1 /* vi: set sw=4 ts=4: */
3 * Mini init implementation for busybox
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.
9 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
15 #include <sys/reboot.h>
16 #include <sys/resource.h>
18 #if ENABLE_FEATURE_UTMP
19 # include <utmp.h> /* DEAD_PROCESS */
23 /* Was a CONFIG_xxx option. A lot of people were building
24 * not fully functional init by switching it on! */
27 #define COMMAND_SIZE 256
28 #define CONSOLE_NAME_SIZE 32
30 /* Default sysinit script. */
32 #define INIT_SCRIPT "/etc/init.d/rcS"
35 /* Each type of actions can appear many times. They will be
36 * handled in order. RESTART is an exception, only 1st is used.
38 /* Start these actions first and wait for completion */
40 /* Start these after SYSINIT and wait for completion */
42 /* Start these after WAIT and *dont* wait for completion */
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".
50 /* Start these after ONCE are started, restart on exit */
52 /* Like RESPAWN, but wait for <Enter> to be pressed on tty */
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.
59 #define CTRLALTDEL 0x20
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.
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.
76 /* A linked list of init_actions, to be read from inittab */
78 struct init_action *next;
81 char terminal[CONSOLE_NAME_SIZE];
82 char command[COMMAND_SIZE];
85 static struct init_action *init_action_list = NULL;
87 static const char *log_console = VC_5;
92 #ifndef RB_HALT_SYSTEM
93 RB_HALT_SYSTEM = 0xcdef0123, /* FIXME: this overflows enum */
94 RB_ENABLE_CAD = 0x89abcdef,
96 RB_POWER_OFF = 0x4321fedc,
97 RB_AUTOBOOT = 0x01234567,
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!
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, ...)
115 va_start(arguments, fmt);
116 l = 1 + vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
117 if (l > sizeof(msg) - 1)
121 #if ENABLE_FEATURE_INIT_SYSLOG
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);
134 static int log_fd = -1;
138 /* Take full control of the log tty, and never close it.
139 * It's mine, all mine! Muhahahaha! */
142 log_fd = STDERR_FILENO;
144 log_fd = device_open(log_console, O_WRONLY | O_NONBLOCK | O_NOCTTY);
146 bb_error_msg("can't log to %s", log_console);
149 close_on_exec_on(log_fd);
154 full_write(log_fd, msg, l);
155 if (log_fd == STDERR_FILENO)
156 return; /* don't print dup messages */
161 if (where & L_CONSOLE) {
162 /* Send console messages to console so people will see them. */
163 full_write(STDERR_FILENO, msg, l);
167 static void console_init(void)
172 s = getenv("CONSOLE");
174 s = getenv("console");
176 int fd = open(s, O_RDWR | O_NONBLOCK | O_NOCTTY);
178 dup2(fd, STDIN_FILENO);
179 dup2(fd, STDOUT_FILENO);
180 xmove_fd(fd, STDERR_FILENO);
182 dbg_message(L_LOG, "console='%s'", s);
184 /* Make sure fd 0,1,2 are not closed
185 * (so that they won't be used by future opens) */
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);
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)
202 putenv((char*)"TERM=linux");
205 /* Set terminal settings to reasonable defaults.
206 * NB: careful, we can be called after vfork! */
207 static void set_sane_term(void)
211 tcgetattr(STDIN_FILENO, &tty);
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 */
223 /* use line discipline 0 */
226 /* Make it be sane */
227 tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD;
228 tty.c_cflag |= CREAD | HUPCL | CLOCAL;
231 tty.c_iflag = ICRNL | IXON | IXOFF;
234 tty.c_oflag = OPOST | ONLCR;
238 ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
240 tcsetattr_stdin_TCSANOW(&tty);
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)
247 /* empty tty_name means "use init's tty", else... */
252 /* fd can be only < 0 or 0: */
253 fd = device_open(tty_name, O_RDWR);
255 message(L_LOG | L_CONSOLE, "can't open %s: %s",
256 tty_name, strerror(errno));
257 return 0; /* failure */
259 dup2(STDIN_FILENO, STDOUT_FILENO);
260 dup2(STDIN_FILENO, STDERR_FILENO);
263 return 1; /* success */
266 static void reset_sighandlers_and_unblock_sigs(void)
278 sigprocmask_allsigs(SIG_UNBLOCK);
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!
