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

# NAME

perlintern - autogenerated documentation of purely internal Perl functions

# DESCRIPTION

This file is the autogenerated documentation of functions in the Perl interpreter that are documented using Perl's internal documentation format but are not marked as part of the Perl API. In other words, they are not for use in extensions!

It has the same sections as perlapi, though some may be empty.

# AV Handling

`av_fetch_simple`

  This is a cut-down version of av_fetch that assumes that the array is very straightforward - no magic, not readonly, and AvREAL - and that `key` is not negative. This function MUST NOT be used in situations where any of those assumptions may not hold.

  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*`.

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

      SV **  av_fetch_simple(AV *av, SSize_t key, I32 lval)

`AvFILLp`

  If the array `av` is empty, this returns -1; otherwise it returns the maximum value of the indices of all the array elements which are currently defined in `av`. It does not handle magic, hence the `p` private indication in its name.

      SSize_t  AvFILLp(AV* av)

`av_new_alloc`

  This implements "`newAV_alloc_x`" in perlapi and "`newAV_alloc_xz`" in perlapi, which are the public API for this functionality.

  Creates a new AV and allocates its SV* array.

  This is similar to, but more efficient than doing:

      AV *av = newAV();
      av_extend(av, key);

  The size parameter is used to pre-allocate a SV* array large enough to hold at least elements `0..(size-1)`. `size` must be at least 1.

  The `zeroflag` parameter controls whether or not the array is NULL initialized.

      AV *  av_new_alloc(SSize_t size, bool zeroflag)

`av_store_simple`

  This is a cut-down version of av_store that assumes that the array is very straightforward - no magic, not readonly, and AvREAL - and that `key` is not negative. This function MUST NOT be used in situations where any of those assumptions may not hold.

  Stores an SV in an array. The array index is specified as `key`. 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.

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

      SV **  av_store_simple(AV *av, SSize_t key, SV *val)

# Callback Functions

`dowantarray`

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

  Implements the deprecated "`GIMME`" in perlapi.

      U8  dowantarray()

`leave_scope`

  Implements `LEAVE_SCOPE` which you should use instead.

      void  leave_scope(I32 base)

`magic_freedestruct`

  This function is called via magic to implement the `mortal_destructor_sv()` and `mortal_destructor_x()` functions. It should not be called directly and has no user servicable parts.

      int  magic_freedestruct(SV *sv, MAGIC *mg)

`mortal_svfunc_x`

  This function arranges for a C function reference to be called at the end of the current statement with the arguments provided. It is a wrapper around `mortal_destructor_sv()` which ensures that the latter function is called appropriately.

  Be aware that there is a signficant difference in timing between the end of the current statement and the end of the current pseudo block. If you are looking for a mechanism to trigger a function at the end of the current pseudo block you should look at `SAVEDESTRUCTORX()` instead of this function.

      void  mortal_svfunc_x(SVFUNC_t f, SV *p)

`pop_scope`

  Implements "`LEAVE`" in perlapi

      void  pop_scope()

`push_scope`

  Implements "`ENTER`" in perlapi

      void  push_scope()

`save_adelete`

  Implements `SAVEADELETE`.

      void  save_adelete(AV *av, SSize_t key)

`save_freercpv`

  Implements `SAVEFREERCPV`.

  Saves and frees a refcounted string. Calls rcpv_free() on the argument when the current pseudo block is finished.

      void  save_freercpv(char *rcpv)

`save_generic_pvref`

  Implements `SAVEGENERICPV`.

  Like save_pptr(), but also Safefree()s the new value if it is different from the old one. Can be used to restore a global char* to its prior contents, freeing new value.

      void  save_generic_pvref(char **str)

`save_generic_svref`

  Implements `SAVEGENERICSV`.

  Like save_sptr(), but also SvREFCNT_dec()s the new value. Can be used to restore a global SV to its prior contents, freeing new value.

      void  save_generic_svref(SV **sptr)

`save_hdelete`

  Implements `SAVEHDELETE`.

      void  save_hdelete(HV *hv, SV *keysv)

`save_hints`

  Implements `SAVEHINTS`.

      void  save_hints()

`save_op`

  Implements `SAVEOP`.

      void  save_op()

`save_padsv_and_mortalize`

  Implements `SAVEPADSVANDMORTALIZE`.

      void  save_padsv_and_mortalize(PADOFFSET off)

`save_pushptr`

  The refcnt of object `ptr` will be decremented at the end of the current pseudo-block. `type` gives the type of `ptr`, expressed as one of the constants in scope.h whose name begins with `SAVEt_`.

  This is the underlying implementation of several macros, like `SAVEFREESV`.

      void  save_pushptr(void * const ptr, const int type)

`save_rcpv`

  Implements `SAVERCPV`.

  Saves and restores a refcounted string, similar to what save_generic_svref would do for a SV*. Can be used to restore a refcounted string to its previous state. Performs the appropriate refcount counting so that nothing should leak or be prematurely freed.

      void  save_rcpv(char **prcpv)

`save_scalar_at`

  A helper function for localizing the SV referenced by `*sptr`.

  If `SAVEf_KEEPOLDELEM` is set in in `flags`, the function returns the input scalar untouched.

  Otherwise it replaces `*sptr` with a new `undef` scalar, and returns that. The new scalar will have the old one's magic (if any) copied to it. If there is such magic, and `SAVEf_SETMAGIC` is set in in `flags`, 'set' magic will be processed on the new scalar. If unset, 'set' magic will be skipped. The latter typically means that assignment will soon follow (e.g., `'local $x = $y'`), and that will handle the magic.

      SV *  save_scalar_at(SV **sptr, const U32 flags)

`save_set_svflags`

  Implements `SAVESETSVFLAGS`.

  Set the SvFLAGS specified by mask to the values in val

      void  save_set_svflags(SV *sv, U32 mask, U32 val)

`save_shared_pvref`

  Implements `SAVESHAREDPV`.

  Like save_generic_pvref(), but uses PerlMemShared_free() rather than Safefree(). Can be used to restore a shared global char* to its prior contents, freeing new value.

      void  save_shared_pvref(char **str)

`save_vptr`

  Implements `SAVEVPTR`.

      void  save_vptr(void *ptr)

# Casting

There are currently no internal API items in Casting

# Character case changing

There are currently no internal API items in Character case changing

# Character classification

There are currently no internal API items in Character classification

# Compiler and Preprocessor information

There are currently no internal API items in Compiler and Preprocessor information

# Compiler directives

There are currently no internal API items in Compiler directives

# Compile-time scope hooks

`BhkENTRY`

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

  Return an entry from the BHK structure. `which` is a preprocessor token indicating which entry to return. If the appropriate flag is not set this will return `NULL`. The type of the return value depends on which entry you ask for.

      void *  BhkENTRY(BHK *hk, token which)

`BhkFLAGS`

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

  Return the BHK's flags.

      U32  BhkFLAGS(BHK *hk)

`CALL_BLOCK_HOOKS`

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

  Call all the registered block hooks for type `which`. `which` is a preprocessing token; the type of `arg` depends on `which`.

      void  CALL_BLOCK_HOOKS(token which, arg)

# Concurrency

`CVf_SLABBED`
`CvROOT`
`CvSTART`

  Described in perlguts.

`CX_CUR`

  Described in perlguts.

      CX_CUR()

`CXINC`

  Described in perlguts.

`CX_LEAVE_SCOPE`

  Described in perlguts.

      void  CX_LEAVE_SCOPE(PERL_CONTEXT* cx)

`CX_POP`

  Described in perlguts.

      void  CX_POP(PERL_CONTEXT* cx)

`cxstack`

  Described in perlguts.

`cxstack_ix`

  Described in perlguts.

`CXt_BLOCK`
`CXt_EVAL`
`CXt_FORMAT`
`CXt_GIVEN`
`CXt_LOOP_ARY`
`CXt_LOOP_LAZYIV`
`CXt_LOOP_LAZYSV`
`CXt_LOOP_LIST`
`CXt_LOOP_PLAIN`
`CXt_NULL`
`CXt_SUB`
`CXt_SUBST`
`CXt_WHEN`

  Described in perlguts.

`cx_type`

  Described in perlguts.

`dounwind`

  Described in perlguts.

      void  dounwind(I32 cxix)

`my_fork`

  This is for the use of `PerlProc_fork` as a wrapper for the C library fork(2) on some platforms to hide some platform quirks. It should not be used except through `PerlProc_fork`.

      Pid_t  my_fork()

`PERL_CONTEXT`

  Described in perlguts.

# COPs and Hint Hashes

There are currently no internal API items in COPs and Hint Hashes

# Custom Operators

`core_prototype`

  This function assigns the prototype of the named core function to `sv`, or to a new mortal SV if `sv` is `NULL`. It returns the modified `sv`, or `NULL` if the core function has no prototype. `code` is a code as returned by `keyword()`. It must not be equal to 0.

      SV *  core_prototype(SV *sv, const char *name, const int code,
                           int * const opnum)

# CV Handling

`CvREFCOUNTED_ANYSV`

  If true, indicates that the `CvXSUBANY(cv).any_sv` member contains an SV pointer whose reference count should be decremented when the CV itself is freed. In addition, `cv_clone()` will increment the reference count, and `sv_dup()` will duplicate the entire pointed-to SV if this flag is set.

  Any CV that wraps an XSUB has an `ANY` union that the XSUB function is free to use for its own purposes. It may be the case that the code wishes to store an SV in the `any_sv` member of this union. By setting this flag, this SV reference will be properly reclaimed or duplicated when the CV itself is.

      bool  CvREFCOUNTED_ANYSV(CV *cv)

`CvREFCOUNTED_ANYSV_off`

  Helper macro to turn off the `CvREFCOUNTED_ANYSV` flag.

      void  CvREFCOUNTED_ANYSV_off(CV *cv)

`CvREFCOUNTED_ANYSV_on`

  Helper macro to turn on the `CvREFCOUNTED_ANYSV` flag.

      void  CvREFCOUNTED_ANYSV_on(CV *cv)

`CvWEAKOUTSIDE`

  Each CV has a pointer, `CvOUTSIDE()`, to its lexically enclosing CV (if any). Because pointers to anonymous sub prototypes are stored in `&` pad slots, it is a possible to get a circular reference, with the parent pointing to the child and vice-versa. To avoid the ensuing memory leak, we do not increment the reference count of the CV pointed to by `CvOUTSIDE` in the one specific instance that the parent has a `&` pad slot pointing back to us. In this case, we set the `CvWEAKOUTSIDE` flag in the child. This allows us to determine under what circumstances we should decrement the refcount of the parent when freeing the child.

  There is a further complication with non-closure anonymous subs (i.e. those that do not refer to any lexicals outside that sub). In this case, the anonymous prototype is shared rather than being cloned. This has the consequence that the parent may be freed while there are still active children, e.g.,

      BEGIN { $a = sub { eval '$x' } }

  In this case, the BEGIN is freed immediately after execution since there are no active references to it: the anon sub prototype has `CvWEAKOUTSIDE` set since it's not a closure, and $a points to the same CV, so it doesn't contribute to BEGIN's refcount either. When $a is executed, the `eval '$x'` causes the chain of `CvOUTSIDE`s to be followed, and the freed BEGIN is accessed.

