perlintern(1)
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!
Compile-time scope hooks
BhkENTRY
NOTE: this function 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, which)
BhkFLAGS
NOTE: this function is experimental and may change or be
removed without notice.
Return the BHK's flags.
U32 BhkFLAGS(BHK *hk)
CALL_BLOCK_HOOKS
NOTE: this function 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(which, arg)
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 Manipulation Functions
docatch Check for the cases 0 or 3 of cur_env.je_ret, only used inside
an eval context.
0 is used as continue inside eval,
3 is used for a die caught by an inner eval - continue inner
loop
See cop.h: je_mustcatch, when set at any runlevel to TRUE,
means eval ops must establish a local jmpenv to handle
exception traps.
OP* docatch(OP *o)
CV reference counts and CvOUTSIDE
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)
Embedding Functions
cv_dump dump the contents of a CV
void cv_dump(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)
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
protoypes have to store in "xlow" 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.
void 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_swipe
Abandon the tmp in the current pad at offset "po" and replace
with a new one.
void pad_swipe(PADOFFSET po, bool refadjust)
GV Functions
gv_try_downgrade
NOTE: this function 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)
Hash Manipulation Functions
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)
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 "NUL"-terminated
literal string instead of a string/length pair, and no
precomputed hash.
SV * refcounted_he_fetch_pvs(
const struct refcounted_he *chain,
const char *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 "NUL"-terminated
literal string instead of a string/length pair, and no
precomputed hash.
struct refcounted_he * refcounted_he_new_pvs(
struct refcounted_he *parent,
const char *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
)
IO Functions
start_glob
NOTE: this function 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.
PerlIO* start_glob(SV *tmpglob, IO *io)
Lexer interface
validate_proto
NOTE: this function 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".
NOTE: the perl_ form of this function is deprecated.
bool validate_proto(SV *name, SV *proto, bool warn)
Magical Functions
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.
SV* magic_methcall(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_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)
Miscellaneous Functions
free_c_backtrace
Deallocates a backtrace received from get_c_bracktrace.
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)
MRO Functions
mro_get_linear_isa_dfs
Returns the Depth-First Search linearization of @ISA the given
stash. The return value is a read-only AV*. "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)
Optree Manipulation Functions
finalize_optree
This function finalizes the optree. Should be called directly
after the complete optree is built. It does some additional
checking which can't be done in the normal "ck_"xxx functions
and makes the tree thread-safe.
void finalize_optree(OP* o)
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)
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()
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_SETSV
Set the slot at offset "po" in the current pad to "sv"
SV * PAD_SETSV(PADOFFSET po, SV* sv)
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_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)
XXX DAPM it would make more sense to make the arg a PADOFFSET
void SAVEPADSV(PADOFFSET po)
Per-Interpreter Variables
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".
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".
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".
SV * PL_DBtrace
PL_dowarn
The C variable which corresponds to Perl's $^W warning
variable.
bool PL_dowarn
PL_last_in_gv
The GV which was last used for a filehandle input operation.
("<FH>")
GV* PL_last_in_gv
PL_ofsgv
The glob containing the output field separator - "*," in Perl
space.
GV* PL_ofsgv
PL_rs The input record separator - $/ in Perl space.
SV* PL_rs
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
SV-Body Allocation
sv_2num NOTE: this function 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_copypv
Copies a stringified representation of the source SV into the
destination SV. Automatically performs any necessary "mg_get"
and coercion of numeric values into strings. Guaranteed to
preserve "UTF8" flag even from overloaded objects. Similar in
nature to "sv_2pv[_flags]" but operates directly on an SV
instead of just the string. Mostly uses "sv_2pv_flags" to do
its work, except when that would lose the UTF-8'ness of the PV.
void sv_copypv(SV *const dsv, SV *const ssv)
SV Manipulation Functions
An SV (or AV, HV, etc.) is allocated in two parts: the head (struct sv,
av, hv...) contains type and reference count information, and for many
types, a pointer to the body (struct xrv, xpv, xpviv...), which
contains fields specific to each type. Some types store all they need
in the head, so don't have a body.
In all but the most memory-paranoid configurations (ex: PURIFY), heads
and bodies are allocated out of arenas, which by default are
approximately 4K chunks of memory parcelled up into N heads or bodies.
