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/* Implementation of sigwait function from POSIX.1c.
Copyright (C) 1996-2017 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;
}
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