Contents of /tags/mkinitrd-6_3_1/busybox/init/init.c
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Thu Aug 19 12:44:27 2010 UTC (14 years, 1 month ago) by niro
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Thu Aug 19 12:44:27 2010 UTC (14 years, 1 month ago) by niro
File MIME type: text/plain
File size: 28579 byte(s)
tagged 'mkinitrd-6_3_1'
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Mini init implementation for busybox |
4 | * |
5 | * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>. |
6 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> |
7 | * Adjusted by so many folks, it's impossible to keep track. |
8 | * |
9 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
10 | */ |
11 | |
12 | #include "libbb.h" |
13 | #include <syslog.h> |
14 | #include <paths.h> |
15 | #include <sys/reboot.h> |
16 | #include <sys/resource.h> |
17 | #include <linux/vt.h> |
18 | #if ENABLE_FEATURE_UTMP |
19 | # include <utmp.h> /* DEAD_PROCESS */ |
20 | #endif |
21 | |
22 | |
23 | /* Was a CONFIG_xxx option. A lot of people were building |
24 | * not fully functional init by switching it on! */ |
25 | #define DEBUG_INIT 0 |
26 | |
27 | #define COMMAND_SIZE 256 |
28 | #define CONSOLE_NAME_SIZE 32 |
29 | |
30 | /* Default sysinit script. */ |
31 | #ifndef INIT_SCRIPT |
32 | #define INIT_SCRIPT "/etc/init.d/rcS" |
33 | #endif |
34 | |
35 | /* Each type of actions can appear many times. They will be |
36 | * handled in order. RESTART is an exception, only 1st is used. |
37 | */ |
38 | /* Start these actions first and wait for completion */ |
39 | #define SYSINIT 0x01 |
40 | /* Start these after SYSINIT and wait for completion */ |
41 | #define WAIT 0x02 |
42 | /* Start these after WAIT and *dont* wait for completion */ |
43 | #define ONCE 0x04 |
44 | /* |
45 | * NB: while SYSINIT/WAIT/ONCE are being processed, |
46 | * SIGHUP ("reread /etc/inittab") will be processed only after |
47 | * each group of actions. If new inittab adds, say, a SYSINIT action, |
48 | * it will not be run, since init is already "past SYSINIT stage". |
49 | */ |
50 | /* Start these after ONCE are started, restart on exit */ |
51 | #define RESPAWN 0x08 |
52 | /* Like RESPAWN, but wait for <Enter> to be pressed on tty */ |
53 | #define ASKFIRST 0x10 |
54 | /* |
55 | * Start these on SIGINT, and wait for completion. |
56 | * Then go back to respawning RESPAWN and ASKFIRST actions. |
57 | * NB: kernel sends SIGINT to us if Ctrl-Alt-Del was pressed. |
58 | */ |
59 | #define CTRLALTDEL 0x20 |
60 | /* |
61 | * Start these before killing all processes in preparation for |
62 | * running RESTART actions or doing low-level halt/reboot/poweroff |
63 | * (initiated by SIGUSR1/SIGTERM/SIGUSR2). |
64 | * Wait for completion before proceeding. |
65 | */ |
66 | #define SHUTDOWN 0x40 |
67 | /* |
68 | * exec() on SIGQUIT. SHUTDOWN actions are started and waited for, |
69 | * then all processes are killed, then init exec's 1st RESTART action, |
70 | * replacing itself by it. If no RESTART action specified, |
71 | * SIGQUIT has no effect. |
72 | */ |
73 | #define RESTART 0x80 |
74 | |
75 | |
76 | /* A linked list of init_actions, to be read from inittab */ |
77 | struct init_action { |
78 | struct init_action *next; |
79 | pid_t pid; |
80 | uint8_t action_type; |
81 | char terminal[CONSOLE_NAME_SIZE]; |
82 | char command[COMMAND_SIZE]; |
83 | }; |
84 | |
85 | static struct init_action *init_action_list = NULL; |
86 | |
87 | static const char *log_console = VC_5; |
88 | |
89 | enum { |
90 | L_LOG = 0x1, |
91 | L_CONSOLE = 0x2, |
92 | #ifndef RB_HALT_SYSTEM |
93 | RB_HALT_SYSTEM = 0xcdef0123, /* FIXME: this overflows enum */ |
94 | RB_ENABLE_CAD = 0x89abcdef, |
95 | RB_DISABLE_CAD = 0, |
96 | RB_POWER_OFF = 0x4321fedc, |
97 | RB_AUTOBOOT = 0x01234567, |
98 | #endif |
99 | }; |
100 | |
101 | /* Print a message to the specified device. |
102 | * "where" may be bitwise-or'd from L_LOG | L_CONSOLE |
103 | * NB: careful, we can be called after vfork! |
104 | */ |
105 | #define dbg_message(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0) |
106 | static void message(int where, const char *fmt, ...) |
107 | __attribute__ ((format(printf, 2, 3))); |
108 | static void message(int where, const char *fmt, ...) |
109 | { |
110 | va_list arguments; |
111 | unsigned l; |
112 | char msg[128]; |
113 | |
114 | msg[0] = '\r'; |
115 | va_start(arguments, fmt); |
