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 source tree.
12 //applet:IF_INIT(APPLET(init, BB_DIR_SBIN, BB_SUID_DROP))
13 //applet:IF_FEATURE_INITRD(APPLET_ODDNAME(linuxrc, init, BB_DIR_ROOT, BB_SUID_DROP, linuxrc))
15 //kbuild:lib-$(CONFIG_INIT) += init.o
20 //config: select FEATURE_SYSLOG
22 //config: init is the first program run when the system boots.
24 //config:config FEATURE_USE_INITTAB
25 //config: bool "Support reading an inittab file"
27 //config: depends on INIT
29 //config: Allow init to read an inittab file when the system boot.
31 //config:config FEATURE_KILL_REMOVED
32 //config: bool "Support killing processes that have been removed from inittab"
34 //config: depends on FEATURE_USE_INITTAB
36 //config: When respawn entries are removed from inittab and a SIGHUP is
37 //config: sent to init, this option will make init kill the processes
38 //config: that have been removed.
40 //config:config FEATURE_KILL_DELAY
41 //config: int "How long to wait between TERM and KILL (0 - send TERM only)" if FEATURE_KILL_REMOVED
42 //config: range 0 1024
44 //config: depends on FEATURE_KILL_REMOVED
46 //config: With nonzero setting, init sends TERM, forks, child waits N
47 //config: seconds, sends KILL and exits. Setting it too high is unwise
48 //config: (child will hang around for too long and could actually kill
49 //config: the wrong process!)
51 //config:config FEATURE_INIT_SCTTY
52 //config: bool "Run commands with leading dash with controlling tty"
54 //config: depends on INIT
56 //config: If this option is enabled, init will try to give a controlling
57 //config: tty to any command which has leading hyphen (often it's "-/bin/sh").
58 //config: More precisely, init will do "ioctl(STDIN_FILENO, TIOCSCTTY, 0)".
59 //config: If device attached to STDIN_FILENO can be a ctty but is not yet
60 //config: a ctty for other session, it will become this process' ctty.
61 //config: This is not the traditional init behavour, but is often what you want
62 //config: in an embedded system where the console is only accessed during
63 //config: development or for maintenance.
64 //config: NB: using cttyhack applet may work better.
66 //config:config FEATURE_INIT_SYSLOG
67 //config: bool "Enable init to write to syslog"
69 //config: depends on INIT
71 //config:config FEATURE_EXTRA_QUIET
72 //config: bool "Be _extra_ quiet on boot"
74 //config: depends on INIT
76 //config: Prevent init from logging some messages to the console during boot.
78 //config:config FEATURE_INIT_COREDUMPS
79 //config: bool "Support dumping core for child processes (debugging only)"
81 //config: depends on INIT
83 //config: If this option is enabled and the file /.init_enable_core
84 //config: exists, then init will call setrlimit() to allow unlimited
85 //config: core file sizes. If this option is disabled, processes
86 //config: will not generate any core files.
88 //config:config FEATURE_INITRD
89 //config: bool "Support running init from within an initrd (not initramfs)"
91 //config: depends on INIT
93 //config: Legacy support for running init under the old-style initrd. Allows
94 //config: the name linuxrc to act as init, and it doesn't assume init is PID 1.
96 //config: This does not apply to initramfs, which runs /init as PID 1 and
97 //config: requires no special support.
99 //config:config INIT_TERMINAL_TYPE
100 //config: string "Initial terminal type"
101 //config: default "linux"
102 //config: depends on INIT
104 //config: This is the initial value set by init for the TERM environment
105 //config: variable. This variable is used by programs which make use of
106 //config: extended terminal capabilities.
108 //config: Note that on Linux, init attempts to detect serial terminal and
109 //config: sets TERM to "vt102" if one is found.