  To avoid this, whenever a CV and its associated pad is freed, any `&` entries in the pad are explicitly removed from the pad, and if the refcount of the pointed-to anon sub is still positive, then that child's `CvOUTSIDE` is set to point to its grandparent. This will only occur in the single specific case of a non-closure anon prototype having one or more active references (such as `$a` above).

  One other thing to consider is that a CV may be merely undefined rather than freed, eg `undef &foo`. In this case, its refcount may not have reached zero, but we still delete its pad and its `CvROOT` etc. Since various children may still have their `CvOUTSIDE` pointing at this undefined CV, we keep its own `CvOUTSIDE` for the time being, so that the chain of lexical scopes is unbroken. For example, the following should print 123:

      my $x = 123;
      sub tmp { sub { eval '$x' } }
      my $a = tmp();
      undef &tmp;
      print  $a->();

      bool  CvWEAKOUTSIDE(CV *cv)

`docatch`

  Interpose, for the current op and RUNOPS loop,

      - a new JMPENV stack catch frame, and
      - an inner RUNOPS loop to run all the remaining ops following the
        current PL_op.

  Then handle any exceptions raised while in that loop. For a caught eval at this level, re-enter the loop with the specified restart op (i.e. the op following the OP_LEAVETRY etc); otherwise re-throw the exception.

  docatch() is intended to be used like this:

      PP(pp_entertry)
      {
          if (CATCH_GET)
              return docatch(Perl_pp_entertry);

          ... rest of function ...
          return PL_op->op_next;
      }

  If a new catch frame isn't needed, the op behaves normally. Otherwise it calls docatch(), which recursively calls pp_entertry(), this time with CATCH_GET() false, so the rest of the body of the entertry is run. Then docatch() calls CALLRUNOPS() which executes all the ops following the entertry. When the loop finally finishes, control returns to docatch(), which pops the JMPENV and returns to the parent pp_entertry(), which itself immediately returns. Note that *all* subsequent ops are run within the inner RUNOPS loop, not just the body of the eval. For example, in

      sub TIEARRAY { eval {1}; my $x }
      tie @a, "main";

  at the point the 'my' is executed, the C stack will look something like:

      #10 main()
      #9  perl_run()              # JMPENV_PUSH level 1 here
      #8  S_run_body()
      #7  Perl_runops_standard()  # main RUNOPS loop
      #6  Perl_pp_tie()
      #5  Perl_call_sv()
      #4  Perl_runops_standard()  # unguarded RUNOPS loop: no new JMPENV
      #3  Perl_pp_entertry()
      #2  S_docatch()             # JMPENV_PUSH level 2 here
      #1  Perl_runops_standard()  # docatch()'s RUNOPs loop
      #0  Perl_pp_padsv()

  Basically, any section of the perl core which starts a RUNOPS loop may make a promise that it will catch any exceptions and restart the loop if necessary. If it's not prepared to do that (like call_sv() isn't), then it sets CATCH_GET() to true, so that any later eval-like code knows to set up a new handler and loop (via docatch()).

  See "Exception handing" in perlinterp for further details.

      OP *  docatch(Perl_ppaddr_t firstpp)

# Debugging

`comma_aDEPTH`

  Some functions when compiled under DEBUGGING take an extra final argument named `depth`, indicating the C stack depth. This argument is omitted otherwise. This macro expands to either `, depth` under DEBUGGING, or to nothing at all when not under DEBUGGING, reducing the number of `#ifdef`'s in the code.

  The program is responsible for maintaining the correct value for `depth`.

      comma_aDEPTH

`comma_pDEPTH`

  This is used in the prototype declarations for functions that take a "`comma_aDEPTH`" final parameter, much like `pTHX_` is used in functions that take a thread context initial parameter.

`debop`

  Implements -Dt perl command line option on OP `o`.

      I32  debop(const OP *o)

`debprof`

  Called to indicate that `o` was executed, for profiling purposes under the `-DP` command line option.

      void  debprof(const OP *o)

`debprofdump`

  Dumps the contents of the data collected by the `-DP` perl command line option.

      void  debprofdump()

`debug_aDEPTH`

  Same as "`comma_aDEPTH`" but with no leading argument. Intended for functions with no normal arguments, and used by "`comma_aDEPTH`" itself.

      debug_aDEPTH

`debug_pDEPTH`

  Same as "`comma_pDEPTH`" but with no leading argument. Intended for functions with no normal arguments, and used by "`comma_pDEPTH`" itself.

      debug_pDEPTH

`free_c_backtrace`

  Deallocates a backtrace received from get_c_backtrace.

      void  free_c_backtrace(Perl_c_backtrace *bt)

`get_c_backtrace`

  Collects the backtrace (aka "stacktrace") into a single linear malloced buffer, which the caller must `Perl_free_c_backtrace()`.

  Scans the frames back by `depth + skip`, then drops the `skip` innermost, returning at most `depth` frames.

      Perl_c_backtrace *  get_c_backtrace(int max_depth, int skip)

`PL_DBsingle`

  When Perl is run in debugging mode, with the -d switch, this SV is a boolean which indicates whether subs are being single-stepped. Single-stepping is automatically turned on after every step. This is the C variable which corresponds to Perl's $DB::single variable. See `"PL_DBsub"`.

  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.

      SV *  PL_DBsingle

`PL_DBsub`

  When Perl is run in debugging mode, with the -d switch, this GV contains the SV which holds the name of the sub being debugged. This is the C variable which corresponds to Perl's $DB::sub variable. See `"PL_DBsingle"`.

  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_DBsub

`PL_DBtrace`

  Trace variable used when Perl is run in debugging mode, with the -d switch. This is the C variable which corresponds to Perl's $DB::trace variable. See `"PL_DBsingle"`.

  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.

      SV *  PL_DBtrace

`runops_debug`

  Described in perlguts.

      int  runops_debug()

`runops_standard`

  Described in perlguts.

      int  runops_standard()

# Display functions

`sv_peek`

  Implements `SvPEEK`

      char *  sv_peek(SV *sv)

# Embedding, Threads, and Interpreter Cloning

`cv_dump`

  dump the contents of a CV

      void  cv_dump(const CV *cv, const char *title)

`cv_forget_slab`

  When a CV has a reference count on its slab (`CvSLABBED`), it is responsible for making sure it is freed. (Hence, no two CVs should ever have a reference count on the same slab.) The CV only needs to reference the slab during compilation. Once it is compiled and `CvROOT` attached, it has finished its job, so it can forget the slab.

      void  cv_forget_slab(CV *cv)

`do_dump_pad`

  Dump the contents of a padlist

      void  do_dump_pad(I32 level, PerlIO *file, PADLIST *padlist,
                        int full)

`get_context`

  Implements "`PERL_GET_CONTEXT`" in perlapi, which you should use instead.

      void *  get_context()

`pad_alloc_name`

  Allocates a place in the currently-compiling pad (via "pad_alloc" in perlapi) and then stores a name for that entry. `name` is adopted and becomes the name entry; it must already contain the name string. `typestash` and `ourstash` and the `padadd_STATE` flag get added to `name`. None of the other processing of "pad_add_name_pvn" in perlapi is done. Returns the offset of the allocated pad slot.

      PADOFFSET  pad_alloc_name(PADNAME *name, U32 flags, HV *typestash,
                                HV *ourstash)

`pad_block_start`

  Update the pad compilation state variables on entry to a new block.

      void  pad_block_start(int full)

`pad_check_dup`

  Check for duplicate declarations: report any of:

      * a 'my' in the current scope with the same name;
      * an 'our' (anywhere in the pad) with the same name and the
        same stash as 'ourstash'

  `is_our` indicates that the name to check is an `"our"` declaration.

      void  pad_check_dup(PADNAME *name, U32 flags, const HV *ourstash)

`pad_findlex`

  Find a named lexical anywhere in a chain of nested pads. Add fake entries in the inner pads if it's found in an outer one.

  Returns the offset in the bottom pad of the lex or the fake lex. `cv` is the CV in which to start the search, and seq is the current `cop_seq` to match against. If `warn` is true, print appropriate warnings. The `out_`* vars return values, and so are pointers to where the returned values should be stored. `out_capture`, if non-null, requests that the innermost instance of the lexical is captured; `out_name` is set to the innermost matched pad name or fake pad name; `out_flags` returns the flags normally associated with the `PARENT_FAKELEX_FLAGS` field of a fake pad name.

  Note that `pad_findlex()` is recursive; it recurses up the chain of CVs, then comes back down, adding fake entries as it goes. It has to be this way because fake names in anon prototypes have to store in `xpadn_low` the index into the parent pad.

      PADOFFSET  pad_findlex(const char *namepv, STRLEN namelen,
                             U32 flags, const CV *cv, U32 seq, int warn,
                             SV **out_capture, PADNAME **out_name,
                             int *out_flags)

`pad_fixup_inner_anons`

  For any anon CVs in the pad, change `CvOUTSIDE` of that CV from `old_cv` to `new_cv` if necessary. Needed when a newly-compiled CV has to be moved to a pre-existing CV struct.

      void  pad_fixup_inner_anons(PADLIST *padlist, CV *old_cv,
                                  CV *new_cv)

`pad_free`

  Free the SV at offset po in the current pad.

      void  pad_free(PADOFFSET po)

`pad_leavemy`

  Cleanup at end of scope during compilation: set the max seq number for lexicals in this scope and warn of any lexicals that never got introduced.

      OP *  pad_leavemy()

`padlist_dup`

  Duplicates a pad.

      PADLIST *  padlist_dup(PADLIST *srcpad, CLONE_PARAMS *param)

`padname_dup`

  Duplicates a pad name.

      PADNAME *  padname_dup(PADNAME *src, CLONE_PARAMS *param)

`padnamelist_dup`

  Duplicates a pad name list.

      PADNAMELIST *  padnamelist_dup(PADNAMELIST *srcpad,
                                     CLONE_PARAMS *param)

`pad_push`

  Push a new pad frame onto the padlist, unless there's already a pad at this depth, in which case don't bother creating a new one. Then give the new pad an `@_` in slot zero.

      void  pad_push(PADLIST *padlist, int depth)

`pad_reset`

  Mark all the current temporaries for reuse

      void  pad_reset()

`pad_setsv`

  Set the value at offset `po` in the current (compiling or executing) pad. Use the macro `PAD_SETSV()` rather than calling this function directly.

      void  pad_setsv(PADOFFSET po, SV *sv)

`pad_sv`

  Get the value at offset `po` in the current (compiling or executing) pad. Use macro `PAD_SV` instead of calling this function directly.

      SV *  pad_sv(PADOFFSET po)

`pad_swipe`

  Abandon the tmp in the current pad at offset `po` and replace with a new one.

      void  pad_swipe(PADOFFSET po, bool refadjust)

`set_context`

  Implements "`PERL_SET_CONTEXT`" in perlapi, which you should use instead.

      void  set_context(void *t)

`si_dup`

  Duplicate a stack info structure, returning a pointer to the cloned object.

      PERL_SI *  si_dup(PERL_SI *si, CLONE_PARAMS *param)

`ss_dup`

  Duplicate the save stack, returning a pointer to the cloned object.