116 | l = 1 + vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments); |
117 | if (l > sizeof(msg) - 1) |
118 | l = sizeof(msg) - 1; |
119 | va_end(arguments); |
120 | |
121 | #if ENABLE_FEATURE_INIT_SYSLOG |
122 | msg[l] = '\0'; |
123 | if (where & L_LOG) { |
124 | /* Log the message to syslogd */ |
125 | openlog(applet_name, 0, LOG_DAEMON); |
126 | /* don't print "\r" */ |
127 | syslog(LOG_INFO, "%s", msg + 1); |
128 | closelog(); |
129 | } |
130 | msg[l++] = '\n'; |
131 | msg[l] = '\0'; |
132 | #else |
133 | { |
134 | static int log_fd = -1; |
135 | |
136 | msg[l++] = '\n'; |
137 | msg[l] = '\0'; |
138 | /* Take full control of the log tty, and never close it. |
139 | * It's mine, all mine! Muhahahaha! */ |
140 | if (log_fd < 0) { |
141 | if (!log_console) { |
142 | log_fd = STDERR_FILENO; |
143 | } else { |
144 | log_fd = device_open(log_console, O_WRONLY | O_NONBLOCK | O_NOCTTY); |
145 | if (log_fd < 0) { |
146 | bb_error_msg("can't log to %s", log_console); |
147 | where = L_CONSOLE; |
148 | } else { |
149 | close_on_exec_on(log_fd); |
150 | } |
151 | } |
152 | } |
153 | if (where & L_LOG) { |
154 | full_write(log_fd, msg, l); |
155 | if (log_fd == STDERR_FILENO) |
156 | return; /* don't print dup messages */ |
157 | } |
158 | } |
159 | #endif |
160 | |
161 | if (where & L_CONSOLE) { |
162 | /* Send console messages to console so people will see them. */ |
163 | full_write(STDERR_FILENO, msg, l); |
164 | } |
165 | } |
166 | |
167 | static void console_init(void) |
168 | { |
169 | int vtno; |
170 | char *s; |
171 | |
172 | s = getenv("CONSOLE"); |
173 | if (!s) |
174 | s = getenv("console"); |
175 | if (s) { |
176 | int fd = open(s, O_RDWR | O_NONBLOCK | O_NOCTTY); |
177 | if (fd >= 0) { |
178 | dup2(fd, STDIN_FILENO); |
179 | dup2(fd, STDOUT_FILENO); |
180 | xmove_fd(fd, STDERR_FILENO); |
181 | } |
182 | dbg_message(L_LOG, "console='%s'", s); |
183 | } else { |
184 | /* Make sure fd 0,1,2 are not closed |
185 | * (so that they won't be used by future opens) */ |
186 | bb_sanitize_stdio(); |
187 | // Users report problems |
188 | // /* Make sure init can't be blocked by writing to stderr */ |
189 | // fcntl(STDERR_FILENO, F_SETFL, fcntl(STDERR_FILENO, F_GETFL) | O_NONBLOCK); |
190 | } |
191 | |
192 | s = getenv("TERM"); |
193 | if (ioctl(STDIN_FILENO, VT_OPENQRY, &vtno) != 0) { |
194 | /* Not a linux terminal, probably serial console. |
195 | * Force the TERM setting to vt102 |
196 | * if TERM is set to linux (the default) */ |
197 | if (!s || strcmp(s, "linux") == 0) |
198 | putenv((char*)"TERM=vt102"); |
199 | if (!ENABLE_FEATURE_INIT_SYSLOG) |
200 | log_console = NULL; |
201 | } else if (!s) |
202 | putenv((char*)"TERM=linux"); |
203 | } |
204 | |
205 | /* Set terminal settings to reasonable defaults. |
206 | * NB: careful, we can be called after vfork! */ |
207 | static void set_sane_term(void) |
208 | { |
209 | struct termios tty; |
210 | |
211 | tcgetattr(STDIN_FILENO, &tty); |
212 | |
213 | /* set control chars */ |
214 | tty.c_cc[VINTR] = 3; /* C-c */ |
215 | tty.c_cc[VQUIT] = 28; /* C-\ */ |
216 | tty.c_cc[VERASE] = 127; /* C-? */ |
217 | tty.c_cc[VKILL] = 21; /* C-u */ |
218 | tty.c_cc[VEOF] = 4; /* C-d */ |
219 | tty.c_cc[VSTART] = 17; /* C-q */ |
220 | tty.c_cc[VSTOP] = 19; /* C-s */ |
221 | tty.c_cc[VSUSP] = 26; /* C-z */ |
222 | |
223 | /* use line discipline 0 */ |
224 | tty.c_line = 0; |
225 | |
226 | /* Make it be sane */ |
227 | tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD; |
228 | tty.c_cflag |= CREAD | HUPCL | CLOCAL; |
229 | |
230 | /* input modes */ |
231 | tty.c_iflag = ICRNL | IXON | IXOFF; |
232 | |
233 | /* output modes */ |
234 | tty.c_oflag = OPOST | ONLCR; |
235 | |
236 | /* local modes */ |
237 | tty.c_lflag = |
238 | ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN; |
239 | |
240 | tcsetattr_stdin_TCSANOW(&tty); |
241 | } |
242 | |
243 | /* Open the new terminal device. |
244 | * NB: careful, we can be called after vfork! */ |
245 | static int open_stdio_to_tty(const char* tty_name) |
246 | { |
247 | /* empty tty_name means "use init's tty", else... */ |
248 | if (tty_name[0]) { |
249 | int fd; |
250 | |
251 | close(STDIN_FILENO); |
252 | /* fd can be only < 0 or 0: */ |
253 | fd = device_open(tty_name, O_RDWR); |
254 | if (fd) { |
255 | message(L_LOG | L_CONSOLE, "can't open %s: %s", |
256 | tty_name, strerror(errno)); |
257 | return 0; /* failure */ |
258 | } |
259 | dup2(STDIN_FILENO, STDOUT_FILENO); |