288 static void init_exec(const char *command)
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] == '/' */);
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";
304 /* Convert command (char*) into cmd (char**, one word per string) */
307 next = strcpy(buf, command); /* including "-" */
308 while ((word = strsep(&next, " \t")) != NULL) {
309 if (*word != '\0') { /* not two spaces/tabs together? */
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. */
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*/);
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 */
329 /* Used only by run_actions */
330 static pid_t run(const struct init_action *a)
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))
341 message(L_LOG | L_CONSOLE, "can't fork");
343 sigprocmask_allsigs(SIG_UNBLOCK);
344 return pid; /* Parent or error */
349 /* Reset signal handlers that were set by the parent process */
350 reset_sighandlers_and_unblock_sigs();
352 /* Create a new session and make ourself the process group leader */
355 /* Open the new terminal device */
356 if (!open_stdio_to_tty(a->terminal))
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
366 "\nPlease press Enter to activate this console. ";
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
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')
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....
390 if (ENABLE_FEATURE_INIT_COREDUMPS) {
391 if (access("/.init_enable_core", F_OK) == 0) {
393 limit.rlim_cur = RLIM_INFINITY;
394 limit.rlim_max = RLIM_INFINITY;
395 setrlimit(RLIMIT_CORE, &limit);
399 /* Log the process name and args */
400 message(L_LOG, "starting pid %d, tty '%s': '%s'",
401 getpid(), a->terminal, a->command);
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. */
410 static struct init_action *mark_terminated(pid_t pid)
412 struct init_action *a;
415 for (a = init_action_list; a; a = a->next) {
421 update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
426 static void waitfor(pid_t pid)
428 /* waitfor(run(x)): protect against failed fork inside run() */
432 /* Wait for any child (prevent zombies from exiting orphaned processes)
433 * but exit the loop only when specified one has exited. */
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;*/
445 /* Run all commands of a particular type */
446 static void run_actions(int action_type)
448 struct init_action *a;
450 for (a = init_action_list; a; a = a->next) {
451 if (!(a->action_type & action_type))
454 if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) {
456 if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN))
459 if (a->action_type & (RESPAWN | ASKFIRST)) {
460 /* Only run stuff with pid == 0. If pid != 0,
461 * it is already running
469 static void new_init_action(uint8_t action_type, const char *command, const char *cons)
471 struct init_action *a, **nextp;
475 * ::shutdown:umount -a -r
476 * ::shutdown:swapoff -a
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
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.
489 if (strcmp(a->command, command) == 0
490 && strcmp(a->terminal, cons) == 0
492 /* Remove from list */
494 /* Find the end of the list */
495 while (*nextp != NULL)
496 nextp = &(*nextp)->next;
504 a = xzalloc(sizeof(*a));
505 /* Append to the end of the list */
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);
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.
