit variant of localtime ()

HAS_LOCALTIME_R

This symbol, if defined, indicates that the localtime_r routine is available to localtime re-entrantly.

HAS_MKTIME

This symbol, if defined, indicates that the mktime routine is available.

HAS_MKTIME64

This symbol, if defined, indicates that the mktime64 () routine is available to do the 64bit variant of mktime ()

HAS_NANOSLEEP

This symbol, if defined, indicates that the nanosleep system call is available to sleep with 1E-9 sec accuracy.

HAS_SETITIMER

This symbol, if defined, indicates that the setitimer routine is available to set interval timers.

HAS_STRFTIME

This symbol, if defined, indicates that the strftime routine is available to do time formatting.

HAS_TIME

This symbol, if defined, indicates that the time() routine exists.

HAS_TIMEGM

This symbol, if defined, indicates that the timegm routine is available to do the opposite of gmtime ()

HAS_TIMES

This symbol, if defined, indicates that the times() routine exists. Note that this became obsolete on some systems (SUNOS), which now use getrusage(). It may be necessary to include sys/times.h.

HAS_TM_TM_GMTOFF

This symbol, if defined, indicates to the C program that the struct tm has a tm_gmtoff field.

HAS_TM_TM_ZONE

This symbol, if defined, indicates to the C program that the struct tm has a tm_zone field.

HAS_TZNAME

This symbol, if defined, indicates that the tzname[] array is available to access timezone names.

HAS_USLEEP

This symbol, if defined, indicates that the usleep routine is available to let the process sleep on a sub-second accuracy.

HAS_USLEEP_PROTO

This symbol, if defined, indicates that the system provides a prototype for the usleep() function. Otherwise, it is up to the program to supply one. A good guess is

extern int usleep(useconds_t);
I_TIME

This symbol is always defined, and indicates to the C program that it should include time.h.

    #ifdef I_TIME
        #include <time.h>
    #endif
I_UTIME

This symbol, if defined, indicates to the C program that it should include utime.h.

    #ifdef I_UTIME
        #include <utime.h>
    #endif
LOCALTIME_MAX

This symbol contains the maximum value for the time_t offset that the system function localtime () accepts, and defaults to 0

LOCALTIME_MIN

This symbol contains the minimum value for the time_t offset that the system function localtime () accepts, and defaults to 0

LOCALTIME_R_NEEDS_TZSET

Many libc's localtime_r implementations do not call tzset, making them differ from localtime(), and making timezone changes using $ENV{TZ} without explicitly calling tzset impossible. This symbol makes us call tzset before localtime_r

LOCALTIME_R_PROTO

This symbol encodes the prototype of localtime_r. It is zero if d_localtime_r is undef, and one of the REENTRANT_PROTO_T_ABC macros of reentr.h if d_localtime_r is defined.

L_R_TZSET

If localtime_r() needs tzset, it is defined in this define

mini_mktime

normalise struct tm values without the localtime() semantics (and overhead) of mktime().

    void  mini_mktime(struct tm *ptm)
my_strftime

strftime(), but with a different API so that the return value is a pointer to the formatted result (which MUST be arranged to be FREED BY THE CALLER). This allows this function to increase the buffer size as needed, so that the caller doesn't have to worry about that.

Note that yday and wday effectively are ignored by this function, as mini_mktime() overwrites them

Also note that this is always executed in the underlying locale of the program, giving localized results.

NOTE: my_strftime must be explicitly called as Perl_my_strftime with an aTHX_ parameter.

    char *  Perl_my_strftime(pTHX_ const char *fmt, int sec, int min,
                             int hour, int mday, int mon, int year,
                             int wday, int yday, int isdst)

Typedef names

DB_Hash_t

This symbol contains the type of the prefix structure element in the db.h header file. In older versions of DB, it was int, while in newer ones it is size_t.

DB_Prefix_t

This symbol contains the type of the prefix structure element in the db.h header file. In older versions of DB, it was int, while in newer ones it is u_int32_t.

Direntry_t

This symbol is set to 'struct direct' or 'struct dirent' depending on whether dirent is available or not. You should use this pseudo type to portably declare your directory entries.

Fpos_t

This symbol holds the type used to declare file positions in libc. It can be fpos_t, long, uint, etc... It may be necessary to include sys/types.h to get any typedef'ed information.

Free_t

This variable contains the return type of free(). It is usually void, but occasionally int.

Gid_t

This symbol holds the return type of getgid() and the type of argument to setrgid() and related functions. Typically, it is the type of group ids in the kernel. It can be int, ushort, gid_t, etc... It may be necessary to include sys/types.h to get any typedef'ed information.

Gid_t_f

This symbol defines the format string used for printing a Gid_t.

Gid_t_sign

This symbol holds the signedness of a Gid_t. 1 for unsigned, -1 for signed.

Gid_t_size

This symbol holds the size of a Gid_t in bytes.

Groups_t

This symbol holds the type used for the second argument to getgroups() and setgroups(). Usually, this is the same as gidtype (gid_t) , but sometimes it isn't. It can be int, ushort, gid_t, etc... It may be necessary to include sys/types.h to get any typedef'ed information. This is only required if you have getgroups() or setgroups()..

Malloc_t

This symbol is the type of pointer returned by malloc and realloc.

Mmap_t

This symbol holds the return type of the mmap() system call (and simultaneously the type of the first argument). Usually set to 'void *' or 'caddr_t'.

Mode_t

This symbol holds the type used to declare file modes for systems calls. It is usually mode_t, but may be int or unsigned short. It may be necessary to include sys/types.h to get any typedef'ed information.

Netdb_hlen_t

This symbol holds the type used for the 2nd argument to gethostbyaddr().

Netdb_host_t

This symbol holds the type used for the 1st argument to gethostbyaddr().

Netdb_name_t

This symbol holds the type used for the argument to gethostbyname().

Netdb_net_t

This symbol holds the type used for the 1st argument to getnetbyaddr().

Off_t

This symbol holds the type used to declare offsets in the kernel. It can be int, long, off_t, etc... It may be necessary to include sys/types.h to get any typedef'ed information.

Off_t_size

This symbol holds the number of bytes used by the Off_t.

Pid_t

This symbol holds the type used to declare process ids in the kernel. It can be int, uint, pid_t, etc... It may be necessary to include sys/types.h to get any typedef'ed information.

Rand_seed_t

This symbol defines the type of the argument of the random seed function.

Select_fd_set_t

This symbol holds the type used for the 2nd, 3rd, and 4th arguments to select. Usually, this is 'fd_set *', if HAS_FD_SET is defined, and 'int *' otherwise. This is only useful if you have select(), of course.

Shmat_t

This symbol holds the return type of the shmat() system call. Usually set to 'void *' or 'char *'.

Signal_t

This symbol's value is either "void" or "int", corresponding to the appropriate return type of a signal handler. Thus, you can declare a signal handler using "Signal_t (*handler)()", and define the handler using "Signal_t handler(sig)".

Size_t

This symbol holds the type used to declare length parameters for string functions. It is usually size_t, but may be unsigned long, int, etc. It may be necessary to include sys/types.h to get any typedef'ed information.

Size_t_size

This symbol holds the size of a Size_t in bytes.

Sock_size_t

This symbol holds the type used for the size argument of various socket calls (just the base type, not the pointer-to).

SSize_t

This symbol holds the type used by functions that return a count of bytes or an error condition. It must be a signed type. It is usually ssize_t, but may be long or int, etc. It may be necessary to include sys/types.h or unistd.h to get any typedef'ed information. We will pick a type such that sizeof(SSize_t) == sizeof(Size_t).

Time_t

This symbol holds the type returned by time(). It can be long, or time_t on BSD sites (in which case sys/types.h should be included).

Uid_t

This symbol holds the type used to declare user ids in the kernel. It can be int, ushort, uid_t, etc... It may be necessary to include sys/types.h to get any typedef'ed information.

Uid_t_f

This symbol defines the format string used for printing a Uid_t.

Uid_t_sign

This symbol holds the signedness of a Uid_t. 1 for unsigned, -1 for signed.

Uid_t_size

This symbol holds the size of a Uid_t in bytes.

Unicode Support

"Unicode Support" in perlguts has an introduction to this API.

See also "Character classification", "Character case changing", and "String Handling". Various functions outside this section also work specially with Unicode. Search for the string "utf8" in this document.

BOM_UTF8

This is a macro that evaluates to a string constant of the UTF-8 bytes that define the Unicode BYTE ORDER MARK (U+FEFF) for the platform that perl is compiled on. This allows code to use a mnemonic for this character that works on both ASCII and EBCDIC platforms. sizeof(BOM_UTF8) - 1 can be used to get its length in bytes.

bytes_cmp_utf8

Compares the sequence of characters (stored as octets) in b, blen with the sequence of characters (stored as UTF-8) in u, ulen. Returns 0 if they are equal, -1 or -2 if the first string is less than the second string, +1 or +2 if the first string is greater than the second string.

-1 or +1 is returned if the shorter string was identical to the start of the longer string. -2 or +2 is returned if there was a difference between characters within the strings.

    int  bytes_cmp_utf8(const U8 *b, STRLEN blen, const U8 *u,
                        STRLEN ulen)
bytes_from_utf8

NOTE: bytes_from_utf8 is experimental and may change or be removed without notice.

Converts a potentially UTF-8 encoded string s of length *lenp into native byte encoding. On input, the boolean *is_utf8p gives whether or not s is actually encoded in UTF-8.

Unlike "utf8_to_bytes" but like "bytes_to_utf8", this is non-destructive of the input string.

Do nothing if *is_utf8p is 0, or if there are code points in the string not expressible in native byte encoding. In these cases, *is_utf8p and *lenp are unchanged, and the return value is the original s.

