sig.c

   1 /* sig.c - interface for shell signal handlers and signal initialization. */
   2
   3 /* Copyright (C) 1994 Free Software Foundation, Inc.
   4
   5    This file is part of GNU Bash, the Bourne Again SHell.
   6
   7    Bash is free software; you can redistribute it and/or modify it under
   8    the terms of the GNU General Public License as published by the Free
   9    Software Foundation; either version 2, or (at your option) any later
  10    version.
  11
  12    Bash is distributed in the hope that it will be useful, but WITHOUT ANY
  13    WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15    for more details.
  16
  17    You should have received a copy of the GNU General Public License along
  18    with Bash; see the file COPYING.  If not, write to the Free Software
  19    Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */
  20
  21 #include "config.h"
  22
  23 #include "bashtypes.h"
  24
  25 #if defined (HAVE_UNISTD_H)
  26 #  ifdef _MINIX
  27 #    include <sys/types.h>
  28 #  endif
  29 #  include <unistd.h>
  30 #endif
  31
  32 #include <stdio.h>
  33 #include <signal.h>
  34
  35 #include "shell.h"
  36 #if defined (JOB_CONTROL)
  37 #include "jobs.h"
  38 #endif /* JOB_CONTROL */
  39 #include "siglist.h"
  40 #include "sig.h"
  41 #include "trap.h"
  42
  43 #include "builtins/common.h"
  44
  45 #if defined (READLINE)
  46 #  include "bashline.h"
  47 #endif
  48
  49 #if defined (HISTORY)
  50 #  include "bashhist.h"
  51 #endif
  52
  53 extern int last_command_exit_value;
  54 extern int return_catch_flag;
  55 extern int loop_level, continuing, breaking;
  56 extern int parse_and_execute_level, shell_initialized;
  57 extern int startup_state;
  58
  59 /* Non-zero after SIGINT. */
  60 int interrupt_state;
  61
  62 /* The environment at the top-level R-E loop.  We use this in
  63    the case of error return. */
  64 procenv_t top_level;
  65
  66 #if defined (JOB_CONTROL) || defined (HAVE_POSIX_SIGNALS)
  67 /* The signal masks that this shell runs with. */
  68 sigset_t top_level_mask;
  69 #endif /* JOB_CONTROL */
  70
  71 /* When non-zero, we throw_to_top_level (). */
  72 int interrupt_immediately = 0;
  73
  74 static void initialize_shell_signals __P((void));
  75
  76 void
  77 initialize_signals ()
  78 {
  79   initialize_shell_signals ();
  80   initialize_job_signals ();
  81 #if !defined (HAVE_SYS_SIGLIST) && !defined (HAVE_UNDER_SYS_SIGLIST) && !defined (HAVE_STRSIGNAL)
  82   initialize_siglist ();
  83 #endif /* !HAVE_SYS_SIGLIST && !HAVE_UNDER_SYS_SIGLIST && !HAVE_STRSIGNAL */
  84 }
  85
  86 void
  87 reinitialize_signals ()
  88 {
  89   initialize_shell_signals ();
  90   initialize_job_signals ();
  91 }
  92
  93 /* A structure describing a signal that terminates the shell if not
  94    caught.  The orig_handler member is present so children can reset
  95    these signals back to their original handlers. */
  96 struct termsig {
  97      int signum;
  98      SigHandler *orig_handler;
  99 };
 100
 101 #define NULL_HANDLER (SigHandler *)SIG_DFL
 102
 103 /* The list of signals that would terminate the shell if not caught.
