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/resource.h>
19 #if ENABLE_FEATURE_UTMP
20 # include <utmp.h> /* DEAD_PROCESS */
22 #include "reboot.h" /* reboot() constants */
24 /* Used only for sanitizing purposes in set_sane_term() below. On systems where
25 * the baud rate is stored in a separate field, we can safely disable them. */
31 /* Was a CONFIG_xxx option. A lot of people were building
32 * not fully functional init by switching it on! */
35 #define COMMAND_SIZE 256
36 #define CONSOLE_NAME_SIZE 32
38 /* Default sysinit script. */
40 #define INIT_SCRIPT "/etc/init.d/rcS"
43 /* Each type of actions can appear many times. They will be
44 * handled in order. RESTART is an exception, only 1st is used.
46 /* Start these actions first and wait for completion */
48 /* Start these after SYSINIT and wait for completion */
50 /* Start these after WAIT and *dont* wait for completion */
53 * NB: while SYSINIT/WAIT/ONCE are being processed,
54 * SIGHUP ("reread /etc/inittab") will be processed only after
55 * each group of actions. If new inittab adds, say, a SYSINIT action,
56 * it will not be run, since init is already "past SYSINIT stage".
58 /* Start these after ONCE are started, restart on exit */
60 /* Like RESPAWN, but wait for <Enter> to be pressed on tty */
63 * Start these on SIGINT, and wait for completion.
64 * Then go back to respawning RESPAWN and ASKFIRST actions.
65 * NB: kernel sends SIGINT to us if Ctrl-Alt-Del was pressed.
67 #define CTRLALTDEL 0x20
69 * Start these before killing all processes in preparation for
70 * running RESTART actions or doing low-level halt/reboot/poweroff
71 * (initiated by SIGUSR1/SIGTERM/SIGUSR2).
72 * Wait for completion before proceeding.
76 * exec() on SIGQUIT. SHUTDOWN actions are started and waited for,
77 * then all processes are killed, then init exec's 1st RESTART action,
78 * replacing itself by it. If no RESTART action specified,
79 * SIGQUIT has no effect.
84 /* A linked list of init_actions, to be read from inittab */
86 struct init_action *next;
89 char terminal[CONSOLE_NAME_SIZE];
90 char command[COMMAND_SIZE];
93 static struct init_action *init_action_list = NULL;
95 static const char *log_console = VC_5;
102 /* Print a message to the specified device.
103 * "where" may be bitwise-or'd from L_LOG | L_CONSOLE
104 * NB: careful, we can be called after vfork!
106 #define dbg_message(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0)
107 static void message(int where, const char *fmt, ...)
108 __attribute__ ((format(printf, 2, 3)));
109 static void message(int where, const char *fmt, ...)
116 va_start(arguments, fmt);
117 l = 1 + vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
118 if (l > sizeof(msg) - 1)
122 #if ENABLE_FEATURE_INIT_SYSLOG
125 /* Log the message to syslogd */
126 openlog(applet_name, 0, LOG_DAEMON);
127 /* don't print "\r" */
128 syslog(LOG_INFO, "%s", msg + 1);
135 static int log_fd = -1;
139 /* Take full control of the log tty, and never close it.
140 * It's mine, all mine! Muhahahaha! */
143 log_fd = STDERR_FILENO;
145 log_fd = device_open(log_console, O_WRONLY | O_NONBLOCK | O_NOCTTY);
147 bb_error_msg("can't log to %s", log_console);
150 close_on_exec_on(log_fd);
155 full_write(log_fd, msg, l);
156 if (log_fd == STDERR_FILENO)
157 return; /* don't print dup messages */
162 if (where & L_CONSOLE) {
163 /* Send console messages to console so people will see them. */
164 full_write(STDERR_FILENO, msg, l);
168 static void console_init(void)
175 s = getenv("CONSOLE");
177 s = getenv("console");
179 int fd = open(s, O_RDWR | O_NONBLOCK | O_NOCTTY);
181 dup2(fd, STDIN_FILENO);
182 dup2(fd, STDOUT_FILENO);
183 xmove_fd(fd, STDERR_FILENO);
185 dbg_message(L_LOG, "console='%s'", s);
187 /* Make sure fd 0,1,2 are not closed
188 * (so that they won't be used by future opens) */
190 // Users report problems
191 // /* Make sure init can't be blocked by writing to stderr */
192 // fcntl(STDERR_FILENO, F_SETFL, fcntl(STDERR_FILENO, F_GETFL) | O_NONBLOCK);
197 if (ioctl(STDIN_FILENO, VT_OPENQRY, &vtno) != 0) {
198 /* Not a linux terminal, probably serial console.