Otherwise, *is_utf8p is set to 0, and the return value is a pointer to a newly created string containing a downgraded copy of s, and whose length is returned in *lenp, updated. The new string is NUL-terminated. The caller is responsible for arranging for the memory used by this string to get freed.

Upon successful return, the number of variants in the string can be computed by having saved the value of *lenp before the call, and subtracting the after-call value of *lenp from it.

    U8*  bytes_from_utf8(const U8 *s, STRLEN *lenp, bool *is_utf8p)
bytes_to_utf8

NOTE: bytes_to_utf8 is experimental and may change or be removed without notice.

Converts a string s of length *lenp bytes from the native encoding into UTF-8. Returns a pointer to the newly-created string, and sets *lenp to reflect the new length in bytes. The caller is responsible for arranging for the memory used by this string to get freed.

Upon successful return, the number of variants in the string can be computed by having saved the value of *lenp before the call, and subtracting it from the after-call value of *lenp.

A NUL character will be written after the end of the string.

If you want to convert to UTF-8 from encodings other than the native (Latin1 or EBCDIC), see "sv_recode_to_utf8"().

    U8*  bytes_to_utf8(const U8 *s, STRLEN *lenp)
DO_UTF8

Returns a bool giving whether or not the PV in sv is to be treated as being encoded in UTF-8.

You should use this after a call to SvPV() or one of its variants, in case any call to string overloading updates the internal UTF-8 encoding flag.

    bool  DO_UTF8(SV* sv)
foldEQ_utf8

Returns true if the leading portions of the strings s1 and s2 (either or both of which may be in UTF-8) are the same case-insensitively; false otherwise. How far into the strings to compare is determined by other input parameters.

If u1 is true, the string s1 is assumed to be in UTF-8-encoded Unicode; otherwise it is assumed to be in native 8-bit encoding. Correspondingly for u2 with respect to s2.

If the byte length l1 is non-zero, it says how far into s1 to check for fold equality. In other words, s1+l1 will be used as a goal to reach. The scan will not be considered to be a match unless the goal is reached, and scanning won't continue past that goal. Correspondingly for l2 with respect to s2.

If pe1 is non-NULL and the pointer it points to is not NULL, that pointer is considered an end pointer to the position 1 byte past the maximum point in s1 beyond which scanning will not continue under any circumstances. (This routine assumes that UTF-8 encoded input strings are not malformed; malformed input can cause it to read past pe1). This means that if both l1 and pe1 are specified, and pe1 is less than s1+l1, the match will never be successful because it can never get as far as its goal (and in fact is asserted against). Correspondingly for pe2 with respect to s2.

At least one of s1 and s2 must have a goal (at least one of l1 and l2 must be non-zero), and if both do, both have to be reached for a successful match. Also, if the fold of a character is multiple characters, all of them must be matched (see tr21 reference below for 'folding').

Upon a successful match, if pe1 is non-NULL, it will be set to point to the beginning of the next character of s1 beyond what was matched. Correspondingly for pe2 and s2.

For case-insensitiveness, the "casefolding" of Unicode is used instead of upper/lowercasing both the characters, see https://www.unicode.org/unicode/reports/tr21/ (Case Mappings).

    I32  foldEQ_utf8(const char *s1, char **pe1, UV l1, bool u1,
                     const char *s2, char **pe2, UV l2, bool u2)
is_ascii_string

This is a misleadingly-named synonym for "is_utf8_invariant_string". On ASCII-ish platforms, the name isn't misleading: the ASCII-range characters are exactly the UTF-8 invariants. But EBCDIC machines have more invariants than just the ASCII characters, so is_utf8_invariant_string is preferred.

    bool  is_ascii_string(const U8* const s, STRLEN len)
is_c9strict_utf8_string

Returns TRUE if the first len bytes of string s form a valid UTF-8-encoded string that conforms to Unicode Corrigendum #9; otherwise it returns FALSE. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

This function returns FALSE for strings containing any code points above the Unicode max of 0x10FFFF or surrogate code points, but accepts non-character code points per Corrigendum #9.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string", "is_utf8_string_flags", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

    bool  is_c9strict_utf8_string(const U8 *s, STRLEN len)
is_c9strict_utf8_string_loc

Like "is_c9strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_c9strict_utf8_string_loclen".

    bool  is_c9strict_utf8_string_loc(const U8 *s, STRLEN len,
                                      const U8 **ep)
is_c9strict_utf8_string_loclen

Like "is_c9strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_c9strict_utf8_string_loc".

    bool  is_c9strict_utf8_string_loclen(const U8 *s, STRLEN len,
                                         const U8 **ep, STRLEN *el)
isC9_STRICT_UTF8_CHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents some Unicode non-surrogate code point; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

The largest acceptable code point is the Unicode maximum 0x10FFFF. This differs from "isSTRICT_UTF8_CHAR" only in that it accepts non-character code points. This corresponds to Unicode Corrigendum #9. which said that non-character code points are merely discouraged rather than completely forbidden in open interchange. See "Noncharacter code points" in perlunicode.

Use "isUTF8_CHAR" to check for Perl's extended UTF-8; and "isUTF8_CHAR_flags" for a more customized definition.

Use "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen" to check entire strings.

    Size_t  isC9_STRICT_UTF8_CHAR(const U8 * const s0,
                                  const U8 * const e)
is_invariant_string

This is a somewhat misleadingly-named synonym for "is_utf8_invariant_string". is_utf8_invariant_string is preferred, as it indicates under what conditions the string is invariant.

    bool  is_invariant_string(const U8* const s, STRLEN len)
isSTRICT_UTF8_CHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents some Unicode code point completely acceptable for open interchange between all applications; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

The largest acceptable code point is the Unicode maximum 0x10FFFF, and must not be a surrogate nor a non-character code point. Thus this excludes any code point from Perl's extended UTF-8.

This is used to efficiently decide if the next few bytes in s is legal Unicode-acceptable UTF-8 for a single character.

Use "isC9_STRICT_UTF8_CHAR" to use the Unicode Corrigendum #9 definition of allowable code points; "isUTF8_CHAR" to check for Perl's extended UTF-8; and "isUTF8_CHAR_flags" for a more customized definition.

Use "is_strict_utf8_string", "is_strict_utf8_string_loc", and "is_strict_utf8_string_loclen" to check entire strings.

    Size_t  isSTRICT_UTF8_CHAR(const U8 * const s0,
                               const U8 * const e)
is_strict_utf8_string

Returns TRUE if the first len bytes of string s form a valid UTF-8-encoded string that is fully interchangeable by any application using Unicode rules; otherwise it returns FALSE. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

This function returns FALSE for strings containing any code points above the Unicode max of 0x10FFFF, surrogate code points, or non-character code points.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string", "is_utf8_string_flags", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

    bool  is_strict_utf8_string(const U8 *s, STRLEN len)
is_strict_utf8_string_loc

Like "is_strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_strict_utf8_string_loclen".

    bool  is_strict_utf8_string_loc(const U8 *s, STRLEN len,
                                    const U8 **ep)
is_strict_utf8_string_loclen

Like "is_strict_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_strict_utf8_string_loc".

    bool  is_strict_utf8_string_loclen(const U8 *s, STRLEN len,
                                       const U8 **ep, STRLEN *el)
is_utf8_char

DEPRECATED! It is planned to remove is_utf8_char from a future release of Perl. Do not use it for new code; remove it from existing code.

Tests if some arbitrary number of bytes begins in a valid UTF-8 character. Note that an INVARIANT (i.e. ASCII on non-EBCDIC machines) character is a valid UTF-8 character. The actual number of bytes in the UTF-8 character will be returned if it is valid, otherwise 0.

This function is deprecated due to the possibility that malformed input could cause reading beyond the end of the input buffer. Use "isUTF8_CHAR" instead.

    STRLEN  is_utf8_char(const U8 *s)
is_utf8_char_buf

This is identical to the macro "isUTF8_CHAR" in perlapi.

    STRLEN  is_utf8_char_buf(const U8 *buf, const U8 *buf_end)
is_utf8_fixed_width_buf_flags

Returns TRUE if the fixed-width buffer starting at s with length len is entirely valid UTF-8, subject to the restrictions given by flags; otherwise it returns FALSE.

If flags is 0, any well-formed UTF-8, as extended by Perl, is accepted without restriction. If the final few bytes of the buffer do not form a complete code point, this will return TRUE anyway, provided that "is_utf8_valid_partial_char_flags" returns TRUE for them.

If flags in non-zero, it can be any combination of the UTF8_DISALLOW_foo flags accepted by "utf8n_to_uvchr", and with the same meanings.

This function differs from "is_utf8_string_flags" only in that the latter returns FALSE if the final few bytes of the string don't form a complete code point.

    bool  is_utf8_fixed_width_buf_flags(const U8 * const s,
                                        STRLEN len, const U32 flags)
is_utf8_fixed_width_buf_loclen_flags

Like "is_utf8_fixed_width_buf_loc_flags" but stores the number of complete, valid characters found in the el pointer.

    bool  is_utf8_fixed_width_buf_loclen_flags(const U8 * const s,
                                               STRLEN len,
                                               const U8 **ep,
                                               STRLEN *el,
                                               const U32 flags)
is_utf8_fixed_width_buf_loc_flags

Like "is_utf8_fixed_width_buf_flags" but stores the location of the failure in the ep pointer. If the function returns TRUE, *ep will point to the beginning of any partial character at the end of the buffer; if there is no partial character *ep will contain s+len.

