text: /* sigwait
   *
   * Copyright (C) 2006 by Steven J. Hill <sjhill@realitydiluted.com>
   * Copyright (C) 2003-2005 by Erik Andersen <andersen@uclibc.org>
   *
   * This program 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; see the file COPYING.LIB.  If
   * not, see <http://www.gnu.org/licenses/>.
   */
  
  #define __need_NULL
  #include <stddef.h>
  #include <sys/syscall.h>
  #include <signal.h>
  #include <cancel.h>
  
  #if defined __NR_rt_sigtimedwait && defined __UCLIBC_HAS_REALTIME__
  
  #include <string.h>
  
  /* Return any pending signal or wait for one for the given time.  */
  static int __NC(sigwait)(const sigset_t *set, int *sig)
  {
  	int ret;
  
  	do
  		/* we might as well use sigtimedwait and do not care about cancellation */
  		ret = __NC(sigtimedwait)(set, NULL, NULL);
  	while (ret == -1 && errno == EINTR);
  	if (ret != -1) {
  		*sig = ret;
  		ret = 0;
  	} else
  		ret = errno;
  
  	return ret;
  }
  
  #else /* __NR_rt_sigtimedwait */
  
  /* variant without REALTIME extensions */
  #include <unistd.h>	/* smallint */
  
  static smallint was_sig; /* obviously not thread-safe */
  
  static void ignore_signal(int sig)
  {
  	was_sig = sig;
  }
  
  static int __NC(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.  */
          /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
          /* (so, will it work correctly if set has, say, SIGSTOP?) */
          if (sigaction (this, &action, &saved[this]) != 0)
            goto restore_handler;
        }
  
    /* Now we can wait for signals.  */
    __NC(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;
  }
  #endif /* __NR_rt_sigtimedwait */
  
  CANCELLABLE_SYSCALL(int, sigwait, (const sigset_t *set, int *sig), (set, sig))
  