199 * Force the TERM setting to vt102
200 * if TERM is set to linux (the default) */
201 if (!s || strcmp(s, "linux") == 0)
202 putenv((char*)"TERM=vt102");
203 if (!ENABLE_FEATURE_INIT_SYSLOG)
208 putenv((char*)"TERM=" CONFIG_INIT_TERMINAL_TYPE);
211 /* Set terminal settings to reasonable defaults.
212 * NB: careful, we can be called after vfork! */
213 static void set_sane_term(void)
217 tcgetattr(STDIN_FILENO, &tty);
219 /* set control chars */
220 tty.c_cc[VINTR] = 3; /* C-c */
221 tty.c_cc[VQUIT] = 28; /* C-\ */
222 tty.c_cc[VERASE] = 127; /* C-? */
223 tty.c_cc[VKILL] = 21; /* C-u */
224 tty.c_cc[VEOF] = 4; /* C-d */
225 tty.c_cc[VSTART] = 17; /* C-q */
226 tty.c_cc[VSTOP] = 19; /* C-s */
227 tty.c_cc[VSUSP] = 26; /* C-z */
230 /* use line discipline 0 */
234 /* Make it be sane */
235 tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD;
236 tty.c_cflag |= CREAD | HUPCL | CLOCAL;
239 tty.c_iflag = ICRNL | IXON | IXOFF;
242 tty.c_oflag = OPOST | ONLCR;
246 ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
248 tcsetattr_stdin_TCSANOW(&tty);
251 /* Open the new terminal device.
252 * NB: careful, we can be called after vfork! */
253 static int open_stdio_to_tty(const char* tty_name)
255 /* empty tty_name means "use init's tty", else... */
260 /* fd can be only < 0 or 0: */
261 fd = device_open(tty_name, O_RDWR);
263 message(L_LOG | L_CONSOLE, "can't open %s: %s",
264 tty_name, strerror(errno));
265 return 0; /* failure */
267 dup2(STDIN_FILENO, STDOUT_FILENO);
268 dup2(STDIN_FILENO, STDERR_FILENO);
271 return 1; /* success */
274 static void reset_sighandlers_and_unblock_sigs(void)
286 sigprocmask_allsigs(SIG_UNBLOCK);
289 /* Wrapper around exec:
290 * Takes string (max COMMAND_SIZE chars).
291 * If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'.
292 * Otherwise splits words on whitespace, deals with leading dash,
293 * and uses plain exec().
294 * NB: careful, we can be called after vfork!
296 static void init_exec(const char *command)
298 char *cmd[COMMAND_SIZE / 2];
299 char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */
300 int dash = (command[0] == '-' /* maybe? && command[1] == '/' */);
302 /* See if any special /bin/sh requiring characters are present */
303 if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
304 strcpy(buf, "exec ");
305 strcpy(buf + 5, command + dash); /* excluding "-" */
306 /* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */
307 cmd[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL + !dash);
308 cmd[1] = (char*)"-c";
312 /* Convert command (char*) into cmd (char**, one word per string) */
315 next = strcpy(buf, command); /* including "-" */
316 while ((word = strsep(&next, " \t")) != NULL) {
317 if (*word != '\0') { /* not two spaces/tabs together? */
324 /* If we saw leading "-", it is interactive shell.
325 * Try harder to give it a controlling tty.
