1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Mini watchdog implementation for busybox
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4 | *
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5 | * Copyright (C) 2003 Paul Mundt <lethal@linux-sh.org>
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6 | * Copyright (C) 2006 Bernhard Reutner-Fischer <busybox@busybox.net>
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7 | * Copyright (C) 2008 Darius Augulis <augulis.darius@gmail.com>
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8 | *
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9 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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10 | */
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11 |
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12 | #include "libbb.h"
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13 | #include "linux/types.h" /* for __u32 */
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14 | #include "linux/watchdog.h"
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15 |
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16 | #define OPT_FOREGROUND (1 << 0)
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17 | #define OPT_STIMER (1 << 1)
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18 | #define OPT_HTIMER (1 << 2)
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19 |
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20 | static void watchdog_shutdown(int sig UNUSED_PARAM)
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21 | {
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22 | static const char V = 'V';
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23 |
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24 | write(3, &V, 1); /* Magic, see watchdog-api.txt in kernel */
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25 | if (ENABLE_FEATURE_CLEAN_UP)
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26 | close(3);
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27 | _exit(EXIT_SUCCESS);
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28 | }
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29 |
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30 | int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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31 | int watchdog_main(int argc, char **argv)
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32 | {
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33 | static const struct suffix_mult suffixes[] = {
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34 | { "ms", 1 },
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35 | { "", 1000 },
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36 | { "", 0 }
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37 | };
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38 |
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39 | unsigned opts;
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40 | unsigned stimer_duration; /* how often to restart */
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41 | unsigned htimer_duration = 60000; /* reboots after N ms if not restarted */
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42 | char *st_arg;
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43 | char *ht_arg;
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44 |
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45 | opt_complementary = "=1"; /* must have exactly 1 argument */
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46 | opts = getopt32(argv, "Ft:T:", &st_arg, &ht_arg);
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47 |
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48 | /* We need to daemonize *before* opening the watchdog as many drivers
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49 | * will only allow one process at a time to do so. Since daemonizing
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50 | * is not perfect (child may run before parent finishes exiting), we
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51 | * can't rely on parent exiting before us (let alone *cleanly* releasing
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52 | * the watchdog fd -- something else that may not even be allowed).
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53 | */
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54 | if (!(opts & OPT_FOREGROUND))
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55 | bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
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56 |
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57 | if (opts & OPT_HTIMER)
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58 | htimer_duration = xatou_sfx(ht_arg, suffixes);
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59 | stimer_duration = htimer_duration / 2;
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60 | if (opts & OPT_STIMER)
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61 | stimer_duration = xatou_sfx(st_arg, suffixes);
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62 |
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63 | bb_signals(BB_FATAL_SIGS, watchdog_shutdown);
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64 |
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65 | /* Use known fd # - avoid needing global 'int fd' */
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66 | xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);
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67 |
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68 | /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */
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69 | htimer_duration = htimer_duration / 1000;
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70 | #ifndef WDIOC_SETTIMEOUT
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71 | # error WDIOC_SETTIMEOUT is not defined, cannot compile watchdog applet
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72 | #else
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73 | # if defined WDIOC_SETOPTIONS && defined WDIOS_ENABLECARD
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74 | {
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75 | static const int enable = WDIOS_ENABLECARD;
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76 | ioctl_or_warn(3, WDIOC_SETOPTIONS, (void*) &enable);
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77 | }
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78 | # endif
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79 | ioctl_or_warn(3, WDIOC_SETTIMEOUT, &htimer_duration);
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80 | #endif
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81 |
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82 | #if 0
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83 | ioctl_or_warn(3, WDIOC_GETTIMEOUT, &htimer_duration);
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84 | printf("watchdog: SW timer is %dms, HW timer is %ds\n",
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85 | stimer_duration, htimer_duration * 1000);
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86 | #endif
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87 |
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88 | while (1) {
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89 | /*
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90 | * Make sure we clear the counter before sleeping,
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91 | * as the counter value is undefined at this point -- PFM
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92 | */
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93 | write(3, "", 1); /* write zero byte */
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94 | usleep(stimer_duration * 1000L);
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95 | }
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96 | return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */
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97 | }
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