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 GPLv2 or later, see file LICENSE in this source tree.
  10 */
  11
  12//usage:#define watchdog_trivial_usage
  13//usage:       "[-t N[ms]] [-T N[ms]] [-F] DEV"
  14//usage:#define watchdog_full_usage "\n\n"
  15//usage:       "Periodically write to watchdog device DEV\n"
  16//usage:     "\n        -T N    Reboot after N seconds if not reset (default 60)"
  17//usage:     "\n        -t N    Reset every N seconds (default 30)"
  18//usage:     "\n        -F      Run in foreground"
  19//usage:     "\n"
  20//usage:     "\nUse 500ms to specify period in milliseconds"
  21
  22#include "libbb.h"
  23#include "linux/types.h" /* for __u32 */
  24#include "linux/watchdog.h"
  25
  26#define OPT_FOREGROUND  (1 << 0)
  27#define OPT_STIMER      (1 << 1)
  28#define OPT_HTIMER      (1 << 2)
  29
  30static void watchdog_shutdown(int sig UNUSED_PARAM)
  31{
  32        static const char V = 'V';
  33
  34        write(3, &V, 1);  /* Magic, see watchdog-api.txt in kernel */
  35        if (ENABLE_FEATURE_CLEAN_UP)
  36                close(3);
  37        _exit(EXIT_SUCCESS);
  38}
  39
  40int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  41int watchdog_main(int argc, char **argv)
  42{
  43        static const struct suffix_mult suffixes[] = {
  44                { "ms", 1 },
  45                { "", 1000 },
  46                { "", 0 }
  47        };
  48
  49        unsigned opts;
  50        unsigned stimer_duration; /* how often to restart */
  51        unsigned htimer_duration = 60000; /* reboots after N ms if not restarted */
  52        char *st_arg;
  53        char *ht_arg;
  54
  55        opt_complementary = "=1"; /* must have exactly 1 argument */
  56        opts = getopt32(argv, "Ft:T:", &st_arg, &ht_arg);
  57
  58        /* We need to daemonize *before* opening the watchdog as many drivers
  59         * will only allow one process at a time to do so.  Since daemonizing
  60         * is not perfect (child may run before parent finishes exiting), we
  61         * can't rely on parent exiting before us (let alone *cleanly* releasing
  62         * the watchdog fd -- something else that may not even be allowed).
  63         */
  64        if (!(opts & OPT_FOREGROUND))
  65                bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
  66
  67        if (opts & OPT_HTIMER)
  68                htimer_duration = xatou_sfx(ht_arg, suffixes);
  69        stimer_duration = htimer_duration / 2;
  70        if (opts & OPT_STIMER)
  71                stimer_duration = xatou_sfx(st_arg, suffixes);
  72
  73        bb_signals(BB_FATAL_SIGS, watchdog_shutdown);
  74
  75        /* Use known fd # - avoid needing global 'int fd' */
  76        xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);
  77
  78        /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */
  79        htimer_duration = htimer_duration / 1000;
  80#ifndef WDIOC_SETTIMEOUT
  81# error WDIOC_SETTIMEOUT is not defined, cannot compile watchdog applet
  82#else
  83# if defined WDIOC_SETOPTIONS && defined WDIOS_ENABLECARD
  84        {
  85                static const int enable = WDIOS_ENABLECARD;
  86                ioctl_or_warn(3, WDIOC_SETOPTIONS, (void*) &enable);
  87        }
  88# endif
  89        ioctl_or_warn(3, WDIOC_SETTIMEOUT, &htimer_duration);
  90#endif
  91
  92#if 0
  93        ioctl_or_warn(3, WDIOC_GETTIMEOUT, &htimer_duration);
  94        printf("watchdog: SW timer is %dms, HW timer is %ds\n",
  95                stimer_duration, htimer_duration * 1000);
  96#endif
  97
  98        while (1) {
  99                /*
 100                 * Make sure we clear the counter before sleeping,
 101                 * as the counter value is undefined at this point -- PFM
 102                 */
 103                write(3, "", 1); /* write zero byte */
 104                usleep(stimer_duration * 1000L);
 105        }
 106        return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */
 107}
 108