See also "is_utf8_fixed_width_buf_loclen_flags".

    bool  is_utf8_fixed_width_buf_loc_flags(const U8 * const s,
                                            STRLEN len, const U8 **ep,
                                            const U32 flags)
is_utf8_invariant_string

Returns TRUE if the first len bytes of the string s are the same regardless of the UTF-8 encoding of the string (or UTF-EBCDIC encoding on EBCDIC machines); otherwise it returns FALSE. That is, it returns TRUE if they are UTF-8 invariant. On ASCII-ish machines, all the ASCII characters and only the ASCII characters fit this definition. On EBCDIC machines, the ASCII-range characters are invariant, but so also are the C1 controls.

If len is 0, it will be calculated using strlen(s), (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte).

See also "is_utf8_string", "is_utf8_string_flags", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

    bool  is_utf8_invariant_string(const U8* const s, STRLEN len)
is_utf8_invariant_string_loc

Like "is_utf8_invariant_string" but upon failure, stores the location of the first UTF-8 variant character in the ep pointer; if all characters are UTF-8 invariant, this function does not change the contents of *ep.

    bool  is_utf8_invariant_string_loc(const U8* const s, STRLEN len,
                                       const U8 ** ep)
is_utf8_string

Returns TRUE if the first len bytes of string s form a valid Perl-extended-UTF-8 string; returns FALSE otherwise. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

This function considers Perl's extended UTF-8 to be valid. That means that code points above Unicode, surrogates, and non-character code points are considered valid by this function. Use "is_strict_utf8_string", "is_c9strict_utf8_string", or "is_utf8_string_flags" to restrict what code points are considered valid.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string_loc", "is_utf8_string_loclen", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags",

    bool  is_utf8_string(const U8 *s, STRLEN len)
is_utf8_string_flags

Returns TRUE if the first len bytes of string s form a valid UTF-8 string, subject to the restrictions imposed by flags; returns FALSE otherwise. If len is 0, it will be calculated using strlen(s) (which means if you use this option, that s can't have embedded NUL characters and has to have a terminating NUL byte). Note that all characters being ASCII constitute 'a valid UTF-8 string'.

If flags is 0, this gives the same results as "is_utf8_string"; if flags is UTF8_DISALLOW_ILLEGAL_INTERCHANGE, this gives the same results as "is_strict_utf8_string"; and if flags is UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE, this gives the same results as "is_c9strict_utf8_string". Otherwise flags may be any combination of the UTF8_DISALLOW_foo flags understood by "utf8n_to_uvchr", with the same meanings.

See also "is_utf8_invariant_string", "is_utf8_invariant_string_loc", "is_utf8_string", "is_utf8_string_loc", "is_utf8_string_loc_flags", "is_utf8_string_loclen", "is_utf8_string_loclen_flags", "is_utf8_fixed_width_buf_flags", "is_utf8_fixed_width_buf_loc_flags", "is_utf8_fixed_width_buf_loclen_flags", "is_strict_utf8_string", "is_strict_utf8_string_loc", "is_strict_utf8_string_loclen", "is_c9strict_utf8_string", "is_c9strict_utf8_string_loc", and "is_c9strict_utf8_string_loclen".

    bool  is_utf8_string_flags(const U8 *s, STRLEN len,
                               const U32 flags)
is_utf8_string_loc

Like "is_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_utf8_string_loclen".

    bool  is_utf8_string_loc(const U8 *s, const STRLEN len,
                             const U8 **ep)
is_utf8_string_loclen

Like "is_utf8_string" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_utf8_string_loc".

    bool  is_utf8_string_loclen(const U8 *s, STRLEN len,
                                const U8 **ep, STRLEN *el)
is_utf8_string_loclen_flags

Like "is_utf8_string_flags" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer, and the number of UTF-8 encoded characters in the el pointer.

See also "is_utf8_string_loc_flags".

    bool  is_utf8_string_loclen_flags(const U8 *s, STRLEN len,
                                      const U8 **ep, STRLEN *el,
                                      const U32 flags)
is_utf8_string_loc_flags

Like "is_utf8_string_flags" but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the ep pointer.

See also "is_utf8_string_loclen_flags".

    bool  is_utf8_string_loc_flags(const U8 *s, STRLEN len,
                                   const U8 **ep, const U32 flags)
is_utf8_valid_partial_char

Returns 0 if the sequence of bytes starting at s and looking no further than e - 1 is the UTF-8 encoding, as extended by Perl, for one or more code points. Otherwise, it returns 1 if there exists at least one non-empty sequence of bytes that when appended to sequence s, starting at position e causes the entire sequence to be the well-formed UTF-8 of some code point; otherwise returns 0.

In other words this returns TRUE if s points to a partial UTF-8-encoded code point.

This is useful when a fixed-length buffer is being tested for being well-formed UTF-8, but the final few bytes in it don't comprise a full character; that is, it is split somewhere in the middle of the final code point's UTF-8 representation. (Presumably when the buffer is refreshed with the next chunk of data, the new first bytes will complete the partial code point.) This function is used to verify that the final bytes in the current buffer are in fact the legal beginning of some code point, so that if they aren't, the failure can be signalled without having to wait for the next read.

    bool  is_utf8_valid_partial_char(const U8 * const s,
                                     const U8 * const e)
is_utf8_valid_partial_char_flags

Like "is_utf8_valid_partial_char", it returns a boolean giving whether or not the input is a valid UTF-8 encoded partial character, but it takes an extra parameter, flags, which can further restrict which code points are considered valid.

If flags is 0, this behaves identically to "is_utf8_valid_partial_char". Otherwise flags can be any combination of the UTF8_DISALLOW_foo flags accepted by "utf8n_to_uvchr". If there is any sequence of bytes that can complete the input partial character in such a way that a non-prohibited character is formed, the function returns TRUE; otherwise FALSE. Non character code points cannot be determined based on partial character input. But many of the other possible excluded types can be determined from just the first one or two bytes.

    bool  is_utf8_valid_partial_char_flags(const U8 * const s,
                                           const U8 * const e,
                                           const U32 flags)
isUTF8_CHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8, as extended by Perl, that represents some code point; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

The code point can be any that will fit in an IV on this machine, using Perl's extension to official UTF-8 to represent those higher than the Unicode maximum of 0x10FFFF. That means that this macro is used to efficiently decide if the next few bytes in s is legal UTF-8 for a single character.

Use "isSTRICT_UTF8_CHAR" to restrict the acceptable code points to those defined by Unicode to be fully interchangeable across applications; "isC9_STRICT_UTF8_CHAR" to use the Unicode Corrigendum #9 definition of allowable code points; and "isUTF8_CHAR_flags" for a more customized definition.

Use "is_utf8_string", "is_utf8_string_loc", and "is_utf8_string_loclen" to check entire strings.

Note also that a UTF-8 "invariant" character (i.e. ASCII on non-EBCDIC machines) is a valid UTF-8 character.

    Size_t  isUTF8_CHAR(const U8 * const s0, const U8 * const e)
isUTF8_CHAR_flags

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8, as extended by Perl, that represents some code point, subject to the restrictions given by flags; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation. Any bytes remaining before e, but beyond the ones needed to form the first code point in s, are not examined.

If flags is 0, this gives the same results as "isUTF8_CHAR"; if flags is UTF8_DISALLOW_ILLEGAL_INTERCHANGE, this gives the same results as "isSTRICT_UTF8_CHAR"; and if flags is UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE, this gives the same results as "isC9_STRICT_UTF8_CHAR". Otherwise flags may be any combination of the UTF8_DISALLOW_foo flags understood by "utf8n_to_uvchr", with the same meanings.

The three alternative macros are for the most commonly needed validations; they are likely to run somewhat faster than this more general one, as they can be inlined into your code.

Use "is_utf8_string_flags", "is_utf8_string_loc_flags", and "is_utf8_string_loclen_flags" to check entire strings.

    STRLEN  isUTF8_CHAR_flags(const U8 *s, const U8 *e,
                              const U32 flags)
LATIN1_TO_NATIVE

Returns the native equivalent of the input Latin-1 code point (including ASCII and control characters) given by ch. Thus, LATIN1_TO_NATIVE(66) on EBCDIC platforms returns 194. These each represent the character "B" on their respective platforms. On ASCII platforms no conversion is needed, so this macro expands to just its input, adding no time nor space requirements to the implementation.

For conversion of code points potentially larger than will fit in a character, use "UNI_TO_NATIVE".

    U8  LATIN1_TO_NATIVE(U8 ch)
NATIVE_TO_LATIN1

Returns the Latin-1 (including ASCII and control characters) equivalent of the input native code point given by ch. Thus, NATIVE_TO_LATIN1(193) on EBCDIC platforms returns 65. These each represent the character "A" on their respective platforms. On ASCII platforms no conversion is needed, so this macro expands to just its input, adding no time nor space requirements to the implementation.

For conversion of code points potentially larger than will fit in a character, use "NATIVE_TO_UNI".

    U8  NATIVE_TO_LATIN1(U8 ch)
NATIVE_TO_UNI

Returns the Unicode equivalent of the input native code point given by ch. Thus, NATIVE_TO_UNI(195) on EBCDIC platforms returns 67. These each represent the character "C" on their respective platforms. On ASCII platforms no conversion is needed, so this macro expands to just its input, adding no time nor space requirements to the implementation.

    UV  NATIVE_TO_UNI(UV ch)
pad_compname_type

DEPRECATED! It is planned to remove pad_compname_type from a future release of Perl. Do not use it for new code; remove it from existing code.

Looks up the type of the lexical variable at position po in the currently-compiling pad. If the variable is typed, the stash of the class to which it is typed is returned. If not, NULL is returned.

Use "PAD_COMPNAME_TYPE" in perlintern instead.