111 #define DEBUG_SEGV_HANDLER 0
116 #include <sys/resource.h>
118 # include <linux/vt.h>
119 # include <sys/sysinfo.h>
121 #include "reboot.h" /* reboot() constants */
123 #if DEBUG_SEGV_HANDLER
125 # define _GNU_SOURCE 1
128 # include <execinfo.h>
129 # include <sys/ucontext.h>
132 /* Used only for sanitizing purposes in set_sane_term() below. On systems where
133 * the baud rate is stored in a separate field, we can safely disable them. */
139 /* Was a CONFIG_xxx option. A lot of people were building
140 * not fully functional init by switching it on! */
143 #define COMMAND_SIZE 256
144 #define CONSOLE_NAME_SIZE 32
146 /* Default sysinit script. */
148 #define INIT_SCRIPT "/etc/init.d/rcS"
151 /* Each type of actions can appear many times. They will be
152 * handled in order. RESTART is an exception, only 1st is used.
154 /* Start these actions first and wait for completion */
156 /* Start these after SYSINIT and wait for completion */
158 /* Start these after WAIT and *dont* wait for completion */
161 * NB: while SYSINIT/WAIT/ONCE are being processed,
162 * SIGHUP ("reread /etc/inittab") will be processed only after
163 * each group of actions. If new inittab adds, say, a SYSINIT action,
164 * it will not be run, since init is already "past SYSINIT stage".
166 /* Start these after ONCE are started, restart on exit */
168 /* Like RESPAWN, but wait for <Enter> to be pressed on tty */
169 #define ASKFIRST 0x10
171 * Start these on SIGINT, and wait for completion.
172 * Then go back to respawning RESPAWN and ASKFIRST actions.
173 * NB: kernel sends SIGINT to us if Ctrl-Alt-Del was pressed.
175 #define CTRLALTDEL 0x20
177 * Start these before killing all processes in preparation for
178 * running RESTART actions or doing low-level halt/reboot/poweroff
179 * (initiated by SIGUSR1/SIGTERM/SIGUSR2).
180 * Wait for completion before proceeding.
182 #define SHUTDOWN 0x40
184 * exec() on SIGQUIT. SHUTDOWN actions are started and waited for,
185 * then all processes are killed, then init exec's 1st RESTART action,
186 * replacing itself by it. If no RESTART action specified,
187 * SIGQUIT has no effect.
192 /* A linked list of init_actions, to be read from inittab */
194 struct init_action
*next
;
197 char terminal
[CONSOLE_NAME_SIZE
];
198 char command
[COMMAND_SIZE
];
201 static struct init_action
*init_action_list
= NULL
;
203 static const char *log_console
= VC_5
;
210 /* Print a message to the specified device.
211 * "where" may be bitwise-or'd from L_LOG | L_CONSOLE
212 * NB: careful, we can be called after vfork!
214 #define dbg_message(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0)
215 static void message(int where
, const char *fmt
, ...)
216 __attribute__ ((format(printf
, 2, 3)));
217 static void message(int where
, const char *fmt
, ...)
224 va_start(arguments
, fmt
);
225 l
= 1 + vsnprintf(msg
+ 1, sizeof(msg
) - 2, fmt
, arguments
);
226 if (l
> sizeof(msg
) - 1)
230 #if ENABLE_FEATURE_INIT_SYSLOG
233 /* Log the message to syslogd */
234 openlog(applet_name
, 0, LOG_DAEMON
);
235 /* don't print "\r" */
236 syslog(LOG_INFO
, "%s", msg
+ 1);
243 static int log_fd
= -1;
247 /* Take full control of the log tty, and never close it.
