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 if (BB_MMU && (a->action_type & ASKFIRST))
344 message(L_LOG | L_CONSOLE, "can't fork");
346 return pid; /* Parent or error */
350 /* Reset signal handlers that were set by the parent process */
351 //TODO: block signals across fork(), prevent them to affect child before
363 /* Create a new session and make ourself the process group leader */
366 /* Open the new terminal device */
367 if (!open_stdio_to_tty(a->terminal))
370 /* NB: on NOMMU we can't wait for input in child, so
371 * "askfirst" will work the same as "respawn". */
372 if (BB_MMU && (a->action_type & ASKFIRST)) {
373 static const char press_enter[] ALIGN1 =
374 #ifdef CUSTOMIZED_BANNER
375 #include CUSTOMIZED_BANNER
377 "\nPlease press Enter to activate this console. ";
380 * Save memory by not exec-ing anything large (like a shell)
381 * before the user wants it. This is critical if swap is not
382 * enabled and the system has low memory. Generally this will
383 * be run on the second virtual console, and the first will
384 * be allowed to start a shell or whatever an init script
387 dbg_message(L_LOG, "waiting for enter to start '%s'"
388 "(pid %d, tty '%s')\n",
389 a->command, getpid(), a->terminal);
390 full_write(STDOUT_FILENO, press_enter, sizeof(press_enter) - 1);
391 while (safe_read(STDIN_FILENO, &c, 1) == 1 && c != '\n')
396 * When a file named /.init_enable_core exists, setrlimit is called
397 * before processes are spawned to set core file size as unlimited.
398 * This is for debugging only. Don't use this is production, unless
399 * you want core dumps lying about....
401 if (ENABLE_FEATURE_INIT_COREDUMPS) {
402 if (access("/.init_enable_core", F_OK) == 0) {
404 limit.rlim_cur = RLIM_INFINITY;
405 limit.rlim_max = RLIM_INFINITY;
406 setrlimit(RLIMIT_CORE, &limit);
410 /* Log the process name and args */
411 message(L_LOG, "starting pid %d, tty '%s': '%s'",
412 getpid(), a->terminal, a->command);
414 /* Now run it. The new program will take over this PID,
415 * so nothing further in init.c should be run. */
416 init_exec(a->command);
417 /* We're still here? Some error happened. */
421 static struct init_action *mark_terminated(pid_t pid)
423 struct init_action *a;
426 for (a = init_action_list; a; a = a->next) {
436 static void waitfor(pid_t pid)
438 /* waitfor(run(x)): protect against failed fork inside run() */
442 /* Wait for any child (prevent zombies from exiting orphaned processes)
443 * but exit the loop only when specified one has exited. */
445 pid_t wpid = wait(NULL);
446 mark_terminated(wpid);
447 /* Unsafe. SIGTSTP handler might have wait'ed it already */
448 /*if (wpid == pid) break;*/
455 /* Run all commands of a particular type */
456 static void run_actions(int action_type)
458 struct init_action *a;
460 for (a = init_action_list; a; a = a->next) {
461 if (!(a->action_type & action_type))
464 if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) {
466 if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN))
469 if (a->action_type & (RESPAWN | ASKFIRST)) {
470 /* Only run stuff with pid == 0. If pid != 0,
471 * it is already running
479 static void new_init_action(uint8_t action_type, const char *command, const char *cons)
481 struct init_action *a, **nextp;
485 * ::shutdown:umount -a -r
486 * ::shutdown:swapoff -a
488 * ::shutdown:swapoff -a
489 * ::shutdown:umount -a -r
490 * On reload, we must ensure entries end up in correct order.
491 * To achieve that, if we find a matching entry, we move it
494 nextp = &init_action_list;
495 while ((a = *nextp) != NULL) {
496 /* Don't enter action if it's already in the list,
497 * This prevents losing running RESPAWNs.
499 if ((strcmp(a->command, command) == 0)
500 && (strcmp(a->terminal, cons) == 0)
502 /* Remove from list */
504 /* Find the end of the list */
505 while (*nextp != NULL)
506 nextp = &(*nextp)->next;
514 a = xzalloc(sizeof(*a));
515 /* Append to the end of the list */
517 a->action_type = action_type;
518 safe_strncpy(a->command, command, sizeof(a->command));
519 safe_strncpy(a->terminal, cons, sizeof(a->terminal));
520 dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n",
521 a->command, a->action_type, a->terminal);
524 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
525 * then parse_inittab() simply adds in some default
526 * actions(i.e., runs INIT_SCRIPT and then starts a pair
527 * of "askfirst" shells). If CONFIG_FEATURE_USE_INITTAB
528 * _is_ defined, but /etc/inittab is missing, this
529 * results in the same set of default behaviors.
