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 Fischer <busybox@busybox.net>
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7 | *
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8 | * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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9 | */
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10 |
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11 | #include "busybox.h"
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12 | #include <stdio.h>
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13 | #include <fcntl.h>
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14 | #include <unistd.h>
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15 | #include <stdlib.h>
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16 | #include <signal.h>
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17 |
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18 | #define OPT_FOREGROUND 0x01
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19 | #define OPT_TIMER 0x02
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20 |
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21 | /* Watchdog file descriptor */
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22 | static int fd;
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23 |
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24 | static void watchdog_shutdown(int ATTRIBUTE_UNUSED unused)
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25 | {
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26 | write(fd, "V", 1); /* Magic, see watchdog-api.txt in kernel */
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27 | close(fd);
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28 | exit(0);
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29 | }
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30 |
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31 | int watchdog_main(int argc, char **argv)
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32 | {
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33 | unsigned long opts;
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34 | unsigned long timer_duration = 30; /* Userspace timer duration, in seconds */
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35 | char *t_arg;
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36 |
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37 | opts = bb_getopt_ulflags(argc, argv, "Ft:", &t_arg);
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38 |
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39 | if (opts & OPT_TIMER)
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40 | timer_duration = bb_xgetlarg(t_arg, 10, 0, INT_MAX);
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41 |
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42 | /* We're only interested in the watchdog device .. */
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43 | if (optind < argc - 1 || argc == 1)
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44 | bb_show_usage();
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45 |
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46 | #ifdef BB_NOMMU
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47 | if (!(opts & OPT_FOREGROUND))
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48 | vfork_daemon_rexec(0, 1, argc, argv, "-F");
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49 | #else
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50 | bb_xdaemon(0, 1);
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51 | #endif
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52 |
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53 | signal(SIGHUP, watchdog_shutdown);
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54 | signal(SIGINT, watchdog_shutdown);
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55 |
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56 | fd = bb_xopen(argv[argc - 1], O_WRONLY);
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57 |
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58 | while (1) {
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59 | /*
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60 | * Make sure we clear the counter before sleeping, as the counter value
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61 | * is undefined at this point -- PFM
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62 | */
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63 | write(fd, "\0", 1);
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64 | sleep(timer_duration);
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65 | }
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66 |
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67 | watchdog_shutdown(0);
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68 |
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69 | return EXIT_SUCCESS;
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70 | }
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