      ANY *  ss_dup(PerlInterpreter *proto_perl, CLONE_PARAMS *param)

# Errno

`dSAVEDERRNO`

  Declare variables needed to save `errno` and any operating system specific error number.

      void  dSAVEDERRNO

`dSAVE_ERRNO`

  Declare variables needed to save `errno` and any operating system specific error number, and save them for optional later restoration by `RESTORE_ERRNO`.

      void  dSAVE_ERRNO

`RESTORE_ERRNO`

  Restore `errno` and any operating system specific error number that was saved by `dSAVE_ERRNO` or `RESTORE_ERRNO`.

      void  RESTORE_ERRNO

`SAVE_ERRNO`

  Save `errno` and any operating system specific error number for optional later restoration by `RESTORE_ERRNO`. Requires `dSAVEDERRNO` or `dSAVE_ERRNO` in scope.

      void  SAVE_ERRNO

`SETERRNO`

  Set `errno`, and on VMS set `vaxc$errno`.

      void  SETERRNO(int errcode, int vmserrcode)

# Exception Handling (simple) Macros

There are currently no internal API items in Exception Handling (simple) Macros

# Filesystem configuration values

There are currently no internal API items in Filesystem configuration values

# Floating point

There are currently no internal API items in Floating point

# General Configuration

There are currently no internal API items in General Configuration

# Global Variables

There are currently no internal API items in Global Variables

# GV Handling and Stashes

`amagic_applies`

  Check `sv` to see if the overloaded (active magic) operation `method` applies to it. If the sv is not SvROK or it is not an object then returns false, otherwise checks if the object is blessed into a class supporting overloaded operations, and returns true if a call to amagic_call() with this SV and the given method would trigger an amagic operation, including via the overload fallback rules or via nomethod. Thus a call like:

      amagic_applies(sv, string_amg, AMG_unary)

  would return true for an object with overloading set up in any of the following ways:

      use overload q("") => sub { ... };
      use overload q(0+) => sub { ... }, fallback => 1;

  and could be used to tell if a given object would stringify to something other than the normal default ref stringification.

  Note that the fact that this function returns TRUE does not mean you can succesfully perform the operation with amagic_call(), for instance any overloaded method might throw a fatal exception, however if this function returns FALSE you can be confident that it will NOT perform the given overload operation.

  `method` is an integer enum, one of the values found in overload.h, for instance `string_amg`.

  `flags` should be set to AMG_unary for unary operations.

      bool  amagic_applies(SV *sv, int method, int flags)

`gp_dup`

  Duplicate a typeglob, returning a pointer to the cloned object.

      GP *  gp_dup(GP * const gp, CLONE_PARAMS * const param)

`gv_handler`

  Implements `StashHANDLER`, which you should use instead

      CV *  gv_handler(HV *stash, I32 id)

`gv_stashsvpvn_cached`

  Returns a pointer to the stash for a specified package, possibly cached. Implements both "`gv_stashpvn`" in perlapi and "`gv_stashsv`" in perlapi.

  Requires one of either `namesv` or `namepv` to be non-null.

  If the flag `GV_CACHE_ONLY` is set, return the stash only if found in the cache; see "`gv_stashpvn`" in perlapi for details on the other `flags`.

  Note it is strongly preferred for `namesv` to be non-null, for performance reasons.

      HV *  gv_stashsvpvn_cached(SV *namesv, const char *name,
                                 U32 namelen, I32 flags)

`gv_try_downgrade`

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

  If the typeglob `gv` can be expressed more succinctly, by having something other than a real GV in its place in the stash, replace it with the optimised form. Basic requirements for this are that `gv` is a real typeglob, is sufficiently ordinary, and is only referenced from its package. This function is meant to be used when a GV has been looked up in part to see what was there, causing upgrading, but based on what was found it turns out that the real GV isn't required after all.

  If `gv` is a completely empty typeglob, it is deleted from the stash.

  If `gv` is a typeglob containing only a sufficiently-ordinary constant sub, the typeglob is replaced with a scalar-reference placeholder that more compactly represents the same thing.

      void  gv_try_downgrade(GV *gv)

# Hook manipulation

There are currently no internal API items in Hook manipulation

# HV Handling

`hv_eiter_p`

  Implements `HvEITER` which you should use instead.

  NOTE: `hv_eiter_p` must be explicitly called as `Perl_hv_eiter_p` with an `aTHX_` parameter.

      HE **  Perl_hv_eiter_p(pTHX_ HV *hv)

`hv_eiter_set`

  Implements `HvEITER_set` which you should use instead.

  NOTE: `hv_eiter_set` must be explicitly called as `Perl_hv_eiter_set` with an `aTHX_` parameter.

      void  Perl_hv_eiter_set(pTHX_ HV *hv, HE *eiter)

`hv_ename_add`

  Adds a name to a stash's internal list of effective names. See `"hv_ename_delete"`.

  This is called when a stash is assigned to a new location in the symbol table.

      void  hv_ename_add(HV *hv, const char *name, U32 len, U32 flags)

`hv_ename_delete`

  Removes a name from a stash's internal list of effective names. If this is the name returned by `HvENAME`, then another name in the list will take its place (`HvENAME` will use it).

  This is called when a stash is deleted from the symbol table.

      void  hv_ename_delete(HV *hv, const char *name, U32 len,
                            U32 flags)

`hv_fill`

  Returns the number of hash buckets that happen to be in use.

  This function implements the `HvFILL` macro which you should use instead.

  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_placeholders_get`

  Implements `HvPLACEHOLDERS_get`, which you should use instead.

  NOTE: `hv_placeholders_get` must be explicitly called as `Perl_hv_placeholders_get` with an `aTHX_` parameter.

      I32  Perl_hv_placeholders_get(pTHX_ const HV *hv)

`hv_placeholders_set`

  Implements `HvPLACEHOLDERS_set`, which you should use instead.

  NOTE: `hv_placeholders_set` must be explicitly called as `Perl_hv_placeholders_set` with an `aTHX_` parameter.

      void  Perl_hv_placeholders_set(pTHX_ HV *hv, I32 ph)

`hv_riter_p`

  Implements `HvRITER` which you should use instead.

  NOTE: `hv_riter_p` must be explicitly called as `Perl_hv_riter_p` with an `aTHX_` parameter.

      I32 *  Perl_hv_riter_p(pTHX_ HV *hv)

`hv_riter_set`

  Implements `HvRITER_set` which you should use instead.

  NOTE: `hv_riter_set` must be explicitly called as `Perl_hv_riter_set` with an `aTHX_` parameter.

      void  Perl_hv_riter_set(pTHX_ HV *hv, I32 riter)

`refcounted_he_chain_2hv`

  Generates and returns a `HV *` representing the content of a `refcounted_he` chain. `flags` is currently unused and must be zero.

      HV *  refcounted_he_chain_2hv(const struct refcounted_he *c,
                                    U32 flags)

`refcounted_he_fetch_pv`

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

      SV *  refcounted_he_fetch_pv(const struct refcounted_he *chain,
                                   const char *key, U32 hash, U32 flags)

`refcounted_he_fetch_pvn`

  Search along a `refcounted_he` chain for an entry with the key specified by `keypv` and `keylen`. If `flags` has the `REFCOUNTED_HE_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 representing the value associated with the key, or `&PL_sv_placeholder` if there is no value associated with the key.

      SV *  refcounted_he_fetch_pvn(const struct refcounted_he *chain,
                                    const char *keypv, STRLEN keylen,
                                    U32 hash, U32 flags)

`refcounted_he_fetch_pvs`

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

      SV *  refcounted_he_fetch_pvs(const struct refcounted_he *chain,
                                    "key", U32 flags)

`refcounted_he_fetch_sv`

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

      SV *  refcounted_he_fetch_sv(const struct refcounted_he *chain,
                                   SV *key, U32 hash, U32 flags)

`refcounted_he_free`

  Decrements the reference count of a `refcounted_he` by one. If the reference count reaches zero the structure's memory is freed, which (recursively) causes a reduction of its parent `refcounted_he`'s reference count. It is safe to pass a null pointer to this function: no action occurs in this case.

      void  refcounted_he_free(struct refcounted_he *he)

`refcounted_he_inc`

  Increment the reference count of a `refcounted_he`. The pointer to the `refcounted_he` is also returned. It is safe to pass a null pointer to this function: no action occurs and a null pointer is returned.

      struct refcounted_he *  refcounted_he_inc(
                                               struct refcounted_he *he)

`refcounted_he_new_pv`

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

      struct refcounted_he *  refcounted_he_new_pv(
                                           struct refcounted_he *parent,
                                           const char *key, U32 hash,
                                           SV *value, U32 flags)

`refcounted_he_new_pvn`

  Creates a new `refcounted_he`. This consists of a single key/value pair and a reference to an existing `refcounted_he` chain (which may be empty), and thus forms a longer chain. When using the longer chain, the new key/value pair takes precedence over any entry for the same key further along the chain.

  The new key is specified by `keypv` and `keylen`. If `flags` has the `REFCOUNTED_HE_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 `refcounted_he`. Complex types of scalar will not be stored with referential integrity, but will be coerced to strings. `value` may be either null or `&PL_sv_placeholder` to indicate that no value is to be associated with the key; this, as with any non-null value, takes precedence over the existence of a value for the key further along the chain.

  `parent` points to the rest of the `refcounted_he` chain to be attached to the new `refcounted_he`. This function takes ownership of one reference to `parent`, and returns one reference to the new `refcounted_he`.

      struct refcounted_he *  refcounted_he_new_pvn(
                                           struct refcounted_he *parent,
                                           const char *keypv,
                                           STRLEN keylen, U32 hash,
                                           SV *value, U32 flags)

`refcounted_he_new_pvs`

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

      struct refcounted_he *  refcounted_he_new_pvs(
                                           struct refcounted_he *parent,
                                           "key", SV *value, U32 flags)

`refcounted_he_new_sv`

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

      struct refcounted_he *  refcounted_he_new_sv(
                                           struct refcounted_he *parent,
                                           SV *key, U32 hash, SV *value,
                                           U32 flags)

`unsharepvn`

  If no one has access to shared string `str` with length `len`, free it.

  `len` and `hash` must both be valid for `str`.

      void  unsharepvn(const char *sv, I32 len, U32 hash)

# Input/Output

`dirp_dup`

  Duplicate a directory handle, returning a pointer to the cloned object.

      DIR *  dirp_dup(DIR * const dp, CLONE_PARAMS * const param)

`fp_dup`

  Duplicate a file handle, returning a pointer to the cloned object.

      PerlIO *  fp_dup(PerlIO * const fp, const char type,
                       CLONE_PARAMS * const param)

`my_fflush_all`

  Implements `PERL_FLUSHALL_FOR_CHILD` on some platforms.

      I32  my_fflush_all()

`my_mkostemp`

  The C library `mkostemp(3)` if available, or a Perl implementation of it.

  NOTE: `my_mkostemp` must be explicitly called as `Perl_my_mkostemp` .

      int  Perl_my_mkostemp(char *templte, int flags)

`my_mkstemp`

  The C library `mkstemp(3)` if available, or a Perl implementation of it.

  NOTE: `my_mkstemp` must be explicitly called as `Perl_my_mkstemp` .

      int  Perl_my_mkstemp(char *templte)

`PL_last_in_gv`

  The GV which was last used for a filehandle input operation. (`<FH>`)

  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_last_in_gv

`PL_ofsgv`

  The glob containing the output field separator - `*,` in Perl space.

