LXR busybox/miscutils/watchdog.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini watchdog implementation for busybox
   4 *
   5 * Copyright (C) 2003  Paul Mundt <lethal@linux-sh.org>
   6 * Copyright (C) 2006  Bernhard Reutner-Fischer <busybox@busybox.net>
   7 * Copyright (C) 2008  Darius Augulis <augulis.darius@gmail.com>
   8 *
   9 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  10 */
  11
  12#include "libbb.h"
  13#include "linux/types.h" /* for __u32 */
  14#include "linux/watchdog.h"
  15
  16#define OPT_FOREGROUND  (1 << 0)
  17#define OPT_STIMER      (1 << 1)
  18#define OPT_HTIMER      (1 << 2)
  19
  20static void watchdog_shutdown(int sig UNUSED_PARAM)
  21{
  22        static const char V = 'V';
  23
  24        write(3, &V, 1);        /* Magic, see watchdog-api.txt in kernel */
  25        if (ENABLE_FEATURE_CLEAN_UP)
  26                close(3);
  27        exit(EXIT_SUCCESS);
  28}
  29
  30int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  31int watchdog_main(int argc, char **argv)
  32{
  33        static const struct suffix_mult suffixes[] = {
  34                { "ms", 1 },
  35                { "", 1000 },
  36                { }
  37        };
  38
  39        unsigned opts;
  40        unsigned stimer_duration; /* how often to restart */
  41        unsigned htimer_duration = 60000; /* reboots after N ms if not restarted */
  42        char *st_arg;
  43        char *ht_arg;
  44
  45        opt_complementary = "=1"; /* must have exactly 1 argument */
  46        opts = getopt32(argv, "Ft:T:", &st_arg, &ht_arg);
  47
  48        if (opts & OPT_HTIMER)
  49                htimer_duration = xatou_sfx(ht_arg, suffixes);
  50        stimer_duration = htimer_duration / 2;
  51        if (opts & OPT_STIMER)
  52                stimer_duration = xatou_sfx(st_arg, suffixes);
  53
  54        bb_signals(BB_FATAL_SIGS, watchdog_shutdown);
  55
  56        /* Use known fd # - avoid needing global 'int fd' */
  57        xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);
  58
  59        /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */
  60        htimer_duration = htimer_duration / 1000;
  61#ifndef WDIOC_SETTIMEOUT
  62#error WDIOC_SETTIMEOUT is not defined, cannot compile watchdog applet
  63#else
  64        ioctl_or_warn(3, WDIOC_SETTIMEOUT, &htimer_duration);
  65#endif
  66#if 0
  67        ioctl_or_warn(3, WDIOC_GETTIMEOUT, &htimer_duration);
  68        printf("watchdog: SW timer is %dms, HW timer is %dms\n",
  69                stimer_duration, htimer_duration * 1000);
  70#endif
  71
  72        if (!(opts & OPT_FOREGROUND)) {
  73                bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
  74        }
  75
  76        while (1) {
  77                /*
  78                 * Make sure we clear the counter before sleeping,
  79                 * as the counter value is undefined at this point -- PFM
  80                 */
  81                write(3, "", 1); /* write zero byte */
  82                usleep(stimer_duration * 1000L);
  83        }
  84        return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */
  85}
  86