260 | dup2(STDIN_FILENO, STDERR_FILENO); |
261 | } |
262 | set_sane_term(); |
263 | return 1; /* success */ |
264 | } |
265 | |
266 | static void reset_sighandlers_and_unblock_sigs(void) |
267 | { |
268 | bb_signals(0 |
269 | + (1 << SIGUSR1) |
270 | + (1 << SIGUSR2) |
271 | + (1 << SIGTERM) |
272 | + (1 << SIGQUIT) |
273 | + (1 << SIGINT) |
274 | + (1 << SIGHUP) |
275 | + (1 << SIGTSTP) |
276 | + (1 << SIGSTOP) |
277 | , SIG_DFL); |
278 | sigprocmask_allsigs(SIG_UNBLOCK); |
279 | } |
280 | |
281 | /* Wrapper around exec: |
282 | * Takes string (max COMMAND_SIZE chars). |
283 | * If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'. |
284 | * Otherwise splits words on whitespace, deals with leading dash, |
285 | * and uses plain exec(). |
286 | * NB: careful, we can be called after vfork! |
287 | */ |
288 | static void init_exec(const char *command) |
289 | { |
290 | char *cmd[COMMAND_SIZE / 2]; |
291 | char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */ |
292 | int dash = (command[0] == '-' /* maybe? && command[1] == '/' */); |
293 | |
294 | /* See if any special /bin/sh requiring characters are present */ |
295 | if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) { |
296 | strcpy(buf, "exec "); |
297 | strcpy(buf + 5, command + dash); /* excluding "-" */ |
298 | /* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */ |
299 | cmd[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL + !dash); |
300 | cmd[1] = (char*)"-c"; |
301 | cmd[2] = buf; |
302 | cmd[3] = NULL; |
303 | } else { |
304 | /* Convert command (char*) into cmd (char**, one word per string) */ |
305 | char *word, *next; |
306 | int i = 0; |
307 | next = strcpy(buf, command); /* including "-" */ |
308 | while ((word = strsep(&next, " \t")) != NULL) { |
309 | if (*word != '\0') { /* not two spaces/tabs together? */ |
310 | cmd[i] = word; |
311 | i++; |
312 | } |
313 | } |
314 | cmd[i] = NULL; |
315 | } |
316 | /* If we saw leading "-", it is interactive shell. |
317 | * Try harder to give it a controlling tty. |
318 | * And skip "-" in actual exec call. */ |
319 | if (dash) { |
320 | /* _Attempt_ to make stdin a controlling tty. */ |
321 | if (ENABLE_FEATURE_INIT_SCTTY) |
322 | ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/); |
323 | } |
324 | BB_EXECVP(cmd[0] + dash, cmd); |
325 | message(L_LOG | L_CONSOLE, "can't run '%s': %s", cmd[0], strerror(errno)); |
326 | /* returns if execvp fails */ |
327 | } |
328 | |
329 | /* Used only by run_actions */ |
330 | static pid_t run(const struct init_action *a) |
331 | { |
332 | pid_t pid; |
333 | |
334 | /* Careful: don't be affected by a signal in vforked child */ |
335 | sigprocmask_allsigs(SIG_BLOCK); |
336 | if (BB_MMU && (a->action_type & ASKFIRST)) |
337 | pid = fork(); |
338 | else |
339 | pid = vfork(); |
340 | if (pid < 0) |
341 | message(L_LOG | L_CONSOLE, "can't fork"); |
342 | if (pid) { |
343 | sigprocmask_allsigs(SIG_UNBLOCK); |
344 | return pid; /* Parent or error */ |
345 | } |
346 | |
347 | /* Child */ |
348 | |
349 | /* Reset signal handlers that were set by the parent process */ |
350 | reset_sighandlers_and_unblock_sigs(); |
351 | |
352 | /* Create a new session and make ourself the process group leader */ |
353 | setsid(); |
354 | |
355 | /* Open the new terminal device */ |
356 | if (!open_stdio_to_tty(a->terminal)) |
357 | _exit(EXIT_FAILURE); |
358 | |
359 | /* NB: on NOMMU we can't wait for input in child, so |
360 | * "askfirst" will work the same as "respawn". */ |
361 | if (BB_MMU && (a->action_type & ASKFIRST)) { |
362 | static const char press_enter[] ALIGN1 = |
363 | #ifdef CUSTOMIZED_BANNER |
364 | #include CUSTOMIZED_BANNER |
365 | #endif |
366 | "\nPlease press Enter to activate this console. "; |
367 | char c; |
368 | /* |
369 | * Save memory by not exec-ing anything large (like a shell) |
370 | * before the user wants it. This is critical if swap is not |
371 | * enabled and the system has low memory. Generally this will |
372 | * be run on the second virtual console, and the first will |
373 | * be allowed to start a shell or whatever an init script |
374 | * specifies. |
375 | */ |
376 | dbg_message(L_LOG, "waiting for enter to start '%s'" |
377 | "(pid %d, tty '%s')\n", |
378 | a->command, getpid(), a->terminal); |
379 | full_write(STDOUT_FILENO, press_enter, sizeof(press_enter) - 1); |
380 | while (safe_read(STDIN_FILENO, &c, 1) == 1 && c != '\n') |
381 | continue; |
382 | } |
