release/src/router/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
  30 static 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
  40 int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  41 int 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 }