/* Copyright (C) 1998-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#define __need_NULL

#include <stddef.h>

#include <signal.h>

#include <string.h>	/* For the real memset prototype.  */

#include <sigsetops.h>

/* Set the disposition for SIG.  */

__sighandler_t

sigset (int sig, __sighandler_t disp)

{

  struct sigaction act;

  struct sigaction oact;

  sigset_t set;

  sigset_t oset;

  __sigemptyset (&set);

  if (sigaddset (&set, sig) < 0)

    return SIG_ERR;

  if (disp == SIG_HOLD)

    {

      /* Add the signal to the current signal mask.  */

      if (__sigprocmask (SIG_BLOCK, &set, &oset) < 0)

	return SIG_ERR;

      /* If the signal was already blocked signal this to the caller.  */

      if (__sigismember (&oset, sig))

	return SIG_HOLD;

      /* We need to determine whether a specific handler is installed.  */

      if (__sigaction (sig, NULL, &oact) < 0)

	return SIG_ERR;

      return oact.sa_handler;

    }

  else

    {

      act.sa_handler = disp;

      __sigemptyset (&act.sa_mask);

      act.sa_flags = 0;

      if (__sigaction (sig, &act, &oact) < 0)

	return SIG_ERR;

      /* Remove the signal from the current signal mask.  */

      if (__sigprocmask (SIG_UNBLOCK, &set, &oset) < 0)

	return SIG_ERR;

      /* If the signal was already blocked return SIG_HOLD.  */

      return __sigismember (&oset, sig) ? SIG_HOLD : oact.sa_handler;

    }

}