 104    We catch them, but just so that we can write the history file,
 105    and so forth. */
 106 static struct termsig terminating_signals[] = {
 107 #ifdef SIGHUP
 108 {  SIGHUP, NULL_HANDLER },
 109 #endif
 110
 111 #ifdef SIGINT
 112 {  SIGINT, NULL_HANDLER },
 113 #endif
 114
 115 #ifdef SIGILL
 116 {  SIGILL, NULL_HANDLER },
 117 #endif
 118
 119 #ifdef SIGTRAP
 120 {  SIGTRAP, NULL_HANDLER },
 121 #endif
 122
 123 #ifdef SIGIOT
 124 {  SIGIOT, NULL_HANDLER },
 125 #endif
 126
 127 #ifdef SIGDANGER
 128 {  SIGDANGER, NULL_HANDLER },
 129 #endif
 130
 131 #ifdef SIGEMT
 132 {  SIGEMT, NULL_HANDLER },
 133 #endif
 134
 135 #ifdef SIGFPE
 136 {  SIGFPE, NULL_HANDLER },
 137 #endif
 138
 139 #ifdef SIGBUS
 140 {  SIGBUS, NULL_HANDLER },
 141 #endif
 142
 143 #ifdef SIGSEGV
 144 {  SIGSEGV, NULL_HANDLER },
 145 #endif
 146
 147 #ifdef SIGSYS
 148 {  SIGSYS, NULL_HANDLER },
 149 #endif
 150
 151 #ifdef SIGPIPE
 152 {  SIGPIPE, NULL_HANDLER },
 153 #endif
 154
 155 #ifdef SIGALRM
 156 {  SIGALRM, NULL_HANDLER },
 157 #endif
 158
 159 #ifdef SIGTERM
 160 {  SIGTERM, NULL_HANDLER },
 161 #endif
 162
 163 #ifdef SIGXCPU
 164 {  SIGXCPU, NULL_HANDLER },
 165 #endif
 166
 167 #ifdef SIGXFSZ
 168 {  SIGXFSZ, NULL_HANDLER },
 169 #endif
 170
 171 #ifdef SIGVTALRM
 172 {  SIGVTALRM, NULL_HANDLER },
 173 #endif
 174
 175 #if 0
 176 #ifdef SIGPROF
 177 {  SIGPROF, NULL_HANDLER },
 178 #endif
 179 #endif
 180
 181 #ifdef SIGLOST
 182 {  SIGLOST, NULL_HANDLER },
 183 #endif
 184
 185 #ifdef SIGUSR1
 186 {  SIGUSR1, NULL_HANDLER },
 187 #endif
 188
 189 #ifdef SIGUSR2
 190 {  SIGUSR2, NULL_HANDLER },
 191 #endif
 192 };
 193
 194 #define TERMSIGS_LENGTH (sizeof (terminating_signals) / sizeof (struct termsig))
 195
 196 #define XSIG(x) (terminating_signals[x].signum)
 197 #define XHANDLER(x) (terminating_signals[x].orig_handler)
 198
 199 static int termsigs_initialized = 0;
 200
 201 /* Initialize signals that will terminate the shell to do some
 202    unwind protection.  For non-interactive shells, we only call
 203    this when a trap is defined for EXIT (0). */
 204 void
 205 initialize_terminating_signals ()
 206 {
 207   register int i;
 208 #if defined (HAVE_POSIX_SIGNALS)
 209   struct sigaction act, oact;
 210 #endif
 211
 212   if (termsigs_initialized)
 213     return;
 214
 215   /* The following code is to avoid an expensive call to
 216      set_signal_handler () for each terminating_signals.  Fortunately,
 217      this is possible in Posix.  Unfortunately, we have to call signal ()
 218      on non-Posix systems for each signal in terminating_signals. */
 219 #if defined (HAVE_POSIX_SIGNALS)
 220   act.sa_handler = termination_unwind_protect;
 221   act.sa_flags = 0;
 222   sigemptyset (&act.sa_mask);
 223   sigemptyset (&oact.sa_mask);
 224   for (i = 0; i < TERMSIGS_LENGTH; i++)
 225     sigaddset (&act.sa_mask, XSIG (i));
 226   for (i = 0; i < TERMSIGS_LENGTH; i++)
 227     {
 228       sigaction (XSIG (i), &act, &oact);
 229       XHANDLER(i) = oact.sa_handler;
 230       /* Don't do anything with signals that are ignored at shell entry
 231          if the shell is not interactive. */
 232       if (!interactive_shell && XHANDLER (i) == SIG_IGN)
 233         {
 234           sigaction (XSIG (i), &oact, &act);
 235           set_signal_ignored (XSIG (i));
 236         }
 237 #if defined (SIGPROF) && !defined (_MINIX)
 238       if (XSIG (i) == SIGPROF && XHANDLER (i) != SIG_DFL && XHANDLER (i) != SIG_IGN)
 239         sigaction (XSIG (i), &oact, (struct sigaction *)NULL);
 240 #endif /* SIGPROF && !_MINIX */
 241     }
 242
 243 #else /* !HAVE_POSIX_SIGNALS */
 244
 245   for (i = 0; i < TERMSIGS_LENGTH; i++)
