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>
19 /* Was a CONFIG_xxx option. A lot of people were building
20 * not fully functional init by switching it on! */
23 #define COMMAND_SIZE 256
24 #define CONSOLE_NAME_SIZE 32
26 /* Default sysinit script. */
28 #define INIT_SCRIPT "/etc/init.d/rcS"
31 /* Each type of actions can appear many times. They will be
32 * handled in order. RESTART is an exception, only 1st is used.
34 /* Start these actions first and wait for completion */
36 /* Start these after SYSINIT and wait for completion */
38 /* Start these after WAIT and *dont* wait for completion */
41 * NB: while SYSINIT/WAIT/ONCE are being processed,
42 * SIGHUP ("reread /etc/inittab") will be ignored.
43 * Rationale: it would be ambiguous whether SYSINIT/WAIT/ONCE
44 * need to be rerun or not.
46 /* Start these after ONCE are started, restart on exit */
48 /* Like RESPAWN, but wait for <Enter> to be pressed on tty */
51 * Start these on SIGINT, and wait for completion.
52 * Then go back to respawning RESPAWN and ASKFIRST actions.
53 * NB: kernel sends SIGINT to us if Ctrl-Alt-Del was pressed.
55 #define CTRLALTDEL 0x20
57 * Start these before killing all processes in preparation for
58 * running RESTART actions or doing low-level halt/reboot/poweroff
59 * (initiated by SIGUSR1/SIGTERM/SIGUSR2).
60 * Wait for completion before proceeding.
64 * exec() on SIGQUIT. SHUTDOWN actions are started and waited for,
65 * then all processes are killed, then init exec's 1st RESTART action,
66 * replacing itself by it. If no RESTART action specified,
67 * SIGQUIT has no effect.
72 /* A linked list of init_actions, to be read from inittab */
74 struct init_action *next;
77 char terminal[CONSOLE_NAME_SIZE];
78 char command[COMMAND_SIZE];
81 static struct init_action *init_action_list = NULL;
83 static const char *log_console = VC_5;
88 MAYBE_CONSOLE = L_CONSOLE * !ENABLE_FEATURE_EXTRA_QUIET,
89 #ifndef RB_HALT_SYSTEM
90 RB_HALT_SYSTEM = 0xcdef0123, /* FIXME: this overflows enum */
91 RB_ENABLE_CAD = 0x89abcdef,
93 RB_POWER_OFF = 0x4321fedc,
94 RB_AUTOBOOT = 0x01234567,
98 /* Print a message to the specified device.
99 * "where" may be bitwise-or'd from L_LOG | L_CONSOLE
100 * NB: careful, we can be called after vfork!
102 #define dbg_message(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0)
103 static void message(int where, const char *fmt, ...)
104 __attribute__ ((format(printf, 2, 3)));
105 static void message(int where, const char *fmt, ...)
112 va_start(arguments, fmt);
113 l = 1 + vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
114 if (l > sizeof(msg) - 1)
118 #if ENABLE_FEATURE_INIT_SYSLOG
121 /* Log the message to syslogd */
122 openlog("init", 0, LOG_DAEMON);
123 /* don't print "\r" */
124 syslog(LOG_INFO, "%s", msg + 1);
131 static int log_fd = -1;
135 /* Take full control of the log tty, and never close it.
