[thirdparty/bash.git] / builtins / trap.def

This file is trap.def, from which is created trap.c.
It implements the builtin "trap" in Bash.

Copyright (C) 1987-2010 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/>.

$PRODUCES trap.c

$BUILTIN trap
$FUNCTION trap_builtin
$SHORT_DOC trap [-lp] [[arg] signal_spec ...]
Trap signals and other events.

Defines and activates handlers to be run when the shell receives signals
or other conditions.

ARG is a command to be read and executed when the shell receives the
signal(s) SIGNAL_SPEC.  If ARG is absent (and a single SIGNAL_SPEC
is supplied) or `-', each specified signal is reset to its original
value.  If ARG is the null string each SIGNAL_SPEC is ignored by the
shell and by the commands it invokes.

If a SIGNAL_SPEC is EXIT (0) ARG is executed on exit from the shell.  If
a SIGNAL_SPEC is DEBUG, ARG is executed before every simple command.  If
a SIGNAL_SPEC is RETURN, ARG is executed each time a shell function or a
script run by the . or source builtins finishes executing.  A SIGNAL_SPEC
of ERR means to execute ARG each time a command's failure would cause the
shell to exit when the -e option is enabled.

If no arguments are supplied, trap prints the list of commands associated
with each signal.

Options:
  -l	print a list of signal names and their corresponding numbers
  -p	display the trap commands associated with each SIGNAL_SPEC

Each SIGNAL_SPEC is either a signal name in <signal.h> or a signal number.
Signal names are case insensitive and the SIG prefix is optional.  A
signal may be sent to the shell with "kill -signal $$".

Exit Status:
Returns success unless a SIGSPEC is invalid or an invalid option is given.
$END

#include <config.h>

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

#include "../bashtypes.h"
#include <signal.h>
#include <stdio.h>
#include "../bashansi.h"

#include "../shell.h"
#include "../trap.h"
#include "common.h"
#include "bashgetopt.h"

static void showtrap __P((int));
static int display_traps __P((WORD_LIST *));

/* The trap command:

   trap <arg> <signal ...>
   trap <signal ...>
   trap -l
   trap -p [sigspec ...]
   trap [--]

   Set things up so that ARG is executed when SIGNAL(s) N is recieved.
   If ARG is the empty string, then ignore the SIGNAL(s).  If there is
   no ARG, then set the trap for SIGNAL(s) to its original value.  Just
   plain "trap" means to print out the list of commands associated with
   each signal number.  Single arg of "-l" means list the signal names. */

/* Possible operations to perform on the list of signals.*/
#define SET 0			/* Set this signal to first_arg. */
#define REVERT 1		/* Revert to this signals original value. */
#define IGNORE 2		/* Ignore this signal. */

extern int posixly_correct, subshell_environment;

int
trap_builtin (list)
     WORD_LIST *list;
{
  int list_signal_names, display, result, opt;

  list_signal_names = display = 0;
  result = EXECUTION_SUCCESS;

  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "lp")) != -1)
    {
      switch (opt)
	{
	case 'l':
	  list_signal_names++;
	  break;
	case 'p':
	  display++;
	  break;
	default:
	  builtin_usage ();
	  return (EX_USAGE);
	}
    }
  list = loptend;

  opt = DSIG_NOCASE|DSIG_SIGPREFIX;	/* flags for decode_signal */

  if (list_signal_names)
    return (sh_chkwrite (display_signal_list ((WORD_LIST *)NULL, 1)));
  else if (display || list == 0)
    {
      initialize_terminating_signals ();
      get_all_original_signals ();
      return (sh_chkwrite (display_traps (list)));
    }
  else
    {
      char *first_arg;
      int operation, sig, first_signal;

      operation = SET;
      first_arg = list->word->word;
      first_signal = first_arg && *first_arg && all_digits (first_arg) && signal_object_p (first_arg, opt);

