/* Provide a replacement for the POSIX nanosleep function.
   Copyright (C) 1999 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* written by Jim Meyering */

#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <signal.h>

#if HAVE_UNISTD_H
# include <unistd.h>
#endif

#include <time.h>
/* FIXME: is including both like this kosher?  */
#include <sys/time.h>

static int suspended;

/* Handle SIGCONT. */

static void
sighandler (int sig)
{
#ifdef SA_INTERRUPT
  struct sigaction sigact;

  sigact.sa_handler = SIG_DFL;
  sigemptyset (&sigact.sa_mask);
  sigact.sa_flags = 0;
  sigaction (sig, &sigact, NULL);
#else
  signal (sig, SIG_DFL);
#endif

  suspended = 1;
  kill (getpid (), sig);
}

/* Sleep for USEC microseconds. */

static void
my_usleep (const struct timespec *ts_delay)
{
  struct timeval tv_delay;
  tv_delay.tv_sec = ts_delay->tv_sec;
  tv_delay.tv_usec = 1000 * ts_delay->tv_nsec;
  select (0, (void *) 0, (void *) 0, (void *) 0, &tv_delay);
}

int
nanosleep (const struct timespec *requested_delay,
	   struct timespec *remaining_delay)
{
#ifdef SA_INTERRUPT
  struct sigaction oldact, newact;
#endif

  suspended = 0;

  /* set up sig handler -- but maybe only do this the first time?  */
#ifdef SA_INTERRUPT
  newact.sa_handler = sighandler;
  sigemptyset (&newact.sa_mask);
  newact.sa_flags = 0;

  sigaction (SIGCONT, NULL, &oldact);
  if (oldact.sa_handler != SIG_IGN)
    sigaction (SIGCONT, &newact, NULL);
#else
  if (signal (SIGCONT, SIG_IGN) != SIG_IGN)
    signal (SIGCONT, sighandler);
#endif

  my_usleep (requested_delay);

  if (suspended)
    {
      /* Calculate time remaining.  */
      /* FIXME: the code in sleep doesn't use this, so there's no
	 rush to implement it.  */
    }

  /* FIXME: Restore sig handler?  */

  return suspended;
}