326 * And skip "-" in actual exec call. */
328 /* _Attempt_ to make stdin a controlling tty. */
329 if (ENABLE_FEATURE_INIT_SCTTY)
330 ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/);
332 BB_EXECVP(cmd[0] + dash, cmd);
333 message(L_LOG | L_CONSOLE, "can't run '%s': %s", cmd[0], strerror(errno));
334 /* returns if execvp fails */
337 /* Used only by run_actions */
338 static pid_t run(const struct init_action *a)
342 /* Careful: don't be affected by a signal in vforked child */
343 sigprocmask_allsigs(SIG_BLOCK);
344 if (BB_MMU && (a->action_type & ASKFIRST))
349 message(L_LOG | L_CONSOLE, "can't fork");
351 sigprocmask_allsigs(SIG_UNBLOCK);
352 return pid; /* Parent or error */
357 /* Reset signal handlers that were set by the parent process */
358 reset_sighandlers_and_unblock_sigs();
360 /* Create a new session and make ourself the process group leader */
363 /* Open the new terminal device */
364 if (!open_stdio_to_tty(a->terminal))
367 /* NB: on NOMMU we can't wait for input in child, so
368 * "askfirst" will work the same as "respawn". */
369 if (BB_MMU && (a->action_type & ASKFIRST)) {
370 static const char press_enter[] ALIGN1 =
371 #ifdef CUSTOMIZED_BANNER
372 #include CUSTOMIZED_BANNER
374 "\nPlease press Enter to activate this console. ";
377 * Save memory by not exec-ing anything large (like a shell)
378 * before the user wants it. This is critical if swap is not
379 * enabled and the system has low memory. Generally this will
380 * be run on the second virtual console, and the first will
381 * be allowed to start a shell or whatever an init script
384 dbg_message(L_LOG, "waiting for enter to start '%s'"
385 "(pid %d, tty '%s')\n",
386 a->command, getpid(), a->terminal);
387 full_write(STDOUT_FILENO, press_enter, sizeof(press_enter) - 1);
388 while (safe_read(STDIN_FILENO, &c, 1) == 1 && c != '\n')
393 * When a file named /.init_enable_core exists, setrlimit is called
394 * before processes are spawned to set core file size as unlimited.
395 * This is for debugging only. Don't use this is production, unless
396 * you want core dumps lying about....
398 if (ENABLE_FEATURE_INIT_COREDUMPS) {
399 if (access("/.init_enable_core", F_OK) == 0) {
401 limit.rlim_cur = RLIM_INFINITY;
402 limit.rlim_max = RLIM_INFINITY;
403 setrlimit(RLIMIT_CORE, &limit);
407 /* Log the process name and args */
408 message(L_LOG, "starting pid %d, tty '%s': '%s'",
409 getpid(), a->terminal, a->command);
411 /* Now run it. The new program will take over this PID,
412 * so nothing further in init.c should be run. */
413 init_exec(a->command);
414 /* We're still here? Some error happened. */
418 static struct init_action *mark_terminated(pid_t pid)
420 struct init_action *a;
423 for (a = init_action_list; a; a = a->next) {
429 update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
434 static void waitfor(pid_t pid)
436 /* waitfor(run(x)): protect against failed fork inside run() */
440 /* Wait for any child (prevent zombies from exiting orphaned processes)
441 * but exit the loop only when specified one has exited. */
443 pid_t wpid = wait(NULL);
444 mark_terminated(wpid);
445 /* Unsafe. SIGTSTP handler might have wait'ed it already */
446 /*if (wpid == pid) break;*/
453 /* Run all commands of a particular type */
454 static void run_actions(int action_type)
456 struct init_action *a;
458 for (a = init_action_list; a; a = a->next) {
459 if (!(a->action_type & action_type))
462 if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) {
464 if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN))
467 if (a->action_type & (RESPAWN | ASKFIRST)) {
468 /* Only run stuff with pid == 0. If pid != 0,
469 * it is already running
477 static void new_init_action(uint8_t action_type, const char *command, const char *cons)
479 struct init_action *a, **nextp;
483 * ::shutdown:umount -a -r
484 * ::shutdown:swapoff -a
486 * ::shutdown:swapoff -a
487 * ::shutdown:umount -a -r
488 * On reload, we must ensure entries end up in correct order.