 246     {
 247       XHANDLER(i) = signal (XSIG (i), termination_unwind_protect);
 248       /* Don't do anything with signals that are ignored at shell entry
 249          if the shell is not interactive. */
 250       if (!interactive_shell && XHANDLER (i) == SIG_IGN)
 251         {
 252           signal (XSIG (i), SIG_IGN);
 253           set_signal_ignored (XSIG (i));
 254         }
 255 #ifdef SIGPROF
 256       if (XSIG (i) == SIGPROF && XHANDLER (i) != SIG_DFL && XHANDLER (i) != SIG_IGN)
 257         signal (XSIG (i), XHANDLER (i));
 258 #endif
 259     }
 260
 261 #endif /* !HAVE_POSIX_SIGNALS */
 262
 263   termsigs_initialized = 1;
 264 }
 265
 266 static void
 267 initialize_shell_signals ()
 268 {
 269   if (interactive)
 270     initialize_terminating_signals ();
 271
 272 #if defined (JOB_CONTROL) || defined (HAVE_POSIX_SIGNALS)
 273   /* All shells use the signal mask they inherit, and pass it along
 274      to child processes.  Children will never block SIGCHLD, though. */
 275   sigemptyset (&top_level_mask);
 276   sigprocmask (SIG_BLOCK, (sigset_t *)NULL, &top_level_mask);
 277 #  if defined (SIGCHLD)
 278   sigdelset (&top_level_mask, SIGCHLD);
 279 #  endif
 280 #endif /* JOB_CONTROL || HAVE_POSIX_SIGNALS */
 281
 282   /* And, some signals that are specifically ignored by the shell. */
 283   set_signal_handler (SIGQUIT, SIG_IGN);
 284
 285   if (interactive)
 286     {
 287       set_signal_handler (SIGINT, sigint_sighandler);
 288       set_signal_handler (SIGTERM, SIG_IGN);
 289     }
 290 }
 291
 292 void
 293 reset_terminating_signals ()
 294 {
 295   register int i;
 296 #if defined (HAVE_POSIX_SIGNALS)
 297   struct sigaction act;
 298 #endif
 299
 300   if (termsigs_initialized == 0)
 301     return;
 302
 303 #if defined (HAVE_POSIX_SIGNALS)
 304   act.sa_flags = 0;
 305   sigemptyset (&act.sa_mask);
 306   for (i = 0; i < TERMSIGS_LENGTH; i++)
 307     {
 308       /* Skip a signal if it's trapped or handled specially, because the
 309          trap code will restore the correct value. */
 310       if (signal_is_trapped (XSIG (i)) || signal_is_special (XSIG (i)))
 311         continue;
 312
 313       act.sa_handler = XHANDLER (i);
 314       sigaction (XSIG (i), &act, (struct sigaction *) NULL);
 315     }
 316 #else /* !HAVE_POSIX_SIGNALS */
 317   for (i = 0; i < TERMSIGS_LENGTH; i++)
 318     {
 319       if (signal_is_trapped (XSIG (i)) || signal_is_special (XSIG (i)))
 320         continue;
 321
 322       signal (XSIG (i), XHANDLER (i));
 323     }
 324 #endif /* !HAVE_POSIX_SIGNALS */
 325 }
 326 #undef XSIG
 327 #undef XHANDLER
 328
 329 /* What to do when we've been interrupted, and it is safe to handle it. */
 330 void
 331 throw_to_top_level ()
 332 {
 333   int print_newline = 0;
 334
 335   if (interrupt_state)
 336     {
 337       print_newline = 1;
 338       DELINTERRUPT;
 339     }
 340
 341   if (interrupt_state)
 342     return;
 343
 344   last_command_exit_value |= 128;
 345
 346   /* Run any traps set on SIGINT. */
 347   run_interrupt_trap ();
 348
 349   /* Cleanup string parser environment. */
 350   while (parse_and_execute_level)
 351     parse_and_execute_cleanup ();
 352
 353 #if defined (JOB_CONTROL)
 354   give_terminal_to (shell_pgrp, 0);
 355 #endif /* JOB_CONTROL */
 356
 357 #if defined (JOB_CONTROL) || defined (HAVE_POSIX_SIGNALS)
 358   /* This should not be necessary on systems using sigsetjmp/siglongjmp. */
 359   sigprocmask (SIG_SETMASK, &top_level_mask, (sigset_t *)NULL);
 360 #endif
 361
 362   reset_parser ();
 363
 364 #if defined (READLINE)
 365   if (interactive)
 366     bashline_reinitialize ();
 367 #endif /* READLINE */
 368