531 static void parse_inittab(void)
533 #if ENABLE_FEATURE_USE_INITTAB
535 parser_t *parser = config_open2("/etc/inittab", fopen_for_read);
540 /* No inittab file - set up some default behavior */
541 /* Reboot on Ctrl-Alt-Del */
542 new_init_action(CTRLALTDEL, "reboot", "");
543 /* Umount all filesystems on halt/reboot */
544 new_init_action(SHUTDOWN, "umount -a -r", "");
545 /* Swapoff on halt/reboot */
546 if (ENABLE_SWAPONOFF)
547 new_init_action(SHUTDOWN, "swapoff -a", "");
548 /* Prepare to restart init when a QUIT is received */
549 new_init_action(RESTART, "init", "");
550 /* Askfirst shell on tty1-4 */
551 new_init_action(ASKFIRST, bb_default_login_shell, "");
552 //TODO: VC_1 instead of ""? "" is console -> ctty problems -> angry users
553 new_init_action(ASKFIRST, bb_default_login_shell, VC_2);
554 new_init_action(ASKFIRST, bb_default_login_shell, VC_3);
555 new_init_action(ASKFIRST, bb_default_login_shell, VC_4);
557 new_init_action(SYSINIT, INIT_SCRIPT, "");
561 #if ENABLE_FEATURE_USE_INITTAB
562 /* optional_tty:ignored_runlevel:action:command
563 * Delims are not to be collapsed and need exactly 4 tokens
565 while (config_read(parser, token, 4, 0, "#:",
566 PARSE_NORMAL & ~(PARSE_TRIM | PARSE_COLLAPSE))) {
567 /* order must correspond to SYSINIT..RESTART constants */
568 static const char actions[] ALIGN1 =
569 "sysinit\0""wait\0""once\0""respawn\0""askfirst\0"
570 "ctrlaltdel\0""shutdown\0""restart\0";
572 char *tty = token[0];
574 if (!token[3]) /* less than 4 tokens */
576 action = index_in_strings(actions, token[2]);
577 if (action < 0 || !token[3][0]) /* token[3]: command */
579 /* turn .*TTY -> /dev/TTY */
581 if (strncmp(tty, "/dev/", 5) == 0)
583 tty = concat_path_file("/dev/", tty);
585 new_init_action(1 << action, token[3], tty);
590 message(L_LOG | L_CONSOLE, "Bad inittab entry at line %d",
593 config_close(parser);
597 static void pause_and_low_level_reboot(unsigned magic) NORETURN;
598 static void pause_and_low_level_reboot(unsigned magic)
602 /* Allow time for last message to reach serial console, etc */
605 /* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
606 * in linux/kernel/sys.c, which can cause the machine to panic when
607 * the init process exits... */
609 if (pid == 0) { /* child */
617 static void run_shutdown_and_kill_processes(void)
619 /* Run everything to be run at "shutdown". This is done _prior_
620 * to killing everything, in case people wish to use scripts to
621 * shut things down gracefully... */
622 run_actions(SHUTDOWN);
624 message(L_CONSOLE | L_LOG, "The system is going down NOW!");
626 /* Send signals to every process _except_ pid 1 */
628 message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM");
633 message(L_CONSOLE, "Sent SIG%s to all processes", "KILL");
635 /*sleep(1); - callers take care about making a pause */
638 /* Signal handling by init:
640 * For process with PID==1, on entry kernel sets all signals to SIG_DFL
641 * and unmasks all signals. However, for process with PID==1,
642 * default action (SIG_DFL) on any signal is to ignore it,
643 * even for special signals SIGKILL and SIGCONT.
644 * Also, any signal can be caught or blocked.
645 * (but SIGSTOP is still handled specially, at least in 2.6.20)
647 * We install two kinds of handlers, "immediate" and "delayed".
649 * Immediate handlers execute at any time, even while, say, sysinit
652 * Delayed handlers just set a flag variable. The variable is checked
653 * in the main loop and acted upon.
655 * halt/poweroff/reboot and restart have immediate handlers.
656 * They only traverse linked list of struct action's, never modify it,
657 * this should be safe to do even in signal handler. Also they
660 * SIGSTOP and SIGTSTP have immediate handlers. They just wait
661 * for SIGCONT to happen.
