sig.c

android-w.song.android.widget

/* sig.c - interface for shell signal handlers and signal initialization. */

/* Copyright (C) 1994-2010 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/>.
*/

#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, funcnest;
extern int executing_list;
extern int comsub_ignore_return;
extern int parse_and_execute_level, shell_initialized;
#if defined (HISTORY)
extern int history_lines_this_session;
#endif

extern void initialize_siglist ();

/* 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) or when trap is run
   to display signal dispositions. */
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. */
      /* XXX - should we do this for interactive shells, too? */
      if (interactive_shell == 0 && 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. */
      /* XXX - should we do this for interactive shells, too? */
      if (interactive_shell == 0 && 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++)