    HV*  pad_compname_type(const PADOFFSET po)
pv_uni_display

Build to the scalar dsv a displayable version of the UTF-8 encoded string spv, length len, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

The flags argument can have UNI_DISPLAY_ISPRINT set to display isPRINT()able characters as themselves, UNI_DISPLAY_BACKSLASH to display the \\[nrfta\\] as the backslashed versions (like "\n") (UNI_DISPLAY_BACKSLASH is preferred over UNI_DISPLAY_ISPRINT for "\\"). UNI_DISPLAY_QQ (and its alias UNI_DISPLAY_REGEX) have both UNI_DISPLAY_BACKSLASH and UNI_DISPLAY_ISPRINT turned on.

Additionally, there is now UNI_DISPLAY_BACKSPACE which allows \b for a backspace, but only when UNI_DISPLAY_BACKSLASH also is set.

The pointer to the PV of the dsv is returned.

See also "sv_uni_display".

    char*  pv_uni_display(SV *dsv, const U8 *spv, STRLEN len,
                          STRLEN pvlim, UV flags)
REPLACEMENT_CHARACTER_UTF8

This is a macro that evaluates to a string constant of the UTF-8 bytes that define the Unicode REPLACEMENT CHARACTER (U+FFFD) for the platform that perl is compiled on. This allows code to use a mnemonic for this character that works on both ASCII and EBCDIC platforms. sizeof(REPLACEMENT_CHARACTER_UTF8) - 1 can be used to get its length in bytes.

sv_cat_decode

encoding is assumed to be an Encode object, the PV of ssv is assumed to be octets in that encoding and decoding the input starts from the position which (PV + *offset) pointed to. dsv will be concatenated with the decoded UTF-8 string from ssv. Decoding will terminate when the string tstr appears in decoding output or the input ends on the PV of ssv. The value which offset points will be modified to the last input position on ssv.

Returns TRUE if the terminator was found, else returns FALSE.

    bool  sv_cat_decode(SV* dsv, SV *encoding, SV *ssv, int *offset,
                        char* tstr, int tlen)
sv_recode_to_utf8

encoding is assumed to be an Encode object, on entry the PV of sv is assumed to be octets in that encoding, and sv will be converted into Unicode (and UTF-8).

If sv already is UTF-8 (or if it is not POK), or if encoding is not a reference, nothing is done to sv. If encoding is not an Encode::XS Encoding object, bad things will happen. (See cpan/Encode/encoding.pm and Encode.)

The PV of sv is returned.

    char*  sv_recode_to_utf8(SV* sv, SV *encoding)
sv_uni_display

Build to the scalar dsv a displayable version of the scalar sv, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

The flags argument is as in "pv_uni_display"().

The pointer to the PV of the dsv is returned.

    char*  sv_uni_display(SV *dsv, SV *ssv, STRLEN pvlim, UV flags)
UNICODE_REPLACEMENT

Evaluates to 0xFFFD, the code point of the Unicode REPLACEMENT CHARACTER

UNI_TO_NATIVE

Returns the native equivalent of the input Unicode code point given by ch. Thus, UNI_TO_NATIVE(68) on EBCDIC platforms returns 196. These each represent the character "D" on their respective platforms. On ASCII platforms no conversion is needed, so this macro expands to just its input, adding no time nor space requirements to the implementation.

    UV  UNI_TO_NATIVE(UV ch)
utf8n_to_uvchr

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Most code should use "utf8_to_uvchr_buf"() rather than call this directly.

Bottom level UTF-8 decode routine. Returns the native code point value of the first character in the string s, which is assumed to be in UTF-8 (or UTF-EBCDIC) encoding, and no longer than curlen bytes; *retlen (if retlen isn't NULL) will be set to the length, in bytes, of that character.

The value of flags determines the behavior when s does not point to a well-formed UTF-8 character. If flags is 0, encountering a malformation causes zero to be returned and *retlen is set so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. Also, if UTF-8 warnings haven't been lexically disabled, a warning is raised. Some UTF-8 input sequences may contain multiple malformations. This function tries to find every possible one in each call, so multiple warnings can be raised for the same sequence.

Various ALLOW flags can be set in flags to allow (and not warn on) individual types of malformations, such as the sequence being overlong (that is, when there is a shorter sequence that can express the same code point; overlong sequences are expressly forbidden in the UTF-8 standard due to potential security issues). Another malformation example is the first byte of a character not being a legal first byte. See utf8.h for the list of such flags. Even if allowed, this function generally returns the Unicode REPLACEMENT CHARACTER when it encounters a malformation. There are flags in utf8.h to override this behavior for the overlong malformations, but don't do that except for very specialized purposes.

The UTF8_CHECK_ONLY flag overrides the behavior when a non-allowed (by other flags) malformation is found. If this flag is set, the routine assumes that the caller will raise a warning, and this function will silently just set retlen to -1 (cast to STRLEN) and return zero.

Note that this API requires disambiguation between successful decoding a NUL character, and an error return (unless the UTF8_CHECK_ONLY flag is set), as in both cases, 0 is returned, and, depending on the malformation, retlen may be set to 1. To disambiguate, upon a zero return, see if the first byte of s is 0 as well. If so, the input was a NUL; if not, the input had an error. Or you can use "utf8n_to_uvchr_error".

Certain code points are considered problematic. These are Unicode surrogates, Unicode non-characters, and code points above the Unicode maximum of 0x10FFFF. By default these are considered regular code points, but certain situations warrant special handling for them, which can be specified using the flags parameter. If flags contains UTF8_DISALLOW_ILLEGAL_INTERCHANGE, all three classes are treated as malformations and handled as such. The flags UTF8_DISALLOW_SURROGATE, UTF8_DISALLOW_NONCHAR, and UTF8_DISALLOW_SUPER (meaning above the legal Unicode maximum) can be set to disallow these categories individually. UTF8_DISALLOW_ILLEGAL_INTERCHANGE restricts the allowed inputs to the strict UTF-8 traditionally defined by Unicode. Use UTF8_DISALLOW_ILLEGAL_C9_INTERCHANGE to use the strictness definition given by Unicode Corrigendum #9. The difference between traditional strictness and C9 strictness is that the latter does not forbid non-character code points. (They are still discouraged, however.) For more discussion see "Noncharacter code points" in perlunicode.

The flags UTF8_WARN_ILLEGAL_INTERCHANGE, UTF8_WARN_ILLEGAL_C9_INTERCHANGE, UTF8_WARN_SURROGATE, UTF8_WARN_NONCHAR, and UTF8_WARN_SUPER will cause warning messages to be raised for their respective categories, but otherwise the code points are considered valid (not malformations). To get a category to both be treated as a malformation and raise a warning, specify both the WARN and DISALLOW flags. (But note that warnings are not raised if lexically disabled nor if UTF8_CHECK_ONLY is also specified.)

Extremely high code points were never specified in any standard, and require an extension to UTF-8 to express, which Perl does. It is likely that programs written in something other than Perl would not be able to read files that contain these; nor would Perl understand files written by something that uses a different extension. For these reasons, there is a separate set of flags that can warn and/or disallow these extremely high code points, even if other above-Unicode ones are accepted. They are the UTF8_WARN_PERL_EXTENDED and UTF8_DISALLOW_PERL_EXTENDED flags. For more information see "UTF8_GOT_PERL_EXTENDED". Of course UTF8_DISALLOW_SUPER will treat all above-Unicode code points, including these, as malformations. (Note that the Unicode standard considers anything above 0x10FFFF to be illegal, but there are standards predating it that allow up to 0x7FFF_FFFF (2**31 -1))

A somewhat misleadingly named synonym for UTF8_WARN_PERL_EXTENDED is retained for backward compatibility: UTF8_WARN_ABOVE_31_BIT. Similarly, UTF8_DISALLOW_ABOVE_31_BIT is usable instead of the more accurately named UTF8_DISALLOW_PERL_EXTENDED. The names are misleading because these flags can apply to code points that actually do fit in 31 bits. This happens on EBCDIC platforms, and sometimes when the overlong malformation is also present. The new names accurately describe the situation in all cases.

All other code points corresponding to Unicode characters, including private use and those yet to be assigned, are never considered malformed and never warn.

    UV  utf8n_to_uvchr(const U8 *s, STRLEN curlen, STRLEN *retlen,
                       const U32 flags)
utf8n_to_uvchr_error

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Most code should use "utf8_to_uvchr_buf"() rather than call this directly.

This function is for code that needs to know what the precise malformation(s) are when an error is found. If you also need to know the generated warning messages, use "utf8n_to_uvchr_msgs"() instead.

It is like "utf8n_to_uvchr" but it takes an extra parameter placed after all the others, errors. If this parameter is 0, this function behaves identically to "utf8n_to_uvchr". Otherwise, errors should be a pointer to a U32 variable, which this function sets to indicate any errors found. Upon return, if *errors is 0, there were no errors found. Otherwise, *errors is the bit-wise OR of the bits described in the list below. Some of these bits will be set if a malformation is found, even if the input flags parameter indicates that the given malformation is allowed; those exceptions are noted:

UTF8_GOT_PERL_EXTENDED

The input sequence is not standard UTF-8, but a Perl extension. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_PERL_EXTENDED or the UTF8_WARN_PERL_EXTENDED flags.

Code points above 0x7FFF_FFFF (2**31 - 1) were never specified in any standard, and so some extension must be used to express them. Perl uses a natural extension to UTF-8 to represent the ones up to 2**36-1, and invented a further extension to represent even higher ones, so that any code point that fits in a 64-bit word can be represented. Text using these extensions is not likely to be portable to non-Perl code. We lump both of these extensions together and refer to them as Perl extended UTF-8. There exist other extensions that people have invented, incompatible with Perl's.

On EBCDIC platforms starting in Perl v5.24, the Perl extension for representing extremely high code points kicks in at 0x3FFF_FFFF (2**30 -1), which is lower than on ASCII. Prior to that, code points 2**31 and higher were simply unrepresentable, and a different, incompatible method was used to represent code points between 2**30 and 2**31 - 1.