248 * It's mine, all mine! Muhahahaha! */
251 log_fd
= STDERR_FILENO
;
253 log_fd
= device_open(log_console
, O_WRONLY
| O_NONBLOCK
| O_NOCTTY
);
255 bb_error_msg("can't log to %s", log_console
);
258 close_on_exec_on(log_fd
);
263 full_write(log_fd
, msg
, l
);
264 if (log_fd
== STDERR_FILENO
)
265 return; /* don't print dup messages */
270 if (where
& L_CONSOLE
) {
271 /* Send console messages to console so people will see them. */
272 full_write(STDERR_FILENO
, msg
, l
);
276 static void console_init(void)
283 s
= getenv("CONSOLE");
285 s
= getenv("console");
287 int fd
= open(s
, O_RDWR
| O_NONBLOCK
| O_NOCTTY
);
289 dup2(fd
, STDIN_FILENO
);
290 dup2(fd
, STDOUT_FILENO
);
291 xmove_fd(fd
, STDERR_FILENO
);
293 dbg_message(L_LOG
, "console='%s'", s
);
295 /* Make sure fd 0,1,2 are not closed
296 * (so that they won't be used by future opens) */
298 // Users report problems
299 // /* Make sure init can't be blocked by writing to stderr */
300 // fcntl(STDERR_FILENO, F_SETFL, fcntl(STDERR_FILENO, F_GETFL) | O_NONBLOCK);
305 if (ioctl(STDIN_FILENO
, VT_OPENQRY
, &vtno
) != 0) {
306 /* Not a linux terminal, probably serial console.
307 * Force the TERM setting to vt102
308 * if TERM is set to linux (the default) */
309 if (!s
|| strcmp(s
, "linux") == 0)
310 putenv((char*)"TERM=vt102");
311 if (!ENABLE_FEATURE_INIT_SYSLOG
)
316 putenv((char*)"TERM=" CONFIG_INIT_TERMINAL_TYPE
);
319 /* Set terminal settings to reasonable defaults.
320 * NB: careful, we can be called after vfork! */
321 static void set_sane_term(void)
325 tcgetattr(STDIN_FILENO
, &tty
);
327 /* set control chars */
328 tty
.c_cc
[VINTR
] = 3; /* C-c */
329 tty
.c_cc
[VQUIT
] = 28; /* C-\ */
330 tty
.c_cc
[VERASE
] = 127; /* C-? */
331 tty
.c_cc
[VKILL
] = 21; /* C-u */
332 tty
.c_cc
[VEOF
] = 4; /* C-d */
333 tty
.c_cc
[VSTART
] = 17; /* C-q */
334 tty
.c_cc
[VSTOP
] = 19; /* C-s */
335 tty
.c_cc
[VSUSP
] = 26; /* C-z */
338 /* use line discipline 0 */
342 /* Make it be sane */
346 /* added CRTSCTS to fix Debian bug 528560 */
347 tty
.c_cflag
&= CBAUD
| CBAUDEX
| CSIZE
| CSTOPB
| PARENB
| PARODD
| CRTSCTS
;
348 tty
.c_cflag
|= CREAD
| HUPCL
| CLOCAL
;
351 tty
.c_iflag
= ICRNL
| IXON
| IXOFF
;
354 tty
.c_oflag
= OPOST
| ONLCR
;
357 tty
.c_lflag
= ISIG
| ICANON
| ECHO
| ECHOE
| ECHOK
| ECHOCTL
| ECHOKE
| IEXTEN
;
359 tcsetattr_stdin_TCSANOW(&tty
);
362 /* Open the new terminal device.
363 * NB: careful, we can be called after vfork! */
364 static int open_stdio_to_tty(const char* tty_name
)
366 /* empty tty_name means "use init's tty", else... */
371 /* fd can be only < 0 or 0: */
372 fd
= device_open(tty_name
, O_RDWR
);
374 message(L_LOG
| L_CONSOLE
, "can't open %s: %s",
375 tty_name
, strerror(errno
));
376 return 0; /* failure */
378 dup2(STDIN_FILENO
, STDOUT_FILENO
);
379 dup2(STDIN_FILENO
, STDERR_FILENO
);
382 return 1; /* success */
385 static void reset_sighandlers_and_unblock_sigs(void)
397 sigprocmask_allsigs(SIG_UNBLOCK
);
400 /* Wrapper around exec:
401 * Takes string (max COMMAND_SIZE chars).
402 * If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'.
403 * Otherwise splits words on whitespace, deals with leading dash,
404 * and uses plain exec().
405 * NB: careful, we can be called after vfork!
