path: root/scratch/bash-3.1-postpatch/builtins/trap.def

This file is trapdef, from which is created trapc
It implements the builtin "trap" in Bash

Copyright (C) 1987-2005 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 2, 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; see the file COPYING  If not, write to the Free Software
Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA

$PRODUCES trapc

$BUILTIN trap
$FUNCTION trap_builtin
$SHORT_DOC trap [-lp] [arg signal_spec ...]
The command ARG is to be read and executed when the shell receives
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)
the command ARG is executed on exit from the shell  If a SIGNAL_SPEC
is DEBUG, ARG is executed after every simple command  If the-p' option
is supplied then the trap commands associated with each SIGNAL_SPEC are
displayed  If no arguments are supplied or if only `-p' is given, trap
prints the list of commands associated with each signal  Each SIGNAL_SPEC
is either a signal name in <signalh or a signal number  Signal names
are case insensitive and the SIG prefix is optional  `trap -l' prints
a list of signal names and their corresponding numbers  Note that a
signal can be sent to the shell with "kill -signal $$".
$END

#include <configh

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/typesh
#  endif
#  include <unistdh
#endif

#include "../bashtypesh"
#include <signalh
#include <stdioh
#include "../bashansih"

#include "../shellh"
#include "../traph"
#include "commonh"
#include "bashgetopth"

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;

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

  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_NOCASEDSIG_SIGPREFIX;	/* flags for decode_signal */

  if (list_signal_names)
    return (display_signal_list ((WORD_LIST *)NULL, 1));
  else if (display || list == 0)
    return (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 */
      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;
	}

      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:
			if (interactive)
			  set_signal_handler (SIGINT, sigint_sighandler);
			else
			  set_signal_handler (SIGINT, termination_unwind_protect);
			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)
    return;

  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_NOCASEDSIG_SIGPREFIX);
      if (i == NO_SIG)
	{
	  sh_invalidsig (list->word->word);
	  result = EXECUTION_FAILURE;
	}
      else
	showtrap (i);
    }

  return (result);
}