On both platforms, ASCII and EBCDIC, UTF8_GOT_PERL_EXTENDED is set if Perl extended UTF-8 is used.

In earlier Perls, this bit was named UTF8_GOT_ABOVE_31_BIT, which you still may use for backward compatibility. That name is misleading, as this flag may be set when the code point actually does fit in 31 bits. This happens on EBCDIC platforms, and sometimes when the overlong malformation is also present. The new name accurately describes the situation in all cases.

UTF8_GOT_CONTINUATION

The input sequence was malformed in that the first byte was a UTF-8 continuation byte.

UTF8_GOT_EMPTY

The input curlen parameter was 0.

UTF8_GOT_LONG

The input sequence was malformed in that there is some other sequence that evaluates to the same code point, but that sequence is shorter than this one.

Until Unicode 3.1, it was legal for programs to accept this malformation, but it was discovered that this created security issues.

UTF8_GOT_NONCHAR

The code point represented by the input UTF-8 sequence is for a Unicode non-character code point. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_NONCHAR or the UTF8_WARN_NONCHAR flags.

UTF8_GOT_NON_CONTINUATION

The input sequence was malformed in that a non-continuation type byte was found in a position where only a continuation type one should be. See also "UTF8_GOT_SHORT".

UTF8_GOT_OVERFLOW

The input sequence was malformed in that it is for a code point that is not representable in the number of bits available in an IV on the current platform.

UTF8_GOT_SHORT

The input sequence was malformed in that curlen is smaller than required for a complete sequence. In other words, the input is for a partial character sequence.

UTF8_GOT_SHORT and UTF8_GOT_NON_CONTINUATION both indicate a too short sequence. The difference is that UTF8_GOT_NON_CONTINUATION indicates always that there is an error, while UTF8_GOT_SHORT means that an incomplete sequence was looked at. If no other flags are present, it means that the sequence was valid as far as it went. Depending on the application, this could mean one of three things:

  • The curlen length parameter passed in was too small, and the function was prevented from examining all the necessary bytes.

  • The buffer being looked at is based on reading data, and the data received so far stopped in the middle of a character, so that the next read will read the remainder of this character. (It is up to the caller to deal with the split bytes somehow.)

  • This is a real error, and the partial sequence is all we're going to get.

UTF8_GOT_SUPER

The input sequence was malformed in that it is for a non-Unicode code point; that is, one above the legal Unicode maximum. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_SUPER or the UTF8_WARN_SUPER flags.

UTF8_GOT_SURROGATE

The input sequence was malformed in that it is for a -Unicode UTF-16 surrogate code point. This bit is set only if the input flags parameter contains either the UTF8_DISALLOW_SURROGATE or the UTF8_WARN_SURROGATE flags.

To do your own error handling, call this function with the UTF8_CHECK_ONLY flag to suppress any warnings, and then examine the *errors return.

    UV  utf8n_to_uvchr_error(const U8 *s, STRLEN curlen,
                             STRLEN *retlen, const U32 flags,
                             U32 * errors)
utf8n_to_uvchr_msgs

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Most code should use "utf8_to_uvchr_buf"() rather than call this directly.

This function is for code that needs to know what the precise malformation(s) are when an error is found, and wants the corresponding warning and/or error messages to be returned to the caller rather than be displayed. All messages that would have been displayed if all lexical warnings are enabled will be returned.

It is just like "utf8n_to_uvchr_error" but it takes an extra parameter placed after all the others, msgs. If this parameter is 0, this function behaves identically to "utf8n_to_uvchr_error". Otherwise, msgs should be a pointer to an AV * variable, in which this function creates a new AV to contain any appropriate messages. The elements of the array are ordered so that the first message that would have been displayed is in the 0th element, and so on. Each element is a hash with three key-value pairs, as follows:

text

The text of the message as a SVpv.

warn_categories

The warning category (or categories) packed into a SVuv.

flag

A single flag bit associated with this message, in a SVuv. The bit corresponds to some bit in the *errors return value, such as UTF8_GOT_LONG.

It's important to note that specifying this parameter as non-null will cause any warnings this function would otherwise generate to be suppressed, and instead be placed in *msgs. The caller can check the lexical warnings state (or not) when choosing what to do with the returned messages.

If the flag UTF8_CHECK_ONLY is passed, no warnings are generated, and hence no AV is created.

The caller, of course, is responsible for freeing any returned AV.

    UV  utf8n_to_uvchr_msgs(const U8 *s, STRLEN curlen,
                            STRLEN *retlen, const U32 flags,
                            U32 * errors, AV ** msgs)
UTF8SKIP

returns the number of bytes a non-malformed UTF-8 encoded character whose first (perhaps only) byte is pointed to by s.

If there is a possibility of malformed input, use instead:

"UTF8_SAFE_SKIP" if you know the maximum ending pointer in the buffer pointed to by s; or
"UTF8_CHK_SKIP" if you don't know it.

It is better to restructure your code so the end pointer is passed down so that you know what it actually is at the point of this call, but if that isn't possible, "UTF8_CHK_SKIP" can minimize the chance of accessing beyond the end of the input buffer.

    STRLEN  UTF8SKIP(char* s)
UTF8_CHK_SKIP

This is a safer version of "UTF8SKIP", but still not as safe as "UTF8_SAFE_SKIP". This version doesn't blindly assume that the input string pointed to by s is well-formed, but verifies that there isn't a NUL terminating character before the expected end of the next character in s. The length UTF8_CHK_SKIP returns stops just before any such NUL.

Perl tends to add NULs, as an insurance policy, after the end of strings in SV's, so it is likely that using this macro will prevent inadvertent reading beyond the end of the input buffer, even if it is malformed UTF-8.

This macro is intended to be used by XS modules where the inputs could be malformed, and it isn't feasible to restructure to use the safer "UTF8_SAFE_SKIP", for example when interfacing with a C library.

    STRLEN  UTF8_CHK_SKIP(char* s)
utf8_distance

Returns the number of UTF-8 characters between the UTF-8 pointers a and b.

WARNING: use only if you *know* that the pointers point inside the same UTF-8 buffer.

    IV  utf8_distance(const U8 *a, const U8 *b)
utf8_hop

Return the UTF-8 pointer s displaced by off characters, either forward or backward.

WARNING: do not use the following unless you *know* off is within the UTF-8 data pointed to by s *and* that on entry s is aligned on the first byte of character or just after the last byte of a character.

    U8*  utf8_hop(const U8 *s, SSize_t off)
utf8_hop_back

Return the UTF-8 pointer s displaced by up to off characters, backward.

off must be non-positive.

s must be after or equal to start.

When moving backward it will not move before start.

Will not exceed this limit even if the string is not valid "UTF-8".

    U8*  utf8_hop_back(const U8 *s, SSize_t off, const U8 *start)
utf8_hop_forward

Return the UTF-8 pointer s displaced by up to off characters, forward.

off must be non-negative.

s must be before or equal to end.

When moving forward it will not move beyond end.

Will not exceed this limit even if the string is not valid "UTF-8".

    U8*  utf8_hop_forward(const U8 *s, SSize_t off, const U8 *end)
utf8_hop_safe

Return the UTF-8 pointer s displaced by up to off characters, either forward or backward.

When moving backward it will not move before start.

When moving forward it will not move beyond end.

Will not exceed those limits even if the string is not valid "UTF-8".

    U8*  utf8_hop_safe(const U8 *s, SSize_t off, const U8 *start,
                       const U8 *end)
UTF8_IS_INVARIANT

Evaluates to 1 if the byte c represents the same character when encoded in UTF-8 as when not; otherwise evaluates to 0. UTF-8 invariant characters can be copied as-is when converting to/from UTF-8, saving time.

In spite of the name, this macro gives the correct result if the input string from which c comes is not encoded in UTF-8.

See "UVCHR_IS_INVARIANT" for checking if a UV is invariant.

    bool  UTF8_IS_INVARIANT(char c)
UTF8_IS_NONCHAR

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents one of the Unicode non-character code points; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation.

    bool  UTF8_IS_NONCHAR(const U8 *s, const U8 *e)
UTF8_IS_SUPER

Recall that Perl recognizes an extension to UTF-8 that can encode code points larger than the ones defined by Unicode, which are 0..0x10FFFF.

This macro evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are from this UTF-8 extension; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation.

0 is returned if the bytes are not well-formed extended UTF-8, or if they represent a code point that cannot fit in a UV on the current platform. Hence this macro can give different results when run on a 64-bit word machine than on one with a 32-bit word size.

Note that it is illegal to have code points that are larger than what can fit in an IV on the current machine.

    bool  UTF8_IS_SUPER(const U8 *s, const U8 *e)
UTF8_IS_SURROGATE

Evaluates to non-zero if the first few bytes of the string starting at s and looking no further than e - 1 are well-formed UTF-8 that represents one of the Unicode surrogate code points; otherwise it evaluates to 0. If non-zero, the value gives how many bytes starting at s comprise the code point's representation.

    bool  UTF8_IS_SURROGATE(const U8 *s, const U8 *e)
utf8_length

Returns the number of characters in the sequence of UTF-8-encoded bytes starting at s and ending at the byte just before e. If <s> and <e> point to the same place, it returns 0 with no warning raised.

If e < s or if the scan would end up past e, it raises a UTF8 warning and returns the number of valid characters.

    STRLEN  utf8_length(const U8* s, const U8 *e)
UTF8_MAXBYTES

The maximum width of a single UTF-8 encoded character, in bytes.

NOTE: Strictly speaking Perl's UTF-8 should not be called UTF-8 since UTF-8 is an encoding of Unicode, and Unicode's upper limit, 0x10FFFF, can be expressed with 4 bytes. However, Perl thinks of UTF-8 as a way to encode non-negative integers in a binary format, even those above Unicode.