      /* Backwards compatibility.  XXX - question about whether or not we
	 should throw an error if an all-digit argument doesn't correspond
	 to a valid signal number (e.g., if it's `50' on a system with only
	 32 signals).  */
      if (first_signal)
	operation = REVERT;
      /* When in posix mode, the historical behavior of looking for a
	 missing first argument is disabled.  To revert to the original
	 signal handling disposition, use `-' as the first argument. */
      else if (posixly_correct == 0 && first_arg && *first_arg &&
		(*first_arg != '-' || first_arg[1]) &&
		signal_object_p (first_arg, opt) && list->next == 0)
	operation = REVERT;
      else
	{
	  list = list->next;
	  if (list == 0)
	    {
	      builtin_usage ();
	      return (EX_USAGE);
	    }
	  else if (*first_arg == '\0')
	    operation = IGNORE;
	  else if (first_arg[0] == '-' && !first_arg[1])
	    operation = REVERT;
	}

      /* If we're in a command substitution, we haven't freed the trap strings
	 (though we reset the signal handlers).  If we're setting a trap to
	 handle a signal here, free the rest of the trap strings since they
	 don't apply any more. */
      if (subshell_environment & SUBSHELL_RESETTRAP)
	{
	  free_trap_strings ();
	  subshell_environment &= ~SUBSHELL_RESETTRAP;
	}

      while (list)
	{
	  sig = decode_signal (list->word->word, opt);

	  if (sig == NO_SIG)
	    {
	      sh_invalidsig (list->word->word);
	      result = EXECUTION_FAILURE;
	    }
	  else
	    {
	      switch (operation)
		{
		  case SET:
		    set_signal (sig, first_arg);
		    break;

		  case REVERT:
		    restore_default_signal (sig);

		    /* Signals that the shell treats specially need special
		       handling. */
		    switch (sig)
		      {
		      case SIGINT:
			/* XXX - should we do this if original disposition
			   was SIG_IGN? */
			if (interactive)
			  set_signal_handler (SIGINT, sigint_sighandler);
			else
			  set_signal_handler (SIGINT, termsig_sighandler);
			break;

		      case SIGQUIT:
			/* Always ignore SIGQUIT. */
			set_signal_handler (SIGQUIT, SIG_IGN);
			break;
		      case SIGTERM:
#if defined (JOB_CONTROL)
		      case SIGTTIN:
		      case SIGTTOU:
		      case SIGTSTP:
#endif /* JOB_CONTROL */
			if (interactive)
			  set_signal_handler (sig, SIG_IGN);
			break;
		      }
		    break;

		  case IGNORE:
		    ignore_signal (sig);
		    break;
		}
	    }
	  list = list->next;
	}
    }

  return (result);
}

static void
showtrap (i)
     int i;
{
  char *t, *p, *sn;

  p = trap_list[i];
  if (p == (char *)DEFAULT_SIG && signal_is_hard_ignored (i) == 0)
    return;
  else if (signal_is_hard_ignored (i))
    t = (char *)NULL;
  else
    t = (p == (char *)IGNORE_SIG) ? (char *)NULL : sh_single_quote (p);

  sn = signal_name (i);
  /* Make sure that signals whose names are unknown (for whatever reason)
     are printed as signal numbers. */
  if (STREQN (sn, "SIGJUNK", 7) || STREQN (sn, "unknown", 7))
    printf ("trap -- %s %d\n", t ? t : "''", i);
  else if (posixly_correct)
    {
      if (STREQN (sn, "SIG", 3))
	printf ("trap -- %s %s\n", t ? t : "''", sn+3);
      else
	printf ("trap -- %s %s\n", t ? t : "''", sn);
    }
  else
    printf ("trap -- %s %s\n", t ? t : "''", sn);

  FREE (t);
}

static int
display_traps (list)
     WORD_LIST *list;
{
  int result, i;

  if (list == 0)
    {
      for (i = 0; i < BASH_NSIG; i++)
	showtrap (i);
      return (EXECUTION_SUCCESS);
    }

  for (result = EXECUTION_SUCCESS; list; list = list->next)
    {
      i = decode_signal (list->word->word, DSIG_NOCASE|DSIG_SIGPREFIX);
      if (i == NO_SIG)
	{
	  sh_invalidsig (list->word->word);
	  result = EXECUTION_FAILURE;
	}
      else
	showtrap (i);
    }