383 | |
384 | /* |
385 | * When a file named /.init_enable_core exists, setrlimit is called |
386 | * before processes are spawned to set core file size as unlimited. |
387 | * This is for debugging only. Don't use this is production, unless |
388 | * you want core dumps lying about.... |
389 | */ |
390 | if (ENABLE_FEATURE_INIT_COREDUMPS) { |
391 | if (access("/.init_enable_core", F_OK) == 0) { |
392 | struct rlimit limit; |
393 | limit.rlim_cur = RLIM_INFINITY; |
394 | limit.rlim_max = RLIM_INFINITY; |
395 | setrlimit(RLIMIT_CORE, &limit); |
396 | } |
397 | } |
398 | |
399 | /* Log the process name and args */ |
400 | message(L_LOG, "starting pid %d, tty '%s': '%s'", |
401 | getpid(), a->terminal, a->command); |
402 | |
403 | /* Now run it. The new program will take over this PID, |
404 | * so nothing further in init.c should be run. */ |
405 | init_exec(a->command); |
406 | /* We're still here? Some error happened. */ |
407 | _exit(-1); |
408 | } |
409 | |
410 | static struct init_action *mark_terminated(pid_t pid) |
411 | { |
412 | struct init_action *a; |
413 | |
414 | if (pid > 0) { |
415 | for (a = init_action_list; a; a = a->next) { |
416 | if (a->pid == pid) { |
417 | a->pid = 0; |
418 | return a; |
419 | } |
420 | } |
421 | update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL); |
422 | } |
423 | return NULL; |
424 | } |
425 | |
426 | static void waitfor(pid_t pid) |
427 | { |
428 | /* waitfor(run(x)): protect against failed fork inside run() */ |
429 | if (pid <= 0) |
430 | return; |
431 | |
432 | /* Wait for any child (prevent zombies from exiting orphaned processes) |
433 | * but exit the loop only when specified one has exited. */ |
434 | while (1) { |
435 | pid_t wpid = wait(NULL); |
436 | mark_terminated(wpid); |
437 | /* Unsafe. SIGTSTP handler might have wait'ed it already */ |
438 | /*if (wpid == pid) break;*/ |
439 | /* More reliable: */ |
440 | if (kill(pid, 0)) |
441 | break; |
442 | } |
443 | } |
444 | |
445 | /* Run all commands of a particular type */ |
446 | static void run_actions(int action_type) |
447 | { |
448 | struct init_action *a; |
449 | |
450 | for (a = init_action_list; a; a = a->next) { |
451 | if (!(a->action_type & action_type)) |
452 | continue; |
453 | |
454 | if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) { |
455 | pid_t pid = run(a); |
456 | if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN)) |
457 | waitfor(pid); |
458 | } |
459 | if (a->action_type & (RESPAWN | ASKFIRST)) { |
460 | /* Only run stuff with pid == 0. If pid != 0, |
461 | * it is already running |
462 | */ |
463 | if (a->pid == 0) |
464 | a->pid = run(a); |
465 | } |
466 | } |
467 | } |
468 | |
469 | static void new_init_action(uint8_t action_type, const char *command, const char *cons) |
470 | { |
471 | struct init_action *a, **nextp; |
472 | |
473 | /* Scenario: |
474 | * old inittab: |
475 | * ::shutdown:umount -a -r |
476 | * ::shutdown:swapoff -a |
477 | * new inittab: |
478 | * ::shutdown:swapoff -a |
479 | * ::shutdown:umount -a -r |
480 | * On reload, we must ensure entries end up in correct order. |
481 | * To achieve that, if we find a matching entry, we move it |
482 | * to the end. |
483 | */ |
484 | nextp = &init_action_list; |
485 | while ((a = *nextp) != NULL) { |
486 | /* Don't enter action if it's already in the list, |
487 | * This prevents losing running RESPAWNs. |
488 | */ |
489 | if (strcmp(a->command, command) == 0 |
490 | && strcmp(a->terminal, cons) == 0 |
491 | ) { |
492 | /* Remove from list */ |
493 | *nextp = a->next; |
494 | /* Find the end of the list */ |
495 | while (*nextp != NULL) |
496 | nextp = &(*nextp)->next; |
497 | a->next = NULL; |
498 | break; |
499 | } |
500 | nextp = &a->next; |
501 | } |
502 | |
503 | if (!a) |
504 | a = xzalloc(sizeof(*a)); |
505 | /* Append to the end of the list */ |
506 | *nextp = a; |
507 | a->action_type = action_type; |
508 | safe_strncpy(a->command, command, sizeof(a->command)); |
509 | safe_strncpy(a->terminal, cons, sizeof(a->terminal)); |
510 | dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n", |
511 | a->command, a->action_type, a->terminal); |
512 | } |
513 | |
514 | /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined, |
515 | * then parse_inittab() simply adds in some default |
516 | * actions(i.e., runs INIT_SCRIPT and then starts a pair |
517 | * of "askfirst" shells). If CONFIG_FEATURE_USE_INITTAB |