407 static void init_exec(const char *command
)
409 char *cmd
[COMMAND_SIZE
/ 2];
410 char buf
[COMMAND_SIZE
+ 6]; /* COMMAND_SIZE+strlen("exec ")+1 */
411 int dash
= (command
[0] == '-' /* maybe? && command[1] == '/' */);
415 /* See if any special /bin/sh requiring characters are present */
416 if (strpbrk(command
, "~`!$^&*()=|\\{}[];\"'<>?") != NULL
) {
417 sprintf(buf
, "exec %s", command
); /* excluding "-" */
418 /* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */
419 cmd
[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL
+ !dash
);
420 cmd
[1] = (char*)"-c";
423 command
= LIBBB_DEFAULT_LOGIN_SHELL
+ 1;
425 /* Convert command (char*) into cmd (char**, one word per string) */
428 next
= strcpy(buf
, command
- dash
); /* command including "-" */
429 command
= next
+ dash
;
430 while ((word
= strsep(&next
, " \t")) != NULL
) {
431 if (*word
!= '\0') { /* not two spaces/tabs together? */
438 /* If we saw leading "-", it is interactive shell.
439 * Try harder to give it a controlling tty.
441 if (ENABLE_FEATURE_INIT_SCTTY
&& dash
) {
442 /* _Attempt_ to make stdin a controlling tty. */
443 ioctl(STDIN_FILENO
, TIOCSCTTY
, 0 /*only try, don't steal*/);
445 /* Here command never contains the dash, cmd[0] might */
446 BB_EXECVP(command
, cmd
);
447 message(L_LOG
| L_CONSOLE
, "can't run '%s': %s", command
, strerror(errno
));
448 /* returns if execvp fails */
451 /* Used only by run_actions */
452 static pid_t
run(const struct init_action
*a
)
456 /* Careful: don't be affected by a signal in vforked child */
457 sigprocmask_allsigs(SIG_BLOCK
);
458 if (BB_MMU
&& (a
->action_type
& ASKFIRST
))
463 message(L_LOG
| L_CONSOLE
, "can't fork");
465 sigprocmask_allsigs(SIG_UNBLOCK
);
466 return pid
; /* Parent or error */
471 /* Reset signal handlers that were set by the parent process */
472 reset_sighandlers_and_unblock_sigs();
474 /* Create a new session and make ourself the process group leader */
477 /* Open the new terminal device */
478 if (!open_stdio_to_tty(a
->terminal
))
481 /* NB: on NOMMU we can't wait for input in child, so
482 * "askfirst" will work the same as "respawn". */
483 if (BB_MMU
&& (a
->action_type
& ASKFIRST
)) {
484 static const char press_enter
[] ALIGN1
=
485 #ifdef CUSTOMIZED_BANNER
486 #include CUSTOMIZED_BANNER
488 "\nPlease press Enter to activate this console. ";
491 * Save memory by not exec-ing anything large (like a shell)
492 * before the user wants it. This is critical if swap is not
493 * enabled and the system has low memory. Generally this will
494 * be run on the second virtual console, and the first will
495 * be allowed to start a shell or whatever an init script
498 dbg_message(L_LOG
, "waiting for enter to start '%s'"
499 "(pid %d, tty '%s')\n",
500 a
->command
, getpid(), a
->terminal
);
501 full_write(STDOUT_FILENO
, press_enter
, sizeof(press_enter
) - 1);
502 while (safe_read(STDIN_FILENO
, &c
, 1) == 1 && c
!= '\n')
507 * When a file named /.init_enable_core exists, setrlimit is called
508 * before processes are spawned to set core file size as unlimited.
509 * This is for debugging only. Don't use this is production, unless
510 * you want core dumps lying about....
