summaryrefslogtreecommitdiff
path: root/sig.c
blob: a217b8947cd9300411aec74fcbbe4928f0b0090e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
/* sig.c - interface for shell signal handlers and signal initialization. */

/* Copyright (C) 1994-2009 Free Software Foundation, Inc.

   This file is part of GNU Bash, the Bourne Again SHell.

   Bash is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   Bash is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with Bash.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "config.h"

#include "bashtypes.h"

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include <stdio.h>
#include <signal.h>

#include "bashintl.h"

#include "shell.h"
#if defined (JOB_CONTROL)
#include "jobs.h"
#endif /* JOB_CONTROL */
#include "siglist.h"
#include "sig.h"
#include "trap.h"

#include "builtins/common.h"

#if defined (READLINE)
#  include "bashline.h"
#endif

#if defined (HISTORY)
#  include "bashhist.h"
#endif

extern int last_command_exit_value;
extern int last_command_exit_signal;
extern int return_catch_flag;
extern int loop_level, continuing, breaking;
extern int executing_list;
extern int comsub_ignore_return;
extern int parse_and_execute_level, shell_initialized;

/* Non-zero after SIGINT. */
volatile int interrupt_state = 0;

/* Non-zero after SIGWINCH */
volatile int sigwinch_received = 0;

/* Set to the value of any terminating signal received. */
volatile int terminating_signal = 0;

/* The environment at the top-level R-E loop.  We use this in
   the case of error return. */
procenv_t top_level;

#if defined (JOB_CONTROL) || defined (HAVE_POSIX_SIGNALS)
/* The signal masks that this shell runs with. */
sigset_t top_level_mask;
#endif /* JOB_CONTROL */

/* When non-zero, we throw_to_top_level (). */
int interrupt_immediately = 0;

/* When non-zero, we call the terminating signal handler immediately. */
int terminate_immediately = 0;

#if defined (SIGWINCH)
static SigHandler *old_winch = (SigHandler *)SIG_DFL;
#endif

static void initialize_shell_signals __P((void));

void
initialize_signals (reinit)
     int reinit;
{
  initialize_shell_signals ();
  initialize_job_signals ();
#if !defined (HAVE_SYS_SIGLIST) && !defined (HAVE_UNDER_SYS_SIGLIST) && !defined (HAVE_STRSIGNAL)
  if (reinit == 0)
    initialize_siglist ();
#endif /* !HAVE_SYS_SIGLIST && !HAVE_UNDER_SYS_SIGLIST && !HAVE_STRSIGNAL */
}

/* A structure describing a signal that terminates the shell if not
   caught.  The orig_handler member is present so children can reset
   these signals back to their original handlers. */
struct termsig {
     int signum;
     SigHandler *orig_handler;
     int orig_flags;
};

#define NULL_HANDLER (SigHandler *)SIG_DFL

/* The list of signals that would terminate the shell if not caught.
   We catch them, but just so that we can write the history file,
   and so forth. */
static struct termsig terminating_signals[] = {
#ifdef SIGHUP
{  SIGHUP, NULL_HANDLER, 0 },
#endif

#ifdef SIGINT
{  SIGINT, NULL_HANDLER, 0 },
#endif

#ifdef SIGILL
{  SIGILL, NULL_HANDLER, 0 },
#endif

#ifdef SIGTRAP
{  SIGTRAP, NULL_HANDLER, 0 },
#endif

#ifdef SIGIOT
{  SIGIOT, NULL_HANDLER, 0 },
#endif

#ifdef SIGDANGER
{  SIGDANGER, NULL_HANDLER, 0 },
#endif

#ifdef SIGEMT
{  SIGEMT, NULL_HANDLER, 0 },
#endif

#ifdef SIGFPE
{  SIGFPE, NULL_HANDLER, 0 },
#endif

#ifdef SIGBUS
{  SIGBUS, NULL_HANDLER, 0 },
#endif

#ifdef SIGSEGV
{  SIGSEGV, NULL_HANDLER, 0 },
#endif

#ifdef SIGSYS
{  SIGSYS, NULL_HANDLER, 0 },
#endif

#ifdef SIGPIPE
{  SIGPIPE, NULL_HANDLER, 0 },
#endif

#ifdef SIGALRM
{  SIGALRM, NULL_HANDLER, 0 },
#endif

#ifdef SIGTERM
{  SIGTERM, NULL_HANDLER, 0 },
#endif

#ifdef SIGXCPU
{  SIGXCPU, NULL_HANDLER, 0 },
#endif

#ifdef SIGXFSZ
{  SIGXFSZ, NULL_HANDLER, 0 },
#endif

#ifdef SIGVTALRM
{  SIGVTALRM, NULL_HANDLER, 0 },
#endif

#if 0
#ifdef SIGPROF
{  SIGPROF, NULL_HANDLER, 0 },
#endif
#endif

#ifdef SIGLOST
{  SIGLOST, NULL_HANDLER, 0 },
#endif

#ifdef SIGUSR1
{  SIGUSR1, NULL_HANDLER, 0 },
#endif

#ifdef SIGUSR2
{  SIGUSR2, NULL_HANDLER, 0 },
#endif
};