489 * To achieve that, if we find a matching entry, we move it
492 nextp = &init_action_list;
493 while ((a = *nextp) != NULL) {
494 /* Don't enter action if it's already in the list,
495 * This prevents losing running RESPAWNs.
497 if (strcmp(a->command, command) == 0
498 && strcmp(a->terminal, cons) == 0
500 /* Remove from list */
502 /* Find the end of the list */
503 while (*nextp != NULL)
504 nextp = &(*nextp)->next;
512 a = xzalloc(sizeof(*a));
513 /* Append to the end of the list */
515 a->action_type = action_type;
516 safe_strncpy(a->command, command, sizeof(a->command));
517 safe_strncpy(a->terminal, cons, sizeof(a->terminal));
518 dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n",
519 a->command, a->action_type, a->terminal);
522 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
523 * then parse_inittab() simply adds in some default
524 * actions(i.e., runs INIT_SCRIPT and then starts a pair
525 * of "askfirst" shells). If CONFIG_FEATURE_USE_INITTAB
526 * _is_ defined, but /etc/inittab is missing, this
527 * results in the same set of default behaviors.
529 static void parse_inittab(void)
531 #if ENABLE_FEATURE_USE_INITTAB
533 parser_t *parser = config_open2("/etc/inittab", fopen_for_read);
538 /* No inittab file - set up some default behavior */
539 /* Reboot on Ctrl-Alt-Del */
540 new_init_action(CTRLALTDEL, "reboot", "");
541 /* Umount all filesystems on halt/reboot */
542 new_init_action(SHUTDOWN, "umount -a -r", "");
543 /* Swapoff on halt/reboot */
544 if (ENABLE_SWAPONOFF)
545 new_init_action(SHUTDOWN, "swapoff -a", "");
546 /* Prepare to restart init when a QUIT is received */
547 new_init_action(RESTART, "init", "");
548 /* Askfirst shell on tty1-4 */
549 new_init_action(ASKFIRST, bb_default_login_shell, "");
550 //TODO: VC_1 instead of ""? "" is console -> ctty problems -> angry users
551 new_init_action(ASKFIRST, bb_default_login_shell, VC_2);
552 new_init_action(ASKFIRST, bb_default_login_shell, VC_3);
553 new_init_action(ASKFIRST, bb_default_login_shell, VC_4);
555 new_init_action(SYSINIT, INIT_SCRIPT, "");
559 #if ENABLE_FEATURE_USE_INITTAB
560 /* optional_tty:ignored_runlevel:action:command
561 * Delims are not to be collapsed and need exactly 4 tokens
563 while (config_read(parser, token, 4, 0, "#:",
564 PARSE_NORMAL & ~(PARSE_TRIM | PARSE_COLLAPSE))) {
565 /* order must correspond to SYSINIT..RESTART constants */
566 static const char actions[] ALIGN1 =
567 "sysinit\0""wait\0""once\0""respawn\0""askfirst\0"
568 "ctrlaltdel\0""shutdown\0""restart\0";
570 char *tty = token[0];
572 if (!token[3]) /* less than 4 tokens */
574 action = index_in_strings(actions, token[2]);
575 if (action < 0 || !token[3][0]) /* token[3]: command */
577 /* turn .*TTY -> /dev/TTY */
579 tty = concat_path_file("/dev/", skip_dev_pfx(tty));
581 new_init_action(1 << action, token[3], tty);
586 message(L_LOG | L_CONSOLE, "Bad inittab entry at line %d",
589 config_close(parser);
593 static void pause_and_low_level_reboot(unsigned magic) NORETURN;
594 static void pause_and_low_level_reboot(unsigned magic)
598 /* Allow time for last message to reach serial console, etc */
601 /* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
602 * in linux/kernel/sys.c, which can cause the machine to panic when
603 * the init process exits... */
605 if (pid == 0) { /* child */
613 static void run_shutdown_and_kill_processes(void)
615 /* Run everything to be run at "shutdown". This is done _prior_
616 * to killing everything, in case people wish to use scripts to
617 * shut things down gracefully... */
618 run_actions(SHUTDOWN);
620 message(L_CONSOLE | L_LOG, "The system is going down NOW!");
622 /* Send signals to every process _except_ pid 1 */
624 message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM");
629 message(L_CONSOLE, "Sent SIG%s to all processes", "KILL");
631 /*sleep(1); - callers take care about making a pause */
634 /* Signal handling by init:
636 * For process with PID==1, on entry kernel sets all signals to SIG_DFL
637 * and unmasks all signals. However, for process with PID==1,
638 * default action (SIG_DFL) on any signal is to ignore it,
639 * even for special signals SIGKILL and SIGCONT.