512 if (ENABLE_FEATURE_INIT_COREDUMPS
) {
513 if (access("/.init_enable_core", F_OK
) == 0) {
515 limit
.rlim_cur
= RLIM_INFINITY
;
516 limit
.rlim_max
= RLIM_INFINITY
;
517 setrlimit(RLIMIT_CORE
, &limit
);
521 /* Log the process name and args */
522 message(L_LOG
, "starting pid %d, tty '%s': '%s'",
523 getpid(), a
->terminal
, a
->command
);
525 /* Now run it. The new program will take over this PID,
526 * so nothing further in init.c should be run. */
527 init_exec(a
->command
);
528 /* We're still here? Some error happened. */
532 static struct init_action
*mark_terminated(pid_t pid
)
534 struct init_action
*a
;
537 update_utmp(pid
, DEAD_PROCESS
,
542 for (a
= init_action_list
; a
; a
= a
->next
) {
552 static void waitfor(pid_t pid
)
554 /* waitfor(run(x)): protect against failed fork inside run() */
558 /* Wait for any child (prevent zombies from exiting orphaned processes)
559 * but exit the loop only when specified one has exited. */
561 pid_t wpid
= wait(NULL
);
562 mark_terminated(wpid
);
563 /* Unsafe. SIGTSTP handler might have wait'ed it already */
564 /*if (wpid == pid) break;*/
571 /* Run all commands of a particular type */
572 static void run_actions(int action_type
)
574 struct init_action
*a
;
576 for (a
= init_action_list
; a
; a
= a
->next
) {
577 if (!(a
->action_type
& action_type
))
580 if (a
->action_type
& (SYSINIT
| WAIT
| ONCE
| CTRLALTDEL
| SHUTDOWN
)) {
582 if (a
->action_type
& (SYSINIT
| WAIT
| CTRLALTDEL
| SHUTDOWN
))
585 if (a
->action_type
& (RESPAWN
| ASKFIRST
)) {
586 /* Only run stuff with pid == 0. If pid != 0,
587 * it is already running
595 static void new_init_action(uint8_t action_type
, const char *command
, const char *cons
)
597 struct init_action
*a
, **nextp
;
601 * ::shutdown:umount -a -r
602 * ::shutdown:swapoff -a
604 * ::shutdown:swapoff -a
605 * ::shutdown:umount -a -r
606 * On reload, we must ensure entries end up in correct order.
607 * To achieve that, if we find a matching entry, we move it
610 nextp
= &init_action_list
;
611 while ((a
= *nextp
) != NULL
) {
612 /* Don't enter action if it's already in the list.
613 * This prevents losing running RESPAWNs.
615 if (strcmp(a
->command
, command
) == 0
616 && strcmp(a
->terminal
, cons
) == 0
618 /* Remove from list */
620 /* Find the end of the list */
621 while (*nextp
!= NULL
)
622 nextp
= &(*nextp
)->next
;
629 a
= xzalloc(sizeof(*a
));
631 /* Append to the end of the list */
634 a
->action_type
= action_type
;
635 safe_strncpy(a
->command
, command
, sizeof(a
->command
));
636 safe_strncpy(a
->terminal
, cons
, sizeof(a
->terminal
));
637 dbg_message(L_LOG
| L_CONSOLE
, "command='%s' action=%d tty='%s'\n",
638 a
->command
, a
->action_type
, a
->terminal
);
641 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
642 * then parse_inittab() simply adds in some default
643 * actions(i.e., runs INIT_SCRIPT and then starts a pair
644 * of "askfirst" shells). If CONFIG_FEATURE_USE_INITTAB
645 * _is_ defined, but /etc/inittab is missing, this
646 * results in the same set of default behaviors.