  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_ofsgv

`PL_rs`

  The input record separator - `$/` in Perl space.

  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.

      SV*  PL_rs

`start_glob`

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

  Function called by `do_readline` to spawn a glob (or do the glob inside perl on VMS). This code used to be inline, but now perl uses `File::Glob` this glob starter is only used by miniperl during the build process, or when PERL_EXTERNAL_GLOB is defined. Moving it away shrinks pp_hot.c; shrinking pp_hot.c helps speed perl up.

  NOTE: `start_glob` must be explicitly called as `Perl_start_glob` with an `aTHX_` parameter.

      PerlIO *  Perl_start_glob(pTHX_ SV *tmpglob, IO *io)

# Integer

There are currently no internal API items in Integer

# I/O Formats

There are currently no internal API items in I/O Formats

# Lexer interface

`resume_compcv_and_save`

  Resumes a buffer previously suspended by the `suspend_compcv` function, in a way that will be re-suspended at the end of the scope so it can be used again later. This should be used within an `ENTER`/`LEAVE` scoped pair.

      void  resume_compcv_and_save(struct suspended_compcv *buffer)

`resume_compcv_final`

  Resumes the parser state previously saved using the `suspend_compcv` function for a final time before being compiled into a full CV. This should be used within an `ENTER`/`LEAVE` scoped pair.

      void  resume_compcv_final(struct suspended_compcv *buffer)

`validate_proto`

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

  This function performs syntax checking on a prototype, `proto`. If `warn` is true, any illegal characters or mismatched brackets will trigger illegalproto warnings, declaring that they were detected in the prototype for `name`.

  The return value is `true` if this is a valid prototype, and `false` if it is not, regardless of whether `warn` was `true` or `false`.

  Note that `NULL` is a valid `proto` and will always return `true`.

      bool  validate_proto(SV *name, SV *proto, bool warn,
                           bool curstash)

# Locales

There are currently no internal API items in Locales

# Magic

`magic_clearhint`

  Triggered by a delete from `%^H`, records the key to `PL_compiling.cop_hints_hash`.

      int  magic_clearhint(SV *sv, MAGIC *mg)

`magic_clearhints`

  Triggered by clearing `%^H`, resets `PL_compiling.cop_hints_hash`.

      int  magic_clearhints(SV *sv, MAGIC *mg)

`magic_methcall`

  Invoke a magic method (like FETCH).

  `sv` and `mg` are the tied thingy and the tie magic.

  `meth` is the name of the method to call.

  `argc` is the number of args (in addition to $self) to pass to the method.

  The `flags` can be:

      G_DISCARD     invoke method with G_DISCARD flag and don't
                    return a value
      G_UNDEF_FILL  fill the stack with argc pointers to
                    PL_sv_undef

  The arguments themselves are any values following the `flags` argument.

  Returns the SV (if any) returned by the method, or `NULL` on failure.

  NOTE: `magic_methcall` must be explicitly called as `Perl_magic_methcall` with an `aTHX_` parameter.

      SV *  Perl_magic_methcall(pTHX_ SV *sv, const MAGIC *mg,
                                SV *meth, U32 flags, U32 argc, ...)

`magic_sethint`

  Triggered by a store to `%^H`, records the key/value pair to `PL_compiling.cop_hints_hash`. It is assumed that hints aren't storing anything that would need a deep copy. Maybe we should warn if we find a reference.

      int  magic_sethint(SV *sv, MAGIC *mg)

`mg_dup`

  Duplicate a chain of magic, returning a pointer to the cloned object.

      MAGIC *  mg_dup(MAGIC *mg, CLONE_PARAMS * const param)

`mg_localize`

  Copy some of the magic from an existing SV to new localized version of that SV. Container magic (e.g., `%ENV`, `$1`, `tie`) gets copied, value magic doesn't (e.g., `taint`, `pos`).

  If `setmagic` is false then no set magic will be called on the new (empty) SV. This typically means that assignment will soon follow (e.g. `'local $x = $y'`), and that will handle the magic.

      void  mg_localize(SV *sv, SV *nsv, bool setmagic)

# Memory Management

`calloc`

  Implements "`Newxz`" in perlapi which you should use instead.

  NOTE: `calloc` must be explicitly called as `Perl_calloc` .

      Malloc_t  Perl_calloc(MEM_SIZE elements, MEM_SIZE size)

`malloc`

  Implements "`Newx`" in perlapi which you should use instead.

  NOTE: `malloc` must be explicitly called as `Perl_malloc` .

      Malloc_t  Perl_malloc(MEM_SIZE nbytes)

`mfree`

  Implements "`Safefree`" in perlapi which you should use instead.

  NOTE: `mfree` must be explicitly called as `Perl_mfree` .

      Free_t  Perl_mfree(Malloc_t where)

`realloc`

  Implements "`Renew`" in perlapi which you should use instead.

  NOTE: `realloc` must be explicitly called as `Perl_realloc` .

      Malloc_t  Perl_realloc(Malloc_t where, MEM_SIZE nbytes)

# MRO

`mro_get_linear_isa_dfs`

  Returns the Depth-First Search linearization of `@ISA` the given stash. The return value is a read-only AV* whose elements are string SVs giving class names. `level` should be 0 (it is used internally in this function's recursion).

  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_dfs(HV *stash, U32 level)

`mro_isa_changed_in`

  Takes the necessary steps (cache invalidations, mostly) when the `@ISA` of the given package has changed. Invoked by the `setisa` magic, should not need to invoke directly.

      void  mro_isa_changed_in(HV *stash)

`mro_package_moved`

  Call this function to signal to a stash that it has been assigned to another spot in the stash hierarchy. `stash` is the stash that has been assigned. `oldstash` is the stash it replaces, if any. `gv` is the glob that is actually being assigned to.

  This can also be called with a null first argument to indicate that `oldstash` has been deleted.

  This function invalidates isa caches on the old stash, on all subpackages nested inside it, and on the subclasses of all those, including non-existent packages that have corresponding entries in `stash`.

  It also sets the effective names (`HvENAME`) on all the stashes as appropriate.

  If the `gv` is present and is not in the symbol table, then this function simply returns. This checked will be skipped if `flags & 1`.

      void  mro_package_moved(HV * const stash, HV * const oldstash,
                              const GV * const gv, U32 flags)

# Multicall Functions

There are currently no internal API items in Multicall Functions

# Numeric Functions

`isinfnansv`

  Checks whether the argument would be either an infinity or `NaN` when used as a number, but is careful not to trigger non-numeric or uninitialized warnings. it assumes the caller has done `SvGETMAGIC(sv)` already.

  Note that this always accepts trailing garbage (similar to `grok_number_flags` with `PERL_SCAN_TRAILING`), so `"inferior"` and `"NAND gates"` will return true.

      bool  isinfnansv(SV *sv)

# Optrees

`newATTRSUB_x`

  Construct a Perl subroutine, also performing some surrounding jobs.

  This function is expected to be called in a Perl compilation context, and some aspects of the subroutine are taken from global variables associated with compilation. In particular, `PL_compcv` represents the subroutine that is currently being compiled. It must be non-null when this function is called, and some aspects of the subroutine being constructed are taken from it. The constructed subroutine may actually be a reuse of the `PL_compcv` object, but will not necessarily be so.

  If `block` is null then the subroutine will have no body, and for the time being it will be an error to call it. This represents a forward subroutine declaration such as `sub foo ($$);`. If `block` is non-null then it provides the Perl code of the subroutine body, which will be executed when the subroutine is called. This body includes any argument unwrapping code resulting from a subroutine signature or similar. The pad use of the code must correspond to the pad attached to `PL_compcv`. The code is not expected to include a `leavesub` or `leavesublv` op; this function will add such an op. `block` is consumed by this function and will become part of the constructed subroutine.

  `proto` specifies the subroutine's prototype, unless one is supplied as an attribute (see below). If `proto` is null, then the subroutine will not have a prototype. If `proto` is non-null, it must point to a `const` op whose value is a string, and the subroutine will have that string as its prototype. If a prototype is supplied as an attribute, the attribute takes precedence over `proto`, but in that case `proto` should preferably be null. In any case, `proto` is consumed by this function.

  `attrs` supplies attributes to be applied the subroutine. A handful of attributes take effect by built-in means, being applied to `PL_compcv` immediately when seen. Other attributes are collected up and attached to the subroutine by this route. `attrs` may be null to supply no attributes, or point to a `const` op for a single attribute, or point to a `list` op whose children apart from the `pushmark` are `const` ops for one or more attributes. Each `const` op must be a string, giving the attribute name optionally followed by parenthesised arguments, in the manner in which attributes appear in Perl source. The attributes will be applied to the sub by this function. `attrs` is consumed by this function.

  If `o_is_gv` is false and `o` is null, then the subroutine will be anonymous. If `o_is_gv` is false and `o` is non-null, then `o` must point to a `const` OP, which will be consumed by this function, and its string value supplies a name for the subroutine. The name may be qualified or unqualified, and if it is unqualified then a default stash will be selected in some manner. If `o_is_gv` is true, then `o` doesn't point to an `OP` at all, but is instead a cast pointer to a `GV` by which the subroutine will be named.

  If there is already a subroutine of the specified name, then the new sub will either replace the existing one in the glob or be merged with the existing one. A warning may be generated about 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. In the case of `BEGIN`, the subroutine will be executed and the reference to it disposed of before this function returns.

  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. But a `BEGIN` subroutine, having already been executed, will quite likely have been destroyed already by the time this function returns, making it erroneous for the caller to make any use of the returned pointer. It is the caller's responsibility to ensure that it knows which of these situations applies.

      CV *  newATTRSUB_x(I32 floor, OP *o, OP *proto, OP *attrs,
                         OP *block, bool o_is_gv)

`newXS_len_flags`

  Construct an XS subroutine, also performing some surrounding jobs.

  The subroutine will have the entry point `subaddr`. It will have the prototype specified by the nul-terminated string `proto`, or no prototype if `proto` is null. The prototype string is copied; the caller can mutate the supplied string afterwards. If `filename` is non-null, it must be a nul-terminated filename, and the subroutine will have its `CvFILE` set accordingly. By default `CvFILE` is set to point directly to the supplied string, which must be static. If `flags` has the `XS_DYNAMIC_FILENAME` bit set, then a copy of the string will be taken instead.

  Other aspects of the subroutine will be left in their default state. If anything else needs to be done to the subroutine for it to function correctly, it is the caller's responsibility to do that after this function has constructed it. However, beware of the subroutine potentially being destroyed before this function returns, as described below.

  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, with the stash defaulting in the same manner as for `gv_fetchpvn_flags`. `flags` may contain flag bits understood by `gv_fetchpvn_flags` with the same meaning as they have there, such as `GV_ADDWARN`. The symbol is always added to the stash if necessary, with `GV_ADDMULTI` semantics.

  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 old subroutine was `CvCONST` then the decision about whether to warn is influenced by an expectation about whether the new subroutine will become a constant of similar value. That expectation is determined by `const_svp`. (Note that the call to this function doesn't make the new subroutine `CvCONST` in any case; that is left to the caller.) If `const_svp` is null then it indicates that the new subroutine will not become a constant. If `const_svp` is non-null then it indicates that the new subroutine will become a constant, and it points to an `SV*` that provides the constant value that the subroutine will have.

