blob: 07ae64e52afbae01f090a6e7c01d6b34018b84bb
| 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 | //config:config WATCHDOG |
| 12 | //config: bool "watchdog" |
| 13 | //config: default y |
| 14 | //config: select PLATFORM_LINUX |
| 15 | //config: help |
| 16 | //config: The watchdog utility is used with hardware or software watchdog |
| 17 | //config: device drivers. It opens the specified watchdog device special file |
| 18 | //config: and periodically writes a magic character to the device. If the |
| 19 | //config: watchdog applet ever fails to write the magic character within a |
| 20 | //config: certain amount of time, the watchdog device assumes the system has |
| 21 | //config: hung, and will cause the hardware to reboot. |
| 22 | |
| 23 | //applet:IF_WATCHDOG(APPLET(watchdog, BB_DIR_SBIN, BB_SUID_DROP)) |
| 24 | |
| 25 | //kbuild:lib-$(CONFIG_WATCHDOG) += watchdog.o |
| 26 | |
| 27 | //usage:#define watchdog_trivial_usage |
| 28 | //usage: "[-t N[ms]] [-T N[ms]] [-F] DEV" |
| 29 | //usage:#define watchdog_full_usage "\n\n" |
| 30 | //usage: "Periodically write to watchdog device DEV\n" |
| 31 | //usage: "\n -T N Reboot after N seconds if not reset (default 60)" |
| 32 | //usage: "\n -t N Reset every N seconds (default 30)" |
| 33 | //usage: "\n -F Run in foreground" |
| 34 | //usage: "\n" |
| 35 | //usage: "\nUse 500ms to specify period in milliseconds" |
| 36 | |
| 37 | #include "libbb.h" |
| 38 | #include "linux/types.h" /* for __u32 */ |
| 39 | #include "linux/watchdog.h" |
| 40 | |
| 41 | #define OPT_FOREGROUND (1 << 0) |
| 42 | #define OPT_STIMER (1 << 1) |
| 43 | #define OPT_HTIMER (1 << 2) |
| 44 | |
| 45 | static void watchdog_shutdown(int sig UNUSED_PARAM) |
| 46 | { |
| 47 | static const char V = 'V'; |
| 48 | |
| 49 | remove_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid"); |
| 50 | write(3, &V, 1); /* Magic, see watchdog-api.txt in kernel */ |
| 51 | if (ENABLE_FEATURE_CLEAN_UP) |
| 52 | close(3); |
| 53 | _exit(EXIT_SUCCESS); |
| 54 | } |
| 55 | |
| 56 | int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| 57 | int watchdog_main(int argc, char **argv) |
| 58 | { |
| 59 | static const struct suffix_mult suffixes[] = { |
| 60 | { "ms", 1 }, |
| 61 | { "", 1000 }, |
| 62 | { "", 0 } |
| 63 | }; |
| 64 | |
| 65 | unsigned opts; |
| 66 | unsigned stimer_duration; /* how often to restart */ |
| 67 | unsigned htimer_duration = 60000; /* reboots after N ms if not restarted */ |
| 68 | char *st_arg; |
| 69 | char *ht_arg; |
| 70 | |
| 71 | opt_complementary = "=1"; /* must have exactly 1 argument */ |
| 72 | opts = getopt32(argv, "Ft:T:", &st_arg, &ht_arg); |
| 73 | |
| 74 | /* We need to daemonize *before* opening the watchdog as many drivers |
| 75 | * will only allow one process at a time to do so. Since daemonizing |
| 76 | * is not perfect (child may run before parent finishes exiting), we |
| 77 | * can't rely on parent exiting before us (let alone *cleanly* releasing |
| 78 | * the watchdog fd -- something else that may not even be allowed). |
| 79 | */ |
| 80 | if (!(opts & OPT_FOREGROUND)) |
| 81 | bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv); |
| 82 | |
| 83 | if (opts & OPT_HTIMER) |
| 84 | htimer_duration = xatou_sfx(ht_arg, suffixes); |
| 85 | stimer_duration = htimer_duration / 2; |
| 86 | if (opts & OPT_STIMER) |
| 87 | stimer_duration = xatou_sfx(st_arg, suffixes); |
| 88 | |
| 89 | bb_signals(BB_FATAL_SIGS, watchdog_shutdown); |
| 90 | |
| 91 | /* Use known fd # - avoid needing global 'int fd' */ |
| 92 | xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3); |
| 93 | |
| 94 | /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */ |
| 95 | htimer_duration = htimer_duration / 1000; |
| 96 | #ifndef WDIOC_SETTIMEOUT |
| 97 | # error WDIOC_SETTIMEOUT is not defined, cannot compile watchdog applet |
| 98 | #else |
| 99 | # if defined WDIOC_SETOPTIONS && defined WDIOS_ENABLECARD |
| 100 | { |
| 101 | static const int enable = WDIOS_ENABLECARD; |
| 102 | ioctl_or_warn(3, WDIOC_SETOPTIONS, (void*) &enable); |
| 103 | } |
| 104 | # endif |
| 105 | ioctl_or_warn(3, WDIOC_SETTIMEOUT, &htimer_duration); |
| 106 | #endif |
| 107 | |
| 108 | #if 0 |
| 109 | ioctl_or_warn(3, WDIOC_GETTIMEOUT, &htimer_duration); |
| 110 | printf("watchdog: SW timer is %dms, HW timer is %ds\n", |
| 111 | stimer_duration, htimer_duration * 1000); |
| 112 | #endif |
| 113 | |
| 114 | write_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid"); |
| 115 | |
| 116 | while (1) { |
| 117 | /* |
| 118 | * Make sure we clear the counter before sleeping, |
| 119 | * as the counter value is undefined at this point -- PFM |
| 120 | */ |
| 121 | write(3, "", 1); /* write zero byte */ |
| 122 | usleep(stimer_duration * 1000L); |
| 123 | } |
| 124 | return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */ |
| 125 | } |
| 126 |