518 | * _is_ defined, but /etc/inittab is missing, this |
519 | * results in the same set of default behaviors. |
520 | */ |
521 | static void parse_inittab(void) |
522 | { |
523 | #if ENABLE_FEATURE_USE_INITTAB |
524 | char *token[4]; |
525 | parser_t *parser = config_open2("/etc/inittab", fopen_for_read); |
526 | |
527 | if (parser == NULL) |
528 | #endif |
529 | { |
530 | /* No inittab file - set up some default behavior */ |
531 | /* Reboot on Ctrl-Alt-Del */ |
532 | new_init_action(CTRLALTDEL, "reboot", ""); |
533 | /* Umount all filesystems on halt/reboot */ |
534 | new_init_action(SHUTDOWN, "umount -a -r", ""); |
535 | /* Swapoff on halt/reboot */ |
536 | if (ENABLE_SWAPONOFF) |
537 | new_init_action(SHUTDOWN, "swapoff -a", ""); |
538 | /* Prepare to restart init when a QUIT is received */ |
539 | new_init_action(RESTART, "init", ""); |
540 | /* Askfirst shell on tty1-4 */ |
541 | new_init_action(ASKFIRST, bb_default_login_shell, ""); |
542 | //TODO: VC_1 instead of ""? "" is console -> ctty problems -> angry users |
543 | new_init_action(ASKFIRST, bb_default_login_shell, VC_2); |
544 | new_init_action(ASKFIRST, bb_default_login_shell, VC_3); |
545 | new_init_action(ASKFIRST, bb_default_login_shell, VC_4); |
546 | /* sysinit */ |
547 | new_init_action(SYSINIT, INIT_SCRIPT, ""); |
548 | return; |
549 | } |
550 | |
551 | #if ENABLE_FEATURE_USE_INITTAB |
552 | /* optional_tty:ignored_runlevel:action:command |
553 | * Delims are not to be collapsed and need exactly 4 tokens |
554 | */ |
555 | while (config_read(parser, token, 4, 0, "#:", |
556 | PARSE_NORMAL & ~(PARSE_TRIM | PARSE_COLLAPSE))) { |
557 | /* order must correspond to SYSINIT..RESTART constants */ |
558 | static const char actions[] ALIGN1 = |
559 | "sysinit\0""wait\0""once\0""respawn\0""askfirst\0" |
560 | "ctrlaltdel\0""shutdown\0""restart\0"; |
561 | int action; |
562 | char *tty = token[0]; |
563 | |
564 | if (!token[3]) /* less than 4 tokens */ |
565 | goto bad_entry; |
566 | action = index_in_strings(actions, token[2]); |
567 | if (action < 0 || !token[3][0]) /* token[3]: command */ |
568 | goto bad_entry; |
569 | /* turn .*TTY -> /dev/TTY */ |
570 | if (tty[0]) { |
571 | tty = concat_path_file("/dev/", skip_dev_pfx(tty)); |
572 | } |
573 | new_init_action(1 << action, token[3], tty); |
574 | if (tty[0]) |
575 | free(tty); |
576 | continue; |
577 | bad_entry: |
578 | message(L_LOG | L_CONSOLE, "Bad inittab entry at line %d", |
579 | parser->lineno); |
580 | } |
581 | config_close(parser); |
582 | #endif |
583 | } |
584 | |
585 | static void pause_and_low_level_reboot(unsigned magic) NORETURN; |
586 | static void pause_and_low_level_reboot(unsigned magic) |
587 | { |
588 | pid_t pid; |
589 | |
590 | /* Allow time for last message to reach serial console, etc */ |
591 | sleep(1); |
592 | |
593 | /* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS) |
594 | * in linux/kernel/sys.c, which can cause the machine to panic when |
595 | * the init process exits... */ |
596 | pid = vfork(); |
597 | if (pid == 0) { /* child */ |
598 | reboot(magic); |
599 | _exit(EXIT_SUCCESS); |
600 | } |
601 | while (1) |
602 | sleep(1); |
603 | } |
604 | |
605 | static void run_shutdown_and_kill_processes(void) |
606 | { |
607 | /* Run everything to be run at "shutdown". This is done _prior_ |
608 | * to killing everything, in case people wish to use scripts to |
609 | * shut things down gracefully... */ |
610 | run_actions(SHUTDOWN); |
611 | |
612 | message(L_CONSOLE | L_LOG, "The system is going down NOW!"); |
613 | |
614 | /* Send signals to every process _except_ pid 1 */ |
615 | kill(-1, SIGTERM); |
616 | message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM"); |
617 | sync(); |
618 | sleep(1); |
619 | |
620 | kill(-1, SIGKILL); |
621 | message(L_CONSOLE, "Sent SIG%s to all processes", "KILL"); |
622 | sync(); |
623 | /*sleep(1); - callers take care about making a pause */ |
624 | } |
625 | |
626 | /* Signal handling by init: |
627 | * |
628 | * For process with PID==1, on entry kernel sets all signals to SIG_DFL |
629 | * and unmasks all signals. However, for process with PID==1, |
630 | * default action (SIG_DFL) on any signal is to ignore it, |
631 | * even for special signals SIGKILL and SIGCONT. |
632 | * Also, any signal can be caught or blocked. |
633 | * (but SIGSTOP is still handled specially, at least in 2.6.20) |
634 | * |
635 | * We install two kinds of handlers, "immediate" and "delayed". |