663 * SIGHUP has a delayed handler, because modifying linked list
664 * of struct action's from a signal handler while it is manipulated
665 * by the program may be disastrous.
667 * Ctrl-Alt-Del has a delayed handler. Not a must, but allowing
668 * it to happen even somewhere inside "sysinit" would be a bit awkward.
670 * There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide
671 * and only one will be remebered and acted upon.
674 static void halt_reboot_pwoff(int sig) NORETURN;
675 static void halt_reboot_pwoff(int sig)
680 run_shutdown_and_kill_processes();
684 if (sig == SIGTERM) {
687 } else if (sig == SIGUSR2) {
691 message(L_CONSOLE, "Requesting system %s", m);
692 pause_and_low_level_reboot(rb);
696 /* The SIGSTOP/SIGTSTP handler
697 * NB: inside it, all signals except SIGCONT are masked
698 * via appropriate setup in sigaction().
700 static void stop_handler(int sig UNUSED_PARAM)
702 smallint saved_bb_got_signal;
705 saved_bb_got_signal = bb_got_signal;
707 signal(SIGCONT, record_signo);
712 if (bb_got_signal == SIGCONT)
714 /* NB: this can accidentally wait() for a process
715 * which we waitfor() elsewhere! waitfor() must have
716 * code which is resilient against this.
718 wpid = wait_any_nohang(NULL);
719 mark_terminated(wpid);
723 signal(SIGCONT, SIG_DFL);
725 bb_got_signal = saved_bb_got_signal;
728 /* Handler for QUIT - exec "restart" action,
729 * else (no such action defined) do nothing */
730 static void restart_handler(int sig UNUSED_PARAM)
732 struct init_action *a;
734 for (a = init_action_list; a; a = a->next) {
735 if (!(a->action_type & RESTART))
738 /* Starting from here, we won't return.
739 * Thus don't need to worry about preserving errno
742 run_shutdown_and_kill_processes();
744 /* Allow Ctrl-Alt-Del to reboot the system.
745 * This is how kernel sets it up for init, we follow suit.
747 reboot(RB_ENABLE_CAD); /* misnomer */
749 if (open_stdio_to_tty(a->terminal)) {
750 dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command);
751 /* Theoretically should be safe.
752 * But in practice, kernel bugs may leave
753 * unkillable processes, and wait() may block forever.
754 * Oh well. Hoping "new" init won't be too surprised
755 * by having children it didn't create.
757 //while (wait(NULL) > 0)
759 init_exec(a->command);
761 /* Open or exec failed */
762 pause_and_low_level_reboot(RB_HALT_SYSTEM);
767 #if ENABLE_FEATURE_USE_INITTAB
768 static void reload_inittab(void)
770 struct init_action *a, **nextp;
772 message(L_LOG, "reloading /etc/inittab");
774 /* Disable old entries */
775 for (a = init_action_list; a; a = a->next)
776 a->action_type = ONCE;
778 /* Append new entries, or modify existing entries
779 * (set a->action_type) if cmd and device name
780 * match new ones. End result: only entries with
781 * a->action_type == ONCE are stale.
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 == ONCE && 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 == ONCE && a->pid != 0)
797 kill(a->pid, SIGKILL);
803 /* Remove stale (ONCE) and not useful (SYSINIT,WAIT) entries */
804 nextp = &init_action_list;
805 while ((a = *nextp) != NULL) {
806 if (a->action_type & (ONCE | SYSINIT | WAIT)) {
815 /* run_actions(RESPAWN | ASKFIRST); */
816 /* - we return to main loop, which does this automagically */
820 static int check_delayed_sigs(void)
825 smallint sig = bb_got_signal;
831 #if ENABLE_FEATURE_USE_INITTAB
836 run_actions(CTRLALTDEL);
840 int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
841 int init_main(int argc UNUSED_PARAM, char **argv)
843 die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */
845 if (argv[1] && !strcmp(argv[1], "-q")) {
846 return kill(1, SIGHUP);
850 /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
852 && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc"))
856 /* Turn off rebooting via CTL-ALT-DEL - we get a
857 * SIGINT on CAD so we can shut things down gracefully... */
858 reboot(RB_DISABLE_CAD); /* misnomer */
861 /* Figure out where the default console should be */
867 /* Make sure environs is set to something sane */