521 static void parse_inittab(void)
523 #if ENABLE_FEATURE_USE_INITTAB
525 parser_t *parser = config_open2("/etc/inittab", fopen_for_read);
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);
547 new_init_action(SYSINIT, INIT_SCRIPT, "");
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
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";
562 char *tty = token[0];
564 if (!token[3]) /* less than 4 tokens */
566 action = index_in_strings(actions, token[2]);
567 if (action < 0 || !token[3][0]) /* token[3]: command */
569 /* turn .*TTY -> /dev/TTY */
571 if (strncmp(tty, "/dev/", 5) == 0)
573 tty = concat_path_file("/dev/", tty);
575 new_init_action(1 << action, token[3], tty);
580 message(L_LOG | L_CONSOLE, "Bad inittab entry at line %d",
583 config_close(parser);
587 static void pause_and_low_level_reboot(unsigned magic) NORETURN;
588 static void pause_and_low_level_reboot(unsigned magic)
592 /* Allow time for last message to reach serial console, etc */
595 /* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
596 * in linux/kernel/sys.c, which can cause the machine to panic when
597 * the init process exits... */
599 if (pid == 0) { /* child */
607 static void run_shutdown_and_kill_processes(void)
609 /* Run everything to be run at "shutdown". This is done _prior_
610 * to killing everything, in case people wish to use scripts to
611 * shut things down gracefully... */
612 run_actions(SHUTDOWN);
614 message(L_CONSOLE | L_LOG, "The system is going down NOW!");
616 /* Send signals to every process _except_ pid 1 */
618 message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM");
623 message(L_CONSOLE, "Sent SIG%s to all processes", "KILL");
625 /*sleep(1); - callers take care about making a pause */
628 /* Signal handling by init:
630 * For process with PID==1, on entry kernel sets all signals to SIG_DFL
631 * and unmasks all signals. However, for process with PID==1,
632 * default action (SIG_DFL) on any signal is to ignore it,
633 * even for special signals SIGKILL and SIGCONT.
634 * Also, any signal can be caught or blocked.
635 * (but SIGSTOP is still handled specially, at least in 2.6.20)
637 * We install two kinds of handlers, "immediate" and "delayed".
639 * Immediate handlers execute at any time, even while, say, sysinit
642 * Delayed handlers just set a flag variable. The variable is checked
643 * in the main loop and acted upon.
645 * halt/poweroff/reboot and restart have immediate handlers.
646 * They only traverse linked list of struct action's, never modify it,
647 * this should be safe to do even in signal handler. Also they
650 * SIGSTOP and SIGTSTP have immediate handlers. They just wait
651 * for SIGCONT to happen.
653 * SIGHUP has a delayed handler, because modifying linked list
654 * of struct action's from a signal handler while it is manipulated
655 * by the program may be disastrous.
657 * Ctrl-Alt-Del has a delayed handler. Not a must, but allowing
658 * it to happen even somewhere inside "sysinit" would be a bit awkward.
660 * There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide
661 * and only one will be remembered and acted upon.
664 /* The SIGUSR[12]/SIGTERM handler */
665 static void halt_reboot_pwoff(int sig) NORETURN;
666 static void halt_reboot_pwoff(int sig)
671 /* We may call run() and it unmasks signals,
672 * including the one masked inside this signal handler.
673 * Testcase which would start multiple reboot scripts:
674 * while true; do reboot; done
677 reset_sighandlers_and_unblock_sigs();
679 run_shutdown_and_kill_processes();
683 if (sig == SIGTERM) {
686 } else if (sig == SIGUSR2) {
690 message(L_CONSOLE, "Requesting system %s", m);
691 pause_and_low_level_reboot(rb);
695 /* Handler for QUIT - exec "restart" action,
696 * else (no such action defined) do nothing */
697 static void restart_handler(int sig UNUSED_PARAM)
699 struct init_action *a;
701 for (a = init_action_list; a; a = a->next) {
702 if (!(a->action_type & RESTART))
705 /* Starting from here, we won't return.
706 * Thus don't need to worry about preserving errno
710 reset_sighandlers_and_unblock_sigs();
712 run_shutdown_and_kill_processes();
714 /* Allow Ctrl-Alt-Del to reboot the system.
715 * This is how kernel sets it up for init, we follow suit.
717 reboot(RB_ENABLE_CAD); /* misnomer */
719 if (open_stdio_to_tty(a->terminal)) {
720 dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command);
721 /* Theoretically should be safe.
722 * But in practice, kernel bugs may leave
723 * unkillable processes, and wait() may block forever.
724 * Oh well. Hoping "new" init won't be too surprised
725 * by having children it didn't create.
727 //while (wait(NULL) > 0)
729 init_exec(a->command);
731 /* Open or exec failed */
732 pause_and_low_level_reboot(RB_HALT_SYSTEM);
737 /* The SIGSTOP/SIGTSTP handler
738 * NB: inside it, all signals except SIGCONT are masked
739 * via appropriate setup in sigaction().