136 * It's mine, all mine! Muhahahaha! */
139 log_fd = STDERR_FILENO;
141 log_fd = device_open(log_console, O_WRONLY | O_NONBLOCK | O_NOCTTY);
143 bb_error_msg("can't log to %s", log_console);
146 close_on_exec_on(log_fd);
151 full_write(log_fd, msg, l);
152 if (log_fd == STDERR_FILENO)
153 return; /* don't print dup messages */
158 if (where & L_CONSOLE) {
159 /* Send console messages to console so people will see them. */
160 full_write(STDERR_FILENO, msg, l);
164 /* From <linux/serial.h> */
165 struct serial_struct {
174 unsigned short close_delay;
176 char reserved_char[1];
178 unsigned short closing_wait; /* time to wait before closing */
179 unsigned short closing_wait2; /* no longer used... */
180 unsigned char *iomem_base;
181 unsigned short iomem_reg_shift;
182 unsigned int port_high;
183 unsigned long iomap_base; /* cookie passed into ioremap */
185 /* Paranoia (imagine 64bit kernel overwriting 32bit userspace stack) */
186 uint32_t bbox_reserved[16];
188 static void console_init(void)
190 struct serial_struct sr;
193 s = getenv("CONSOLE");
195 s = getenv("console");
197 int fd = open(s, O_RDWR | O_NONBLOCK | O_NOCTTY);
199 dup2(fd, STDIN_FILENO);
200 dup2(fd, STDOUT_FILENO);
201 xmove_fd(fd, STDERR_FILENO);
203 dbg_message(L_LOG, "console='%s'", s);
205 /* Make sure fd 0,1,2 are not closed
206 * (so that they won't be used by future opens) */
208 // Users report problems
209 // /* Make sure init can't be blocked by writing to stderr */
210 // fcntl(STDERR_FILENO, F_SETFL, fcntl(STDERR_FILENO, F_GETFL) | O_NONBLOCK);
214 if (ioctl(STDIN_FILENO, TIOCGSERIAL, &sr) == 0) {
215 /* Force the TERM setting to vt102 for serial console
216 * if TERM is set to linux (the default) */
217 if (!s || strcmp(s, "linux") == 0)
218 putenv((char*)"TERM=vt102");
219 if (!ENABLE_FEATURE_INIT_SYSLOG)
222 putenv((char*)"TERM=linux");
225 /* Set terminal settings to reasonable defaults.
226 * NB: careful, we can be called after vfork! */
227 static void set_sane_term(void)
231 tcgetattr(STDIN_FILENO, &tty);
233 /* set control chars */
234 tty.c_cc[VINTR] = 3; /* C-c */
235 tty.c_cc[VQUIT] = 28; /* C-\ */
236 tty.c_cc[VERASE] = 127; /* C-? */
237 tty.c_cc[VKILL] = 21; /* C-u */
238 tty.c_cc[VEOF] = 4; /* C-d */
239 tty.c_cc[VSTART] = 17; /* C-q */
240 tty.c_cc[VSTOP] = 19; /* C-s */
241 tty.c_cc[VSUSP] = 26; /* C-z */
243 /* use line discipline 0 */
246 /* Make it be sane */
247 tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD;
248 tty.c_cflag |= CREAD | HUPCL | CLOCAL;
251 tty.c_iflag = ICRNL | IXON | IXOFF;
254 tty.c_oflag = OPOST | ONLCR;
258 ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
260 tcsetattr_stdin_TCSANOW(&tty);
263 /* Open the new terminal device.
264 * NB: careful, we can be called after vfork! */
265 static int open_stdio_to_tty(const char* tty_name)
267 /* empty tty_name means "use init's tty", else... */
272 /* fd can be only < 0 or 0: */
273 fd = device_open(tty_name, O_RDWR);
275 message(L_LOG | L_CONSOLE, "can't open %s: %s",
276 tty_name, strerror(errno));
277 return 0; /* failure */
279 dup2(STDIN_FILENO, STDOUT_FILENO);
280 dup2(STDIN_FILENO, STDERR_FILENO);
283 return 1; /* success */
286 /* Wrapper around exec:
287 * Takes string (max COMMAND_SIZE chars).
288 * If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'.
289 * Otherwise splits words on whitespace, deals with leading dash,
290 * and uses plain exec().
291 * NB: careful, we can be called after vfork!
