hush/miscutils/watchdog.c

82 lines
2.0 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini watchdog implementation for busybox
*
* Copyright (C) 2003 Paul Mundt <lethal@linux-sh.org>
*
* 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 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include "busybox.h"
/* Userspace timer duration, in seconds */
static unsigned int timer_duration = 30;
/* Watchdog file descriptor */
static int fd;
static void watchdog_shutdown(int unused)
{
write(fd, "V", 1); /* Magic */
close(fd);
exit(0);
}
extern int watchdog_main(int argc, char **argv)
{
int opt;
while ((opt = getopt(argc, argv, "t:")) > 0) {
switch (opt) {
case 't':
timer_duration = bb_xgetlarg(optarg, 10, 0, INT_MAX);
break;
default:
bb_show_usage();
}
}
/* We're only interested in the watchdog device .. */
if (optind < argc - 1 || argc == 1)
bb_show_usage();
if (daemon(0, 1) < 0)
bb_perror_msg_and_die("Failed forking watchdog daemon");
signal(SIGHUP, watchdog_shutdown);
signal(SIGINT, watchdog_shutdown);
fd = bb_xopen(argv[argc - 1], O_WRONLY);
while (1) {
/*
* Make sure we clear the counter before sleeping, as the counter value
* is undefined at this point -- PFM
*/
write(fd, "\0", 1);
sleep(timer_duration);
}
watchdog_shutdown(0);
return EXIT_SUCCESS;
}