  return (result);
}
Commit	Line	Data
726f6388 JA	1	This file is trap.def, from which is created trap.c.
	2	It implements the builtin "trap" in Bash.
	3
495aee44	4	Copyright (C) 1987-2010 Free Software Foundation, Inc.
726f6388 JA	5
	6	This file is part of GNU Bash, the Bourne Again SHell.
	7
3185942a JA	8	Bash is free software: you can redistribute it and/or modify
	9	it under the terms of the GNU General Public License as published by
	10	the Free Software Foundation, either version 3 of the License, or
	11	(at your option) any later version.
726f6388	12
3185942a JA	13	Bash is distributed in the hope that it will be useful,
	14	but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	GNU General Public License for more details.
726f6388	17
3185942a JA	18	You should have received a copy of the GNU General Public License
3185942a JA	19	along with Bash. If not, see <http://www.gnu.org/licenses/>.
726f6388 JA	20
	21	$PRODUCES trap.c
	22
	23	$BUILTIN trap
	24	$FUNCTION trap_builtin
3185942a JA	25	$SHORT_DOC trap [-lp] [[arg] signal_spec ...]
	26	Trap signals and other events.
	27
	28	Defines and activates handlers to be run when the shell receives signals
	29	or other conditions.
	30
	31	ARG is a command to be read and executed when the shell receives the
b80f6443 JA	32	signal(s) SIGNAL_SPEC. If ARG is absent (and a single SIGNAL_SPEC
	33	is supplied) or `-', each specified signal is reset to its original
	34	value. If ARG is the null string each SIGNAL_SPEC is ignored by the
3185942a JA	35	shell and by the commands it invokes.
	36
	37	If a SIGNAL_SPEC is EXIT (0) ARG is executed on exit from the shell. If
495aee44 CR	38	a SIGNAL_SPEC is DEBUG, ARG is executed before every simple command. If
	39	a SIGNAL_SPEC is RETURN, ARG is executed each time a shell function or a
	40	script run by the . or source builtins finishes executing. A SIGNAL_SPEC
	41	of ERR means to execute ARG each time a command's failure would cause the
	42	shell to exit when the -e option is enabled.
3185942a JA	43
	44	If no arguments are supplied, trap prints the list of commands associated
	45	with each signal.
	46
	47	Options:
	48	-l print a list of signal names and their corresponding numbers
	49	-p display the trap commands associated with each SIGNAL_SPEC
	50
	51	Each SIGNAL_SPEC is either a signal name in <signal.h> or a signal number.
	52	Signal names are case insensitive and the SIG prefix is optional. A
	53	signal may be sent to the shell with "kill -signal $$".
	54
	55	Exit Status:
	56	Returns success unless a SIGSPEC is invalid or an invalid option is given.
726f6388 JA	57	$END
726f6388 JA	58
ccc6cda3 JA	59	#include <config.h>
	60
	61	#if defined (HAVE_UNISTD_H)
cce855bc JA	62	# ifdef _MINIX
	63	# include <sys/types.h>
	64	# endif
ccc6cda3 JA	65	# include <unistd.h>
	66	#endif
	67
	68	#include "../bashtypes.h"
726f6388	69	#include <signal.h>
ccc6cda3 JA	70	#include <stdio.h>
	71	#include "../bashansi.h"
	72
726f6388 JA	73	#include "../shell.h"
	74	#include "../trap.h"
	75	#include "common.h"
ccc6cda3 JA	76	#include "bashgetopt.h"
ccc6cda3 JA	77
f73dda09 JA	78	static void showtrap __P((int));
f73dda09 JA	79	static int display_traps __P((WORD_LIST *));
726f6388 JA	80
	81	/* The trap command:
	82
	83	trap <arg> <signal ...>
	84	trap <signal ...>
	85	trap -l
ccc6cda3	86	trap -p [sigspec ...]
726f6388 JA	87	trap [--]