293 static void init_exec(const char *command)
295 char *cmd[COMMAND_SIZE / 2];
296 char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */
297 int dash = (command[0] == '-' /* maybe? && command[1] == '/' */);
299 /* See if any special /bin/sh requiring characters are present */
300 if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
301 strcpy(buf, "exec ");
302 strcpy(buf + 5, command + dash); /* excluding "-" */
303 /* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */
304 cmd[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL + !dash);
305 cmd[1] = (char*)"-c";
309 /* Convert command (char*) into cmd (char**, one word per string) */
312 next = strcpy(buf, command); /* including "-" */
313 while ((word = strsep(&next, " \t")) != NULL) {
314 if (*word != '\0') { /* not two spaces/tabs together? */
321 /* If we saw leading "-", it is interactive shell.
322 * Try harder to give it a controlling tty.
323 * And skip "-" in actual exec call. */
325 /* _Attempt_ to make stdin a controlling tty. */
326 if (ENABLE_FEATURE_INIT_SCTTY)
327 ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/);
329 BB_EXECVP(cmd[0] + dash, cmd);
330 message(L_LOG | L_CONSOLE, "cannot run '%s': %s", cmd[0], strerror(errno));
331 /* returns if execvp fails */
334 /* Used only by run_actions */
335 static pid_t run(const struct init_action *a)
339 /* Careful: don't be affected by a signal in vforked child */
340 sigprocmask_allsigs(SIG_BLOCK);
341 if (BB_MMU && (a->action_type & ASKFIRST))
346 message(L_LOG | L_CONSOLE, "can't fork");
348 sigprocmask_allsigs(SIG_UNBLOCK);
349 return pid; /* Parent or error */
354 /* Reset signal handlers that were set by the parent process */
364 sigprocmask_allsigs(SIG_UNBLOCK);
366 /* Create a new session and make ourself the process group leader */
369 /* Open the new terminal device */
370 if (!open_stdio_to_tty(a->terminal))
373 /* NB: on NOMMU we can't wait for input in child, so
374 * "askfirst" will work the same as "respawn". */
375 if (BB_MMU && (a->action_type & ASKFIRST)) {
376 static const char press_enter[] ALIGN1 =
377 #ifdef CUSTOMIZED_BANNER
378 #include CUSTOMIZED_BANNER
380 "\nPlease press Enter to activate this console. ";
383 * Save memory by not exec-ing anything large (like a shell)
384 * before the user wants it. This is critical if swap is not
385 * enabled and the system has low memory. Generally this will
386 * be run on the second virtual console, and the first will
387 * be allowed to start a shell or whatever an init script
390 dbg_message(L_LOG, "waiting for enter to start '%s'"
391 "(pid %d, tty '%s')\n",
392 a->command, getpid(), a->terminal);
393 full_write(STDOUT_FILENO, press_enter, sizeof(press_enter) - 1);
394 while (safe_read(STDIN_FILENO, &c, 1) == 1 && c != '\n')
399 * When a file named /.init_enable_core exists, setrlimit is called
400 * before processes are spawned to set core file size as unlimited.
401 * This is for debugging only. Don't use this is production, unless
402 * you want core dumps lying about....
404 if (ENABLE_FEATURE_INIT_COREDUMPS) {
405 if (access("/.init_enable_core", F_OK) == 0) {
407 limit.rlim_cur = RLIM_INFINITY;
408 limit.rlim_max = RLIM_INFINITY;
409 setrlimit(RLIMIT_CORE, &limit);
413 /* Log the process name and args */
414 message(L_LOG, "starting pid %d, tty '%s': '%s'",
415 getpid(), a->terminal, a->command);
417 /* Now run it. The new program will take over this PID,
418 * so nothing further in init.c should be run. */
419 init_exec(a->command);
420 /* We're still here? Some error happened. */
424 static struct init_action *mark_terminated(pid_t pid)
426 struct init_action *a;
429 for (a = init_action_list; a; a = a->next) {
439 static void waitfor(pid_t pid)
441 /* waitfor(run(x)): protect against failed fork inside run() */
445 /* Wait for any child (prevent zombies from exiting orphaned processes)
446 * but exit the loop only when specified one has exited. */
448 pid_t wpid = wait(NULL);
449 mark_terminated(wpid);
450 /* Unsafe. SIGTSTP handler might have wait'ed it already */
451 /*if (wpid == pid) break;*/
458 /* Run all commands of a particular type */
459 static void run_actions(int action_type)
461 struct init_action *a;
463 for (a = init_action_list; a; a = a->next) {
464 if (!(a->action_type & action_type))
467 if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) {
469 if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN))
472 if (a->action_type & (RESPAWN | ASKFIRST)) {
473 /* Only run stuff with pid == 0. If pid != 0,
474 * it is already running
482 static void new_init_action(uint8_t action_type, const char *command, const char *cons)
484 struct init_action *a, **nextp;
488 * ::shutdown:umount -a -r
489 * ::shutdown:swapoff -a
491 * ::shutdown:swapoff -a
492 * ::shutdown:umount -a -r
493 * On reload, we must ensure entries end up in correct order.