UTF8_MAXBYTES_CASE

The maximum number of UTF-8 bytes a single Unicode character can uppercase/lowercase/titlecase/fold into.

UTF8_SAFE_SKIP

returns 0 if s >= e; otherwise returns the number of bytes in the UTF-8 encoded character whose first byte is pointed to by s. But it never returns beyond e. On DEBUGGING builds, it asserts that s <= e.

    STRLEN  UTF8_SAFE_SKIP(char* s, char* e)
UTF8_SKIP

This is a synonym for "UTF8SKIP"

    STRLEN  UTF8_SKIP(char* s)
utf8_to_bytes

NOTE: utf8_to_bytes is experimental and may change or be removed without notice.

Converts a string "s" of length *lenp from UTF-8 into native byte encoding. Unlike "bytes_to_utf8", this over-writes the original string, and updates *lenp to contain the new length. Returns zero on failure (leaving "s" unchanged) setting *lenp to -1.

Upon successful return, the number of variants in the string can be computed by having saved the value of *lenp before the call, and subtracting the after-call value of *lenp from it.

If you need a copy of the string, see "bytes_from_utf8".

    U8*  utf8_to_bytes(U8 *s, STRLEN *lenp)
utf8_to_uvchr

DEPRECATED! It is planned to remove utf8_to_uvchr from a future release of Perl. Do not use it for new code; remove it from existing code.

Returns the native code point of the first character in the string s which is assumed to be in UTF-8 encoding; retlen will be set to the length, in bytes, of that character.

Some, but not all, UTF-8 malformations are detected, and in fact, some malformed input could cause reading beyond the end of the input buffer, which is why this function is deprecated. Use "utf8_to_uvchr_buf" instead.

If s points to one of the detected malformations, and UTF8 warnings are enabled, zero is returned and *retlen is set (if retlen isn't NULL) to -1. If those warnings are off, the computed value if well-defined (or the Unicode REPLACEMENT CHARACTER, if not) is silently returned, and *retlen is set (if retlen isn't NULL) so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. See "utf8n_to_uvchr" for details on when the REPLACEMENT CHARACTER is returned.

    UV  utf8_to_uvchr(const U8 *s, STRLEN *retlen)
utf8_to_uvchr_buf

Returns the native code point of the first character in the string s which is assumed to be in UTF-8 encoding; send points to 1 beyond the end of s. *retlen will be set to the length, in bytes, of that character.

If s does not point to a well-formed UTF-8 character and UTF8 warnings are enabled, zero is returned and *retlen is set (if retlen isn't NULL) to -1. If those warnings are off, the computed value, if well-defined (or the Unicode REPLACEMENT CHARACTER if not), is silently returned, and *retlen is set (if retlen isn't NULL) so that (s + *retlen) is the next possible position in s that could begin a non-malformed character. See "utf8n_to_uvchr" for details on when the REPLACEMENT CHARACTER is returned.

    UV  utf8_to_uvchr_buf(const U8 *s, const U8 *send, STRLEN *retlen)
UVCHR_IS_INVARIANT

Evaluates to 1 if the representation of code point cp is the same whether or not it is encoded in UTF-8; otherwise evaluates to 0. UTF-8 invariant characters can be copied as-is when converting to/from UTF-8, saving time. cp is Unicode if above 255; otherwise is platform-native.

    bool  UVCHR_IS_INVARIANT(UV cp)
UVCHR_SKIP

returns the number of bytes required to represent the code point cp when encoded as UTF-8. cp is a native (ASCII or EBCDIC) code point if less than 255; a Unicode code point otherwise.

    STRLEN  UVCHR_SKIP(UV cp)
uvchr_to_utf8

Adds the UTF-8 representation of the native code point uv to the end of the string d; d should have at least UVCHR_SKIP(uv)+1 (up to UTF8_MAXBYTES+1) free bytes available. The return value is the pointer to the byte after the end of the new character. In other words,

d = uvchr_to_utf8(d, uv);

is the recommended wide native character-aware way of saying

*(d++) = uv;

This function accepts any code point from 0..IV_MAX as input. IV_MAX is typically 0x7FFF_FFFF in a 32-bit word.

It is possible to forbid or warn on non-Unicode code points, or those that may be problematic by using "uvchr_to_utf8_flags".

    U8*  uvchr_to_utf8(U8 *d, UV uv)
uvchr_to_utf8_flags

Adds the UTF-8 representation of the native code point uv to the end of the string d; d should have at least UVCHR_SKIP(uv)+1 (up to UTF8_MAXBYTES+1) free bytes available. The return value is the pointer to the byte after the end of the new character. In other words,

d = uvchr_to_utf8_flags(d, uv, flags);

or, in most cases,

d = uvchr_to_utf8_flags(d, uv, 0);

This is the Unicode-aware way of saying

*(d++) = uv;

If flags is 0, this function accepts any code point from 0..IV_MAX as input. IV_MAX is typically 0x7FFF_FFFF in a 32-bit word.

Specifying flags can further restrict what is allowed and not warned on, as follows:

If uv is a Unicode surrogate code point and UNICODE_WARN_SURROGATE is set, the function will raise a warning, provided UTF8 warnings are enabled. If instead UNICODE_DISALLOW_SURROGATE is set, the function will fail and return NULL. If both flags are set, the function will both warn and return NULL.

Similarly, the UNICODE_WARN_NONCHAR and UNICODE_DISALLOW_NONCHAR flags affect how the function handles a Unicode non-character.

And likewise, the UNICODE_WARN_SUPER and UNICODE_DISALLOW_SUPER flags affect the handling of code points that are above the Unicode maximum of 0x10FFFF. Languages other than Perl may not be able to accept files that contain these.

The flag UNICODE_WARN_ILLEGAL_INTERCHANGE selects all three of the above WARN flags; and UNICODE_DISALLOW_ILLEGAL_INTERCHANGE selects all three DISALLOW flags. UNICODE_DISALLOW_ILLEGAL_INTERCHANGE restricts the allowed inputs to the strict UTF-8 traditionally defined by Unicode. Similarly, UNICODE_WARN_ILLEGAL_C9_INTERCHANGE and UNICODE_DISALLOW_ILLEGAL_C9_INTERCHANGE are shortcuts to select the above-Unicode and surrogate flags, but not the non-character ones, as defined in Unicode Corrigendum #9. See "Noncharacter code points" in perlunicode.

Extremely high code points were never specified in any standard, and require an extension to UTF-8 to express, which Perl does. It is likely that programs written in something other than Perl would not be able to read files that contain these; nor would Perl understand files written by something that uses a different extension. For these reasons, there is a separate set of flags that can warn and/or disallow these extremely high code points, even if other above-Unicode ones are accepted. They are the UNICODE_WARN_PERL_EXTENDED and UNICODE_DISALLOW_PERL_EXTENDED flags. For more information see "UTF8_GOT_PERL_EXTENDED". Of course UNICODE_DISALLOW_SUPER will treat all above-Unicode code points, including these, as malformations. (Note that the Unicode standard considers anything above 0x10FFFF to be illegal, but there are standards predating it that allow up to 0x7FFF_FFFF (2**31 -1))

A somewhat misleadingly named synonym for UNICODE_WARN_PERL_EXTENDED is retained for backward compatibility: UNICODE_WARN_ABOVE_31_BIT. Similarly, UNICODE_DISALLOW_ABOVE_31_BIT is usable instead of the more accurately named UNICODE_DISALLOW_PERL_EXTENDED. The names are misleading because on EBCDIC platforms,these flags can apply to code points that actually do fit in 31 bits. The new names accurately describe the situation in all cases.

    U8*  uvchr_to_utf8_flags(U8 *d, UV uv, UV flags)
uvchr_to_utf8_flags_msgs

THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES.

Most code should use "uvchr_to_utf8_flags"() rather than call this directly.

This function is for code that wants any warning and/or error messages to be returned to the caller rather than be displayed. All messages that would have been displayed if all lexical warnings are enabled will be returned.

It is just like "uvchr_to_utf8_flags" but it takes an extra parameter placed after all the others, msgs. If this parameter is 0, this function behaves identically to "uvchr_to_utf8_flags". Otherwise, msgs should be a pointer to an HV * variable, in which this function creates a new HV to contain any appropriate messages. The hash has three key-value pairs, as follows:

text

The text of the message as a SVpv.

warn_categories

The warning category (or categories) packed into a SVuv.

flag

A single flag bit associated with this message, in a SVuv. The bit corresponds to some bit in the *errors return value, such as UNICODE_GOT_SURROGATE.

It's important to note that specifying this parameter as non-null will cause any warnings this function would otherwise generate to be suppressed, and instead be placed in *msgs. The caller can check the lexical warnings state (or not) when choosing what to do with the returned messages.

The caller, of course, is responsible for freeing any returned HV.

    U8*  uvchr_to_utf8_flags_msgs(U8 *d, UV uv, UV flags, HV ** msgs)

Utility Functions

C_ARRAY_END

Returns a pointer to one element past the final element of the input C array.

    void *  C_ARRAY_END(void *a)
C_ARRAY_LENGTH

Returns the number of elements in the input C array (so you want your zero-based indices to be less than but not equal to).

    STRLEN  C_ARRAY_LENGTH(void *a)
getcwd_sv

Fill sv with current working directory

    int  getcwd_sv(SV* sv)
IN_PERL_COMPILETIME

Returns 1 if this macro is being called during the compilation phase of the program; otherwise 0;

    bool  IN_PERL_COMPILETIME
IN_PERL_RUNTIME

Returns 1 if this macro is being called during the execution phase of the program; otherwise 0;

    bool  IN_PERL_RUNTIME
IS_SAFE_SYSCALL

Same as "is_safe_syscall".

    bool  IS_SAFE_SYSCALL(NN const char *pv, STRLEN len,
                          NN const char *what, NN const char *op_name)
is_safe_syscall

Test that the given pv (with length len) doesn't contain any internal NUL characters. If it does, set errno to ENOENT, optionally warn using the syscalls category, and return FALSE.

