#include <config.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>

int volatile got_sigchld, got_sigalrm;

void
sighan (int sig)
{
  switch (sig)
    {
    case SIGCHLD:
      got_sigchld = 1;
      break;

    case SIGALRM:
      got_sigalrm = 1;
      break;
    }
}

int
main (int argc, char **argv)
{
  char *progname = argv[0];
  unsigned long n;
  char *p;
  pid_t pid, ret;
  int status;

  if (argc < 3)
    {
      fprintf (stderr, "usage: %s TIMEOUT COMMAND ...\n", progname);
      exit (1);
    }
  errno = 0;
  n = strtoul (argv[1], &p, 10);
  if (errno || *p || n == 0)
    {
      fprintf (stderr, "%s: %s is not a valid timeout\n", progname, argv[1]);
      exit (1);
    }

  argc -= 2;
  argv += 2;

  signal (SIGALRM, sighan);
  signal (SIGCHLD, sighan);

  pid = fork ();
  if (pid == -1)
    {
      perror ("fork");
      exit (127);
    }

  if (pid == 0)
    {
      execvp (argv[0], argv);
      perror (argv[0]);
      exit (127);
    }

  alarm (n);
  while (1)
    {
      pause ();
      if (got_sigchld)
	{
	  alarm (0);
	  break;
	}
      if (got_sigalrm)
	{
	  fprintf (stderr, "%s: timed out\n", progname);
	  kill (pid, SIGKILL);
	  exit (127);
	}
    }

  ret = wait (&status);

  if (ret != pid)
    {
      perror ("wait");
      exit (127);
    }

  if (WIFEXITED (status))
    return WEXITSTATUS (status);

  if (WIFSIGNALED (status))
    fprintf (stderr, "%s: %s terminated on signal %d\n", progname, argv[0],
	     WTERMSIG (status));
  else if (WIFSTOPPED (status))
    fprintf (stderr, "%s: %s stopped\n", progname, argv[0]);
  else
    fprintf (stderr, "%s: %s exited with unrecognized status %d\n",
	     progname, argv[0], status);
  return 127;
}