494 * To achieve that, if we find a matching entry, we move it
497 nextp = &init_action_list;
498 while ((a = *nextp) != NULL) {
499 /* Don't enter action if it's already in the list,
500 * This prevents losing running RESPAWNs.
502 if ((strcmp(a->command, command) == 0)
503 && (strcmp(a->terminal, cons) == 0)
505 /* Remove from list */
507 /* Find the end of the list */
508 while (*nextp != NULL)
509 nextp = &(*nextp)->next;
517 a = xzalloc(sizeof(*a));
518 /* Append to the end of the list */
520 a->action_type = action_type;
521 safe_strncpy(a->command, command, sizeof(a->command));
522 safe_strncpy(a->terminal, cons, sizeof(a->terminal));
523 dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n",
524 a->command, a->action_type, a->terminal);
527 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
528 * then parse_inittab() simply adds in some default
529 * actions(i.e., runs INIT_SCRIPT and then starts a pair
530 * of "askfirst" shells). If CONFIG_FEATURE_USE_INITTAB
531 * _is_ defined, but /etc/inittab is missing, this
532 * results in the same set of default behaviors.
534 static void parse_inittab(void)
536 #if ENABLE_FEATURE_USE_INITTAB
538 parser_t *parser = config_open2("/etc/inittab", fopen_for_read);
543 /* No inittab file - set up some default behavior */
544 /* Reboot on Ctrl-Alt-Del */
545 new_init_action(CTRLALTDEL, "reboot", "");
546 /* Umount all filesystems on halt/reboot */
547 new_init_action(SHUTDOWN, "umount -a -r", "");
548 /* Swapoff on halt/reboot */
549 if (ENABLE_SWAPONOFF)
550 new_init_action(SHUTDOWN, "swapoff -a", "");
551 /* Prepare to restart init when a QUIT is received */
552 new_init_action(RESTART, "init", "");
553 /* Askfirst shell on tty1-4 */
554 new_init_action(ASKFIRST, bb_default_login_shell, "");
555 //TODO: VC_1 instead of ""? "" is console -> ctty problems -> angry users
556 new_init_action(ASKFIRST, bb_default_login_shell, VC_2);
557 new_init_action(ASKFIRST, bb_default_login_shell, VC_3);
558 new_init_action(ASKFIRST, bb_default_login_shell, VC_4);
560 new_init_action(SYSINIT, INIT_SCRIPT, "");
564 #if ENABLE_FEATURE_USE_INITTAB
565 /* optional_tty:ignored_runlevel:action:command
566 * Delims are not to be collapsed and need exactly 4 tokens
568 while (config_read(parser, token, 4, 0, "#:",
569 PARSE_NORMAL & ~(PARSE_TRIM | PARSE_COLLAPSE))) {
570 /* order must correspond to SYSINIT..RESTART constants */
571 static const char actions[] ALIGN1 =
572 "sysinit\0""wait\0""once\0""respawn\0""askfirst\0"
573 "ctrlaltdel\0""shutdown\0""restart\0";
575 char *tty = token[0];
577 if (!token[3]) /* less than 4 tokens */
579 action = index_in_strings(actions, token[2]);
580 if (action < 0 || !token[3][0]) /* token[3]: command */
582 /* turn .*TTY -> /dev/TTY */
584 if (strncmp(tty, "/dev/", 5) == 0)
586 tty = concat_path_file("/dev/", tty);
588 new_init_action(1 << action, token[3], tty);
593 message(L_LOG | L_CONSOLE, "Bad inittab entry at line %d",
596 config_close(parser);
600 static void pause_and_low_level_reboot(unsigned magic) NORETURN;
601 static void pause_and_low_level_reboot(unsigned magic)
605 /* Allow time for last message to reach serial console, etc */
608 /* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
609 * in linux/kernel/sys.c, which can cause the machine to panic when
