/* Implementation of sigwait function from POSIX.1c.

   Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   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>

#include <signal.h>

#include <stddef.h>		/* For NULL.  */

#include <sysdep-cancel.h>

/* This is our dummy signal handler we use here.  */

static void ignore_signal (int sig);

/* Place where to remember which signal we got.  Please note that this

   implementation cannot be used for the threaded libc.  The

   libpthread must provide an own version.  */

static int was_sig;

static int

do_sigwait (const sigset_t *set, int *sig)

{

  sigset_t tmp_mask;

  struct sigaction saved[NSIG];

  struct sigaction action;

  int save_errno;

  int this;

  /* Prepare set.  */

  __sigfillset (&tmp_mask);

  /* Unblock all signals in the SET and register our nice handler.  */

  action.sa_handler = ignore_signal;

  action.sa_flags = 0;

  __sigfillset (&action.sa_mask);	/* Block all signals for handler.  */

  /* Make sure we recognize error conditions by setting WAS_SIG to a

     value which does not describe a legal signal number.  */

  was_sig = -1;

  for (this = 1; this < NSIG; ++this)

    if (__sigismember (set, this))

      {

	/* Unblock this signal.  */

	__sigdelset (&tmp_mask, this);

	/* Register temporary action handler.  */

	if (__sigaction (this, &action, &saved[this]) != 0)

	  goto restore_handler;

      }

  /* Now we can wait for signals.  */

  __sigsuspend (&tmp_mask);

 restore_handler:

  save_errno = errno;

  while (--this >= 1)

    if (__sigismember (set, this))

      /* We ignore errors here since we must restore all handlers.  */

      __sigaction (this, &saved[this], NULL);

  __set_errno (save_errno);

  /* Store the result and return.  */

  *sig = was_sig;

  return was_sig == -1 ? -1 : 0;

}

int

__sigwait (const sigset_t *set, int *sig)

{

  if (SINGLE_THREAD_P)

    return do_sigwait (set, sig);

  int oldtype = LIBC_CANCEL_ASYNC ();

  int result = do_sigwait (set, sig);

  LIBC_CANCEL_RESET (oldtype);

  return result;

}

libc_hidden_def (__sigwait)

weak_alias (__sigwait, sigwait)

static void

ignore_signal (int sig)

{

  /* Remember the signal.  */

  was_sig = sig;

}