648 static void parse_inittab(void)
650 #if ENABLE_FEATURE_USE_INITTAB
652 parser_t
*parser
= config_open2("/etc/inittab", fopen_for_read
);
657 /* No inittab file - set up some default behavior */
658 /* Reboot on Ctrl-Alt-Del */
659 new_init_action(CTRLALTDEL
, "reboot", "");
660 /* Umount all filesystems on halt/reboot */
661 new_init_action(SHUTDOWN
, "umount -a -r", "");
662 /* Swapoff on halt/reboot */
663 if (ENABLE_SWAPONOFF
)
664 new_init_action(SHUTDOWN
, "swapoff -a", "");
665 /* Prepare to restart init when a QUIT is received */
666 new_init_action(RESTART
, "init", "");
667 /* Askfirst shell on tty1-4 */
668 new_init_action(ASKFIRST
, bb_default_login_shell
, "");
669 //TODO: VC_1 instead of ""? "" is console -> ctty problems -> angry users
670 new_init_action(ASKFIRST
, bb_default_login_shell
, VC_2
);
671 new_init_action(ASKFIRST
, bb_default_login_shell
, VC_3
);
672 new_init_action(ASKFIRST
, bb_default_login_shell
, VC_4
);
674 new_init_action(SYSINIT
, INIT_SCRIPT
, "");
678 #if ENABLE_FEATURE_USE_INITTAB
679 /* optional_tty:ignored_runlevel:action:command
680 * Delims are not to be collapsed and need exactly 4 tokens
682 while (config_read(parser
, token
, 4, 0, "#:",
683 PARSE_NORMAL
& ~(PARSE_TRIM
| PARSE_COLLAPSE
))) {
684 /* order must correspond to SYSINIT..RESTART constants */
685 static const char actions
[] ALIGN1
=
686 "sysinit\0""wait\0""once\0""respawn\0""askfirst\0"
687 "ctrlaltdel\0""shutdown\0""restart\0";
689 char *tty
= token
[0];
691 if (!token
[3]) /* less than 4 tokens */
693 action
= index_in_strings(actions
, token
[2]);
694 if (action
< 0 || !token
[3][0]) /* token[3]: command */
696 /* turn .*TTY -> /dev/TTY */
698 tty
= concat_path_file("/dev/", skip_dev_pfx(tty
));
700 new_init_action(1 << action
, token
[3], tty
);
705 message(L_LOG
| L_CONSOLE
, "Bad inittab entry at line %d",
708 config_close(parser
);
712 static void pause_and_low_level_reboot(unsigned magic
) NORETURN
;
713 static void pause_and_low_level_reboot(unsigned magic
)
717 /* Allow time for last message to reach serial console, etc */
720 /* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
721 * in linux/kernel/sys.c, which can cause the machine to panic when
722 * the init process exits... */
724 if (pid
== 0) { /* child */
732 static void run_shutdown_and_kill_processes(void)
734 /* Run everything to be run at "shutdown". This is done _prior_
735 * to killing everything, in case people wish to use scripts to
736 * shut things down gracefully... */
737 run_actions(SHUTDOWN
);
739 message(L_CONSOLE
| L_LOG
, "The system is going down NOW!");
741 /* Send signals to every process _except_ pid 1 */
743 message(L_CONSOLE
| L_LOG
, "Sent SIG%s to all processes", "TERM");
748 message(L_CONSOLE
, "Sent SIG%s to all processes", "KILL");
750 /*sleep(1); - callers take care about making a pause */
753 /* Signal handling by init:
755 * For process with PID==1, on entry kernel sets all signals to SIG_DFL
756 * and unmasks all signals. However, for process with PID==1,
757 * default action (SIG_DFL) on any signal is to ignore it,
758 * even for special signals SIGKILL and SIGCONT.
759 * Also, any signal can be caught or blocked.
760 * (but SIGSTOP is still handled specially, at least in 2.6.20)
762 * We install two kinds of handlers, "immediate" and "delayed".
764 * Immediate handlers execute at any time, even while, say, sysinit
767 * Delayed handlers just set a flag variable. The variable is checked
768 * in the main loop and acted upon.
770 * halt/poweroff/reboot and restart have immediate handlers.
771 * They only traverse linked list of struct action's, never modify it,
772 * this should be safe to do even in signal handler. Also they
775 * SIGSTOP and SIGTSTP have immediate handlers. They just wait
776 * for SIGCONT to happen.
778 * SIGHUP has a delayed handler, because modifying linked list
779 * of struct action's from a signal handler while it is manipulated
780 * by the program may be disastrous.
782 * Ctrl-Alt-Del has a delayed handler. Not a must, but allowing
783 * it to happen even somewhere inside "sysinit" would be a bit awkward.
785 * There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide
786 * and only one will be remembered and acted upon.
789 /* The SIGUSR[12]/SIGTERM handler */
790 static void halt_reboot_pwoff(int sig
) NORETURN
;
791 static void halt_reboot_pwoff(int sig
)
796 /* We may call run() and it unmasks signals,
797 * including the one masked inside this signal handler.
