gnupg/common/signal.c

/* signal.c - signal handling
 * Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG 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 of the License, or
 * (at your option) any later version.
 *
 * GnuPG 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <assert.h>

#include "util.h"


static volatile int caught_fatal_sig = 0;
static volatile int caught_sigusr1 = 0;
static void (*cleanup_fnc)(void);


static void
init_one_signal (int sig, RETSIGTYPE (*handler)(int), int check_ign )
{
#ifndef HAVE_DOSISH_SYSTEM
# ifdef HAVE_SIGACTION
  struct sigaction oact, nact;
  
  if (check_ign)
    {
      /* we don't want to change an IGN handler */
      sigaction (sig, NULL, &oact );
      if (oact.sa_handler == SIG_IGN )
        return;
    }

  nact.sa_handler = handler;
  sigemptyset (&nact.sa_mask);
  nact.sa_flags = 0;
  sigaction ( sig, &nact, NULL);
# else 
  RETSIGTYPE (*ohandler)(int);
  
  ohandler = signal (sig, handler);
  if (check_ign && ohandler == SIG_IGN) 
    {
      /* Change it back if it was already set to IGN */
      signal (sig, SIG_IGN);
    }
# endif
#endif /*!HAVE_DOSISH_SYSTEM*/
}

static const char *
get_signal_name( int signum )
{
#if defined(SYS_SIGLIST_DECLARED) && defined(NSIG)
  return (signum >= 0 && signum < NSIG) ? sys_siglist[signum] : "?";
#else
  return "some signal";
#endif
}

static RETSIGTYPE
got_fatal_signal (int sig)
{
  const char *s;

  if (caught_fatal_sig)
	raise (sig);
  caught_fatal_sig = 1;

  if (cleanup_fnc)
    cleanup_fnc ();
  /* better don't translate these messages */
  write (2, "\n", 1 );
  s = log_get_prefix (NULL);
  if (s)
    write(2, s, strlen (s));
  write (2, ": ", 2 );
  s = get_signal_name(sig);
  write (2, s, strlen(s) );
  write (2, " caught ... exiting\n", 20);
  
  /* reset action to default action and raise signal again */
  init_one_signal (sig, SIG_DFL, 0);
  /* fixme: remove_lockfiles ();*/
#ifdef __riscos__
  close_fds ();
#endif /* __riscos__ */
  raise( sig );
}


static RETSIGTYPE
got_usr_signal (int sig)
{
  caught_sigusr1 = 1;
}


void
gnupg_init_signals (int mode, void (*fast_cleanup)(void))
{
  assert (!mode);

  cleanup_fnc = fast_cleanup;
#ifndef HAVE_DOSISH_SYSTEM
  init_one_signal (SIGINT, got_fatal_signal, 1 );
  init_one_signal (SIGHUP, got_fatal_signal, 1 );
  init_one_signal (SIGTERM, got_fatal_signal, 1 );
  init_one_signal (SIGQUIT, got_fatal_signal, 1 );
  init_one_signal (SIGSEGV, got_fatal_signal, 1 );
  init_one_signal (SIGUSR1, got_usr_signal, 0 );
  init_one_signal (SIGPIPE, SIG_IGN, 0 );
#endif
}

void
gnupg_pause_on_sigusr (int which)
{
#ifndef HAVE_DOSISH_SYSTEM
# ifdef HAVE_SIGPROCMASK
  sigset_t mask, oldmask;

  assert (which == 1);
  sigemptyset( &mask );
  sigaddset( &mask, SIGUSR1 );
  
  sigprocmask( SIG_BLOCK, &mask, &oldmask );
  while (!caught_sigusr1)
    sigsuspend (&oldmask);
  caught_sigusr1 = 0;
  sigprocmask (SIG_UNBLOCK, &mask, NULL);
# else 
  assert (which == 1);
  sighold (SIGUSR1);
  while (!caught_sigusr1)
    sigpause(SIGUSR1);
  caught_sigusr1 = 0;
  sigrelease(SIGUSR1);
# endif /*!HAVE_SIGPROCMASK*/
#endif
}


static void
do_block( int block )
{
#ifndef HAVE_DOSISH_SYSTEM
  static int is_blocked;
#ifdef HAVE_SIGPROCMASK
  static sigset_t oldmask;

  if (block)
    {
      sigset_t newmask;

      if (is_blocked)
        log_bug ("signals are already blocked\n");
      sigfillset( &newmask );
      sigprocmask( SIG_BLOCK, &newmask, &oldmask );
      is_blocked = 1;
    }
  else
    {
      if (!is_blocked)
        log_bug("signals are not blocked\n");
      sigprocmask (SIG_SETMASK, &oldmask, NULL);
      is_blocked = 0;
    }
#else /*!HAVE_SIGPROCMASK*/
  static void (*disposition[MAXSIG])();
  int sig;

  if (block)
    {
      if (is_blocked)
        log_bug("signals are already blocked\n");
      for (sig=1; sig < MAXSIG; sig++)
        {
          disposition[sig] = sigset (sig, SIG_HOLD);
        }
      is_blocked = 1;
    }
  else
    {
      if (!is_blocked)
        log_bug ("signals are not blocked\n");
      for (sig=1; sig < MAXSIG; sig++) {
        sigset (sig, disposition[sig]);
      }
      is_blocked = 0;
    }
#endif /*!HAVE_SIGPROCMASK*/
#endif /*HAVE_DOSISH_SYSTEM*/
}


void
gnupg_block_all_signals ()
{
  do_block(1);
}

void
gnupg_unblock_all_signals ()
{
  do_block(0);
}