/*      $NetBSD: raise_default_signal.c,v 1.3 2008/04/28 20:23:03 martin Exp $   */

/*-
* Copyright (c) 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Luke Mewburn.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: raise_default_signal.c,v 1.3 2008/04/28 20:23:03 martin Exp $");
#endif

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <util.h>

#if ! HAVE_RAISE_DEFAULT_SIGNAL
/*
* raise_default_signal sig
*      Raise the default signal handler for sig, by
*      - block all signals
*      - set the signal handler to SIG_DFL
*      - raise the signal
*      - unblock the signal to deliver it
*
*      The original signal mask and signal handler is restored on exit
*      (whether successful or not).
*
*      Returns 0 on success, or -1 on failure with errno set to
*      on of the values for sigemptyset(), sigaddset(), sigprocmask(),
*      sigaction(), or raise().
*/
int
raise_default_signal(int sig)
{
       struct sigaction origact, act;
       sigset_t origmask, fullmask, mask;
       int retval, oerrno;

       retval = -1;

               /* Setup data structures */
               /* XXX memset(3) isn't async-safe according to signal(7) */
       (void)memset(&act, 0, sizeof(act));
       act.sa_handler = SIG_DFL;
       act.sa_flags = 0;
       if ((sigemptyset(&act.sa_mask) == -1) ||
           (sigfillset(&fullmask) == -1) ||
           (sigemptyset(&mask) == -1) ||
           (sigaddset(&mask, sig) == -1))
               goto restore_none;

               /* Block all signals */
       if (sigprocmask(SIG_BLOCK, &fullmask, &origmask) == -1)
               goto restore_none;
               /* (use 'goto restore_mask' to restore state) */

               /* Enable the SIG_DFL handler */
       if (sigaction(sig, &act, &origact) == -1)
               goto restore_mask;
               /* (use 'goto restore_act' to restore state) */

               /* Raise the signal, and unblock the signal to deliver it */
       if ((raise(sig) == -1) ||
           (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1))
               goto restore_act;

               /* Flag successful raise() */
       retval = 0;

               /* Restore the original handler */
restore_act:
       oerrno = errno;
       (void)sigaction(sig, &origact, NULL);
       errno = oerrno;

               /* Restore the original mask */
restore_mask:
       oerrno = errno;
       (void)sigprocmask(SIG_SETMASK, &origmask, NULL);
       errno = oerrno;

restore_none:
       return retval;
}

#endif  /* ! HAVE_RAISE_DEFAULT_SIGNAL */