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 */
105 PERLVARI(G, watch_pvx, char *, NULL)
109 =for apidoc AmU|Perl_check_t *|PL_check
111 Array, indexed by opcode, of functions that will be called for the "check"
112 phase of optree building during compilation of Perl code. For most (but
113 not all) types of op, once the op has been initially built and populated
114 with child ops it will be filtered through the check function referenced
115 by the appropriate element of this array. The new op is passed in as the
116 sole argument to the check function, and the check function returns the
117 completed op. The check function may (as the name suggests) check the op
118 for validity and signal errors. It may also initialise or modify parts of
119 the ops, or perform more radical surgery such as adding or removing child
120 ops, or even throw the op away and return a different op in its place.
122 This array of function pointers is a convenient place to hook into the
123 compilation process. An XS module can put its own custom check function
124 in place of any of the standard ones, to influence the compilation of a
125 particular type of op. However, a custom check function must never fully
126 replace a standard check function (or even a custom check function from
127 another module). A module modifying checking must instead B<wrap> the
128 preexisting check function. A custom check function must be selective
129 about when to apply its custom behaviour. In the usual case where
130 it decides not to do anything special with an op, it must chain the
131 preexisting op function. Check functions are thus linked in a chain,
132 with the core's base checker at the end.
134 For thread safety, modules should not write directly to this array.
135 Instead, use the function L</wrap_op_checker>.
140 #if defined(USE_ITHREADS)
141 PERLVAR(G, check_mutex, perl_mutex) /* Mutex for PL_check */
143 #ifdef PERL_GLOBAL_STRUCT
144 PERLVAR(G, ppaddr, Perl_ppaddr_t *) /* or opcode.h */
145 PERLVAR(G, check, Perl_check_t *) /* or opcode.h */
146 PERLVARA(G, fold_locale, 256, unsigned char) /* or perl.h */
149 #ifdef PERL_NEED_APPCTX
150 PERLVAR(G, appctx, void*) /* the application context */
153 #if defined(HAS_TIMES) && defined(PERL_NEED_TIMESBASE)
154 PERLVAR(G, timesbase, struct tms)
157 /* allocate a unique index to every module that calls MY_CXT_INIT */
159 #ifdef PERL_IMPLICIT_CONTEXT
161 PERLVAR(G, my_ctx_mutex, perl_mutex)
163 PERLVARI(G, my_cxt_index, int, 0)
166 /* this is currently set without MUTEX protection, so keep it a type which
167 * can be set atomically (ie not a bit field) */
168 PERLVARI(G, veto_cleanup, int, FALSE) /* exit without cleanup */
171 =for apidoc AmUx|Perl_keyword_plugin_t|PL_keyword_plugin
173 Function pointer, pointing at a function used to handle extended keywords.
174 The function should be declared as
176 int keyword_plugin_function(pTHX_
177 char *keyword_ptr, STRLEN keyword_len,
180 The function is called from the tokeniser, whenever a possible keyword
181 is seen. C<keyword_ptr> points at the word in the parser's input
182 buffer, and C<keyword_len> gives its length; it is not null-terminated.
183 The function is expected to examine the word, and possibly other state
184 such as L<%^H|perlvar/%^H>, to decide whether it wants to handle it
185 as an extended keyword. If it does not, the function should return
186 C<KEYWORD_PLUGIN_DECLINE>, and the normal parser process will continue.
188 If the function wants to handle the keyword, it first must
189 parse anything following the keyword that is part of the syntax
190 introduced by the keyword. See L</Lexer interface> for details.
192 When a keyword is being handled, the plugin function must build
193 a tree of C<OP> structures, representing the code that was parsed.
194 The root of the tree must be stored in C<*op_ptr>. The function then
195 returns a constant indicating the syntactic role of the construct that
196 it has parsed: C<KEYWORD_PLUGIN_STMT> if it is a complete statement, or
197 C<KEYWORD_PLUGIN_EXPR> if it is an expression. Note that a statement
198 construct cannot be used inside an expression (except via C<do BLOCK>
199 and similar), and an expression is not a complete statement (it requires
200 at least a terminating semicolon).
202 When a keyword is handled, the plugin function may also have
203 (compile-time) side effects. It may modify C<%^H>, define functions, and
204 so on. Typically, if side effects are the main purpose of a handler,
205 it does not wish to generate any ops to be included in the normal
206 compilation. In this case it is still required to supply an op tree,
207 but it suffices to generate a single null op.
209 That's how the C<*PL_keyword_plugin> function needs to behave overall.
210 Conventionally, however, one does not completely replace the existing
211 handler function. Instead, take a copy of C<PL_keyword_plugin> before
212 assigning your own function pointer to it. Your handler function should
213 look for keywords that it is interested in and handle those. Where it
214 is not interested, it should call the saved plugin function, passing on
215 the arguments it received. Thus C<PL_keyword_plugin> actually points
216 at a chain of handler functions, all of which have an opportunity to
217 handle keywords, and only the last function in the chain (built into
218 the Perl core) will normally return C<KEYWORD_PLUGIN_DECLINE>.
223 PERLVARI(G, keyword_plugin, Perl_keyword_plugin_t, Perl_keyword_plugin_standard)
225 PERLVARI(G, op_sequence, HV *, NULL) /* dump.c */
226 PERLVARI(G, op_seq, UV, 0) /* dump.c */
229 PERLVAR(G, dollarzero_mutex, perl_mutex) /* Modifying $0 */
232 /* Restricted hashes placeholder value.
233 In theory, the contents are never used, only the address.
234 In practice, &PL_sv_placeholder is returned by some APIs, and the calling
235 code is checking SvOK(). */
237 PERLVAR(G, sv_placeholder, SV)
239 #if defined(MYMALLOC) && defined(USE_ITHREADS)
240 PERLVAR(G, malloc_mutex, perl_mutex) /* Mutex for malloc */
243 PERLVARI(G, hash_seed_set, bool, FALSE) /* perl.c */
244 PERLVARA(G, hash_seed, PERL_HASH_SEED_BYTES, unsigned char) /* perl.c and hv.h */