  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. In the case of `BEGIN`, the subroutine will be executed and the reference to it disposed of before this function returns, and also before its prototype is set. If a `BEGIN` subroutine would not be sufficiently constructed by this function to be ready for execution then the caller must prevent this happening by giving the subroutine a different name.

  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. But a `BEGIN` subroutine, having already been executed, will quite likely have been destroyed already by the time this function returns, making it erroneous for the caller to make any use of the returned pointer. It is the caller's responsibility to ensure that it knows which of these situations applies.

      CV *  newXS_len_flags(const char *name, STRLEN len,
                            XSUBADDR_t subaddr,
                            const char * const filename,
                            const char * const proto, SV ** const_svp,
                            U32 flags)

`op_refcnt_lock`

  Implements the `OP_REFCNT_LOCK` macro which you should use instead.

      void  op_refcnt_lock()

`op_refcnt_unlock`

  Implements the `OP_REFCNT_UNLOCK` macro which you should use instead.

      void  op_refcnt_unlock()

`traverse_op_tree`

  Return the next op in a depth-first traversal of the op tree, returning NULL when the traversal is complete.

  The initial call must supply the root of the tree as both top and o.

  For now it's static, but it may be exposed to the API in the future.

      OP *  traverse_op_tree(OP *top, OP *o)

# Pack and Unpack

There are currently no internal API items in Pack and Unpack

# Pad Data Structures

`CX_CURPAD_SAVE`

  Save the current pad in the given context block structure.

      void  CX_CURPAD_SAVE(struct context)

`CX_CURPAD_SV`

  Access the SV at offset `po` in the saved current pad in the given context block structure (can be used as an lvalue).

      SV *  CX_CURPAD_SV(struct context, PADOFFSET po)

`PAD_BASE_SV`

  Get the value from slot `po` in the base (DEPTH=1) pad of a padlist

      SV *  PAD_BASE_SV(PADLIST padlist, PADOFFSET po)

`PAD_CLONE_VARS`

  Clone the state variables associated with running and compiling pads.

      void  PAD_CLONE_VARS(PerlInterpreter *proto_perl,
                           CLONE_PARAMS* param)

`PAD_COMPNAME_FLAGS`

  Return the flags for the current compiling pad name at offset `po`. Assumes a valid slot entry.

      U32  PAD_COMPNAME_FLAGS(PADOFFSET po)

`PAD_COMPNAME_GEN`

  The generation number of the name at offset `po` in the current compiling pad (lvalue).

      STRLEN  PAD_COMPNAME_GEN(PADOFFSET po)

`PAD_COMPNAME_GEN_set`

  Sets the generation number of the name at offset `po` in the current ling pad (lvalue) to `gen`.

      STRLEN  PAD_COMPNAME_GEN_set(PADOFFSET po, int gen)

`PAD_COMPNAME_OURSTASH`

  Return the stash associated with an `our` variable. Assumes the slot entry is a valid `our` lexical.

      HV *  PAD_COMPNAME_OURSTASH(PADOFFSET po)

`PAD_COMPNAME_PV`

  Return the name of the current compiling pad name at offset `po`. Assumes a valid slot entry.

      char *  PAD_COMPNAME_PV(PADOFFSET po)

`PAD_COMPNAME_TYPE`

  Return the type (stash) of the current compiling pad name at offset `po`. Must be a valid name. Returns null if not typed.

      HV *  PAD_COMPNAME_TYPE(PADOFFSET po)

`PadnameIsFIELD`

  Whether this is a "field" variable. PADNAMEs where this is true will have additional information available via `PadnameFIELDINFO`.

      bool  PadnameIsFIELD(PADNAME * pn)

`PadnameIsOUR`

  Whether this is an "our" variable.

      bool  PadnameIsOUR(PADNAME * pn)

`PadnameIsSTATE`

  Whether this is a "state" variable.

      bool  PadnameIsSTATE(PADNAME * pn)

`PadnameOURSTASH`

  The stash in which this "our" variable was declared.

      HV *  PadnameOURSTASH(PADNAME * pn)

`PadnameOUTER`

  Whether this entry belongs to an outer pad. Entries for which this is true are often referred to as 'fake'.

      bool  PadnameOUTER(PADNAME * pn)

`PadnameTYPE`

  The stash associated with a typed lexical. This returns the `%Foo::` hash for `my Foo $bar`.

      HV *  PadnameTYPE(PADNAME * pn)

`PAD_RESTORE_LOCAL`

  Restore the old pad saved into the local variable `opad` by `PAD_SAVE_LOCAL()`

      void  PAD_RESTORE_LOCAL(PAD *opad)

`PAD_SAVE_LOCAL`

  Save the current pad to the local variable `opad`, then make the current pad equal to `npad`

      void  PAD_SAVE_LOCAL(PAD *opad, PAD *npad)

`PAD_SAVE_SETNULLPAD`

  Save the current pad then set it to null.

      void  PAD_SAVE_SETNULLPAD()

`PAD_SET_CUR`

  Set the current pad to be pad `n` in the padlist, saving the previous current pad. NB currently this macro expands to a string too long for some compilers, so it's best to replace it with

      SAVECOMPPAD();
      PAD_SET_CUR_NOSAVE(padlist,n);

      void  PAD_SET_CUR(PADLIST padlist, I32 n)

`PAD_SET_CUR_NOSAVE`

  like PAD_SET_CUR, but without the save

      void  PAD_SET_CUR_NOSAVE(PADLIST padlist, I32 n)

`PAD_SETSV`

  Set the slot at offset `po` in the current pad to `sv`

      SV *  PAD_SETSV(PADOFFSET po, SV* sv)

`PAD_SV`

  Get the value at offset `po` in the current pad

      SV *  PAD_SV(PADOFFSET po)

`PAD_SVl`

  Lightweight and lvalue version of `PAD_SV`. Get or set the value at offset `po` in the current pad. Unlike `PAD_SV`, does not print diagnostics with -DX. For internal use only.

      SV *  PAD_SVl(PADOFFSET po)

`SAVECLEARSV`

  Clear the pointed to pad value on scope exit. (i.e. the runtime action of `my`)

      void  SAVECLEARSV(SV **svp)

`SAVECOMPPAD`

  save `PL_comppad` and `PL_curpad`

      void  SAVECOMPPAD()

`SAVEPADSV`

  Save a pad slot (used to restore after an iteration)

      void  SAVEPADSV(PADOFFSET po)

# Password and Group access

There are currently no internal API items in Password and Group access

# Paths to system commands

There are currently no internal API items in Paths to system commands

# Prototype information

There are currently no internal API items in Prototype information

# REGEXP Functions

`regnode`

  Described in perlreguts.

# Reports and Formats

There are currently no internal API items in Reports and Formats

# Signals

There are currently no internal API items in Signals

# Site configuration

There are currently no internal API items in Site configuration

# Sockets configuration values

There are currently no internal API items in Sockets configuration values

# Source Filters

There are currently no internal API items in Source Filters

# Stack Manipulation Macros

`djSP`

  Declare Just `SP`. This is actually identical to `dSP`, and declares a local copy of perl's stack pointer, available via the `SP` macro. See `"SP" in perlapi`. (Available for backward source code compatibility with the old (Perl 5.005) thread model.)

      djSP();

`LVRET`

  True if this op will be the return value of an lvalue subroutine

`save_alloc`

  Implements "`SSNEW`" in perlapi and kin, which should be used instead of this function.

      SSize_t  save_alloc(SSize_t size, I32 pad)

# String Handling

`delimcpy_no_escape`

  Copy a source buffer to a destination buffer, stopping at (but not including) the first occurrence in the source of the 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 `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.

      char *  delimcpy_no_escape(char *to, const char *to_end,
                                 const char *from, const char *from_end,
                                 const int delim, I32 *retlen)

`my_cxt_init`

  Implements the "`MY_CXT_INIT`" in perlxs macro, which you should use instead.

  The first time a module is loaded, the global `PL_my_cxt_index` is incremented, and that value is assigned to that module's static `my_cxt_index` (whose address is passed as an arg). Then, for each interpreter this function is called for, it makes sure a `void*` slot is available to hang the static data off, by allocating or extending the interpreter's `PL_my_cxt_list` array

  NOTE: `my_cxt_init` must be explicitly called as `Perl_my_cxt_init` with an `aTHX_` parameter.

      void *  Perl_my_cxt_init(pTHX_ int *indexp, size_t size)

`quadmath_format_needed`

  `quadmath_format_needed()` returns true if the `format` string seems to contain at least one non-Q-prefixed `%[efgaEFGA]` format specifier, or returns false otherwise.

  The format specifier detection is not complete printf-syntax detection, but it should catch most common cases.

  If true is returned, those arguments should in theory be processed with `quadmath_snprintf()`, but in case there is more than one such format specifier (see "quadmath_format_valid"), and if there is anything else beyond that one (even just a single byte), they cannot be processed because `quadmath_snprintf()` is very strict, accepting only one format spec, and nothing else. In this case, the code should probably fail.

      bool  quadmath_format_needed(const char *format)

`quadmath_format_valid`

  `quadmath_snprintf()` is very strict about its `format` string and will fail, returning -1, if the format is invalid. It accepts exactly one format spec.

  `quadmath_format_valid()` checks that the intended single spec looks sane: begins with `%`, has only one `%`, ends with `[efgaEFGA]`, and has `Q` before it. This is not a full "printf syntax check", just the basics.

  Returns true if it is valid, false if not.

  See also "quadmath_format_needed".

      bool  quadmath_format_valid(const char *format)

# SV Flags

`SVt_INVLIST`

  Type flag for scalars. See "svtype" in perlapi.

# SV Handling

`PL_Sv`

  A scratch pad SV for whatever temporary use you need. Chiefly used as a fallback by macros on platforms where "PERL_USE_GCC_BRACE_GROUPS" in perlapi> is unavailable, and which would otherwise evaluate their SV parameter more than once.

  BUT BEWARE, if this is used in a situation where something that is using it is in a call stack with something else that is using it, this variable would get zapped, leading to hard-to-diagnose errors.

      PL_Sv

`sv_add_arena`

  Given a chunk of memory, link it to the head of the list of arenas, and split it into a list of free SVs.

      void  sv_add_arena(char * const ptr, const U32 size,
                         const U32 flags)

`sv_2bool`

  This macro is only used by `sv_true()` or its macro equivalent, and only if the latter's argument is neither `SvPOK`, `SvIOK` nor `SvNOK`. It calls `sv_2bool_flags` with the `SV_GMAGIC` flag.

      bool  sv_2bool(SV * const sv)

`sv_2bool_flags`

  This function is only used by `sv_true()` and friends, and only if the latter's argument is neither `SvPOK`, `SvIOK` nor `SvNOK`. If the flags contain `SV_GMAGIC`, then it does an `mg_get()` first.

      bool  sv_2bool_flags(SV *sv, I32 flags)

`sv_clean_all`

  Decrement the refcnt of each remaining SV, possibly triggering a cleanup. This function may have to be called multiple times to free SVs which are in complex self-referential hierarchies.