868 putenv((char *) "HOME=/");
869 putenv((char *) bb_PATH_root_path);
870 putenv((char *) "SHELL=/bin/sh");
871 putenv((char *) "USER=root"); /* needed? why? */
874 xsetenv("RUNLEVEL", argv[1]);
877 message(MAYBE_CONSOLE | L_LOG, "init started: %s", bb_banner);
879 /* Make sure there is enough memory to do something useful. */
880 if (ENABLE_SWAPONOFF) {
883 if (sysinfo(&info) == 0
884 && (info.mem_unit ? : 1) * (long long)info.totalram < 1024*1024
886 message(L_CONSOLE, "Low memory, forcing swapon");
887 /* swapon -a requires /proc typically */
888 new_init_action(SYSINIT, "mount -t proc proc /proc", "");
889 /* Try to turn on swap */
890 new_init_action(SYSINIT, "swapon -a", "");
891 run_actions(SYSINIT); /* wait and removing */
895 /* Check if we are supposed to be in single user mode */
897 && (!strcmp(argv[1], "single") || !strcmp(argv[1], "-s") || LONE_CHAR(argv[1], '1'))
899 /* ??? shouldn't we set RUNLEVEL="b" here? */
900 /* Start a shell on console */
901 new_init_action(RESPAWN, bb_default_login_shell, "");
903 /* Not in single user mode - see what inittab says */
905 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
906 * then parse_inittab() simply adds in some default
907 * actions(i.e., INIT_SCRIPT and a pair
908 * of "askfirst" shells */
913 if (getenv("SELINUX_INIT") == NULL) {
916 putenv((char*)"SELINUX_INIT=YES");
917 if (selinux_init_load_policy(&enforce) == 0) {
918 BB_EXECVP(argv[0], argv);
919 } else if (enforce > 0) {
920 /* SELinux in enforcing mode but load_policy failed */
921 message(L_CONSOLE, "cannot load SELinux Policy. "
922 "Machine is in enforcing mode. Halting now.");
928 /* Make the command line just say "init" - thats all, nothing else */
929 strncpy(argv[0], "init", strlen(argv[0]));
930 /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
932 memset(*argv, 0, strlen(*argv));
934 /* Set up signal handlers */
939 + (1 << SIGUSR1) /* halt */
940 + (1 << SIGTERM) /* reboot */
941 + (1 << SIGUSR2) /* poweroff */
942 , halt_reboot_pwoff);
943 signal(SIGQUIT, restart_handler); /* re-exec another init */
945 /* Stop handler must allow only SIGCONT inside itself */
946 memset(&sa, 0, sizeof(sa));
947 sigfillset(&sa.sa_mask);
948 sigdelset(&sa.sa_mask, SIGCONT);
949 sa.sa_handler = stop_handler;
950 /* NB: sa_flags doesn't have SA_RESTART.
951 * It must be able to interrupt wait().
953 sigaction_set(SIGTSTP, &sa); /* pause */
954 /* Does not work as intended, at least in 2.6.20.
955 * SIGSTOP is simply ignored by init:
957 sigaction_set(SIGSTOP, &sa); /* pause */
959 /* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
960 * setting handler without SA_RESTART flag.
962 bb_signals_recursive_norestart((1 << SIGINT), record_signo);
965 /* Now run everything that needs to be run */
966 /* First run the sysinit command */
967 run_actions(SYSINIT);
968 check_delayed_sigs();
969 /* Next run anything that wants to block */
971 check_delayed_sigs();
972 /* Next run anything to be run only once */
975 /* Set up "reread /etc/inittab" handler.
976 * Handler is set up without SA_RESTART, it will interrupt syscalls.
978 if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
979 bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
981 /* Now run the looping stuff for the rest of forever.
982 * NB: if delayed signal happened, avoid blocking in wait().
988 got_sigs = check_delayed_sigs();
990 /* (Re)run the respawn/askfirst stuff */
991 run_actions(RESPAWN | ASKFIRST);
993 got_sigs |= check_delayed_sigs();
995 /* Don't consume all CPU time - sleep a bit */
998 got_sigs |= check_delayed_sigs();
1002 /* Wait for any child process to exit.
1003 * NB: "delayed" signals will also interrupt this wait(),
1004 * bb_signals_recursive_norestart() set them up for that.
1005 * This guarantees we won't be stuck here
1006 * till next orphan dies.
1010 struct init_action *a = mark_terminated(wpid);
1012 message(L_LOG, "process '%s' (pid %d) exited. "
1013 "Scheduling for restart.",
1016 /* See if anyone else is waiting to be reaped */
1018 wpid = wait_any_nohang(NULL);