Return TRUE if the name is safe.

what and op_name are used in any warning.

Used by the IS_SAFE_SYSCALL() macro.

    bool  is_safe_syscall(const char *pv, STRLEN len,
                          const char *what, const char *op_name)
my_setenv

A wrapper for the C library setenv(3). Don't use the latter, as the perl version has desirable safeguards

    void  my_setenv(const char* nam, const char* val)
Poison

PoisonWith(0xEF) for catching access to freed memory.

    void  Poison(void* dest, int nitems, type)
PoisonFree

PoisonWith(0xEF) for catching access to freed memory.

    void  PoisonFree(void* dest, int nitems, type)
PoisonNew

PoisonWith(0xAB) for catching access to allocated but uninitialized memory.

    void  PoisonNew(void* dest, int nitems, type)
PoisonWith

Fill up memory with a byte pattern (a byte repeated over and over again) that hopefully catches attempts to access uninitialized memory.

    void  PoisonWith(void* dest, int nitems, type, U8 byte)
StructCopy

This is an architecture-independent macro to copy one structure to another.

    void  StructCopy(type *src, type *dest, type)
sv_destroyable

Dummy routine which reports that object can be destroyed when there is no sharing module present. It ignores its single SV argument, and returns 'true'. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

    bool  sv_destroyable(SV *sv)
sv_nosharing

Dummy routine which "shares" an SV when there is no sharing module present. Or "locks" it. Or "unlocks" it. In other words, ignores its single SV argument. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

    void  sv_nosharing(SV *sv)

Versioning

new_version

Returns a new version object based on the passed in SV:

SV *sv = new_version(SV *ver);

Does not alter the passed in ver SV. See "upg_version" if you want to upgrade the SV.

    SV*  new_version(SV *ver)
PERL_REVISION

DEPRECATED! It is planned to remove PERL_REVISION from a future release of Perl. Do not use it for new code; remove it from existing code.

The major number component of the perl interpreter currently being compiled or executing. This has been 5 from 1993 into 2020.

Instead use one of the version comparison macros. See "PERL_VERSION_EQ".

PERL_SUBVERSION

DEPRECATED! It is planned to remove PERL_SUBVERSION from a future release of Perl. Do not use it for new code; remove it from existing code.

The micro number component of the perl interpreter currently being compiled or executing. In stable releases this gives the dot release number for maintenance updates. In development releases this gives a tag for a snapshot of the status at various points in the development cycle.

Instead use one of the version comparison macros. See "PERL_VERSION_EQ".

PERL_VERSION

DEPRECATED! It is planned to remove PERL_VERSION from a future release of Perl. Do not use it for new code; remove it from existing code.

The minor number component of the perl interpreter currently being compiled or executing. Between 1993 into 2020, this has ranged from 0 to 33.

Instead use one of the version comparison macros. See "PERL_VERSION_EQ".

PERL_VERSION_EQ
PERL_VERSION_NE
PERL_VERSION_LT
PERL_VERSION_LE
PERL_VERSION_GT
PERL_VERSION_GE

Returns whether or not the perl currently being compiled has the specified relationship to the perl given by the parameters. For example,

#if PERL_VERSION_GT(5,24,2)
  code that will only be compiled on perls after v5.24.2
#else
  fallback code
#endif

Note that this is usable in making compile-time decisions

You may use the special value '*' for the final number to mean ALL possible values for it. Thus,

#if PERL_VERSION_EQ(5,31,'*')

means all perls in the 5.31 series. And

#if PERL_VERSION_NE(5,24,'*')

means all perls EXCEPT 5.24 ones. And

#if PERL_VERSION_LE(5,9,'*')

is effectively

#if PERL_VERSION_LT(5,10,0)

This means you don't have to think so much when converting from the existing deprecated PERL_VERSION to using this macro:

#if PERL_VERSION <= 9

becomes

#if PERL_VERSION_LE(5,9,'*')
    bool  PERL_VERSION_EQ(const U8 major, const U8 minor,
                          const U8 patch)
prescan_version

Validate that a given string can be parsed as a version object, but doesn't actually perform the parsing. Can use either strict or lax validation rules. Can optionally set a number of hint variables to save the parsing code some time when tokenizing.

    const char*  prescan_version(const char *s, bool strict,
                                 const char** errstr, bool *sqv,
                                 int *ssaw_decimal, int *swidth,
                                 bool *salpha)
scan_version

Returns a pointer to the next character after the parsed version string, as well as upgrading the passed in SV to an RV.

Function must be called with an already existing SV like

sv = newSV(0);
s = scan_version(s, SV *sv, bool qv);

Performs some preprocessing to the string to ensure that it has the correct characteristics of a version. Flags the object if it contains an underscore (which denotes this is an alpha version). The boolean qv denotes that the version should be interpreted as if it had multiple decimals, even if it doesn't.

    const char*  scan_version(const char *s, SV *rv, bool qv)
upg_version

In-place upgrade of the supplied SV to a version object.

SV *sv = upg_version(SV *sv, bool qv);

Returns a pointer to the upgraded SV. Set the boolean qv if you want to force this SV to be interpreted as an "extended" version.

    SV*  upg_version(SV *ver, bool qv)
vcmp

Version object aware cmp. Both operands must already have been converted into version objects.

    int  vcmp(SV *lhv, SV *rhv)
vnormal

Accepts a version object and returns the normalized string representation. Call like:

sv = vnormal(rv);

NOTE: you can pass either the object directly or the SV contained within the RV.

The SV returned has a refcount of 1.

    SV*  vnormal(SV *vs)
vnumify

Accepts a version object and returns the normalized floating point representation. Call like:

sv = vnumify(rv);

NOTE: you can pass either the object directly or the SV contained within the RV.

The SV returned has a refcount of 1.

    SV*  vnumify(SV *vs)
vstringify

In order to maintain maximum compatibility with earlier versions of Perl, this function will return either the floating point notation or the multiple dotted notation, depending on whether the original version contained 1 or more dots, respectively.

The SV returned has a refcount of 1.

    SV*  vstringify(SV *vs)
vverify

Validates that the SV contains valid internal structure for a version object. It may be passed either the version object (RV) or the hash itself (HV). If the structure is valid, it returns the HV. If the structure is invalid, it returns NULL.

SV *hv = vverify(sv);

Note that it only confirms the bare minimum structure (so as not to get confused by derived classes which may contain additional hash entries):

  • The SV is an HV or a reference to an HV

  • The hash contains a "version" key

  • The "version" key has a reference to an AV as its value

    SV*  vverify(SV *vs)

Warning and Dieing

In all these calls, the U32 wn parameters are warning category constants. You can see the ones currently available in "Category Hierarchy" in warnings, just capitalize all letters in the names and prefix them by WARN_. So, for example, the category void used in a perl program becomes WARN_VOID when used in XS code and passed to one of the calls below.

ckWARN
ckWARN2
ckWARN3
ckWARN4

These return a boolean as to whether or not warnings are enabled for any of the warning category(ies) parameters: w, w1, ....

Should any of the categories by default be enabled even if not within the scope of use warnings, instead use the "ckWARN_d" macros.

The categories must be completely independent, one may not be subclassed from the other.

    bool  ckWARN (U32 w)
    bool  ckWARN2(U32 w1, U32 w2)
    bool  ckWARN3(U32 w1, U32 w2, U32 w3)
    bool  ckWARN4(U32 w1, U32 w2, U32 w3, U32 w4)
ckWARN_d
ckWARN2_d
ckWARN3_d
ckWARN4_d

Like "ckWARN", but for use if and only if the warning category(ies) is by default enabled even if not within the scope of use warnings.

    bool  ckWARN_d (U32 w)
    bool  ckWARN2_d(U32 w1, U32 w2)
    bool  ckWARN3_d(U32 w1, U32 w2, U32 w3)
    bool  ckWARN4_d(U32 w1, U32 w2, U32 w3, U32 w4)
ck_warner
ck_warner_d

If none of the warning categories given by err are enabled, do nothing; otherwise call "warner" or "warner_nocontext" with the passed-in parameters;.

err must be one of the "packWARN", packWARN2, packWARN3, packWARN4 macros populated with the appropriate number of warning categories.

The two forms differ only in that ck_warner_d should be used if warnings for any of the categories are by default enabled.

NOTE: ck_warner must be explicitly called as Perl_ck_warner with an aTHX_ parameter.

NOTE: ck_warner_d must be explicitly called as Perl_ck_warner_d with an aTHX_ parameter.

    void  Perl_ck_warner(pTHX_ U32 err, const char* pat, ...)
CLEAR_ERRSV

Clear the contents of $@, setting it to the empty string.

This replaces any read-only SV with a fresh SV and removes any magic.

    void  CLEAR_ERRSV()
croak
croak_nocontext

These are XS interfaces to Perl's die function.

They take a sprintf-style format pattern and argument list, which are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message will be used as an exception, by default returning control to the nearest enclosing eval, but subject to modification by a $SIG{__DIE__} handler. In any case, these croak functions never return normally.

For historical reasons, if pat is null then the contents of ERRSV ($@) will be used as an error message or object instead of building an error message from arguments. If you want to throw a non-string object, or build an error message in an SV yourself, it is preferable to use the "croak_sv" function, which does not involve clobbering ERRSV.

The two forms differ only in that croak_nocontext does not take a thread context (aTHX) parameter. It is usually preferred as it takes up fewer bytes of code than plain Perl_croak, and time is rarely a critical resource when you are about to throw an exception.

