source: MondoRescue/branches/2.2.5/mindi-busybox/miscutils/watchdog.c@ 1765

/* vi: set sw=4 ts=4: */
/*
 * Mini watchdog implementation for busybox
 *
 * Copyright (C) 2003  Paul Mundt <lethal@linux-sh.org>
 * Copyright (C) 2006  Bernhard Fischer <busybox@busybox.net>
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 */

#include "libbb.h"

#define OPT_FOREGROUND 0x01
#define OPT_TIMER      0x02

static void watchdog_shutdown(int ATTRIBUTE_UNUSED sig) ATTRIBUTE_NORETURN;
static void watchdog_shutdown(int ATTRIBUTE_UNUSED sig)
{
    write(3, "V", 1);   /* Magic, see watchdog-api.txt in kernel */
    if (ENABLE_FEATURE_CLEAN_UP)
        close(3);
    exit(0);
}

int watchdog_main(int argc, char **argv);
int watchdog_main(int argc, char **argv)
{
    unsigned opts;
    unsigned timer_duration = 30; /* Userspace timer duration, in seconds */
    char *t_arg;

    opt_complementary = "=1"; /* must have 1 argument */
    opts = getopt32(argv, "Ft:", &t_arg);

    if (opts & OPT_TIMER)
        timer_duration = xatou(t_arg);

    if (!(opts & OPT_FOREGROUND)) {
        bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
    }

    signal(SIGHUP, watchdog_shutdown);
    signal(SIGINT, watchdog_shutdown);

    /* Use known fd # - avoid needing global 'int fd' */
    xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);

    while (1) {
        /*
         * Make sure we clear the counter before sleeping, as the counter value
         * is undefined at this point -- PFM
         */
        write(3, "", 1);
        sleep(timer_duration);
    }

    watchdog_shutdown(0);
    /* return EXIT_SUCCESS; */
}