      I32  sv_clean_all()

`sv_clean_objs`

  Attempt to destroy all objects not yet freed.

      void  sv_clean_objs()

`sv_free_arenas`

  Deallocate the memory used by all arenas. Note that all the individual SV heads and bodies within the arenas must already have been freed.

      void  sv_free_arenas()

`sv_grow`

  Expands the character buffer in the SV. If necessary, uses `sv_unref` and upgrades the SV to `SVt_PV`. Returns a pointer to the character buffer. Use the `SvGROW` wrapper instead.

      char *  sv_grow(SV * const sv, STRLEN newlen)

`sv_grow_fresh`

  A cut-down version of sv_grow intended only for when sv is a freshly-minted SVt_PV, SVt_PVIV, SVt_PVNV, or SVt_PVMG. i.e. sv has the default flags, has never been any other type, and does not have an existing string. Basically, just assigns a char buffer and returns a pointer to it.

      char *  sv_grow_fresh(SV * const sv, STRLEN newlen)

`sv_newref`

  Increment an SV's reference count. Use the `SvREFCNT_inc()` wrapper instead.

      SV *  sv_newref(SV * const sv)

`sv_2num`

  NOTE: `sv_2num` is experimental and may change or be removed without notice.

  Return an SV with the numeric value of the source SV, doing any necessary reference or overload conversion. The caller is expected to have handled get-magic already.

      SV *  sv_2num(SV * const sv)

`sv_pv`

  Use the `SvPV_nolen` macro instead

      char *  sv_pv(SV *sv)

`sv_pvbyte`

  Use `SvPVbyte_nolen` instead.

      char *  sv_pvbyte(SV *sv)

`sv_pvbyten_force`

  The backend for the `SvPVbytex_force` macro. Always use the macro instead. If the SV cannot be downgraded from UTF-8, this croaks.

      char *  sv_pvbyten_force(SV * const sv, STRLEN * const lp)

`sv_2pvbyte_nolen`

  Return a pointer to the byte-encoded representation of the SV. May cause the SV to be downgraded from UTF-8 as a side-effect.

  Usually accessed via the `SvPVbyte_nolen` macro.

      char *  sv_2pvbyte_nolen(SV *sv)

`sv_pvn_force`

  Get a sensible string out of the SV somehow. A private implementation of the `SvPV_force` macro for compilers which can't cope with complex macro expressions. Always use the macro instead.

      char *  sv_pvn_force(SV *sv, STRLEN *lp)

`sv_2pv_nolen`

  Like `sv_2pv()`, but doesn't return the length too. You should usually use the macro wrapper `SvPV_nolen(sv)` instead.

      char *  sv_2pv_nolen(SV *sv)

`sv_pvutf8n_force`

  The backend for the `SvPVutf8x_force` macro. Always use the macro instead.

      char *  sv_pvutf8n_force(SV * const sv, STRLEN * const lp)

`sv_2pvutf8_nolen`

  Return a pointer to the UTF-8-encoded representation of the SV. May cause the SV to be upgraded to UTF-8 as a side-effect.

  Usually accessed via the `SvPVutf8_nolen` macro.

      char *  sv_2pvutf8_nolen(SV *sv)

`sv_pvutf8`

  Use the `SvPVutf8_nolen` macro instead

      char *  sv_pvutf8(SV *sv)

`sv_tainted`

  Test an SV for taintedness. Use `SvTAINTED` instead.

      bool  sv_tainted(SV * const sv)

`SvTHINKFIRST`

  A quick flag check to see whether an `sv` should be passed to `sv_force_normal` to be "downgraded" before `SvIVX` or `SvPVX` can be modified directly.

  For example, if your scalar is a reference and you want to modify the `SvIVX` slot, you can't just do `SvROK_off`, as that will leak the referent.

  This is used internally by various sv-modifying functions, such as `sv_setsv`, `sv_setiv` and `sv_pvn_force`.

  One case that this does not handle is a gv without SvFAKE set. After

      if (SvTHINKFIRST(gv)) sv_force_normal(gv);

  it will still be a gv.

  `SvTHINKFIRST` sometimes produces false positives. In those cases `sv_force_normal` does nothing.

      U32  SvTHINKFIRST(SV *sv)

`sv_true`

  Returns true if the SV has a true value by Perl's rules. Use the `SvTRUE` macro instead, which may call `sv_true()` or may instead use an in-line version.

      I32  sv_true(SV * const sv)

`sv_untaint`

  Untaint an SV. Use `SvTAINTED_off` instead.

      void  sv_untaint(SV * const sv)

# Tainting

`sv_taint`

  Taint an SV. Use `SvTAINTED_on` instead.

      void  sv_taint(SV *sv)

`TAINT`

  If we aren't in taint checking mode, do nothing; otherwise indicate to "`TAINT_set`" and "`TAINT_PROPER`" that some unspecified element is tainted.

      void  TAINT()

`TAINT_ENV`

  Looks at several components of `%ENV` for taintedness, and calls "`taint_proper`" if any are tainted. The components it searches are things like `$PATH`.

      void  TAINT_ENV

`taint_env`

  Implements the "TAINT_ENV" macro, which you should generally use instead.

      void  taint_env()

`TAINT_get`

  Returns a boolean as to whether some element is tainted or not.

      bool  TAINT_get()

`TAINT_IF`

  If `c` evaluates to true, call "`TAINT`" to indicate that something is tainted; otherwise do nothing.

      void  TAINT_IF(bool c)

`TAINTING_get`

  Returns a boolean as to whether taint checking is enabled or not.

      bool  TAINTING_get()

`TAINTING_set`

  Turn taint checking mode off/on

      void  TAINTING_set(bool s)

`TAINT_NOT`

  Remove any taintedness previously set by, e.g., `TAINT`.

      void  TAINT_NOT()

`TAINT_PROPER`

  If no element is tainted, do nothing; otherwise output a message (containing `s`) that indicates there is a tainting violation. If such violations are fatal, it croaks.

      void  TAINT_PROPER(const char * s)

`taint_proper`

  Implements the "TAINT_PROPER" macro, which you should generally use instead.

      void  taint_proper(const char *f, const char * const s)

`TAINT_set`

  If `s` is true, "`TAINT_get`" returns true; If `s` is false, "`TAINT_get`" returns false;

      void  TAINT_set(bool s)

`TAINT_WARN_get`

  Returns false if tainting violations are fatal; Returns true if they're just warnings

      bool  TAINT_WARN_get()

`TAINT_WARN_set`

  `s` being true indicates "`TAINT_WARN_get`" should return that tainting violations are just warnings

  `s` being false indicates "`TAINT_WARN_get`" should return that tainting violations are fatal.

      void  TAINT_WARN_set(bool s)

# Time

There are currently no internal API items in Time

# Typedef names

There are currently no internal API items in Typedef names

# Unicode Support

`bytes_from_utf8_loc`

  NOTE: `bytes_from_utf8_loc` is experimental and may change or be removed without notice.

  Like `"bytes_from_utf8" in perlapi()`, but takes an extra parameter, a pointer to where to store the location of the first character in `"s"` that cannot be converted to non-UTF8.

  If that parameter is `NULL`, this function behaves identically to `bytes_from_utf8`.

  Otherwise if `*is_utf8p` is 0 on input, the function behaves identically to `bytes_from_utf8`, except it also sets `*first_non_downgradable` to `NULL`.

  Otherwise, the function returns a newly created `NUL`-terminated string containing the non-UTF8 equivalent of the convertible first portion of `"s"`. `*lenp` is set to its length, not including the terminating `NUL`. If the entire input string was converted, `*is_utf8p` is set to a FALSE value, and `*first_non_downgradable` is set to `NULL`.

  Otherwise, `*first_non_downgradable` is set to point to the first byte of the first character in the original string that wasn't converted. `*is_utf8p` is unchanged. Note that the new string may have length 0.

  Another way to look at it is, if `*first_non_downgradable` is non-`NULL` and `*is_utf8p` is TRUE, this function starts at the beginning of `"s"` and converts as many characters in it as possible stopping at the first one it finds that can't be converted to non-UTF-8. `*first_non_downgradable` is set to point to that. The function returns the portion that could be converted in a newly created `NUL`-terminated string, and `*lenp` is set to its length, not including the terminating `NUL`. If the very first character in the original could not be converted, `*lenp` will be 0, and the new string will contain just a single `NUL`. If the entire input string was converted, `*is_utf8p` is set to FALSE and `*first_non_downgradable` is set to `NULL`.

  Upon successful return, the number of variants in the converted portion of 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_loc(const U8 *s, STRLEN *lenp,
                                bool *is_utf8p,
                                const U8 **first_unconverted)

`find_uninit_var`

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

  Find the name of the undefined variable (if any) that caused the operator to issue a "Use of uninitialized value" warning. If match is true, only return a name if its value matches `uninit_sv`. So roughly speaking, if a unary operator (such as `OP_COS`) generates a warning, then following the direct child of the op may yield an `OP_PADSV` or `OP_GV` that gives the name of the undefined variable. On the other hand, with `OP_ADD` there are two branches to follow, so we only print the variable name if we get an exact match. `desc_p` points to a string pointer holding the description of the op. This may be updated if needed.

  The name is returned as a mortal SV.

  Assumes that `PL_op` is the OP that originally triggered the error, and that `PL_comppad`/`PL_curpad` points to the currently executing pad.

      SV *  find_uninit_var(const OP * const obase,
                            const SV * const uninit_sv, bool match,
                            const char **desc_p)

`isSCRIPT_RUN`

  Returns a bool as to whether or not the sequence of bytes from `s` up to but not including `send` form a "script run". `utf8_target` is TRUE iff the sequence starting at `s` is to be treated as UTF-8. To be precise, except for two degenerate cases given below, this function returns TRUE iff all code points in it come from any combination of three "scripts" given by the Unicode "Script Extensions" property: Common, Inherited, and possibly one other. Additionally all decimal digits must come from the same consecutive sequence of 10.

  For example, if all the characters in the sequence are Greek, or Common, or Inherited, this function will return TRUE, provided any decimal digits in it are from the same block of digits in Common. (These are the ASCII digits "0".."9" and additionally a block for full width forms of these, and several others used in mathematical notation.) For scripts (unlike Greek) that have their own digits defined this will accept either digits from that set or from one of the Common digit sets, but not a combination of the two. Some scripts, such as Arabic, have more than one set of digits. All digits must come from the same set for this function to return TRUE.

  `*ret_script`, if `ret_script` is not NULL, will on return of TRUE contain the script found, using the `SCX_enum` typedef. Its value will be `SCX_INVALID` if the function returns FALSE.

  If the sequence is empty, TRUE is returned, but `*ret_script` (if asked for) will be `SCX_INVALID`.

  If the sequence contains a single code point which is unassigned to a character in the version of Unicode being used, the function will return TRUE, and the script will be `SCX_Unknown`. Any other combination of unassigned code points in the input sequence will result in the function treating the input as not being a script run.

  The returned script will be `SCX_Inherited` iff all the code points in it are from the Inherited script.

  Otherwise, the returned script will be `SCX_Common` iff all the code points in it are from the Inherited or Common scripts.

      bool  isSCRIPT_RUN(const U8 *s, const U8 *send,
                         const bool utf8_target)

`is_utf8_non_invariant_string`

  Returns TRUE if "is_utf8_invariant_string" in perlapi returns FALSE for the first `len` bytes of the string `s`, but they are, nonetheless, legal Perl-extended UTF-8; otherwise returns FALSE.