	88
	89	Set things up so that ARG is executed when SIGNAL(s) N is recieved.
	90	If ARG is the empty string, then ignore the SIGNAL(s). If there is
	91	no ARG, then set the trap for SIGNAL(s) to its original value. Just
	92	plain "trap" means to print out the list of commands associated with
	93	each signal number. Single arg of "-l" means list the signal names. */
	94
	95	/* Possible operations to perform on the list of signals.*/
	96	#define SET 0 /* Set this signal to first_arg. */
	97	#define REVERT 1 /* Revert to this signals original value. */
	98	#define IGNORE 2 /* Ignore this signal. */
	99
495aee44	100	extern int posixly_correct, subshell_environment;
726f6388	101
ccc6cda3	102	int
726f6388 JA	103	trap_builtin (list)
	104	WORD_LIST *list;
	105	{
0628567a	106	int list_signal_names, display, result, opt;
726f6388	107
ccc6cda3 JA	108	list_signal_names = display = 0;
ccc6cda3 JA	109	result = EXECUTION_SUCCESS;
495aee44	110
ccc6cda3 JA	111	reset_internal_getopt ();
ccc6cda3 JA	112	while ((opt = internal_getopt (list, "lp")) != -1)
726f6388	113	{
ccc6cda3	114	switch (opt)
726f6388	115	{
ccc6cda3	116	case 'l':
726f6388	117	list_signal_names++;
726f6388	118	break;
ccc6cda3 JA	119	case 'p':
	120	display++;
	121	break;
	122	default:
	123	builtin_usage ();
726f6388 JA	124	return (EX_USAGE);
726f6388 JA	125	}
726f6388	126	}
ccc6cda3	127	list = loptend;
726f6388	128
b80f6443 JA	129	opt = DSIG_NOCASE\|DSIG_SIGPREFIX; /* flags for decode_signal */
b80f6443 JA	130
726f6388	131	if (list_signal_names)
3185942a	132	return (sh_chkwrite (display_signal_list ((WORD_LIST *)NULL, 1)));
ccc6cda3	133	else if (display \|\| list == 0)
495aee44 CR	134	{
	135	initialize_terminating_signals ();
	136	get_all_original_signals ();
	137	return (sh_chkwrite (display_traps (list)));
	138	}
ccc6cda3	139	else
726f6388	140	{
ccc6cda3	141	char *first_arg;
eb873671	142	int operation, sig, first_signal;
726f6388	143
ccc6cda3 JA	144	operation = SET;
ccc6cda3 JA	145	first_arg = list->word->word;
eb873671 JA	146	first_signal = first_arg && *first_arg && all_digits (first_arg) && signal_object_p (first_arg, opt);
eb873671 JA	147
0628567a JA	148	/* Backwards compatibility. XXX - question about whether or not we
	149	should throw an error if an all-digit argument doesn't correspond
	150	to a valid signal number (e.g., if it's `50' on a system with only
	151	32 signals). */
eb873671 JA	152	if (first_signal)
eb873671 JA	153	operation = REVERT;
b80f6443 JA	154	/* When in posix mode, the historical behavior of looking for a
	155	missing first argument is disabled. To revert to the original
	156	signal handling disposition, use `-' as the first argument. */
eb873671	157	else if (posixly_correct == 0 && first_arg && *first_arg &&
b80f6443 JA	158	(*first_arg != '-' \|\| first_arg[1]) &&
b80f6443 JA	159	signal_object_p (first_arg, opt) && list->next == 0)
726f6388 JA	160	operation = REVERT;
	161	else
	162	{
	163	list = list->next;
b80f6443 JA	164	if (list == 0)
	165	{
	166	builtin_usage ();
	167	return (EX_USAGE);
	168	}
	169	else if (*first_arg == '\0')
726f6388 JA	170	operation = IGNORE;
	171	else if (first_arg[0] == '-' && !first_arg[1])
	172	operation = REVERT;
	173	}
	174
495aee44 CR	175	/* If we're in a command substitution, we haven't freed the trap strings
	176	(though we reset the signal handlers). If we're setting a trap to
