3 * Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
4 * by Larry Wall and others
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Artistic License, as specified in the README file.
12 =head1 Global Variables
13 These variables are global to an entire process. They are shared between
14 all interpreters and all threads in a process. Any variables not documented
15 here may be changed or removed without notice, so don't use them!
16 If you feel you really do need to use an unlisted variable, first send email to
17 L<perl5-porters@perl.org|mailto:perl5-porters@perl.org>. It may be that
18 someone there will point out a way to accomplish what you need without using an
19 internal variable. But if not, you should get a go-ahead to document and then
25 /* Don't forget to re-run regen/embed.pl to propagate changes! */
27 /* This file describes the "global" variables used by perl
28 * This used to be in perl.h directly but we want to abstract out into
29 * distinct files which are per-thread, per-interpreter or really global,
30 * and how they're initialized.
32 * The 'G' prefix is only needed for vars that need appropriate #defines
33 * generated in embed*.h. Such symbols are also used to generate
34 * the appropriate export list for win32. */
37 #if defined(USE_ITHREADS)
38 PERLVAR(G, op_mutex, perl_mutex) /* Mutex for op refcounting */
40 PERLVARI(G, curinterp, PerlInterpreter *, NULL)
41 /* currently running interpreter
42 * (initial parent interpreter under
44 #if defined(USE_ITHREADS)
45 PERLVAR(G, thr_key, perl_key) /* key to retrieve per-thread struct */
48 /* XXX does anyone even use this? */
49 PERLVARI(G, do_undump, bool, FALSE) /* -u or dump seen? */
51 #ifndef PERL_USE_SAFE_PUTENV
52 PERLVARI(G, use_safe_putenv, bool, TRUE)
55 #if defined(FAKE_PERSISTENT_SIGNAL_HANDLERS)||defined(FAKE_DEFAULT_SIGNAL_HANDLERS)
56 PERLVARI(G, sig_handlers_initted, int, 0)
58 #ifdef FAKE_PERSISTENT_SIGNAL_HANDLERS
59 PERLVARA(G, sig_ignoring, SIG_SIZE, int)
60 /* which signals we are ignoring */
62 #ifdef FAKE_DEFAULT_SIGNAL_HANDLERS
63 PERLVARA(G, sig_defaulting, SIG_SIZE, int)
66 /* XXX signals are process-wide anyway, so we
67 * ignore the implications of this for threading */
69 PERLVARI(G, sig_trapped, int, 0)
73 /* If Perl has to ignore SIGPFE, this is its saved state.
74 * See perl.h macros PERL_FPU_INIT and PERL_FPU_{PRE,POST}_EXEC. */
75 PERLVAR(G, sigfpe_saved, Sighandler_t)
76 PERLVARI(G, csighandlerp, Sighandler_t, Perl_csighandler)
77 /* Pointer to C-level sighandler */
80 /* This is constant on most architectures, a global on OS/2 */
82 PERLVARI(G, sh_path, char *, SH_PATH) /* full path of shell */
87 # if defined(USE_ITHREADS)
88 PERLVAR(G, perlio_mutex, perl_mutex) /* Mutex for perlio fd refcounts */
91 PERLVARI(G, perlio_fd_refcnt, int *, 0) /* Pointer to array of fd refcounts. */
92 PERLVARI(G, perlio_fd_refcnt_size, int, 0) /* Size of the array */
93 PERLVARI(G, perlio_debug_fd, int, 0) /* the fd to write perlio debug into, 0 means not set yet */
97 PERLVARI(G, mmap_page_size, IV, 0)
100 #if defined(USE_ITHREADS)
101 PERLVAR(G, hints_mutex, perl_mutex) /* Mutex for refcounted he refcounting */
102 PERLVAR(G, locale_mutex, perl_mutex) /* Mutex for setlocale() changing */
107 PERLVARI(G, watch_pvx, char *, NULL)
111 =for apidoc AmU|Perl_check_t *|PL_check
113 Array, indexed by opcode, of functions that will be called for the "check"
114 phase of optree building during compilation of Perl code. For most (but
115 not all) types of op, once the op has been initially built and populated
116 with child ops it will be filtered through the check function referenced
117 by the appropriate element of this array. The new op is passed in as the
118 sole argument to the check function, and the check function returns the
119 completed op. The check function may (as the name suggests) check the op
120 for validity and signal errors. It may also initialise or modify parts of
121 the ops, or perform more radical surgery such as adding or removing child
122 ops, or even throw the op away and return a different op in its place.
124 This array of function pointers is a convenient place to hook into the
125 compilation process. An XS module can put its own custom check function
126 in place of any of the standard ones, to influence the compilation of a
127 particular type of op. However, a custom check function must never fully
128 replace a standard check function (or even a custom check function from
129 another module). A module modifying checking must instead B<wrap> the
130 preexisting check function. A custom check function must be selective
131 about when to apply its custom behaviour. In the usual case where
132 it decides not to do anything special with an op, it must chain the
133 preexisting op function. Check functions are thus linked in a chain,
134 with the core's base checker at the end.