610 * the init process exits... */
612 if (pid == 0) { /* child */
620 static void run_shutdown_and_kill_processes(void)
622 /* Run everything to be run at "shutdown". This is done _prior_
623 * to killing everything, in case people wish to use scripts to
624 * shut things down gracefully... */
625 run_actions(SHUTDOWN);
627 message(L_CONSOLE | L_LOG, "The system is going down NOW!");
629 /* Send signals to every process _except_ pid 1 */
631 message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM");
636 message(L_CONSOLE, "Sent SIG%s to all processes", "KILL");
638 /*sleep(1); - callers take care about making a pause */
641 /* Signal handling by init:
643 * For process with PID==1, on entry kernel sets all signals to SIG_DFL
644 * and unmasks all signals. However, for process with PID==1,
645 * default action (SIG_DFL) on any signal is to ignore it,
646 * even for special signals SIGKILL and SIGCONT.
647 * Also, any signal can be caught or blocked.
648 * (but SIGSTOP is still handled specially, at least in 2.6.20)
650 * We install two kinds of handlers, "immediate" and "delayed".
652 * Immediate handlers execute at any time, even while, say, sysinit
655 * Delayed handlers just set a flag variable. The variable is checked
656 * in the main loop and acted upon.
658 * halt/poweroff/reboot and restart have immediate handlers.
659 * They only traverse linked list of struct action's, never modify it,
660 * this should be safe to do even in signal handler. Also they
663 * SIGSTOP and SIGTSTP have immediate handlers. They just wait
664 * for SIGCONT to happen.
666 * SIGHUP has a delayed handler, because modifying linked list
667 * of struct action's from a signal handler while it is manipulated
668 * by the program may be disastrous.
670 * Ctrl-Alt-Del has a delayed handler. Not a must, but allowing
671 * it to happen even somewhere inside "sysinit" would be a bit awkward.
673 * There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide
674 * and only one will be remembered and acted upon.
677 static void halt_reboot_pwoff(int sig) NORETURN;
678 static void halt_reboot_pwoff(int sig)
683 run_shutdown_and_kill_processes();
687 if (sig == SIGTERM) {
690 } else if (sig == SIGUSR2) {
694 message(L_CONSOLE, "Requesting system %s", m);
695 pause_and_low_level_reboot(rb);
699 /* The SIGSTOP/SIGTSTP handler
700 * NB: inside it, all signals except SIGCONT are masked
701 * via appropriate setup in sigaction().
703 static void stop_handler(int sig UNUSED_PARAM)
705 smallint saved_bb_got_signal;
708 saved_bb_got_signal = bb_got_signal;
710 signal(SIGCONT, record_signo);
715 if (bb_got_signal == SIGCONT)
717 /* NB: this can accidentally wait() for a process
718 * which we waitfor() elsewhere! waitfor() must have
719 * code which is resilient against this.
721 wpid = wait_any_nohang(NULL);
722 mark_terminated(wpid);
726 signal(SIGCONT, SIG_DFL);
728 bb_got_signal = saved_bb_got_signal;
731 /* Handler for QUIT - exec "restart" action,
732 * else (no such action defined) do nothing */
733 static void restart_handler(int sig UNUSED_PARAM)
735 struct init_action *a;
737 for (a = init_action_list; a; a = a->next) {
738 if (!(a->action_type & RESTART))
741 /* Starting from here, we won't return.