#define TERMSIGS_LENGTH (sizeof (terminating_signals) / sizeof (struct termsig))

#define XSIG(x) (terminating_signals[x].signum)
#define XHANDLER(x) (terminating_signals[x].orig_handler)
#define XSAFLAGS(x) (terminating_signals[x].orig_flags)

static int termsigs_initialized = 0;

/* Initialize signals that will terminate the shell to do some
   unwind protection.  For non-interactive shells, we only call
   this when a trap is defined for EXIT (0). */
void
initialize_terminating_signals ()
{
  register int i;
#if defined (HAVE_POSIX_SIGNALS)
  struct sigaction act, oact;
#endif

  if (termsigs_initialized)
    return;

  /* The following code is to avoid an expensive call to
     set_signal_handler () for each terminating_signals.  Fortunately,
     this is possible in Posix.  Unfortunately, we have to call signal ()
     on non-Posix systems for each signal in terminating_signals. */
#if defined (HAVE_POSIX_SIGNALS)
  act.sa_handler = termsig_sighandler;
  act.sa_flags = 0;
  sigemptyset (&act.sa_mask);
  sigemptyset (&oact.sa_mask);
  for (i = 0; i < TERMSIGS_LENGTH; i++)
    sigaddset (&act.sa_mask, XSIG (i));
  for (i = 0; i < TERMSIGS_LENGTH; i++)
    {
      /* If we've already trapped it, don't do anything. */
      if (signal_is_trapped (XSIG (i)))
	continue;

      sigaction (XSIG (i), &act, &oact);
      XHANDLER(i) = oact.sa_handler;
      XSAFLAGS(i) = oact.sa_flags;
      /* Don't do anything with signals that are ignored at shell entry
	 if the shell is not interactive. */
      if (!interactive_shell && XHANDLER (i) == SIG_IGN)
	{
	  sigaction (XSIG (i), &oact, &act);
	  set_signal_ignored (XSIG (i));
	}
#if defined (SIGPROF) && !defined (_MINIX)
      if (XSIG (i) == SIGPROF && XHANDLER (i) != SIG_DFL && XHANDLER (i) != SIG_IGN)
	sigaction (XSIG (i), &oact, (struct sigaction *)NULL);
#endif /* SIGPROF && !_MINIX */
    }

#else /* !HAVE_POSIX_SIGNALS */

  for (i = 0; i < TERMSIGS_LENGTH; i++)
    {
      /* If we've already trapped it, don't do anything. */
      if (signal_is_trapped (XSIG (i)))
	continue;

      XHANDLER(i) = signal (XSIG (i), termsig_sighandler);
      XSAFLAGS(i) = 0;
      /* Don't do anything with signals that are ignored at shell entry
	 if the shell is not interactive. */
      if (!interactive_shell && XHANDLER (i) == SIG_IGN)
	{
	  signal (XSIG (i), SIG_IGN);
	  set_signal_ignored (XSIG (i));
	}
#ifdef SIGPROF
      if (XSIG (i) == SIGPROF && XHANDLER (i) != SIG_DFL && XHANDLER (i) != SIG_IGN)
	signal (XSIG (i), XHANDLER (i));
#endif
    }

#endif /* !HAVE_POSIX_SIGNALS */

  termsigs_initialized = 1;
}

static void
initialize_shell_signals ()
{
  if (interactive)
    initialize_terminating_signals ();

#if defined (JOB_CONTROL) || defined (HAVE_POSIX_SIGNALS)
  /* All shells use the signal mask they inherit, and pass it along
     to child processes.  Children will never block SIGCHLD, though. */
  sigemptyset (&top_level_mask);
  sigprocmask (SIG_BLOCK, (sigset_t *)NULL, &top_level_mask);
#  if defined (SIGCHLD)
  sigdelset (&top_level_mask, SIGCHLD);
#  endif
#endif /* JOB_CONTROL || HAVE_POSIX_SIGNALS */

  /* And, some signals that are specifically ignored by the shell. */
  set_signal_handler (SIGQUIT, SIG_IGN);

  if (interactive)
    {
      set_signal_handler (SIGINT, sigint_sighandler);
      set_signal_handler (SIGTERM, SIG_IGN);
      set_sigwinch_handler ();
    }
}

void
reset_terminating_signals ()
{
  register int i;
#if defined (HAVE_POSIX_SIGNALS)
  struct sigaction act;
#endif

  if (termsigs_initialized == 0)
    return;