640 * Also, any signal can be caught or blocked.
641 * (but SIGSTOP is still handled specially, at least in 2.6.20)
643 * We install two kinds of handlers, "immediate" and "delayed".
645 * Immediate handlers execute at any time, even while, say, sysinit
648 * Delayed handlers just set a flag variable. The variable is checked
649 * in the main loop and acted upon.
651 * halt/poweroff/reboot and restart have immediate handlers.
652 * They only traverse linked list of struct action's, never modify it,
653 * this should be safe to do even in signal handler. Also they
656 * SIGSTOP and SIGTSTP have immediate handlers. They just wait
657 * for SIGCONT to happen.
659 * SIGHUP has a delayed handler, because modifying linked list
660 * of struct action's from a signal handler while it is manipulated
661 * by the program may be disastrous.
663 * Ctrl-Alt-Del has a delayed handler. Not a must, but allowing
664 * it to happen even somewhere inside "sysinit" would be a bit awkward.
666 * There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide
667 * and only one will be remembered and acted upon.
670 /* The SIGUSR[12]/SIGTERM handler */
671 static void halt_reboot_pwoff(int sig) NORETURN;
672 static void halt_reboot_pwoff(int sig)
677 /* We may call run() and it unmasks signals,
678 * including the one masked inside this signal handler.
679 * Testcase which would start multiple reboot scripts:
680 * while true; do reboot; done
683 reset_sighandlers_and_unblock_sigs();
685 run_shutdown_and_kill_processes();
689 if (sig == SIGTERM) {
692 } else if (sig == SIGUSR2) {
696 message(L_CONSOLE, "Requesting system %s", m);
697 pause_and_low_level_reboot(rb);
701 /* Handler for QUIT - exec "restart" action,
702 * else (no such action defined) do nothing */
703 static void restart_handler(int sig UNUSED_PARAM)
705 struct init_action *a;
707 for (a = init_action_list; a; a = a->next) {
708 if (!(a->action_type & RESTART))
711 /* Starting from here, we won't return.
712 * Thus don't need to worry about preserving errno
716 reset_sighandlers_and_unblock_sigs();
718 run_shutdown_and_kill_processes();
721 /* Allow Ctrl-Alt-Del to reboot the system.
722 * This is how kernel sets it up for init, we follow suit.
724 reboot(RB_ENABLE_CAD); /* misnomer */
727 if (open_stdio_to_tty(a->terminal)) {
728 dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command);
729 /* Theoretically should be safe.
730 * But in practice, kernel bugs may leave
731 * unkillable processes, and wait() may block forever.
732 * Oh well. Hoping "new" init won't be too surprised
733 * by having children it didn't create.
735 //while (wait(NULL) > 0)
737 init_exec(a->command);
739 /* Open or exec failed */
740 pause_and_low_level_reboot(RB_HALT_SYSTEM);
745 /* The SIGSTOP/SIGTSTP handler
746 * NB: inside it, all signals except SIGCONT are masked
747 * via appropriate setup in sigaction().