742 * Thus don't need to worry about preserving errno
745 run_shutdown_and_kill_processes();
747 /* Allow Ctrl-Alt-Del to reboot the system.
748 * This is how kernel sets it up for init, we follow suit.
750 reboot(RB_ENABLE_CAD); /* misnomer */
752 if (open_stdio_to_tty(a->terminal)) {
753 dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command);
754 /* Theoretically should be safe.
755 * But in practice, kernel bugs may leave
756 * unkillable processes, and wait() may block forever.
757 * Oh well. Hoping "new" init won't be too surprised
758 * by having children it didn't create.
760 //while (wait(NULL) > 0)
762 init_exec(a->command);
764 /* Open or exec failed */
765 pause_and_low_level_reboot(RB_HALT_SYSTEM);
770 #if ENABLE_FEATURE_USE_INITTAB
771 static void reload_inittab(void)
773 struct init_action *a, **nextp;
775 message(L_LOG, "reloading /etc/inittab");
777 /* Disable old entries */
778 for (a = init_action_list; a; a = a->next)
779 a->action_type = ONCE;
781 /* Append new entries, or modify existing entries
782 * (set a->action_type) if cmd and device name
783 * match new ones. End result: only entries with
784 * a->action_type == ONCE are stale.
788 #if ENABLE_FEATURE_KILL_REMOVED
789 /* Kill stale entries */
790 /* Be nice and send SIGTERM first */
791 for (a = init_action_list; a; a = a->next)
792 if (a->action_type == ONCE && a->pid != 0)
793 kill(a->pid, SIGTERM);
794 if (CONFIG_FEATURE_KILL_DELAY) {
795 /* NB: parent will wait in NOMMU case */
796 if ((BB_MMU ? fork() : vfork()) == 0) { /* child */
797 sleep(CONFIG_FEATURE_KILL_DELAY);
798 for (a = init_action_list; a; a = a->next)
799 if (a->action_type == ONCE && a->pid != 0)
800 kill(a->pid, SIGKILL);
806 /* Remove stale (ONCE) and not useful (SYSINIT,WAIT) entries */
807 nextp = &init_action_list;
808 while ((a = *nextp) != NULL) {
809 if (a->action_type & (ONCE | SYSINIT | WAIT)) {
818 /* run_actions(RESPAWN | ASKFIRST); */
819 /* - we return to main loop, which does this automagically */
823 static int check_delayed_sigs(void)
828 smallint sig = bb_got_signal;
834 #if ENABLE_FEATURE_USE_INITTAB
839 run_actions(CTRLALTDEL);
843 int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
844 int init_main(int argc UNUSED_PARAM, char **argv)
846 die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */
848 if (argv[1] && !strcmp(argv[1], "-q")) {
849 return kill(1, SIGHUP);
853 /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
855 && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc"))
859 /* Turn off rebooting via CTL-ALT-DEL - we get a
860 * SIGINT on CAD so we can shut things down gracefully... */
861 reboot(RB_DISABLE_CAD); /* misnomer */
864 /* Figure out where the default console should be */
870 /* Make sure environs is set to something sane */
871 putenv((char *) "HOME=/");
872 putenv((char *) bb_PATH_root_path);
873 putenv((char *) "SHELL=/bin/sh");
874 putenv((char *) "USER=root"); /* needed? why? */
877 xsetenv("RUNLEVEL", argv[1]);
880 message(MAYBE_CONSOLE | L_LOG, "init started: %s", bb_banner);
882 /* Make sure there is enough memory to do something useful. */
883 if (ENABLE_SWAPONOFF) {
886 if (sysinfo(&info) == 0
887 && (info.mem_unit ? : 1) * (long long)info.totalram < 1024*1024
889 message(L_CONSOLE, "Low memory, forcing swapon");
890 /* swapon -a requires /proc typically */
891 new_init_action(SYSINIT, "mount -t proc proc /proc", "");
892 /* Try to turn on swap */
893 new_init_action(SYSINIT, "swapon -a", "");