Sv-bodies are allocated by their sv-type, guaranteeing size consistency
needed to allocate safely from arrays.
For SV-heads, the first slot in each arena is reserved, and holds a
link to the next arena, some flags, and a note of the number of slots.
Snaked through each arena chain is a linked list of free items; when
this becomes empty, an extra arena is allocated and divided up into N
items which are threaded into the free list.
SV-bodies are similar, but they use arena-sets by default, which
separate the link and info from the arena itself, and reclaim the 1st
slot in the arena. SV-bodies are further described later.
The following global variables are associated with arenas:
PL_sv_arenaroot pointer to list of SV arenas
PL_sv_root pointer to list of free SV structures
PL_body_arenas head of linked-list of body arenas
PL_body_roots[] array of pointers to list of free bodies of svtype
arrays are indexed by the svtype needed
A few special SV heads are not allocated from an arena, but are instead
directly created in the interpreter structure, eg PL_sv_undef. The
size of arenas can be changed from the default by setting
PERL_ARENA_SIZE appropriately at compile time.
The SV arena serves the secondary purpose of allowing still-live SVs to
be located and destroyed during final cleanup.
At the lowest level, the macros new_SV() and del_SV() grab and free an
SV head. (If debugging with -DD, del_SV() calls the function
S_del_sv() to return the SV to the free list with error checking.)
new_SV() calls more_sv() / sv_add_arena() to add an extra arena if the
free list is empty. SVs in the free list have their SvTYPE field set
to all ones.
At the time of very final cleanup, sv_free_arenas() is called from
perl_destruct() to physically free all the arenas allocated since the
start of the interpreter.
The function visit() scans the SV arenas list, and calls a specified
function for each SV it finds which is still live - ie which has an
SvTYPE other than all 1's, and a non-zero SvREFCNT. visit() is used by
the following functions (specified as [function that calls visit()] /
[function called by visit() for each SV]):
sv_report_used() / do_report_used()
dump all remaining SVs (debugging aid)
sv_clean_objs() / do_clean_objs(),do_clean_named_objs(),
do_clean_named_io_objs(),do_curse()
Attempt to free all objects pointed to by RVs,
try to do the same for all objects indir-
ectly referenced by typeglobs too, and
then do a final sweep, cursing any
objects that remain. Called once from
perl_destruct(), prior to calling sv_clean_all()
below.
sv_clean_all() / do_clean_all()
SvREFCNT_dec(sv) each remaining SV, possibly
triggering an sv_free(). It also sets the
SVf_BREAK flag on the SV to indicate that the
refcnt has been artificially lowered, and thus
stopping sv_free() from giving spurious warnings
about SVs which unexpectedly have a refcnt
of zero. called repeatedly from perl_destruct()
until there are no SVs left.
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_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()
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)
Unicode Support
find_uninit_var
NOTE: this function 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)
report_uninit
Print appropriate "Use of uninitialized variable" warning.
void report_uninit(const SV *uninit_sv)
Undocumented functions
The following functions are currently undocumented. If you use one of them, you may wish to consider creating and submitting documentation for it. PerlIO_restore_errno PerlIO_save_errno Slab_Alloc Slab_Free Slab_to_ro Slab_to_rw _add_range_to_invlist _core_swash_init _get_encoding _get_swash_invlist _invlistEQ _invlist_array_init _invlist_contains_cp _invlist_dump _invlist_intersection _invlist_intersection_maybe_complement_2nd _invlist_invert _invlist_len _invlist_populate_swatch _invlist_search _invlist_subtract _invlist_union _invlist_union_maybe_complement_2nd _load_PL_utf8_foldclosures _new_invlist _setup_canned_invlist _swash_inversion_hash _swash_to_invlist _to_fold_latin1 _to_upper_title_latin1 _warn_problematic_locale add_cp_to_invlist alloc_maybe_populate_EXACT allocmy amagic_is_enabled apply