#include <time.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>

static void
check_for_SIGALRM (int sig)
{
  if (sig != SIGALRM)
    _exit (1);
}

int
main (void)
{
  static struct sigaction act;
  struct timespec forever, remaining;
  time_t time_t_max = (1ull << (sizeof time_t_max * CHAR_BIT - 1)) - 1;
  act.sa_handler = check_for_SIGALRM;
  sigemptyset (&act.sa_mask);
  sigaction (SIGALRM, &act, NULL);
  forever.tv_sec = time_t_max;
  forever.tv_nsec = 999999999;
  printf ("Setting alarm for 1 second from now ...\n");
  alarm (1);
  printf ("Sleeping for %lld.%09ld seconds...\n",
	  (long long) forever.tv_sec, forever.tv_nsec);
  if (nanosleep (&forever, &remaining) == 0)
    return 2;
  if (errno != EINTR)
    return 3;
  if (remaining.tv_sec < time_t_max - 10)
    {
      printf ("After alarm sent off, remaining time is %lld.%09ld seconds;\n",
	      (long long) remaining.tv_sec, remaining.tv_nsec);
      printf ("i.e., nanosleep claimed that it slept for about %f years.\n",
	      (forever.tv_sec - remaining.tv_sec) / (24 * 60 * 60 * 364.2425));
      return 4;
    }
  printf ("ok\n");
  return 0;
}