749 static void stop_handler(int sig UNUSED_PARAM)
751 smallint saved_bb_got_signal;
754 saved_bb_got_signal = bb_got_signal;
756 signal(SIGCONT, record_signo);
761 if (bb_got_signal == SIGCONT)
763 /* NB: this can accidentally wait() for a process
764 * which we waitfor() elsewhere! waitfor() must have
765 * code which is resilient against this.
767 wpid = wait_any_nohang(NULL);
768 mark_terminated(wpid);
772 signal(SIGCONT, SIG_DFL);
774 bb_got_signal = saved_bb_got_signal;
777 #if ENABLE_FEATURE_USE_INITTAB
778 static void reload_inittab(void)
780 struct init_action *a, **nextp;
782 message(L_LOG, "reloading /etc/inittab");
784 /* Disable old entries */
785 for (a = init_action_list; a; a = a->next)
788 /* Append new entries, or modify existing entries
789 * (incl. setting a->action_type) if cmd and device name
790 * match new ones. End result: only entries with
791 * a->action_type == 0 are stale.
795 #if ENABLE_FEATURE_KILL_REMOVED
796 /* Kill stale entries */
797 /* Be nice and send SIGTERM first */
798 for (a = init_action_list; a; a = a->next)
799 if (a->action_type == 0 && a->pid != 0)
800 kill(a->pid, SIGTERM);
801 if (CONFIG_FEATURE_KILL_DELAY) {
802 /* NB: parent will wait in NOMMU case */
803 if ((BB_MMU ? fork() : vfork()) == 0) { /* child */
804 sleep(CONFIG_FEATURE_KILL_DELAY);
805 for (a = init_action_list; a; a = a->next)
806 if (a->action_type == 0 && a->pid != 0)
807 kill(a->pid, SIGKILL);
813 /* Remove stale entries and SYSINIT entries.
814 * We never rerun SYSINIT entries anyway,
815 * removing them too saves a few bytes */
816 nextp = &init_action_list;
817 while ((a = *nextp) != NULL) {
818 if ((a->action_type & ~SYSINIT) == 0) {
827 /* run_actions(RESPAWN | ASKFIRST); */
828 /* - we return to main loop, which does this automagically */
832 static int check_delayed_sigs(void)
837 smallint sig = bb_got_signal;
843 #if ENABLE_FEATURE_USE_INITTAB
848 run_actions(CTRLALTDEL);
852 int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
853 int init_main(int argc UNUSED_PARAM, char **argv)
855 die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */
857 if (argv[1] && strcmp(argv[1], "-q") == 0) {
858 return kill(1, SIGHUP);
862 /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
864 && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc"))
868 #ifdef RB_DISABLE_CAD
869 /* Turn off rebooting via CTL-ALT-DEL - we get a
870 * SIGINT on CAD so we can shut things down gracefully... */
871 reboot(RB_DISABLE_CAD); /* misnomer */
875 /* Figure out where the default console should be */
881 /* Make sure environs is set to something sane */
882 putenv((char *) "HOME=/");
883 putenv((char *) bb_PATH_root_path);
884 putenv((char *) "SHELL=/bin/sh");
885 putenv((char *) "USER=root"); /* needed? why? */
888 xsetenv("RUNLEVEL", argv[1]);
890 #if !ENABLE_FEATURE_EXTRA_QUIET
892 message(L_CONSOLE | L_LOG, "init started: %s", bb_banner);
895 /* struct sysinfo is linux-specific */
897 /* Make sure there is enough memory to do something useful. */
898 if (ENABLE_SWAPONOFF) {
901 if (sysinfo(&info) == 0
902 && (info.mem_unit ? info.mem_unit : 1) * (long long)info.totalram < 1024*1024
904 message(L_CONSOLE, "Low memory, forcing swapon");
905 /* swapon -a requires /proc typically */
906 new_init_action(SYSINIT, "mount -t proc proc /proc", "");
907 /* Try to turn on swap */
908 new_init_action(SYSINIT, "swapon -a", "");
909 run_actions(SYSINIT); /* wait and removing */
914 /* Check if we are supposed to be in single user mode */