#if defined (HAVE_POSIX_SIGNALS)
  act.sa_flags = 0;
  sigemptyset (&act.sa_mask);
  for (i = 0; i < TERMSIGS_LENGTH; i++)
    {
      /* Skip a signal if it's trapped or handled specially, because the
	 trap code will restore the correct value. */
      if (signal_is_trapped (XSIG (i)) || signal_is_special (XSIG (i)))
	continue;

      act.sa_handler = XHANDLER (i);
      act.sa_flags = XSAFLAGS (i);
      sigaction (XSIG (i), &act, (struct sigaction *) NULL);
    }
#else /* !HAVE_POSIX_SIGNALS */
  for (i = 0; i < TERMSIGS_LENGTH; i++)
    {
      if (signal_is_trapped (XSIG (i)) || signal_is_special (XSIG (i)))
	continue;

      signal (XSIG (i), XHANDLER (i));
    }
#endif /* !HAVE_POSIX_SIGNALS */
}
#undef XSIG
#undef XHANDLER

/* Run some of the cleanups that should be performed when we run
   jump_to_top_level from a builtin command context.  XXX - might want to
   also call reset_parser here. */
void
top_level_cleanup ()
{
  /* Clean up string parser environment. */
  while (parse_and_execute_level)
    parse_and_execute_cleanup ();

#if defined (PROCESS_SUBSTITUTION)
  unlink_fifo_list ();
#endif /* PROCESS_SUBSTITUTION */

  run_unwind_protects ();
  loop_level = continuing = breaking = 0;
  executing_list = comsub_ignore_return = return_catch_flag = 0;
}

/* What to do when we've been interrupted, and it is safe to handle it. */
void
throw_to_top_level ()
{
  int print_newline = 0;

  if (interrupt_state)
    {
      print_newline = 1;
      DELINTERRUPT;
    }

  if (interrupt_state)
    return;

  last_command_exit_signal = (last_command_exit_value > 128) ?
				(last_command_exit_value - 128) : 0;
  last_command_exit_value |= 128;

  /* Run any traps set on SIGINT. */
  run_interrupt_trap ();

  /* Clean up string parser environment. */
  while (parse_and_execute_level)
    parse_and_execute_cleanup ();

#if defined (JOB_CONTROL)
  give_terminal_to (shell_pgrp, 0);
#endif /* JOB_CONTROL */

#if defined (JOB_CONTROL) || defined (HAVE_POSIX_SIGNALS)
  /* This should not be necessary on systems using sigsetjmp/siglongjmp. */
  sigprocmask (SIG_SETMASK, &top_level_mask, (sigset_t *)NULL);
#endif

  reset_parser ();

#if defined (READLINE)
  if (interactive)
    bashline_reset ();
#endif /* READLINE */

#if defined (PROCESS_SUBSTITUTION)
  unlink_fifo_list ();
#endif /* PROCESS_SUBSTITUTION */

  run_unwind_protects ();
  loop_level = continuing = breaking = 0;
  executing_list = comsub_ignore_return = return_catch_flag = 0;

  if (interactive && print_newline)
    {
      fflush (stdout);
      fprintf (stderr, "\n");
      fflush (stderr);
    }

  /* An interrupted `wait' command in a script does not exit the script. */
  if (interactive || (interactive_shell && !shell_initialized) ||
      (print_newline && signal_is_trapped (SIGINT)))
    jump_to_top_level (DISCARD);
  else
    jump_to_top_level (EXITPROG);
}

/* This is just here to isolate the longjmp calls. */
void
jump_to_top_level (value)
     int value;
{
  longjmp (top_level, value);
}

sighandler
termsig_sighandler (sig)
     int sig;
{
  /* If we get called twice with the same signal before handling it,
     terminate right away. */
  if (
#ifdef SIGHUP
    sig != SIGHUP &&
#endif
#ifdef SIGINT
    sig != SIGINT &&
#endif
#ifdef SIGDANGER
    sig != SIGDANGER &&
#endif
#ifdef SIGPIPE
    sig != SIGPIPE &&
#endif
#ifdef SIGALRM
    sig != SIGALRM &&
#endif
#ifdef SIGTERM
    sig != SIGTERM &&
#endif
#ifdef SIGXCPU
    sig != SIGXCPU &&
#endif
#ifdef SIGXFSZ
    sig != SIGXFSZ &&
#endif
#ifdef SIGVTALRM
    sig != SIGVTALRM &&
#endif
#ifdef SIGLOST
    sig != SIGLOST &&
#endif
#ifdef SIGUSR1
    sig != SIGUSR1 &&
#endif
#ifdef SIGUSR2
   sig != SIGUSR2 &&
#endif
   sig == terminating_signal)
    terminate_immediately = 1;

  terminating_signal = sig;

