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 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
  20 static 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
  30 int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  31 int 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 }