Mercurial > gnulib
annotate lib/fatal-signal.c @ 7304:1c4ed7637c24
Include <config.h> unconditionally.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Thu, 14 Sep 2006 14:18:36 +0000 |
| parents | 43bb3848f1c7 |
| children | 71b958155bb9 |
| rev | line source |
|---|---|
| 4770 | 1 /* Emergency actions in case of a fatal signal. |
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Include <unistd.h> unconditionally.
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2 Copyright (C) 2003-2004, 2006 Free Software Foundation, Inc. |
| 4770 | 3 Written by Bruno Haible <bruno@clisp.org>, 2003. |
| 4 | |
| 5 This program is free software; you can redistribute it and/or modify | |
| 6 it under the terms of the GNU General Public License as published by | |
| 7 the Free Software Foundation; either version 2, or (at your option) | |
| 8 any later version. | |
| 9 | |
| 10 This program is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 13 GNU General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU General Public License | |
| 16 along with this program; if not, write to the Free Software Foundation, | |
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17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ |
| 4770 | 18 |
| 19 | |
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20 #include <config.h> |
| 4770 | 21 |
| 22 /* Specification. */ | |
| 23 #include "fatal-signal.h" | |
| 24 | |
| 25 #include <stdbool.h> | |
| 26 #include <stdlib.h> | |
| 27 #include <signal.h> | |
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28 #include <unistd.h> |
| 4770 | 29 |
| 30 #include "xalloc.h" | |
| 31 | |
| 32 #define SIZEOF(a) (sizeof(a) / sizeof(a[0])) | |
| 33 | |
| 34 | |
| 35 /* ========================================================================= */ | |
| 36 | |
| 37 | |
| 38 /* The list of fatal signals. | |
| 39 These are those signals whose default action is to terminate the process | |
| 40 without a core dump, except | |
| 41 SIGKILL - because it cannot be caught, | |
| 42 SIGALRM SIGUSR1 SIGUSR2 SIGPOLL SIGIO SIGLOST - because applications | |
| 43 often use them for their own purpose, | |
| 44 SIGPROF SIGVTALRM - because they are used for profiling, | |
| 45 SIGSTKFLT - because it is more similar to SIGFPE, SIGSEGV, SIGBUS, | |
| 46 SIGSYS - because it is more similar to SIGABRT, SIGSEGV, | |
| 47 SIGPWR - because it of too special use, | |
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48 SIGRTMIN...SIGRTMAX - because they are reserved for application use. |
| 4770 | 49 plus |
| 50 SIGXCPU, SIGXFSZ - because they are quite similar to SIGTERM. */ | |
| 51 | |
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52 static int fatal_signals[] = |
| 4770 | 53 { |
| 54 /* ISO C 99 signals. */ | |
| 55 #ifdef SIGINT | |
| 56 SIGINT, | |
| 57 #endif | |
| 58 #ifdef SIGTERM | |
| 59 SIGTERM, | |
| 60 #endif | |
| 61 /* POSIX:2001 signals. */ | |
| 62 #ifdef SIGHUP | |
| 63 SIGHUP, | |
| 64 #endif | |
| 65 #ifdef SIGPIPE | |
| 66 SIGPIPE, | |
| 67 #endif | |
| 68 /* BSD signals. */ | |
| 69 #ifdef SIGXCPU | |
| 70 SIGXCPU, | |
| 71 #endif | |
| 72 #ifdef SIGXFSZ | |
| 73 SIGXFSZ, | |
| 74 #endif | |
| 75 0 | |
| 76 }; | |
| 77 | |
| 78 #define num_fatal_signals (SIZEOF (fatal_signals) - 1) | |
| 79 | |
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80 /* Eliminate signals whose signal handler is SIG_IGN. */ |
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81 |
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82 static void |
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83 init_fatal_signals (void) |
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84 { |
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85 static bool fatal_signals_initialized = false; |
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86 if (!fatal_signals_initialized) |
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87 { |
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88 #if HAVE_SIGACTION |
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89 size_t i; |
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90 |
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91 for (i = 0; i < num_fatal_signals; i++) |
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92 { |
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93 struct sigaction action; |
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94 |
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95 if (sigaction (fatal_signals[i], NULL, &action) >= 0 |
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96 && action.sa_handler == SIG_IGN) |
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97 fatal_signals[i] = -1; |
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98 } |
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99 #endif |
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100 |
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101 fatal_signals_initialized = true; |
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102 } |
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103 } |
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104 |
| 4770 | 105 |
| 106 /* ========================================================================= */ | |
| 107 | |
| 108 | |
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109 typedef void (*action_t) (void); |
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110 |
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111 /* Type of an entry in the actions array. |
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112 The 'action' field is accessed from within the fatal_signal_handler(), |
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113 therefore we mark it as 'volatile'. */ |
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114 typedef struct |
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115 { |
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116 volatile action_t action; |
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117 } |
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118 actions_entry_t; |
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119 |
| 4770 | 120 /* The registered cleanup actions. */ |
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121 static actions_entry_t static_actions[32]; |
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122 static actions_entry_t * volatile actions = static_actions; |
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123 static sig_atomic_t volatile actions_count = 0; |
| 4770 | 124 static size_t actions_allocated = SIZEOF (static_actions); |