  A TRUE return means that at least one code point represented by the sequence either is a wide character not representable as a single byte, or the representation differs depending on whether the sequence is encoded in UTF-8 or not.

  See also `"is_utf8_invariant_string" in perlapi`, `"is_utf8_string" in perlapi`

      bool  is_utf8_non_invariant_string(const U8 * const s, STRLEN len)

`utf8n_to_uvuni`

  `DEPRECATED!` It is planned to remove `utf8n_to_uvuni` from a future release of Perl. Do not use it for new code; remove it from existing code.

  Instead use "utf8_to_uvchr_buf" in perlapi, or rarely, "utf8n_to_uvchr" in perlapi.

  This function was useful for code that wanted to handle both EBCDIC and ASCII platforms with Unicode properties, but starting in Perl v5.20, the distinctions between the platforms have mostly been made invisible to most code, so this function is quite unlikely to be what you want. If you do need this precise functionality, use instead `NATIVE_TO_UNI(utf8_to_uvchr_buf(...))` or `NATIVE_TO_UNI(utf8n_to_uvchr(...))`.

      UV  utf8n_to_uvuni(const U8 *s, STRLEN curlen, STRLEN *retlen,
                         U32 flags)

`utf8_to_uvuni`

  `DEPRECATED!` It is planned to remove `utf8_to_uvuni` from a future release of Perl. Do not use it for new code; remove it from existing code.

  Returns the Unicode 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 one reason why this function is deprecated. The other is that only in extremely limited circumstances should the Unicode versus native code point be of any interest to you.

  If `s` points to one of the detected malformations, and UTF8 warnings are enabled, zero is returned and `*retlen` is set (if `retlen` doesn't point to 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" in perlapi for details on when the REPLACEMENT CHARACTER is returned.

      UV  utf8_to_uvuni(const U8 *s, STRLEN *retlen)

`uvoffuni_to_utf8_flags`

  THIS FUNCTION SHOULD BE USED IN ONLY VERY SPECIALIZED CIRCUMSTANCES. Instead, Almost all code should use "uvchr_to_utf8" in perlapi or "uvchr_to_utf8_flags" in perlapi.

  This function is like them, but the input is a strict Unicode (as opposed to native) code point. Only in very rare circumstances should code not be using the native code point.

  For details, see the description for "uvchr_to_utf8_flags" in perlapi.

      U8 *  uvoffuni_to_utf8_flags(U8 *d, UV uv, UV flags)

`valid_utf8_to_uvchr`

  Like `"utf8_to_uvchr_buf" in perlapi`, but should only be called when it is known that the next character in the input UTF-8 string `s` is well-formed (e.g., it passes `"isUTF8_CHAR" in perlapi`. Surrogates, non-character code points, and non-Unicode code points are allowed.

      UV  valid_utf8_to_uvchr(const U8 *s, STRLEN *retlen)

`variant_under_utf8_count`

  This function looks at the sequence of bytes between `s` and `e`, which are assumed to be encoded in ASCII/Latin1, and returns how many of them would change should the string be translated into UTF-8. Due to the nature of UTF-8, each of these would occupy two bytes instead of the single one in the input string. Thus, this function returns the precise number of bytes the string would expand by when translated to UTF-8.

  Unlike most of the other functions that have `utf8` in their name, the input to this function is NOT a UTF-8-encoded string. The function name is slightly odd to emphasize this.

  This function is internal to Perl because khw thinks that any XS code that would want this is probably operating too close to the internals. Presenting a valid use case could change that.

  See also `"is_utf8_invariant_string" in perlapi` and `"is_utf8_invariant_string_loc" in perlapi`,

      Size_t  variant_under_utf8_count(const U8 * const s,
                                       const U8 * const e)

# Utility Functions

`my_popen_list`

  Implementing function on some systems for PerlProc_popen_list()

      PerlIO *  my_popen_list(const char *mode, int n, SV **args)

`my_socketpair`

  Emulates socketpair(2) on systems that don't have it, but which do have enough functionality for the emulation.

      int  my_socketpair(int family, int type, int protocol, int fd[2])

# Versioning

There are currently no internal API items in Versioning

# Warning and Dieing

`deprecate`

  Wrapper around Perl_ck_warner_d() to produce a deprecated warning in the given category with an appropriate message. The `message` argument must be a C string. The string " is deprecated" will automatically be added to the end of the `message`.

      deprecate(U32 category, "message")

`deprecate_disappears_in`

  Wrapper around Perl_ck_warner_d() to produce a deprecated warning in the given category with an appropriate message that the construct referred to by the message will disappear in a specific release. The `when` and `message` arguments must be a C string. The `when` string is expected to be of the form "5.40", with no minor element in the version. The actual message output will be the result of the following expression `message " is deprecated, and will disappear in Perl " when` which is why `message` and `when` must be literal C strings.

      deprecate_disappears_in(U32 category, "when", "message")

`deprecate_fatal_in`

  Wrapper around Perl_ck_warner_d() to produce a deprecated warning in the given category with an appropriate message that the construct referred to by the message will become fatal in a specific release. The `when` and `message` arguments must be a C string. The `when` string is expected to be of the form "5.40", with no minor element in the version. The actual message output will be the result of the following expression `message " is deprecated, and will become fatal in Perl " when` which is why `message` and `when` must be literal C strings.

      deprecate_fatal_in(U32 category, "when", "message")

`PL_dowarn`

  The C variable that roughly corresponds to Perl's `$^W` warning variable. However, `$^W` is treated as a boolean, whereas `PL_dowarn` is a collection of flag bits.

  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.

      U8  PL_dowarn

`report_uninit`

  Print appropriate "Use of uninitialized variable" warning.

      void  report_uninit(const SV *uninit_sv)

# XS

There are currently no internal API items in XS

# Undocumented elements

This section lists the elements that are otherwise undocumented. If you use any of them, please consider creating and submitting documentation for it.

Experimental and deprecated undocumented elements are listed separately at the end.

