1
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1 /* |
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2 * vinit.c -- vanilla linux init |
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3 * |
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4 * Copyright (c) 2021 David Demelier <markand@malikania.fr> |
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5 * |
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6 * Permission to use, copy, modify, and/or distribute this software for any |
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7 * purpose with or without fee is hereby granted, provided that the above |
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8 * copyright notice and this permission notice appear in all copies. |
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9 * |
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10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
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13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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17 */ |
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18 |
0
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19 #include <sys/wait.h> |
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20 #include <errno.h> |
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21 #include <signal.h> |
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22 #include <stdarg.h> |
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23 #include <stdio.h> |
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24 #include <stdlib.h> |
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25 #include <stdnoreturn.h> |
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26 #include <string.h> |
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27 #include <unistd.h> |
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28 |
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29 static char * const rcinit[] = { "/etc/rc.init", NULL }; |
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30 static char * const rchalt[] = { "/etc/rc.shutdown", "halt", NULL }; |
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31 static char * const rcpoweroff[] = { "/etc/rc.shutdown", "poweroff", NULL }; |
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32 static char * const rcreboot[] = { "/etc/rc.shutdown", "reboot", NULL }; |
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33 |
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34 static sigset_t set; |
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35 |
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36 noreturn static void |
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37 die(const char *fmt, ...) |
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38 { |
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39 va_list ap; |
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40 |
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41 va_start(ap, fmt); |
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42 vfprintf(stderr, fmt, ap); |
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43 va_end(ap); |
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44 exit(1); |
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45 } |
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46 |
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47 static void |
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48 spawn(char * const args[]) |
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49 { |
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50 switch (fork()) { |
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51 case 0: |
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52 sigprocmask(SIG_UNBLOCK, &set, NULL); |
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53 setsid(); |
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54 execv(args[0], args); |
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55 perror("execv"); |
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56 exit(1); |
1
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57 case -1: |
0
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58 perror("fork"); |
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59 default: |
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60 break; |
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61 } |
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62 } |
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63 |
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64 int |
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65 main(void) |
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66 { |
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67 int sig; |
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68 |
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69 if (getpid() != 1) |
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70 die("abort: must be ran as PID 1\n"); |
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71 if (chdir("/") < 0) |
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72 die("abort: %s\n", strerror(errno)); |
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73 |
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74 sigfillset(&set); |
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75 sigprocmask(SIG_BLOCK, &set, NULL); |
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76 spawn(rcinit); |
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77 |
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78 for (;;) { |
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79 sigwait(&set, &sig); |
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80 |
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81 /* Match busybox defaults. */ |
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82 switch (sig) { |
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83 case SIGUSR1: |
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84 spawn(rchalt); |
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85 break; |
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86 case SIGUSR2: |
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87 spawn(rcpoweroff); |
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88 break; |
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89 case SIGTERM: |
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90 spawn(rcreboot); |
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91 break; |
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92 case SIGCHLD: |
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93 while (waitpid(-1, NULL, WNOHANG) > 0) |
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94 continue; |
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95 default: |
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96 break; |
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97 } |
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98 } |
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99 } |