	177	handle a signal here, free the rest of the trap strings since they
	178	don't apply any more. */
	179	if (subshell_environment & SUBSHELL_RESETTRAP)
	180	{
	181	free_trap_strings ();
	182	subshell_environment &= ~SUBSHELL_RESETTRAP;
	183	}
	184
726f6388 JA	185	while (list)
726f6388 JA	186	{
b80f6443	187	sig = decode_signal (list->word->word, opt);
726f6388 JA	188
	189	if (sig == NO_SIG)
	190	{
7117c2d2	191	sh_invalidsig (list->word->word);
ccc6cda3	192	result = EXECUTION_FAILURE;
726f6388 JA	193	}
	194	else
	195	{
	196	switch (operation)
	197	{
	198	case SET:
	199	set_signal (sig, first_arg);
	200	break;
	201
	202	case REVERT:
	203	restore_default_signal (sig);
	204
	205	/* Signals that the shell treats specially need special
	206	handling. */
	207	switch (sig)
	208	{
	209	case SIGINT:
495aee44 CR	210	/* XXX - should we do this if original disposition
495aee44 CR	211	was SIG_IGN? */
726f6388 JA	212	if (interactive)
	213	set_signal_handler (SIGINT, sigint_sighandler);
	214	else
0628567a	215	set_signal_handler (SIGINT, termsig_sighandler);
726f6388 JA	216	break;
	217
	218	case SIGQUIT:
	219	/* Always ignore SIGQUIT. */
	220	set_signal_handler (SIGQUIT, SIG_IGN);
	221	break;
	222	case SIGTERM:
	223	#if defined (JOB_CONTROL)
	224	case SIGTTIN:
	225	case SIGTTOU:
	226	case SIGTSTP:
	227	#endif /* JOB_CONTROL */
	228	if (interactive)
	229	set_signal_handler (sig, SIG_IGN);
	230	break;
	231	}
	232	break;
	233
	234	case IGNORE:
	235	ignore_signal (sig);
	236	break;
	237	}
	238	}
	239	list = list->next;
	240	}
726f6388 JA	241	}
726f6388 JA	242
ccc6cda3 JA	243	return (result);
	244	}
	245
	246	static void
	247	showtrap (i)
	248	int i;
	249	{
e8ce775d	250	char t, p, *sn;
ccc6cda3 JA	251
ccc6cda3 JA	252	p = trap_list[i];
495aee44	253	if (p == (char *)DEFAULT_SIG && signal_is_hard_ignored (i) == 0)
ccc6cda3	254	return;
495aee44 CR	255	else if (signal_is_hard_ignored (i))
	256	t = (char *)NULL;
	257	else
	258	t = (p == (char )IGNORE_SIG) ? (char )NULL : sh_single_quote (p);
ccc6cda3	259
e8ce775d JA	260	sn = signal_name (i);
	261	/* Make sure that signals whose names are unknown (for whatever reason)
	262	are printed as signal numbers. */
	263	if (STREQN (sn, "SIGJUNK", 7) \|\| STREQN (sn, "unknown", 7))
	264	printf ("trap -- %s %d\n", t ? t : "''", i);
28ef6c31 JA	265	else if (posixly_correct)
	266	{
	267	if (STREQN (sn, "SIG", 3))
	268	printf ("trap -- %s %s\n", t ? t : "''", sn+3);
	269	else
	270	printf ("trap -- %s %s\n", t ? t : "''", sn);
	271	}
e8ce775d JA	272	else
	273	printf ("trap -- %s %s\n", t ? t : "''", sn);
	274
	275	FREE (t);
ccc6cda3	276	}
726f6388	277
ccc6cda3 JA	278	static int
	279	display_traps (list)
	280	WORD_LIST *list;
	281	{
	282	int result, i;
726f6388	283
ccc6cda3 JA	284	if (list == 0)
ccc6cda3 JA	285	{
f73dda09	286	for (i = 0; i < BASH_NSIG; i++)
ccc6cda3 JA	287	showtrap (i);
	288	return (EXECUTION_SUCCESS);
	289	}
726f6388	290
ccc6cda3 JA	291	for (result = EXECUTION_SUCCESS; list; list = list->next)
ccc6cda3 JA	292	{
b80f6443	293	i = decode_signal (list->word->word, DSIG_NOCASE\|DSIG_SIGPREFIX);
ccc6cda3 JA	294	if (i == NO_SIG)
ccc6cda3 JA	295	{
7117c2d2	296	sh_invalidsig (list->word->word);
ccc6cda3	297	result = EXECUTION_FAILURE;
ccc6cda3 JA	298	}
	299	else
	300	showtrap (i);
726f6388	301	}
ccc6cda3 JA	302
ccc6cda3 JA	303	return (result);
726f6388	304	}