741 static void stop_handler(int sig UNUSED_PARAM)
743 smallint saved_bb_got_signal;
746 saved_bb_got_signal = bb_got_signal;
748 signal(SIGCONT, record_signo);
753 if (bb_got_signal == SIGCONT)
755 /* NB: this can accidentally wait() for a process
756 * which we waitfor() elsewhere! waitfor() must have
757 * code which is resilient against this.
759 wpid = wait_any_nohang(NULL);
760 mark_terminated(wpid);
764 signal(SIGCONT, SIG_DFL);
766 bb_got_signal = saved_bb_got_signal;
769 #if ENABLE_FEATURE_USE_INITTAB
770 static void reload_inittab(void)
772 struct init_action *a, **nextp;
774 message(L_LOG, "reloading /etc/inittab");
776 /* Disable old entries */
777 for (a = init_action_list; a; a = a->next)
780 /* Append new entries, or modify existing entries
781 * (incl. setting a->action_type) if cmd and device name
782 * match new ones. End result: only entries with
783 * a->action_type == 0 are stale.
787 #if ENABLE_FEATURE_KILL_REMOVED
788 /* Kill stale entries */
789 /* Be nice and send SIGTERM first */
790 for (a = init_action_list; a; a = a->next)
791 if (a->action_type == 0 && a->pid != 0)
792 kill(a->pid, SIGTERM);
793 if (CONFIG_FEATURE_KILL_DELAY) {
794 /* NB: parent will wait in NOMMU case */
795 if ((BB_MMU ? fork() : vfork()) == 0) { /* child */
796 sleep(CONFIG_FEATURE_KILL_DELAY);
797 for (a = init_action_list; a; a = a->next)
798 if (a->action_type == 0 && a->pid != 0)
799 kill(a->pid, SIGKILL);
805 /* Remove stale entries and SYSINIT entries.
806 * We never rerun SYSINIT entries anyway,
807 * removing them too saves a few bytes */
808 nextp = &init_action_list;
809 while ((a = *nextp) != NULL) {
810 if ((a->action_type & ~SYSINIT) == 0) {
819 /* run_actions(RESPAWN | ASKFIRST); */
820 /* - we return to main loop, which does this automagically */
824 static int check_delayed_sigs(void)
829 smallint sig = bb_got_signal;
835 #if ENABLE_FEATURE_USE_INITTAB
840 run_actions(CTRLALTDEL);
844 int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
845 int init_main(int argc UNUSED_PARAM, char **argv)
847 die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */
849 if (argv[1] && strcmp(argv[1], "-q") == 0) {
850 return kill(1, SIGHUP);
854 /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
856 && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc"))
860 /* Turn off rebooting via CTL-ALT-DEL - we get a
861 * SIGINT on CAD so we can shut things down gracefully... */
862 reboot(RB_DISABLE_CAD); /* misnomer */
865 /* Figure out where the default console should be */
871 /* Make sure environs is set to something sane */
872 putenv((char *) "HOME=/");
873 putenv((char *) bb_PATH_root_path);
874 putenv((char *) "SHELL=/bin/sh");
875 putenv((char *) "USER=root"); /* needed? why? */
878 xsetenv("RUNLEVEL", argv[1]);
880 #if !ENABLE_FEATURE_EXTRA_QUIET
882 message(L_CONSOLE | L_LOG, "init started: %s", bb_banner);
885 /* Make sure there is enough memory to do something useful. */
886 if (ENABLE_SWAPONOFF) {
889 if (sysinfo(&info) == 0
890 && (info.mem_unit ? info.mem_unit : 1) * (long long)info.totalram < 1024*1024
892 message(L_CONSOLE, "Low memory, forcing swapon");
893 /* swapon -a requires /proc typically */
894 new_init_action(SYSINIT, "mount -t proc proc /proc", "");
895 /* Try to turn on swap */
896 new_init_action(SYSINIT, "swapon -a", "");
897 run_actions(SYSINIT); /* wait and removing */
901 /* Check if we are supposed to be in single user mode */