136 For thread safety, modules should not write directly to this array.
137 Instead, use the function L</wrap_op_checker>.
142 #if defined(USE_ITHREADS)
143 PERLVAR(G, check_mutex, perl_mutex) /* Mutex for PL_check */
145 #ifdef PERL_GLOBAL_STRUCT
146 PERLVAR(G, ppaddr, Perl_ppaddr_t *) /* or opcode.h */
147 PERLVAR(G, check, Perl_check_t *) /* or opcode.h */
148 PERLVARA(G, fold_locale, 256, unsigned char) /* or perl.h */
151 #ifdef PERL_NEED_APPCTX
152 PERLVAR(G, appctx, void*) /* the application context */
155 #if defined(HAS_TIMES) && defined(PERL_NEED_TIMESBASE)
156 PERLVAR(G, timesbase, struct tms)
159 /* allocate a unique index to every module that calls MY_CXT_INIT */
161 #ifdef PERL_IMPLICIT_CONTEXT
163 PERLVAR(G, my_ctx_mutex, perl_mutex)
165 PERLVARI(G, my_cxt_index, int, 0)
168 /* this is currently set without MUTEX protection, so keep it a type which
169 * can be set atomically (ie not a bit field) */
170 PERLVARI(G, veto_cleanup, int, FALSE) /* exit without cleanup */
173 =for apidoc AmUx|Perl_keyword_plugin_t|PL_keyword_plugin
175 Function pointer, pointing at a function used to handle extended keywords.
176 The function should be declared as
178 int keyword_plugin_function(pTHX_
179 char *keyword_ptr, STRLEN keyword_len,
182 The function is called from the tokeniser, whenever a possible keyword
183 is seen. C<keyword_ptr> points at the word in the parser's input
184 buffer, and C<keyword_len> gives its length; it is not null-terminated.
185 The function is expected to examine the word, and possibly other state
186 such as L<%^H|perlvar/%^H>, to decide whether it wants to handle it
187 as an extended keyword. If it does not, the function should return
188 C<KEYWORD_PLUGIN_DECLINE>, and the normal parser process will continue.
190 If the function wants to handle the keyword, it first must
191 parse anything following the keyword that is part of the syntax
192 introduced by the keyword. See L</Lexer interface> for details.
194 When a keyword is being handled, the plugin function must build
195 a tree of C<OP> structures, representing the code that was parsed.
196 The root of the tree must be stored in C<*op_ptr>. The function then
197 returns a constant indicating the syntactic role of the construct that
198 it has parsed: C<KEYWORD_PLUGIN_STMT> if it is a complete statement, or
199 C<KEYWORD_PLUGIN_EXPR> if it is an expression. Note that a statement
200 construct cannot be used inside an expression (except via C<do BLOCK>
201 and similar), and an expression is not a complete statement (it requires
202 at least a terminating semicolon).
204 When a keyword is handled, the plugin function may also have
205 (compile-time) side effects. It may modify C<%^H>, define functions, and
206 so on. Typically, if side effects are the main purpose of a handler,
207 it does not wish to generate any ops to be included in the normal
208 compilation. In this case it is still required to supply an op tree,
209 but it suffices to generate a single null op.
211 That's how the C<*PL_keyword_plugin> function needs to behave overall.
212 Conventionally, however, one does not completely replace the existing
213 handler function. Instead, take a copy of C<PL_keyword_plugin> before
214 assigning your own function pointer to it. Your handler function should
215 look for keywords that it is interested in and handle those. Where it
216 is not interested, it should call the saved plugin function, passing on
217 the arguments it received. Thus C<PL_keyword_plugin> actually points
218 at a chain of handler functions, all of which have an opportunity to
219 handle keywords, and only the last function in the chain (built into
220 the Perl core) will normally return C<KEYWORD_PLUGIN_DECLINE>.
225 PERLVARI(G, keyword_plugin, Perl_keyword_plugin_t, Perl_keyword_plugin_standard)
227 PERLVARI(G, op_sequence, HV *, NULL) /* dump.c */
228 PERLVARI(G, op_seq, UV, 0) /* dump.c */
231 PERLVAR(G, dollarzero_mutex, perl_mutex) /* Modifying $0 */
234 /* Restricted hashes placeholder value.
235 In theory, the contents are never used, only the address.
236 In practice, &PL_sv_placeholder is returned by some APIs, and the calling
237 code is checking SvOK(). */
239 PERLVAR(G, sv_placeholder, SV)
241 #if defined(MYMALLOC) && defined(USE_ITHREADS)
242 PERLVAR(G, malloc_mutex, perl_mutex) /* Mutex for malloc */
245 PERLVARI(G, hash_seed_set, bool, FALSE) /* perl.c */
246 PERLVARA(G, hash_seed, PERL_HASH_SEED_BYTES, unsigned char) /* perl.c and hv.h */