636 | * |
637 | * Immediate handlers execute at any time, even while, say, sysinit |
638 | * is running. |
639 | * |
640 | * Delayed handlers just set a flag variable. The variable is checked |
641 | * in the main loop and acted upon. |
642 | * |
643 | * halt/poweroff/reboot and restart have immediate handlers. |
644 | * They only traverse linked list of struct action's, never modify it, |
645 | * this should be safe to do even in signal handler. Also they |
646 | * never return. |
647 | * |
648 | * SIGSTOP and SIGTSTP have immediate handlers. They just wait |
649 | * for SIGCONT to happen. |
650 | * |
651 | * SIGHUP has a delayed handler, because modifying linked list |
652 | * of struct action's from a signal handler while it is manipulated |
653 | * by the program may be disastrous. |
654 | * |
655 | * Ctrl-Alt-Del has a delayed handler. Not a must, but allowing |
656 | * it to happen even somewhere inside "sysinit" would be a bit awkward. |
657 | * |
658 | * There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide |
659 | * and only one will be remembered and acted upon. |
660 | */ |
661 | |
662 | /* The SIGUSR[12]/SIGTERM handler */ |
663 | static void halt_reboot_pwoff(int sig) NORETURN; |
664 | static void halt_reboot_pwoff(int sig) |
665 | { |
666 | const char *m; |
667 | unsigned rb; |
668 | |
669 | /* We may call run() and it unmasks signals, |
670 | * including the one masked inside this signal handler. |
671 | * Testcase which would start multiple reboot scripts: |
672 | * while true; do reboot; done |
673 | * Preventing it: |
674 | */ |
675 | reset_sighandlers_and_unblock_sigs(); |
676 | |
677 | run_shutdown_and_kill_processes(); |
678 | |
679 | m = "halt"; |
680 | rb = RB_HALT_SYSTEM; |
681 | if (sig == SIGTERM) { |
682 | m = "reboot"; |
683 | rb = RB_AUTOBOOT; |
684 | } else if (sig == SIGUSR2) { |
685 | m = "poweroff"; |
686 | rb = RB_POWER_OFF; |
687 | } |
688 | message(L_CONSOLE, "Requesting system %s", m); |
689 | pause_and_low_level_reboot(rb); |
690 | /* not reached */ |
691 | } |
692 | |
693 | /* Handler for QUIT - exec "restart" action, |
694 | * else (no such action defined) do nothing */ |
695 | static void restart_handler(int sig UNUSED_PARAM) |
696 | { |
697 | struct init_action *a; |
698 | |
699 | for (a = init_action_list; a; a = a->next) { |
700 | if (!(a->action_type & RESTART)) |
701 | continue; |
702 | |
703 | /* Starting from here, we won't return. |
704 | * Thus don't need to worry about preserving errno |
705 | * and such. |
706 | */ |
707 | |
708 | reset_sighandlers_and_unblock_sigs(); |
709 | |
710 | run_shutdown_and_kill_processes(); |
711 | |
712 | /* Allow Ctrl-Alt-Del to reboot the system. |
713 | * This is how kernel sets it up for init, we follow suit. |
714 | */ |
715 | reboot(RB_ENABLE_CAD); /* misnomer */ |
716 | |
717 | if (open_stdio_to_tty(a->terminal)) { |
718 | dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command); |
719 | /* Theoretically should be safe. |
720 | * But in practice, kernel bugs may leave |
721 | * unkillable processes, and wait() may block forever. |
722 | * Oh well. Hoping "new" init won't be too surprised |
723 | * by having children it didn't create. |
724 | */ |
725 | //while (wait(NULL) > 0) |
726 | // continue; |
727 | init_exec(a->command); |
728 | } |
729 | /* Open or exec failed */ |
730 | pause_and_low_level_reboot(RB_HALT_SYSTEM); |
731 | /* not reached */ |
732 | } |
733 | } |
734 | |
735 | /* The SIGSTOP/SIGTSTP handler |
736 | * NB: inside it, all signals except SIGCONT are masked |
737 | * via appropriate setup in sigaction(). |
738 | */ |
739 | static void stop_handler(int sig UNUSED_PARAM) |
740 | { |
741 | smallint saved_bb_got_signal; |
742 | int saved_errno; |
743 | |
744 | saved_bb_got_signal = bb_got_signal; |
745 | saved_errno = errno; |
746 | signal(SIGCONT, record_signo); |
747 | |
748 | while (1) { |
749 | pid_t wpid; |
750 | |
751 | if (bb_got_signal == SIGCONT) |
752 | break; |
753 | /* NB: this can accidentally wait() for a process |
754 | * which we waitfor() elsewhere! waitfor() must have |
755 | * code which is resilient against this. |
756 | */ |
757 | wpid = wait_any_nohang(NULL); |
758 | mark_terminated(wpid); |
759 | sleep(1); |
760 | } |
761 | |
762 | signal(SIGCONT, SIG_DFL); |
763 | errno = saved_errno; |
764 | bb_got_signal = saved_bb_got_signal; |
765 | } |
766 | |
767 | #if ENABLE_FEATURE_USE_INITTAB |