av_extend_guts av_reify bind_match boot_core_PerlIO boot_core_UNIVERSAL boot_core_mro cando 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_index 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 closest_cop compute_EXACTish coresub_op create_eval_scope croak_no_mem croak_popstack current_re_engine custom_op_get_field cv_ckproto_len_flags cv_clone_into cv_const_sv_or_av cv_undef_flags cvgv_from_hek cvgv_set cvstash_set deb_stack_all defelem_target delete_eval_scope die_unwind do_aexec do_aexec5 do_eof do_exec do_exec3 do_execfree do_ipcctl do_ipcget do_msgrcv do_msgsnd do_ncmp do_open6 do_open_raw do_print do_readline do_seek do_semop do_shmio do_sysseek do_tell do_trans do_vecget do_vecset do_vop dofile drand48_init_r drand48_r dtrace_probe_call dtrace_probe_load dtrace_probe_op dtrace_probe_phase dump_all_perl dump_packsubs_perl dump_sub_perl dump_sv_child emulate_cop_io feature_is_enabled find_lexical_cv find_runcv_where find_script form_short_octal_warning free_tied_hv_pool get_and_check_backslash_N_name get_db_sub get_debug_opts get_hash_seed get_invlist_iter_addr get_invlist_offset_addr get_invlist_previous_index_addr get_no_modify get_opargs get_re_arg getenv_len grok_atoUV grok_bslash_c grok_bslash_o grok_bslash_x gv_fetchmeth_internal gv_override gv_setref gv_stashpvn_internal gv_stashsvpvn_cached handle_named_backref hfree_next_entry hv_backreferences_p hv_kill_backrefs hv_placeholders_p hv_undef_flags init_argv_symbols init_constants init_dbargs init_debugger invert invlist_array invlist_clear invlist_clone invlist_highest invlist_is_iterating invlist_iterfinish invlist_iterinit invlist_max invlist_previous_index invlist_set_len invlist_set_previous_index invlist_trim io_close isGCB is_utf8_common isinfnansv jmaybe keyword keyword_plugin_standard list localize magic_clear_all_env magic_cleararylen_p magic_clearenv magic_clearisa magic_clearpack magic_clearsig magic_copycallchecker magic_existspack magic_freearylen_p magic_freeovrld 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_setisa magic_setlvref magic_setmglob magic_setnkeys magic_setpack magic_setpos magic_setregexp magic_setsig magic_setsubstr magic_settaint magic_setutf8 magic_setuvar magic_setvec magic_sizepack magic_wipepack malloc_good_size malloced_size mem_collxfrm mem_log_alloc mem_log_free mem_log_realloc mg_find_mglob mode_from_discipline more_bodies mro_meta_dup mro_meta_init multideref_stringify my_attrs my_clearenv my_lstat_flags my_stat_flags my_unexec newATTRSUB_x newGP newMETHOP_internal newSTUB newSVavdefelem newXS_deffile newXS_len_flags new_warnings_bitfield nextargv noperl_die oopsAV oopsHV op_clear op_integerize op_lvalue_flags op_refcnt_dec op_refcnt_inc op_relocate_sv op_std_init op_unscope opmethod_stash opslab_force_free opslab_free opslab_free_nopad package package_version pad_add_weakref padlist_store padname_free padnamelist_free parse_subsignature parse_unicode_opts parser_free parser_free_nexttoke_ops path_is_searchable peep pmruntime populate_isa ptr_hash qerror re_exec_indentf re_indentf re_op_compile re_printf reg_named_buff reg_named_buff_iter reg_numbered_buff_fetch reg_numbered_buff_length reg_numbered_buff_store reg_qr_package reg_skipcomment reg_temp_copy regcurly regprop report_evil_fh report_redefined_cv report_wrongway_fh rpeep rsignal_restore rsignal_save rxres_save same_dirent save_strlen sawparens scalar scalarvoid set_caret_X set_padlist should_warn_nl sighandler softref2xv ssc_add_range ssc_clear_locale ssc_cp_and ssc_intersection ssc_union sub_crush_depth sv_add_backref sv_buf_to_ro sv_del_backref sv_free2 sv_kill_backrefs sv_len_utf8_nomg sv_magicext_mglob sv_mortalcopy_flags sv_only_taint_gmagic sv_or_pv_pos_u2b sv_resetpvn sv_sethek sv_setsv_cow sv_unglob tied_method tmps_grow_p translate_substr_offsets try_amagic_bin try_amagic_un unshare_hek utilize varname vivify_defelem vivify_ref wait4pid was_lvalue_sub watch win32_croak_not_implemented write_to_stderr xs_boot_epilog xs_handshake yyerror yyerror_pv yyerror_pvn yylex yyparse yyunlex
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
perlguts, perlapi
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