151 lines
4.7 KiB
C
151 lines
4.7 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini watchdog implementation for busybox
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*
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* Copyright (C) 2003 Paul Mundt <lethal@linux-sh.org>
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* Copyright (C) 2006 Bernhard Reutner-Fischer <busybox@busybox.net>
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* Copyright (C) 2008 Darius Augulis <augulis.darius@gmail.com>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//config:config WATCHDOG
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//config: bool "watchdog (5.3 kb)"
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//config: default y
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//config: select PLATFORM_LINUX
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//config: help
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//config: The watchdog utility is used with hardware or software watchdog
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//config: device drivers. It opens the specified watchdog device special file
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//config: and periodically writes a magic character to the device. If the
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//config: watchdog applet ever fails to write the magic character within a
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//config: certain amount of time, the watchdog device assumes the system has
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//config: hung, and will cause the hardware to reboot.
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//applet:IF_WATCHDOG(APPLET(watchdog, BB_DIR_SBIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_WATCHDOG) += watchdog.o
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//usage:#define watchdog_trivial_usage
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//usage: "[-t N[ms]] [-T N[ms]] [-F] DEV"
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//usage:#define watchdog_full_usage "\n\n"
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//usage: "Periodically write to watchdog device DEV\n"
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//usage: "\n -T N Reboot after N seconds if not reset (default 60)"
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//usage: "\n -t N Reset every N seconds (default 30)"
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//usage: "\n -F Run in foreground"
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//usage: "\n"
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//usage: "\nUse 500ms to specify period in milliseconds"
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#include "libbb.h"
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#include <linux/types.h> /* for __u32 */
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#include <linux/watchdog.h>
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#ifndef WDIOC_SETOPTIONS
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# define WDIOC_SETOPTIONS 0x5704
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#endif
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#ifndef WDIOC_SETTIMEOUT
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# define WDIOC_SETTIMEOUT 0x5706
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#endif
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#ifndef WDIOC_GETTIMEOUT
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# define WDIOC_GETTIMEOUT 0x5707
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#endif
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#ifndef WDIOS_ENABLECARD
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# define WDIOS_ENABLECARD 2
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#endif
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#define OPT_FOREGROUND (1 << 0)
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#define OPT_STIMER (1 << 1)
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#define OPT_HTIMER (1 << 2)
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static void shutdown_watchdog(void)
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{
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static const char V = 'V';
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write(3, &V, 1); /* Magic, see watchdog-api.txt in kernel */
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close(3);
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}
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static void shutdown_on_signal(int sig UNUSED_PARAM)
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{
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remove_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
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shutdown_watchdog();
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_exit(EXIT_SUCCESS);
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}
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static void watchdog_open(const char* device)
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{
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/* Use known fd # - avoid needing global 'int fd' */
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xmove_fd(xopen(device, O_WRONLY), 3);
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/* If the watchdog driver can do something other than cause a reboot
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* on a timeout, then it's possible this program may be starting from
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* a state when the watchdog hadn't been previously stopped with
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* the magic write followed by a close. In this case the driver may
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* not start properly, so always do the proper stop first just in case.
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*/
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shutdown_watchdog();
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xmove_fd(xopen(device, O_WRONLY), 3);
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}
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int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int watchdog_main(int argc UNUSED_PARAM, char **argv)
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{
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static const int enable = WDIOS_ENABLECARD;
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static const struct suffix_mult suffixes[] = {
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{ "ms", 1 },
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{ "", 1000 },
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{ "", 0 }
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};
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unsigned opts;
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unsigned stimer_duration; /* how often to restart */
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unsigned htimer_duration = 60000; /* reboots after N ms if not restarted */
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char *st_arg;
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char *ht_arg;
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opts = getopt32(argv, "^" "Ft:T:" "\0" "=1"/*must have exactly 1 arg*/,
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&st_arg, &ht_arg
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);
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/* We need to daemonize *before* opening the watchdog as many drivers
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* will only allow one process at a time to do so. Since daemonizing
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* is not perfect (child may run before parent finishes exiting), we
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* can't rely on parent exiting before us (let alone *cleanly* releasing
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* the watchdog fd -- something else that may not even be allowed).
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*/
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if (!(opts & OPT_FOREGROUND))
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bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
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/* maybe bb_logenv_override(); here for LOGGING=syslog to work? */
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if (opts & OPT_HTIMER)
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htimer_duration = xatou_sfx(ht_arg, suffixes);
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stimer_duration = htimer_duration / 2;
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if (opts & OPT_STIMER)
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stimer_duration = xatou_sfx(st_arg, suffixes);
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bb_signals(BB_FATAL_SIGS, shutdown_on_signal);
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watchdog_open(argv[optind]);
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/* WDIOC_SETTIMEOUT takes seconds, not milliseconds */
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htimer_duration = htimer_duration / 1000;
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ioctl_or_warn(3, WDIOC_SETOPTIONS, (void*) &enable);
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ioctl_or_warn(3, WDIOC_SETTIMEOUT, &htimer_duration);
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#if 0
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ioctl_or_warn(3, WDIOC_GETTIMEOUT, &htimer_duration);
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printf("watchdog: SW timer is %dms, HW timer is %ds\n",
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stimer_duration, htimer_duration * 1000);
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#endif
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write_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
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while (1) {
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/*
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* Make sure we clear the counter before sleeping,
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* as the counter value is undefined at this point -- PFM
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*/
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write(3, "", 1); /* write zero byte */
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usleep(stimer_duration * 1000L);
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}
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return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */
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}
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