768 | static void reload_inittab(void) |
769 | { |
770 | struct init_action *a, **nextp; |
771 | |
772 | message(L_LOG, "reloading /etc/inittab"); |
773 | |
774 | /* Disable old entries */ |
775 | for (a = init_action_list; a; a = a->next) |
776 | a->action_type = 0; |
777 | |
778 | /* Append new entries, or modify existing entries |
779 | * (incl. setting a->action_type) if cmd and device name |
780 | * match new ones. End result: only entries with |
781 | * a->action_type == 0 are stale. |
782 | */ |
783 | parse_inittab(); |
784 | |
785 | #if ENABLE_FEATURE_KILL_REMOVED |
786 | /* Kill stale entries */ |
787 | /* Be nice and send SIGTERM first */ |
788 | for (a = init_action_list; a; a = a->next) |
789 | if (a->action_type == 0 && a->pid != 0) |
790 | kill(a->pid, SIGTERM); |
791 | if (CONFIG_FEATURE_KILL_DELAY) { |
792 | /* NB: parent will wait in NOMMU case */ |
793 | if ((BB_MMU ? fork() : vfork()) == 0) { /* child */ |
794 | sleep(CONFIG_FEATURE_KILL_DELAY); |
795 | for (a = init_action_list; a; a = a->next) |
796 | if (a->action_type == 0 && a->pid != 0) |
797 | kill(a->pid, SIGKILL); |
798 | _exit(EXIT_SUCCESS); |
799 | } |
800 | } |
801 | #endif |
802 | |
803 | /* Remove stale entries and SYSINIT entries. |
804 | * We never rerun SYSINIT entries anyway, |
805 | * removing them too saves a few bytes */ |
806 | nextp = &init_action_list; |
807 | while ((a = *nextp) != NULL) { |
808 | if ((a->action_type & ~SYSINIT) == 0) { |
809 | *nextp = a->next; |
810 | free(a); |
811 | } else { |
812 | nextp = &a->next; |
813 | } |
814 | } |
815 | |
816 | /* Not needed: */ |
817 | /* run_actions(RESPAWN | ASKFIRST); */ |
818 | /* - we return to main loop, which does this automagically */ |
819 | } |
820 | #endif |
821 | |
822 | static int check_delayed_sigs(void) |
823 | { |
824 | int sigs_seen = 0; |
825 | |
826 | while (1) { |
827 | smallint sig = bb_got_signal; |
828 | |
829 | if (!sig) |
830 | return sigs_seen; |
831 | bb_got_signal = 0; |
832 | sigs_seen = 1; |
833 | #if ENABLE_FEATURE_USE_INITTAB |
834 | if (sig == SIGHUP) |
835 | reload_inittab(); |
836 | #endif |
837 | if (sig == SIGINT) |
838 | run_actions(CTRLALTDEL); |
839 | } |
840 | } |
841 | |
842 | int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
843 | int init_main(int argc UNUSED_PARAM, char **argv) |
844 | { |
845 | die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */ |
846 | |
847 | if (argv[1] && strcmp(argv[1], "-q") == 0) { |
848 | return kill(1, SIGHUP); |
849 | } |
850 | |
851 | if (!DEBUG_INIT) { |
852 | /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */ |
853 | if (getpid() != 1 |
854 | && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc")) |
855 | ) { |
856 | bb_show_usage(); |
857 | } |
858 | /* Turn off rebooting via CTL-ALT-DEL - we get a |
859 | * SIGINT on CAD so we can shut things down gracefully... */ |
860 | reboot(RB_DISABLE_CAD); /* misnomer */ |
861 | } |
862 | |
863 | /* Figure out where the default console should be */ |
864 | console_init(); |
865 | set_sane_term(); |
866 | xchdir("/"); |
867 | setsid(); |
868 | |
869 | /* Make sure environs is set to something sane */ |
870 | putenv((char *) "HOME=/"); |
871 | putenv((char *) bb_PATH_root_path); |
872 | putenv((char *) "SHELL=/bin/sh"); |
873 | putenv((char *) "USER=root"); /* needed? why? */ |
874 | |
875 | if (argv[1]) |
876 | xsetenv("RUNLEVEL", argv[1]); |
877 | |
878 | #if !ENABLE_FEATURE_EXTRA_QUIET |
879 | /* Hello world */ |
880 | message(L_CONSOLE | L_LOG, "init started: %s", bb_banner); |
881 | #endif |
882 | |
883 | /* Make sure there is enough memory to do something useful. */ |
884 | if (ENABLE_SWAPONOFF) { |
885 | struct sysinfo info; |
886 | |
887 | if (sysinfo(&info) == 0 |
888 | && (info.mem_unit ? info.mem_unit : 1) * (long long)info.totalram < 1024*1024 |
889 | ) { |
890 | message(L_CONSOLE, "Low memory, forcing swapon"); |
891 | /* swapon -a requires /proc typically */ |
892 | new_init_action(SYSINIT, "mount -t proc proc /proc", ""); |
893 | /* Try to turn on swap */ |
894 | new_init_action(SYSINIT, "swapon -a", ""); |
895 | run_actions(SYSINIT); /* wait and removing */ |
896 | } |
897 | } |
898 | |
899 | /* Check if we are supposed to be in single user mode */ |
900 | if (argv[1] |
901 | && (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 || LONE_CHAR(argv[1], '1')) |
902 | ) { |
903 | /* ??? shouldn't we set RUNLEVEL="b" here? */ |
