/*
 *  timeout.c -- run commands with a specified timeout
 *  Copyright (C) 2007 Robert Millan <address@hidden>
 *
 *  GRUB 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 3 of the License, 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 GRUB; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <getopt.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>

#include <sys/wait.h>

#define PROGRAM_NAME		"timeout"
#define PROGRAM_VERSION		"0.0.1"

int pid;
int signum = SIGTERM;
int timeout_status = 1;

static struct option options[] =
  {
    {"signal", required_argument, 0, 's'}, 
    {"status", required_argument, 0, 't'},
    {"help", no_argument, 0, 'h'},
    {"version", no_argument, 0, 'v'},
    {0, 0, 0, 0}
  };

static void
usage (int status)
{
  if (status)
    fprintf (stderr, "Try ``" PROGRAM_NAME " --help'' for more information.\n");
  else
    printf ("\
Usage: " PROGRAM_NAME " [OPTION]... NUMBER COMMAND ARGUMENTS\n\
Runs COMMAND with ARGUMENTS, and kills it after NUMBER seconds.\n\
\n\
  -s, --signal SIGNUM	use SIGNUM to kill our child\n\
  -t, --status NUMBER	after killing our child, exit with NUMBER\n\
  -h, --help		display this message and exit\n\
  -v, --version		print version information and exit\n\
\n");

  exit (status);
}

void
handler (int dummy)
{
  kill (signum, pid);
  exit (timeout_status);
}

main (int argc, char **argv)
{
  int timeout;
  char *tail;

  /* Check for options.  */
  while (1)
    {
      int c = getopt_long (argc, argv, "hs:t:v", options, 0);

      if (c == -1)
        break;

      switch (c)
        {
          case 'h':
            usage (0);
          case 'v':
            printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
            exit (0);
            break;
          case 's':
            signum = strtol (optarg, &tail, 10);
            if (tail[0] != '\0')
              usage (1);
            break;
          case 't':
            timeout_status = strtol (optarg, &tail, 10);
            if (tail[0] != '\0')
              usage (1);
            break;
          default:
            usage (1);
        }
    }

  /* Ditch getopt args -- no longer needed */
  argv += optind;

  if (argv[0] == NULL)
    usage (1);

  timeout = strtol (argv[0], &tail, 10);
  if (tail[0] != '\0')
    usage (1);

  /* Ditch timeout -- no longer needed */
  argv++;

  signal (SIGALRM, handler);

  pid = fork ();

  switch (pid)
    {
      case -1:
        perror ("fork");
        exit (1);
      case 0:
        execvp (argv[0], argv);
        perror ("execvp");
        exit (1);
      default:
        {
          int child_status;
          alarm (timeout);
          while (waitpid (pid, &child_status, WNOHANG) == 0);
          exit (child_status);
        }
    }
}