| 125 | |
| 126 | |
| 127 /* Uninstall the handlers. */ | |
| 128 static inline void | |
| 129 uninstall_handlers () | |
| 130 { | |
| 131 size_t i; | |
| 132 | |
| 133 for (i = 0; i < num_fatal_signals; i++) | |
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134 if (fatal_signals[i] >= 0) |
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135 signal (fatal_signals[i], SIG_DFL); |
| 4770 | 136 } |
| 137 | |
| 138 | |
| 139 /* The signal handler. It gets called asynchronously. */ | |
| 140 static void | |
| 141 fatal_signal_handler (int sig) | |
| 142 { | |
| 143 for (;;) | |
| 144 { | |
| 145 /* Get the last registered cleanup action, in a reentrant way. */ | |
| 146 action_t action; | |
| 147 size_t n = actions_count; | |
| 148 if (n == 0) | |
| 149 break; | |
| 150 n--; | |
| 151 actions_count = n; | |
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152 action = actions[n].action; |
| 4770 | 153 /* Execute the action. */ |
| 154 action (); | |
| 155 } | |
| 156 | |
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157 /* Now execute the signal's default action. |
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158 If signal() blocks the signal being delivered for the duration of the |
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159 signal handler's execution, the re-raised signal is delivered when this |
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160 handler returns; otherwise it is delivered already during raise(). */ |
| 4770 | 161 uninstall_handlers (); |
| 162 #if HAVE_RAISE | |
| 163 raise (sig); | |
| 164 #else | |
| 165 kill (getpid (), sig); | |
| 166 #endif | |
| 167 } | |
| 168 | |
| 169 | |
| 170 /* Install the handlers. */ | |
| 171 static inline void | |
| 172 install_handlers () | |
| 173 { | |
| 174 size_t i; | |
| 175 | |
| 176 for (i = 0; i < num_fatal_signals; i++) | |
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177 if (fatal_signals[i] >= 0) |
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178 signal (fatal_signals[i], &fatal_signal_handler); |
| 4770 | 179 } |
| 180 | |
| 181 | |
| 182 /* Register a cleanup function to be executed when a catchable fatal signal | |
| 183 occurs. */ | |
| 184 void | |
| 185 at_fatal_signal (action_t action) | |
| 186 { | |
| 187 static bool cleanup_initialized = false; | |
| 188 if (!cleanup_initialized) | |
| 189 { | |
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190 init_fatal_signals (); |
| 4770 | 191 install_handlers (); |
| 192 cleanup_initialized = true; | |
| 193 } | |
| 194 | |
| 195 if (actions_count == actions_allocated) | |
| 196 { | |
| 197 /* Extend the actions array. Note that we cannot use xrealloc(), | |
| 198 because then the cleanup() function could access an already | |
| 199 deallocated array. */ | |
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200 actions_entry_t *old_actions = actions; |
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201 size_t old_actions_allocated = actions_allocated; |
| 4770 | 202 size_t new_actions_allocated = 2 * actions_allocated; |
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203 actions_entry_t *new_actions = |
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204 xmalloc (new_actions_allocated * sizeof (actions_entry_t)); |
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205 size_t k; |
| 4770 | 206 |
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207 /* Don't use memcpy() here, because memcpy takes non-volatile arguments |
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208 and is therefore not guaranteed to complete all memory stores before |
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209 the next statement. */ |
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210 for (k = 0; k < old_actions_allocated; k++) |
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211 new_actions[k] = old_actions[k]; |
| 4770 | 212 actions = new_actions; |
| 213 actions_allocated = new_actions_allocated; | |
| 214 /* Now we can free the old actions array. */ | |
| 215 if (old_actions != static_actions) | |
| 216 free (old_actions); | |
| 217 } | |
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218 /* The two uses of 'volatile' in the types above (and ISO C 99 section |
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219 5.1.2.3.(5)) ensure that we increment the actions_count only after |
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220 the new action has been written to the memory location |
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221 actions[actions_count]. */ |
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222 actions[actions_count].action = action; |
| 4770 | 223 actions_count++; |
| 224 } | |
| 225 | |
| 226 | |
| 227 /* ========================================================================= */ | |
| 228 | |
| 229 | |
| 230 #if HAVE_POSIX_SIGNALBLOCKING | |
| 231 | |
| 232 static sigset_t fatal_signal_set; | |
| 233 | |
| 234 static void | |
| 235 init_fatal_signal_set () | |
| 236 { | |
| 237 static bool fatal_signal_set_initialized = false; | |
| 238 if (!fatal_signal_set_initialized) | |
| 239 { | |
| 240 size_t i; | |
| 241 | |
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242 init_fatal_signals (); |
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243 |
| 4770 | 244 sigemptyset (&fatal_signal_set); |
| 245 for (i = 0; i < num_fatal_signals; i++) | |
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246 if (fatal_signals[i] >= 0) |
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247 sigaddset (&fatal_signal_set, fatal_signals[i]); |
| 4770 | 248 |
| 249 fatal_signal_set_initialized = true; | |
| 250 } | |
| 251 } | |
| 252 | |
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253 /* Temporarily delay the catchable fatal signals. */ |
| 4770 | 254 void |
| 255 block_fatal_signals () | |
| 256 { | |
| 257 init_fatal_signal_set (); | |
| 258 sigprocmask (SIG_BLOCK, &fatal_signal_set, NULL); | |
| 259 } | |
| 260 | |
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261 /* Stop delaying the catchable fatal signals. */ |
| 4770 | 262 void |
| 263 unblock_fatal_signals () | |
| 264 { | |
| 265 init_fatal_signal_set (); | |
| 266 sigprocmask (SIG_UNBLOCK, &fatal_signal_set, NULL); | |
| 267 } | |
| 268 | |
| 269 #else | |
| 270 | |
| 271 /* Don't bother caring about the old systems which don't have POSIX signal | |
| 272 blocking. */ | |
| 273 | |
| 274 void | |
| 275 block_fatal_signals () | |
| 276 { | |
| 277 } | |
| 278 | |
| 279 void | |
| 280 unblock_fatal_signals () | |
| 281 { | |
| 282 } | |
| 283 | |
| 284 #endif |