    abort_execution
    add_above_Latin1_folds
    add_cp_to_invlist
    _add_range_to_invlist
    allocmy
    amagic_cmp
    amagic_cmp_desc
    amagic_cmp_locale
    amagic_cmp_locale_desc
    amagic_i_ncmp
    amagic_i_ncmp_desc
    amagic_is_enabled
    amagic_ncmp
    amagic_ncmp_desc
    any_dup
    append_utf8_from_native_byte
    apply
    atfork_lock
    atfork_unlock
    av_arylen_p
    av_extend_guts
    av_iter_p
    av_nonelem
    av_reify
    bind_match
    block_gimme
    boot_core_builtin
    boot_core_mro
    boot_core_PerlIO
    boot_core_UNIVERSAL
    build_infix_plugin
    _byte_dump_string
    call_list
    cando
    capture_clear
    cast_iv
    cast_i32
    cast_ulong
    cast_uv
    check_hash_fields_and_hekify
    check_regnode_after
    check_utf8_print
    ck_anoncode
    ck_backtick
    ck_bitop
    ck_cmp
    ck_concat
    ck_defined
    ck_delete
    ck_each
    ck_entersub_args_core
    ck_eof
    ck_eval
    ck_exec
    ck_exists
    ck_ftst
    ck_fun
    ck_glob
    ck_grep
    ck_helemexistsor
    ck_index
    ck_isa
    ck_join
    ck_length
    ck_lfun
    ck_listiob
    ck_match
    ck_method
    ck_null
    ck_open
    ck_prototype
    ck_readline
    ck_refassign
    ck_repeat
    ck_require
    ck_return
    ck_rfun
    ck_rvconst
    ck_sassign
    ck_select
    ck_shift
    ck_smartmatch
    ck_sort
    ck_spair
    ck_split
    ck_stringify
    ck_subr
    ck_substr
    ck_svconst
    ck_tell
    ck_trunc
    ck_trycatch
    ckwarn
    ckwarn_d
    class_add_ADJUST
    class_add_field
    class_apply_attributes
    class_apply_field_attributes
    class_prepare_initfield_parse
    class_prepare_method_parse
    class_seal_stash
    class_set_field_defop
    class_setup_stash
    class_wrap_method_body
    clear_defarray
    closest_cop
    cmpchain_extend
    cmpchain_finish
    cmpchain_start
    cmp_desc
    cmp_locale_desc
    cntrl_to_mnemonic
    construct_ahocorasick_from_trie
    cop_file_avn
    coresub_op
    croak_caller
    croak_kw_unless_class
    croak_memory_wrap
    croak_no_mem
    croak_popstack
    csighandler
    csighandler1
    csighandler3
    current_re_engine
    custom_op_get_field
    cv_clone_into
    cv_const_sv_or_av
    cvgv_from_hek
    cvgv_set
    cvstash_set
    cv_undef_flags
    cx_dump
    cx_dup
    cxinc
    deb_stack_all
    debstackptrs
    debug_hash_seed
    debug_peep
    debug_show_study_flags
    debug_studydata
    defelem_target
    despatch_signals
    die_unwind
    do_aexec
    do_aexec5
    do_aspawn
    do_eof
    does_utf8_overflow
    do_exec
    do_exec3
    dofile
    do_gv_dump
    do_gvgv_dump
    do_hv_dump
    doing_taint
    do_ipcctl
    do_ipcget
    do_magic_dump
    do_msgrcv
    do_msgsnd
    do_ncmp
    do_op_dump
    do_pmop_dump
    do_print
    do_readline
    doref
    do_seek
    do_semop
    do_shmio
    do_spawn
    do_spawn_nowait
    do_sv_dump
    do_sysseek
    do_tell
    do_trans
    do_uniprop_match
    do_vecget
    do_vecset
    do_vop
    drand48_init_r
    drand48_r
    dtrace_probe_call
    dtrace_probe_load
    dtrace_probe_op
    dtrace_probe_phase
    dump_all_perl
    dump_indent
    dump_packsubs_perl
    dump_sub_perl
    dump_sv_child
    dumpuntil
    dump_vindent
    dup_warnings
    find_first_differing_byte_pos
    find_lexical_cv
    find_runcv_where
    find_script
    foldEQ_latin1_s2_folded
    foldEQ_latin1
    foldEQ_utf8_flags
    force_locale_unlock
    _force_out_malformed_utf8_message
    form_alien_digit_msg
    form_cp_too_large_msg
    free_tied_hv_pool
    free_tmps
    get_and_check_backslash_N_name
    get_ANYOFHbbm_contents
    get_ANYOFM_contents
    get_db_sub
    get_debug_opts
    get_deprecated_property_msg
    getenv_len
    get_extended_os_errno
    get_hash_seed
    get_invlist_iter_addr
    get_invlist_offset_addr
    get_invlist_previous_index_addr
    get_mstats
    get_prop_definition
    get_prop_values
    get_regclass_aux_data
    get_re_gclass_aux_data
    get_regex_charset_name
    get_win32_message_utf8ness
    gp_free
    gp_ref
    grok_bin_oct_hex
    grok_bslash_c
    grok_bslash_o
    grok_bslash_x
    gv_check
    gv_fetchmeth_internal
    gv_override
    gv_setref
    gv_stashpvn_internal
    he_dup
    hek_dup
    hfree_next_entry
    hv_auxalloc
    hv_common
    hv_common_key_len
    hv_delayfree_ent
    hv_free_ent
    hv_placeholders_p
    hv_pushkv
    hv_rand_set
    hv_undef_flags
    infix_plugin_standard
    init_argv_symbols
    init_constants
    init_dbargs
    init_debugger
    init_i18nl10n
    init_named_cv
    init_stacks
    init_tm
    init_uniprops
    _inverse_folds
    invert
    invlist_array
    _invlist_array_init
    invlist_clear
    invlist_clone
    _invlist_contains_cp
    invlist_contents
    _invlist_dump
    _invlistEQ
    invlist_extend
    invlist_highest
    _invlist_intersection
    _invlist_intersection_maybe_complement_2nd
    _invlist_invert
    invlist_is_iterating
    invlist_iterfinish
    invlist_iterinit
    invlist_iternext
    _invlist_len
    invlist_max
    invlist_previous_index
    _invlist_search
    invlist_set_len
    invlist_set_previous_index
    _invlist_subtract
    invlist_trim
    _invlist_union
    _invlist_union_maybe_complement_2nd
    invmap_dump
    invoke_exception_hook
    io_close
    isFF_overlong
    is_grapheme
    _is_in_locale_category
    is_invlist
    is_ssc_worth_it
    _is_uni_FOO
    _is_uni_perl_idcont
    _is_uni_perl_idstart
    is_utf8_char_helper_
    is_utf8_common
    is_utf8_FF_helper_
    _is_utf8_FOO
    is_utf8_overlong
    _is_utf8_perl_idcont
    _is_utf8_perl_idstart
    jmaybe
    join_exact
    keyword
    keyword_plugin_standard
    list
    load_charnames
    locale_panic
    localize
    lossless_NV_to_IV
    lsbit_pos32
    lsbit_pos64
    magic_clear_all_env
    magic_cleararylen_p
    magic_clearenv
    magic_clearhook
    magic_clearhookall
    magic_clearisa
    magic_clearpack
    magic_clearsig
    magic_copycallchecker
    magic_existspack
    magic_freearylen_p
    magic_freecollxfrm
    magic_freemglob
    magic_freeovrld
    magic_freeutf8
    magic_get
    magic_getarylen
    magic_getdebugvar
    magic_getdefelem
    magic_getnkeys
    magic_getpack
    magic_getpos
    magic_getsig
    magic_getsubstr
    magic_gettaint
    magic_getuvar
    magic_getvec
    magic_killbackrefs
    magic_nextpack
    magic_regdata_cnt
    magic_regdatum_get
    magic_regdatum_set
    magic_scalarpack
    magic_set
    magic_set_all_env
    magic_setarylen
    magic_setcollxfrm
    magic_setdbline
    magic_setdebugvar
    magic_setdefelem
    magic_setenv
    magic_sethook
    magic_sethookall
    magic_setisa
    magic_setlvref
    magic_setmglob
    magic_setnkeys
    magic_setnonelem
    magic_setpack
    magic_setpos
    magic_setregexp
    magic_setsig
    magic_setsigall
    magic_setsubstr
    magic_settaint
    magic_setutf8
    magic_setuvar
    magic_setvec
    magic_sizepack
    magic_wipepack
    make_trie
    malloced_size
    malloc_good_size
    markstack_grow
    mbtowc_
    mem_collxfrm_
    mem_log_alloc
    mem_log_del_sv
    mem_log_free
    mem_log_new_sv
    mem_log_realloc
    mg_find_mglob
    mg_size
    mode_from_discipline
    more_bodies
    more_sv
    moreswitches
    mortal_getenv
    mortalized_pv_copy
    mro_get_private_data
    mro_meta_dup
    mro_meta_init
    msbit_pos32
    msbit_pos64
    multiconcat_stringify
    multideref_stringify
    my_atof2
    my_atof3
    my_attrs
    my_clearenv
    my_lstat
    my_lstat_flags
    my_memrchr
    my_mkostemp_cloexec
    my_mkstemp_cloexec
    my_stat
    my_stat_flags
    my_strerror
    my_strftime8_temp
    my_unexec
    newFORM
    _new_invlist
    _new_invlist_C_array
    newMETHOP_internal
    newMYSUB
    newPROG
    new_stackinfo
    newSTUB
    newSVavdefelem
    newXS_deffile
    nextargv
    no_bareword_allowed
    no_bareword_filehandle
    noperl_die
    notify_parser_that_changed_to_utf8
    oopsAV
    oopsHV
    op_clear
    op_integerize
    op_lvalue_flags
    opmethod_stash
    op_prune_chain_head
    op_relocate_sv
    opslab_force_free
    opslab_free
    opslab_free_nopad
    op_std_init
    op_varname
    package
    package_version
    pad_add_weakref
    padlist_store
    padname_free
    PadnameIN_SCOPE
    padnamelist_free
    parser_dup
    parser_free
    parser_free_nexttoke_ops
    parse_unicode_opts
    path_is_searchable
    peep
    perl_alloc_using
    perl_clone_using
    PerlEnv_putenv
    PerlIO_context_layers
    PerlIO_restore_errno
    PerlIO_save_errno
    PerlLIO_dup_cloexec
    PerlLIO_dup2_cloexec
    PerlLIO_open_cloexec
    PerlLIO_open3_cloexec
    PerlProc_pipe_cloexec
    PerlSock_accept_cloexec
    PerlSock_socket_cloexec
    PerlSock_socketpair_cloexec
    perly_sighandler
    pmruntime
    POPMARK
    populate_anyof_bitmap_from_invlist
    populate_bitmap_from_invlist
    populate_invlist_from_bitmap
    populate_isa
    pregfree
    pregfree2
    ptr_hash
    qerror
    ReANY
    reentrant_free
    reentrant_init
    reentrant_retry
    reentrant_size
    re_exec_indentf
    ref
    reg_add_data
    regcurly
    regdump
    regdupe_internal
    regexec_flags
    regfree_internal
    reginitcolors
    reg_named_buff
    reg_named_buff_all
    reg_named_buff_exists
    reg_named_buff_fetch
    reg_named_buff_firstkey
    reg_named_buff_iter
    reg_named_buff_nextkey
    reg_named_buff_scalar
    regnext
    regnode_after
    reg_numbered_buff_fetch
    reg_numbered_buff_fetch_flags
    reg_numbered_buff_length
    reg_numbered_buff_store
    regprop
    reg_qr_package
    reg_skipcomment
    reg_temp_copy
    re_indentf
    re_intuit_start
    re_intuit_string
    re_op_compile
    report_evil_fh
    report_redefined_cv
    report_wrongway_fh
    re_printf
    rpeep
    rsignal_restore
    rsignal_save
    rvpv_dup
    rxres_save
    same_dirent
    save_bool
    save_clearsv
    save_delete
    save_destructor
    save_destructor_x
    save_freeop
    save_freepv
    save_freesv
    save_int
    save_iv
    save_I8
    save_I16
    save_I32
    save_mortalizesv
    save_pptr
    save_pushi32ptr
    save_pushptrptr
    save_re_context
    save_sptr
    savestack_grow
    savestack_grow_cnt
    save_strlen
    sawparens
    scalar
    scalarvoid
    scan_commit
    scan_num
    seed
    set_ANYOF_arg
    set_caret_X
    setfd_cloexec
    setfd_cloexec_for_nonsysfd
    setfd_cloexec_or_inhexec_by_sysfdness
    setfd_inhexec
    setfd_inhexec_for_sysfd
    set_numeric_standard
    set_numeric_underlying
    set_padlist
    _setup_canned_invlist
    share_hek
    should_warn_nl
    should_we_output_Debug_r
    sighandler
    sighandler1
    sighandler3
    single_1bit_pos32
    single_1bit_pos64
    Slab_Alloc
    Slab_Free
    Slab_to_ro
    Slab_to_rw
    softref2xv
    sortsv_flags_impl
    ssc_finalize
    ssc_init
    stack_grow
    str_to_version
    strxfrm
    study_chunk
    sub_crush_depth
    sv_add_backref
    sv_buf_to_ro
    sv_del_backref
    sv_i_ncmp
    sv_i_ncmp_desc
    sv_2iv
    sv_magicext_mglob
    sv_ncmp
    sv_ncmp_desc
    sv_only_taint_gmagic
    sv_or_pv_pos_u2b
    sv_pvbyten_force_wrapper
    sv_pvutf8n_force_wrapper
    sv_resetpvn
    sv_sethek
    SvTRUE_common
    sv_unglob
    sv_2uv
    switch_locale_context
    sys_init
    sys_init3
    sys_intern_clear
    sys_intern_dup
    sys_intern_init
    sys_term
    tied_method
    tmps_grow_p
    _to_fold_latin1
    TOPMARK
    to_uni_fold
    _to_uni_fold_flags
    to_uni_lower
    to_uni_title
    to_uni_upper
    _to_upper_title_latin1
    _to_utf8_fold_flags
    _to_utf8_lower_flags
    _to_utf8_title_flags
    _to_utf8_upper_flags
    translate_substr_offsets
    try_amagic_bin
    try_amagic_un
    uiv_2buf
    unlnk
    unshare_hek
    unwind_paren
    _utf8n_to_uvchr_msgs_helper
    utf16_to_utf8_base
    utf16_to_utf8_reversed
    utf16_to_utf8
    utf8_to_uvchr_buf_helper
    utilize
    uvoffuni_to_utf8_flags_msgs
    uvuni_to_utf8
    variant_byte_number
    varname
    vivify_defelem
    vivify_ref
    wait4pid
    warn_elem_scalar_context
    _warn_problematic_locale
    was_lvalue_sub
    watch
    win32_croak_not_implemented
    write_to_stderr
    xs_boot_epilog
    xs_handshake
    yyerror
    yyerror_pv
    yyerror_pvn
    yylex
    yyparse
    yyquit
    yyunlex

Next are the experimental undocumented elements

    alloc_LOGOP           cx_pushloop_for              invlist_lowest
    create_eval_scope     cx_pushloop_plain            newGP
    cv_ckproto_len_flags  cx_pushsub                   new_warnings_bitfield
    cx_popblock           cx_pushtry                   op_refcnt_dec
    cx_popeval            cx_pushwhen                  op_refcnt_inc
    cx_popformat          cx_topblock                  op_unscope
    cx_popgiven           delete_eval_scope            scan_str
    cx_poploop            do_open_raw                  scan_word
    cx_popsub             do_open6                     scan_word6
    cx_popsub_args        emulate_cop_io               skipspace_flags
    cx_popsub_common      get_re_arg                   sv_free2
    cx_popwhen            get_vtbl                     sv_kill_backrefs
    cx_pushblock          gimme_V                      sv_setpv_freshbuf
    cx_pusheval           hv_backreferences_p          sv_setsv_cow
    cx_pushformat         hv_kill_backrefs             utf8_to_utf16_base
    cx_pushgiven          invlist_highest_range_start

Finally are the deprecated undocumented elements. Do not use any for new code; remove all occurrences of all of these from existing code.

    get_no_modify  get_opargs  get_ppaddr

# AUTHORS

The autodocumentation system was originally added to the Perl core by Benjamin Stuhl. Documentation is by whoever was kind enough to document their functions.

# SEE ALSO

config.h, perlapi, perlapio, perlcall, perlclib, perlembed, perlfilter, perlguts, perlhacktips, perlinterp, perliol, perlmroapi, perlreapi, perlreguts, perlxs