 369 #if defined (PROCESS_SUBSTITUTION)
 370   unlink_fifo_list ();
 371 #endif /* PROCESS_SUBSTITUTION */
 372
 373   run_unwind_protects ();
 374   loop_level = continuing = breaking = 0;
 375   return_catch_flag = 0;
 376
 377   if (interactive && print_newline)
 378     {
 379       fflush (stdout);
 380       fprintf (stderr, "\n");
 381       fflush (stderr);
 382     }
 383
 384   /* An interrupted `wait' command in a script does not exit the script. */
 385   if (interactive || (interactive_shell && !shell_initialized) ||
 386       (print_newline && signal_is_trapped (SIGINT)))
 387     jump_to_top_level (DISCARD);
 388   else
 389     jump_to_top_level (EXITPROG);
 390 }
 391
 392 /* This is just here to isolate the longjmp calls. */
 393 void
 394 jump_to_top_level (value)
 395      int value;
 396 {
 397   longjmp (top_level, value);
 398 }
 399
 400 sighandler
 401 termination_unwind_protect (sig)
 402      int sig;
 403 {
 404   if (sig == SIGINT && signal_is_trapped (SIGINT))
 405     run_interrupt_trap ();
 406
 407 #if defined (HISTORY)
 408   if (interactive_shell && sig != SIGABRT)
 409     maybe_save_shell_history ();
 410 #endif /* HISTORY */
 411
 412 #if defined (JOB_CONTROL)
 413   if (interactive && sig == SIGHUP)
 414     hangup_all_jobs ();
 415   end_job_control ();
 416 #endif /* JOB_CONTROL */
 417
 418 #if defined (PROCESS_SUBSTITUTION)
 419   unlink_fifo_list ();
 420 #endif /* PROCESS_SUBSTITUTION */
 421
 422   run_exit_trap ();
 423   set_signal_handler (sig, SIG_DFL);
 424   kill (getpid (), sig);
 425
 426   SIGRETURN (0);
 427 }
 428
 429 /* What we really do when SIGINT occurs. */
 430 sighandler
 431 sigint_sighandler (sig)
 432      int sig;
 433 {
 434 #if defined (MUST_REINSTALL_SIGHANDLERS)
 435   signal (sig, sigint_sighandler);
 436 #endif
 437
 438   /* interrupt_state needs to be set for the stack of interrupts to work
 439      right.  Should it be set unconditionally? */
 440   if (interrupt_state == 0)
 441     ADDINTERRUPT;
 442
 443   if (interrupt_immediately)
 444     {
 445       interrupt_immediately = 0;
 446       throw_to_top_level ();
 447     }
 448
 449   SIGRETURN (0);
 450 }
 451
 452 /* Signal functions used by the rest of the code. */
 453 #if !defined (HAVE_POSIX_SIGNALS)
 454
 455 #if defined (JOB_CONTROL)
 456 /* Perform OPERATION on NEWSET, perhaps leaving information in OLDSET. */
 457 sigprocmask (operation, newset, oldset)
 458      int operation, *newset, *oldset;
 459 {
 460   int old, new;
 461
 462   if (newset)
 463     new = *newset;
 464   else
 465     new = 0;
 466
 467   switch (operation)
 468     {
 469     case SIG_BLOCK:
 470       old = sigblock (new);
 471       break;
 472
 473     case SIG_SETMASK:
 474       sigsetmask (new);
 475       break;
 476
 477     default:
 478       internal_error ("Bad code in sig.c: sigprocmask");
 479     }
 480
 481   if (oldset)
 482     *oldset = old;
 483 }
 484 #endif /* JOB_CONTROL */
 485
 486 #else
 487
 488 #if !defined (SA_INTERRUPT)
 489 #  define SA_INTERRUPT 0
 490 #endif
 491
 492 #if !defined (SA_RESTART)
 493 #  define SA_RESTART 0
 494 #endif
 495
 496 SigHandler *
 497 set_signal_handler (sig, handler)
 498      int sig;
 499      SigHandler *handler;
 500 {
 501   struct sigaction act, oact;
 502
 503   act.sa_handler = handler;
 504   act.sa_flags = 0;
 505 #if 0
 506   if (sig == SIGALRM)
 507     act.sa_flags |= SA_INTERRUPT;       /* XXX */
 508   else
 509     act.sa_flags |= SA_RESTART;         /* XXX */
 510 #endif
 511   sigemptyset (&act.sa_mask);
 512   sigemptyset (&oact.sa_mask);
 513   sigaction (sig, &act, &oact);
 514   return (oact.sa_handler);
 515 }
 516 #endif /* HAVE_POSIX_SIGNALS */