904 | /* Start a shell on console */ |
905 | new_init_action(RESPAWN, bb_default_login_shell, ""); |
906 | } else { |
907 | /* Not in single user mode - see what inittab says */ |
908 | |
909 | /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined, |
910 | * then parse_inittab() simply adds in some default |
911 | * actions(i.e., INIT_SCRIPT and a pair |
912 | * of "askfirst" shells */ |
913 | parse_inittab(); |
914 | } |
915 | |
916 | #if ENABLE_SELINUX |
917 | if (getenv("SELINUX_INIT") == NULL) { |
918 | int enforce = 0; |
919 | |
920 | putenv((char*)"SELINUX_INIT=YES"); |
921 | if (selinux_init_load_policy(&enforce) == 0) { |
922 | BB_EXECVP(argv[0], argv); |
923 | } else if (enforce > 0) { |
924 | /* SELinux in enforcing mode but load_policy failed */ |
925 | message(L_CONSOLE, "can't load SELinux Policy. " |
926 | "Machine is in enforcing mode. Halting now."); |
927 | exit(EXIT_FAILURE); |
928 | } |
929 | } |
930 | #endif |
931 | |
932 | /* Make the command line just say "init" - thats all, nothing else */ |
933 | strncpy(argv[0], "init", strlen(argv[0])); |
934 | /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */ |
935 | while (*++argv) |
936 | memset(*argv, 0, strlen(*argv)); |
937 | |
938 | /* Set up signal handlers */ |
939 | if (!DEBUG_INIT) { |
940 | struct sigaction sa; |
941 | |
942 | bb_signals(0 |
943 | + (1 << SIGUSR1) /* halt */ |
944 | + (1 << SIGTERM) /* reboot */ |
945 | + (1 << SIGUSR2) /* poweroff */ |
946 | , halt_reboot_pwoff); |
947 | signal(SIGQUIT, restart_handler); /* re-exec another init */ |
948 | |
949 | /* Stop handler must allow only SIGCONT inside itself */ |
950 | memset(&sa, 0, sizeof(sa)); |
951 | sigfillset(&sa.sa_mask); |
952 | sigdelset(&sa.sa_mask, SIGCONT); |
953 | sa.sa_handler = stop_handler; |
954 | /* NB: sa_flags doesn't have SA_RESTART. |
955 | * It must be able to interrupt wait(). |
956 | */ |
957 | sigaction_set(SIGTSTP, &sa); /* pause */ |
958 | /* Does not work as intended, at least in 2.6.20. |
959 | * SIGSTOP is simply ignored by init: |
960 | */ |
961 | sigaction_set(SIGSTOP, &sa); /* pause */ |
962 | |
963 | /* SIGINT (Ctrl-Alt-Del) must interrupt wait(), |
964 | * setting handler without SA_RESTART flag. |
965 | */ |
966 | bb_signals_recursive_norestart((1 << SIGINT), record_signo); |
967 | } |
968 | |
969 | /* Set up "reread /etc/inittab" handler. |
970 | * Handler is set up without SA_RESTART, it will interrupt syscalls. |
971 | */ |
972 | if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB) |
973 | bb_signals_recursive_norestart((1 << SIGHUP), record_signo); |
974 | |
975 | /* Now run everything that needs to be run */ |
976 | /* First run the sysinit command */ |
977 | run_actions(SYSINIT); |
978 | check_delayed_sigs(); |
979 | /* Next run anything that wants to block */ |
980 | run_actions(WAIT); |
981 | check_delayed_sigs(); |
982 | /* Next run anything to be run only once */ |
983 | run_actions(ONCE); |
984 | |
985 | /* Now run the looping stuff for the rest of forever. |
986 | */ |
987 | while (1) { |
988 | int maybe_WNOHANG; |
989 | |
990 | maybe_WNOHANG = check_delayed_sigs(); |
991 | |
992 | /* (Re)run the respawn/askfirst stuff */ |
993 | run_actions(RESPAWN | ASKFIRST); |
994 | maybe_WNOHANG |= check_delayed_sigs(); |
995 | |
996 | /* Don't consume all CPU time - sleep a bit */ |
997 | sleep(1); |
998 | maybe_WNOHANG |= check_delayed_sigs(); |
999 | |
1000 | /* Wait for any child process(es) to exit. |
1001 | * |
1002 | * If check_delayed_sigs above reported that a signal |
1003 | * was caught, wait will be nonblocking. This ensures |
1004 | * that if SIGHUP has reloaded inittab, respawn and askfirst |
1005 | * actions will not be delayed until next child death. |
1006 | */ |
1007 | if (maybe_WNOHANG) |
1008 | maybe_WNOHANG = WNOHANG; |
1009 | while (1) { |
1010 | pid_t wpid; |
1011 | struct init_action *a; |
1012 | |
1013 | /* If signals happen _in_ the wait, they interrupt it, |
1014 | * bb_signals_recursive_norestart set them up that way |
1015 | */ |
1016 | wpid = waitpid(-1, NULL, maybe_WNOHANG); |
1017 | if (wpid <= 0) |
1018 | break; |
1019 | |
1020 | a = mark_terminated(wpid); |
1021 | if (a) { |
1022 | message(L_LOG, "process '%s' (pid %d) exited. " |
1023 | "Scheduling for restart.", |
1024 | a->command, wpid); |
1025 | } |
1026 | /* See if anyone else is waiting to be reaped */ |
1027 | maybe_WNOHANG = WNOHANG; |
1028 | } |
1029 | } /* while (1) */ |
1030 | } |