903 && (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 || LONE_CHAR(argv[1], '1'))
905 /* ??? shouldn't we set RUNLEVEL="b" here? */
906 /* Start a shell on console */
907 new_init_action(RESPAWN, bb_default_login_shell, "");
909 /* Not in single user mode - see what inittab says */
911 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
912 * then parse_inittab() simply adds in some default
913 * actions(i.e., INIT_SCRIPT and a pair
914 * of "askfirst" shells */
919 if (getenv("SELINUX_INIT") == NULL) {
922 putenv((char*)"SELINUX_INIT=YES");
923 if (selinux_init_load_policy(&enforce) == 0) {
924 BB_EXECVP(argv[0], argv);
925 } else if (enforce > 0) {
926 /* SELinux in enforcing mode but load_policy failed */
927 message(L_CONSOLE, "can't load SELinux Policy. "
928 "Machine is in enforcing mode. Halting now.");
934 /* Make the command line just say "init" - thats all, nothing else */
935 strncpy(argv[0], "init", strlen(argv[0]));
936 /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
938 memset(*argv, 0, strlen(*argv));
940 /* Set up signal handlers */
945 + (1 << SIGUSR1) /* halt */
946 + (1 << SIGTERM) /* reboot */
947 + (1 << SIGUSR2) /* poweroff */
948 , halt_reboot_pwoff);
949 signal(SIGQUIT, restart_handler); /* re-exec another init */
951 /* Stop handler must allow only SIGCONT inside itself */
952 memset(&sa, 0, sizeof(sa));
953 sigfillset(&sa.sa_mask);
954 sigdelset(&sa.sa_mask, SIGCONT);
955 sa.sa_handler = stop_handler;
956 /* NB: sa_flags doesn't have SA_RESTART.
957 * It must be able to interrupt wait().
959 sigaction_set(SIGTSTP, &sa); /* pause */
960 /* Does not work as intended, at least in 2.6.20.
961 * SIGSTOP is simply ignored by init:
963 sigaction_set(SIGSTOP, &sa); /* pause */
965 /* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
966 * setting handler without SA_RESTART flag.
968 bb_signals_recursive_norestart((1 << SIGINT), record_signo);
971 /* Set up "reread /etc/inittab" handler.
972 * Handler is set up without SA_RESTART, it will interrupt syscalls.
974 if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
975 bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
977 /* Now run everything that needs to be run */
978 /* First run the sysinit command */
979 run_actions(SYSINIT);
980 check_delayed_sigs();
981 /* Next run anything that wants to block */
983 check_delayed_sigs();
984 /* Next run anything to be run only once */
987 /* Now run the looping stuff for the rest of forever.
992 maybe_WNOHANG = check_delayed_sigs();
994 /* (Re)run the respawn/askfirst stuff */
995 run_actions(RESPAWN | ASKFIRST);
996 maybe_WNOHANG |= check_delayed_sigs();
998 /* Don't consume all CPU time - sleep a bit */
1000 maybe_WNOHANG |= check_delayed_sigs();
1002 /* Wait for any child process(es) to exit.
1004 * If check_delayed_sigs above reported that a signal
1005 * was caught, wait will be nonblocking. This ensures
1006 * that if SIGHUP has reloaded inittab, respawn and askfirst
1007 * actions will not be delayed until next child death.
1010 maybe_WNOHANG = WNOHANG;
1013 struct init_action *a;
1015 /* If signals happen _in_ the wait, they interrupt it,
1016 * bb_signals_recursive_norestart set them up that way
1018 wpid = waitpid(-1, NULL, maybe_WNOHANG);
1022 a = mark_terminated(wpid);
1024 message(L_LOG, "process '%s' (pid %d) exited. "
1025 "Scheduling for restart.",
1028 /* See if anyone else is waiting to be reaped */
1029 maybe_WNOHANG = WNOHANG;