916 && (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 || LONE_CHAR(argv[1], '1'))
918 /* ??? shouldn't we set RUNLEVEL="b" here? */
919 /* Start a shell on console */
920 new_init_action(RESPAWN, bb_default_login_shell, "");
922 /* Not in single user mode - see what inittab says */
924 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
925 * then parse_inittab() simply adds in some default
926 * actions(i.e., INIT_SCRIPT and a pair
927 * of "askfirst" shells */
932 if (getenv("SELINUX_INIT") == NULL) {
935 putenv((char*)"SELINUX_INIT=YES");
936 if (selinux_init_load_policy(&enforce) == 0) {
937 BB_EXECVP(argv[0], argv);
938 } else if (enforce > 0) {
939 /* SELinux in enforcing mode but load_policy failed */
940 message(L_CONSOLE, "can't load SELinux Policy. "
941 "Machine is in enforcing mode. Halting now.");
947 /* Make the command line just say "init" - thats all, nothing else */
948 strncpy(argv[0], "init", strlen(argv[0]));
949 /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
951 memset(*argv, 0, strlen(*argv));
953 /* Set up signal handlers */
958 + (1 << SIGUSR1) /* halt */
959 + (1 << SIGTERM) /* reboot */
960 + (1 << SIGUSR2) /* poweroff */
961 , halt_reboot_pwoff);
962 signal(SIGQUIT, restart_handler); /* re-exec another init */
964 /* Stop handler must allow only SIGCONT inside itself */
965 memset(&sa, 0, sizeof(sa));
966 sigfillset(&sa.sa_mask);
967 sigdelset(&sa.sa_mask, SIGCONT);
968 sa.sa_handler = stop_handler;
969 /* NB: sa_flags doesn't have SA_RESTART.
970 * It must be able to interrupt wait().
972 sigaction_set(SIGTSTP, &sa); /* pause */
973 /* Does not work as intended, at least in 2.6.20.
974 * SIGSTOP is simply ignored by init:
976 sigaction_set(SIGSTOP, &sa); /* pause */
978 /* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
979 * setting handler without SA_RESTART flag.
981 bb_signals_recursive_norestart((1 << SIGINT), record_signo);
984 /* Set up "reread /etc/inittab" handler.
985 * Handler is set up without SA_RESTART, it will interrupt syscalls.
987 if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
988 bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
990 /* Now run everything that needs to be run */
991 /* First run the sysinit command */
992 run_actions(SYSINIT);
993 check_delayed_sigs();
994 /* Next run anything that wants to block */
996 check_delayed_sigs();
997 /* Next run anything to be run only once */
1000 /* Now run the looping stuff for the rest of forever.
1005 maybe_WNOHANG = check_delayed_sigs();
1007 /* (Re)run the respawn/askfirst stuff */
1008 run_actions(RESPAWN | ASKFIRST);
1009 maybe_WNOHANG |= check_delayed_sigs();
1011 /* Don't consume all CPU time - sleep a bit */
1013 maybe_WNOHANG |= check_delayed_sigs();
1015 /* Wait for any child process(es) to exit.
1017 * If check_delayed_sigs above reported that a signal
1018 * was caught, wait will be nonblocking. This ensures
1019 * that if SIGHUP has reloaded inittab, respawn and askfirst
1020 * actions will not be delayed until next child death.
1023 maybe_WNOHANG = WNOHANG;
1026 struct init_action *a;
1028 /* If signals happen _in_ the wait, they interrupt it,
1029 * bb_signals_recursive_norestart set them up that way
1031 wpid = waitpid(-1, NULL, maybe_WNOHANG);
1035 a = mark_terminated(wpid);
1037 message(L_LOG, "process '%s' (pid %d) exited. "
1038 "Scheduling for restart.",
1041 /* See if anyone else is waiting to be reaped */
1042 maybe_WNOHANG = WNOHANG;