NOTE: croak must be explicitly called as Perl_croak with an aTHX_ parameter.

    void  Perl_croak     (pTHX_ const char* pat, ...)
    void  croak_nocontext(const char* pat, ...)
croak_no_modify

This encapsulates a common reason for dying, generating terser object code than using the generic Perl_croak. It is exactly equivalent to Perl_croak(aTHX_ "%s", PL_no_modify) (which expands to something like "Modification of a read-only value attempted").

Less code used on exception code paths reduces CPU cache pressure.

    void  croak_no_modify()
croak_sv

This is an XS interface to Perl's die function.

baseex is the error message or object. If it is a reference, it will be used as-is. Otherwise it is used as a string, and if it does not end with a newline then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will be used as an exception, by default returning control to the nearest enclosing eval, but subject to modification by a $SIG{__DIE__} handler. In any case, the croak_sv function never returns normally.

To die with a simple string message, the "croak" function may be more convenient.

    void  croak_sv(SV *baseex)
die

Behaves the same as "croak", except for the return type. It should be used only where the OP * return type is required. The function never actually returns.

NOTE: die must be explicitly called as Perl_die with an aTHX_ parameter.

    OP*  Perl_die(pTHX_ const char* pat, ...)
die_sv
die_nocontext

These ehave the same as "croak_sv", except for the return type. It should be used only where the OP * return type is required. The functions never actually return.

The two forms differ only in that die_nocontext does not take a thread context (aTHX) parameter, so is used in situations where the caller doesn't already have the thread context.

    OP*  die_sv       (SV *baseex)
    OP*  die_nocontext(const char* pat, ...)
ERRSV

Returns the SV for $@, creating it if needed.

    SV *  ERRSV
packWARN
packWARN2
packWARN3
packWARN4

These macros are used to pack warning categories into a single U32 to pass to macros and functions that take a warning category parameter. The number of categories to pack is given by the name, with a corresponding number of category parameters passed.

    U32  packWARN (U32 w1)
    U32  packWARN2(U32 w1, U32 w2)
    U32  packWARN3(U32 w1, U32 w2, U32 w3)
    U32  packWARN4(U32 w1, U32 w2, U32 w3, U32 w4)
PL_curcop

The currently active COP (control op) roughly representing the current statement in the source.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    COP*  PL_curcop
PL_curstash

The stash for the package code will be compiled into.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    HV*  PL_curstash
PL_defgv

The GV representing *_. Useful for access to $_.

On threaded perls, each thread has an independent copy of this variable; each initialized at creation time with the current value of the creating thread's copy.

    GV *  PL_defgv
SANE_ERRSV

Clean up ERRSV so we can safely set it.

This replaces any read-only SV with a fresh writable copy and removes any magic.

    void  SANE_ERRSV()
vcroak

This is an XS interface to Perl's die function.

pat and args are a sprintf-style format pattern and encapsulated argument list. These are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message will be used as an exception, by default returning control to the nearest enclosing eval, but subject to modification by a $SIG{__DIE__} handler. In any case, the croak function never returns normally.

For historical reasons, if pat is null then the contents of ERRSV ($@) will be used as an error message or object instead of building an error message from arguments. If you want to throw a non-string object, or build an error message in an SV yourself, it is preferable to use the "croak_sv" function, which does not involve clobbering ERRSV.

    void  vcroak(const char* pat, va_list* args)
vwarn

This is an XS interface to Perl's warn function.

This is like "warn", but args are an encapsulated argument list.

Unlike with "vcroak", pat is not permitted to be null.

    void  vwarn(const char* pat, va_list* args)
vwarner

This is like "warner", but args are an encapsulated argument list.

    void  vwarner(U32 err, const char* pat, va_list* args)
warn
warn_nocontext

These are XS interfaces to Perl's warn function.

They take a sprintf-style format pattern and argument list, which are used to generate a string message. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will by default be written to standard error, but this is subject to modification by a $SIG{__WARN__} handler.

Unlike with "croak", pat is not permitted to be null.

The two forms differ only in that warn_nocontext does not take a thread context (aTHX) parameter, so is used in situations where the caller doesn't already have the thread context.

NOTE: warn must be explicitly called as Perl_warn with an aTHX_ parameter.

    void  Perl_warn     (pTHX_ const char* pat, ...)
    void  warn_nocontext(const char* pat, ...)
warner
warner_nocontext

These output a warning of the specified category (or categories) given by err, using the sprintf-style format pattern pat, and argument list.

err must be one of the "packWARN", packWARN2, packWARN3, packWARN4 macros populated with the appropriate number of warning categories. If any of the warning categories they specify is fatal, a fatal exception is thrown.

In any event a message is generated by the pattern and arguments. If the message does not end with a newline, then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will by default be written to standard error, but this is subject to modification by a $SIG{__WARN__} handler.

pat is not permitted to be null.

The two forms differ only in that warner_nocontext does not take a thread context (aTHX) parameter, so is used in situations where the caller doesn't already have the thread context.

These functions differ from the similarly named "warn" functions, in that the latter are for XS code to unconditionally display a warning, whereas these are for code that may be compiling a perl program, and does extra checking to see if the warning should be fatal.

NOTE: warner must be explicitly called as Perl_warner with an aTHX_ parameter.

    void  Perl_warner     (pTHX_ U32 err, const char* pat, ...)
    void  warner_nocontext(U32 err, const char* pat, ...)
warn_sv

This is an XS interface to Perl's warn function.

baseex is the error message or object. If it is a reference, it will be used as-is. Otherwise it is used as a string, and if it does not end with a newline then it will be extended with some indication of the current location in the code, as described for "mess_sv".

The error message or object will by default be written to standard error, but this is subject to modification by a $SIG{__WARN__} handler.

To warn with a simple string message, the "warn" function may be more convenient.

    void  warn_sv(SV *baseex)

XS

xsubpp compiles XS code into C. See "xsubpp" in perlutil.

ax

Variable which is setup by xsubpp to indicate the stack base offset, used by the ST, XSprePUSH and XSRETURN macros. The dMARK macro must be called prior to setup the MARK variable.

    I32  ax
CLASS

Variable which is setup by xsubpp to indicate the class name for a C++ XS constructor. This is always a char*. See "THIS".

    char*  CLASS
dAX

Sets up the ax variable. This is usually handled automatically by xsubpp by calling dXSARGS.

    dAX;
dAXMARK

Sets up the ax variable and stack marker variable mark. This is usually handled automatically by xsubpp by calling dXSARGS.

    dAXMARK;
dITEMS

Sets up the items variable. This is usually handled automatically by xsubpp by calling dXSARGS.

    dITEMS;
dMY_CXT_SV

Now a placeholder that declares nothing

    dMY_CXT_SV;
dUNDERBAR

Sets up any variable needed by the UNDERBAR macro. It used to define padoff_du, but it is currently a noop. However, it is strongly advised to still use it for ensuring past and future compatibility.

    dUNDERBAR;
dXSARGS

Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. Sets up the ax and items variables by calling dAX and dITEMS. This is usually handled automatically by xsubpp.

    dXSARGS;
dXSI32

Sets up the ix variable for an XSUB which has aliases. This is usually handled automatically by xsubpp.

    dXSI32;
items

Variable which is setup by xsubpp to indicate the number of items on the stack. See "Variable-length Parameter Lists" in perlxs.

    I32  items
ix

Variable which is setup by xsubpp to indicate which of an XSUB's aliases was used to invoke it. See "The ALIAS: Keyword" in perlxs.

    I32  ix
RETVAL

Variable which is setup by xsubpp to hold the return value for an XSUB. This is always the proper type for the XSUB. See "The RETVAL Variable" in perlxs.

    type  RETVAL
ST

Used to access elements on the XSUB's stack.

    SV*  ST(int ix)
THIS

Variable which is setup by xsubpp to designate the object in a C++ XSUB. This is always the proper type for the C++ object. See "CLASS" and "Using XS With C++" in perlxs.

    type  THIS
UNDERBAR

The SV* corresponding to the $_ variable. Works even if there is a lexical $_ in scope.

XS

Macro to declare an XSUB and its C parameter list. This is handled by xsubpp. It is the same as using the more explicit XS_EXTERNAL macro; the latter is preferred.

XS_EXTERNAL

Macro to declare an XSUB and its C parameter list explicitly exporting the symbols.

XS_INTERNAL

Macro to declare an XSUB and its C parameter list without exporting the symbols. This is handled by xsubpp and generally preferable over exporting the XSUB symbols unnecessarily.

XSPROTO

Macro used by "XS_INTERNAL" and "XS_EXTERNAL" to declare a function prototype. You probably shouldn't be using this directly yourself.

Undocumented elements

The following functions have been flagged as part of the public API, but are currently undocumented. Use them at your own risk, as the interfaces are subject to change. Functions that are not listed in this document are not intended for public use, and should NOT be used under any circumstances.

If you feel you need to use one of these functions, first send email to perl5-porters@perl.org. It may be that there is a good reason for the function not being documented, and it should be removed from this list; or it may just be that no one has gotten around to documenting it. In the latter case, you will be asked to submit a patch to document the function. Once your patch is accepted, it will indicate that the interface is stable (unless it is explicitly marked otherwise) and usable by you.

AUTHORS

Until May 1997, this document was maintained by Jeff Okamoto <okamoto@corp.hp.com>. It is now maintained as part of Perl itself.

With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, Stephen McCamant, and Gurusamy Sarathy.

API Listing originally by Dean Roehrich <roehrich@cray.com>.

Updated to be autogenerated from comments in the source by Benjamin Stuhl.

SEE ALSO

config.h, perlapio, perlcall, perlclib, perlfilter, perlguts, perlintern, perlinterp, perliol, perlmroapi, perlreguts, perlxs