  /* XXX - should this also trigger when interrupt_immediately is set? */
  if (terminate_immediately)
    {
      terminate_immediately = 0;
      termsig_handler (sig);
    }

  SIGRETURN (0);
}

void
termsig_handler (sig)
     int sig;
{
  static int handling_termsig = 0;

  /* Simple semaphore to keep this function from being executed multiple
     times.  Since we no longer are running as a signal handler, we don't
     block multiple occurrences of the terminating signals while running. */
  if (handling_termsig)
    return;
  handling_termsig = 1;
  terminating_signal = 0;	/* keep macro from re-testing true. */

  /* I don't believe this condition ever tests true. */
  if (sig == SIGINT && signal_is_trapped (SIGINT))
    run_interrupt_trap ();

#if defined (HISTORY)
  if (interactive_shell && sig != SIGABRT)
    maybe_save_shell_history ();
#endif /* HISTORY */

#if defined (JOB_CONTROL)
  if (sig == SIGHUP && (interactive || (subshell_environment & (SUBSHELL_COMSUB|SUBSHELL_PROCSUB))))
    hangup_all_jobs ();
  end_job_control ();
#endif /* JOB_CONTROL */

#if defined (PROCESS_SUBSTITUTION)
  unlink_fifo_list ();
#endif /* PROCESS_SUBSTITUTION */

  /* Reset execution context */
  loop_level = continuing = breaking = 0;
  executing_list = comsub_ignore_return = return_catch_flag = 0;

  run_exit_trap ();
  set_signal_handler (sig, SIG_DFL);
  kill (getpid (), sig);
}

/* What we really do when SIGINT occurs. */
sighandler
sigint_sighandler (sig)
     int sig;
{
#if defined (MUST_REINSTALL_SIGHANDLERS)
  signal (sig, sigint_sighandler);
#endif

  /* interrupt_state needs to be set for the stack of interrupts to work
     right.  Should it be set unconditionally? */
  if (interrupt_state == 0)
    ADDINTERRUPT;

  if (interrupt_immediately)
    {
      interrupt_immediately = 0;
      last_command_exit_value = 128 + sig;
      throw_to_top_level ();
    }

  SIGRETURN (0);
}

#if defined (SIGWINCH)
sighandler
sigwinch_sighandler (sig)
     int sig;
{
#if defined (MUST_REINSTALL_SIGHANDLERS)
  set_signal_handler (SIGWINCH, sigwinch_sighandler);
#endif /* MUST_REINSTALL_SIGHANDLERS */
  sigwinch_received = 1;
  SIGRETURN (0);
}
#endif /* SIGWINCH */

void
set_sigwinch_handler ()
{
#if defined (SIGWINCH)
 old_winch = set_signal_handler (SIGWINCH, sigwinch_sighandler);
#endif
}

void
unset_sigwinch_handler ()
{
#if defined (SIGWINCH)
  set_signal_handler (SIGWINCH, old_winch);
#endif
}

/* Signal functions used by the rest of the code. */
#if !defined (HAVE_POSIX_SIGNALS)

#if defined (JOB_CONTROL)
/* Perform OPERATION on NEWSET, perhaps leaving information in OLDSET. */
sigprocmask (operation, newset, oldset)
     int operation, *newset, *oldset;
{
  int old, new;

  if (newset)
    new = *newset;
  else
    new = 0;

  switch (operation)
    {
    case SIG_BLOCK:
      old = sigblock (new);
      break;

    case SIG_SETMASK:
      sigsetmask (new);
      break;

    default:
      internal_error (_("sigprocmask: %d: invalid operation"), operation);
    }

  if (oldset)
    *oldset = old;
}
#endif /* JOB_CONTROL */

#else

#if !defined (SA_INTERRUPT)
#  define SA_INTERRUPT 0
#endif

#if !defined (SA_RESTART)
#  define SA_RESTART 0
#endif

SigHandler *
set_signal_handler (sig, handler)
     int sig;
     SigHandler *handler;
{
  struct sigaction act, oact;

  act.sa_handler = handler;
  act.sa_flags = 0;
#if 0
  if (sig == SIGALRM)
    act.sa_flags |= SA_INTERRUPT;	/* XXX */
  else
    act.sa_flags |= SA_RESTART;		/* XXX */
#endif
  sigemptyset (&act.sa_mask);
  sigemptyset (&oact.sa_mask);
  sigaction (sig, &act, &oact);
  return (oact.sa_handler);
}
#endif /* HAVE_POSIX_SIGNALS */