894 run_actions(SYSINIT); /* wait and removing */
898 /* Check if we are supposed to be in single user mode */
900 && (!strcmp(argv[1], "single") || !strcmp(argv[1], "-s") || LONE_CHAR(argv[1], '1'))
902 /* ??? shouldn't we set RUNLEVEL="b" here? */
903 /* Start a shell on console */
904 new_init_action(RESPAWN, bb_default_login_shell, "");
906 /* Not in single user mode - see what inittab says */
908 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
909 * then parse_inittab() simply adds in some default
910 * actions(i.e., INIT_SCRIPT and a pair
911 * of "askfirst" shells */
916 if (getenv("SELINUX_INIT") == NULL) {
919 putenv((char*)"SELINUX_INIT=YES");
920 if (selinux_init_load_policy(&enforce) == 0) {
921 BB_EXECVP(argv[0], argv);
922 } else if (enforce > 0) {
923 /* SELinux in enforcing mode but load_policy failed */
924 message(L_CONSOLE, "cannot load SELinux Policy. "
925 "Machine is in enforcing mode. Halting now.");
931 /* Make the command line just say "init" - thats all, nothing else */
932 strncpy(argv[0], "init", strlen(argv[0]));
933 /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
935 memset(*argv, 0, strlen(*argv));
937 /* Set up signal handlers */
942 + (1 << SIGUSR1) /* halt */
943 + (1 << SIGTERM) /* reboot */
944 + (1 << SIGUSR2) /* poweroff */
945 , halt_reboot_pwoff);
946 signal(SIGQUIT, restart_handler); /* re-exec another init */
948 /* Stop handler must allow only SIGCONT inside itself */
949 memset(&sa, 0, sizeof(sa));
950 sigfillset(&sa.sa_mask);
951 sigdelset(&sa.sa_mask, SIGCONT);
952 sa.sa_handler = stop_handler;
953 /* NB: sa_flags doesn't have SA_RESTART.
954 * It must be able to interrupt wait().
956 sigaction_set(SIGTSTP, &sa); /* pause */
957 /* Does not work as intended, at least in 2.6.20.
958 * SIGSTOP is simply ignored by init:
960 sigaction_set(SIGSTOP, &sa); /* pause */
962 /* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
963 * setting handler without SA_RESTART flag.
965 bb_signals_recursive_norestart((1 << SIGINT), record_signo);
968 /* Now run everything that needs to be run */
969 /* First run the sysinit command */
970 run_actions(SYSINIT);
971 check_delayed_sigs();
972 /* Next run anything that wants to block */
974 check_delayed_sigs();
975 /* Next run anything to be run only once */
978 /* Set up "reread /etc/inittab" handler.
979 * Handler is set up without SA_RESTART, it will interrupt syscalls.
981 if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
982 bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
984 /* Now run the looping stuff for the rest of forever.
985 * NB: if delayed signal happened, avoid blocking in wait().
990 maybe_WNOHANG = check_delayed_sigs();
992 /* (Re)run the respawn/askfirst stuff */
993 run_actions(RESPAWN | ASKFIRST);
994 maybe_WNOHANG |= check_delayed_sigs();
996 /* Don't consume all CPU time - sleep a bit */
998 maybe_WNOHANG |= check_delayed_sigs();
1000 /* Wait for any child process(es) to exit.
1001 * NB: "delayed" signals will also interrupt this wait(),
1002 * bb_signals_recursive_norestart() set them up for that.
1003 * This guarantees we won't be stuck here
1004 * till next orphan dies.
1007 maybe_WNOHANG = WNOHANG;
1010 struct init_action *a;
1012 wpid = waitpid(-1, NULL, maybe_WNOHANG);
1016 a = mark_terminated(wpid);
1018 message(L_LOG, "process '%s' (pid %d) exited. "
1019 "Scheduling for restart.",
1022 /* See if anyone else is waiting to be reaped */
1023 maybe_WNOHANG = WNOHANG;