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        remove_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
  35        write(3, &V, 1);  /* Magic, see watchdog-api.txt in kernel */
  36        if (ENABLE_FEATURE_CLEAN_UP)
  37                close(3);
  38        _exit(EXIT_SUCCESS);
  39}
  40
  41int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  42int watchdog_main(int argc, char **argv)
  43{
  44        static const struct suffix_mult suffixes[] = {
  45                { "ms", 1 },
  46                { "", 1000 },
  47                { "", 0 }
  48        };
  49
  50        unsigned opts;
  51        unsigned stimer_duration; /* how often to restart */
  52        unsigned htimer_duration = 60000; /* reboots after N ms if not restarted */
  53        char *st_arg;
  54        char *ht_arg;
  55
  56        opt_complementary = "=1"; /* must have exactly 1 argument */
  57        opts = getopt32(argv, "Ft:T:", &st_arg, &ht_arg);
  58
  59        /* We need to daemonize *before* opening the watchdog as many drivers
  60         * will only allow one process at a time to do so.  Since daemonizing
  61         * is not perfect (child may run before parent finishes exiting), we
  62         * can't rely on parent exiting before us (let alone *cleanly* releasing
  63         * the watchdog fd -- something else that may not even be allowed).
  64         */
  65        if (!(opts & OPT_FOREGROUND))
  66                bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
  67
  68        if (opts & OPT_HTIMER)
  69                htimer_duration = xatou_sfx(ht_arg, suffixes);
  70        stimer_duration = htimer_duration / 2;
  71        if (opts & OPT_STIMER)
  72                stimer_duration = xatou_sfx(st_arg, suffixes);
  73
  74        bb_signals(BB_FATAL_SIGS, watchdog_shutdown);
  75
  76        /* Use known fd # - avoid needing global 'int fd' */
  77        xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);
  78
  79        /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */
  80        htimer_duration = htimer_duration / 1000;
  81#ifndef WDIOC_SETTIMEOUT
  82# error WDIOC_SETTIMEOUT is not defined, cannot compile watchdog applet
  83#else
  84# if defined WDIOC_SETOPTIONS && defined WDIOS_ENABLECARD
  85        {
  86                static const int enable = WDIOS_ENABLECARD;
  87                ioctl_or_warn(3, WDIOC_SETOPTIONS, (void*) &enable);
  88        }
  89# endif
  90        ioctl_or_warn(3, WDIOC_SETTIMEOUT, &htimer_duration);
  91#endif
  92
  93#if 0
  94        ioctl_or_warn(3, WDIOC_GETTIMEOUT, &htimer_duration);
  95        printf("watchdog: SW timer is %dms, HW timer is %ds\n",
  96                stimer_duration, htimer_duration * 1000);
  97#endif
  98
  99        write_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
 100
 101        while (1) {
 102                /*
 103                 * Make sure we clear the counter before sleeping,
 104                 * as the counter value is undefined at this point -- PFM
 105                 */
 106                write(3, "", 1); /* write zero byte */
 107                usleep(stimer_duration * 1000L);
 108        }
 109        return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */
 110}
 111