798 * Testcase which would start multiple reboot scripts:
799 * while true; do reboot; done
802 reset_sighandlers_and_unblock_sigs();
804 run_shutdown_and_kill_processes();
808 if (sig
== SIGTERM
) {
811 } else if (sig
== SIGUSR2
) {
815 message(L_CONSOLE
, "Requesting system %s", m
);
816 pause_and_low_level_reboot(rb
);
820 /* Handler for QUIT - exec "restart" action,
821 * else (no such action defined) do nothing */
822 static void restart_handler(int sig UNUSED_PARAM
)
824 struct init_action
*a
;
826 for (a
= init_action_list
; a
; a
= a
->next
) {
827 if (!(a
->action_type
& RESTART
))
830 /* Starting from here, we won't return.
831 * Thus don't need to worry about preserving errno
835 reset_sighandlers_and_unblock_sigs();
837 run_shutdown_and_kill_processes();
840 /* Allow Ctrl-Alt-Del to reboot the system.
841 * This is how kernel sets it up for init, we follow suit.
843 reboot(RB_ENABLE_CAD
); /* misnomer */
846 if (open_stdio_to_tty(a
->terminal
)) {
847 dbg_message(L_CONSOLE
, "Trying to re-exec %s", a
->command
);
848 /* Theoretically should be safe.
849 * But in practice, kernel bugs may leave
850 * unkillable processes, and wait() may block forever.
851 * Oh well. Hoping "new" init won't be too surprised
852 * by having children it didn't create.
854 //while (wait(NULL) > 0)
856 init_exec(a
->command
);
858 /* Open or exec failed */
859 pause_and_low_level_reboot(RB_HALT_SYSTEM
);
864 /* The SIGSTOP/SIGTSTP handler
865 * NB: inside it, all signals except SIGCONT are masked
866 * via appropriate setup in sigaction().
868 static void stop_handler(int sig UNUSED_PARAM
)
870 smallint saved_bb_got_signal
;
873 saved_bb_got_signal
= bb_got_signal
;
875 signal(SIGCONT
, record_signo
);
880 if (bb_got_signal
== SIGCONT
)
882 /* NB: this can accidentally wait() for a process
883 * which we waitfor() elsewhere! waitfor() must have
884 * code which is resilient against this.
886 wpid
= wait_any_nohang(NULL
);
887 mark_terminated(wpid
);
891 signal(SIGCONT
, SIG_DFL
);
893 bb_got_signal
= saved_bb_got_signal
;
896 #if ENABLE_FEATURE_USE_INITTAB
897 static void reload_inittab(void)
899 struct init_action
*a
, **nextp
;
901 message(L_LOG
, "reloading /etc/inittab");
903 /* Disable old entries */
904 for (a
= init_action_list
; a
; a
= a
->next
)
907 /* Append new entries, or modify existing entries
908 * (incl. setting a->action_type) if cmd and device name
909 * match new ones. End result: only entries with
910 * a->action_type == 0 are stale.
914 #if ENABLE_FEATURE_KILL_REMOVED
915 /* Kill stale entries */
916 /* Be nice and send SIGTERM first */
917 for (a
= init_action_list
; a
; a
= a
->next
)
918 if (a
->action_type
== 0 && a
->pid
!= 0)
919 kill(a
->pid
, SIGTERM
);
920 if (CONFIG_FEATURE_KILL_DELAY
) {
921 /* NB: parent will wait in NOMMU case */
922 if ((BB_MMU
? fork() : vfork()) == 0) { /* child */
923 sleep(CONFIG_FEATURE_KILL_DELAY
);
924 for (a
= init_action_list
; a
; a
= a
->next
)
925 if (a
->action_type
== 0 && a
->pid
!= 0)
926 kill(a
->pid
, SIGKILL
);
932 /* Remove stale entries and SYSINIT entries.
933 * We never rerun SYSINIT entries anyway,
934 * removing them too saves a few bytes */
935 nextp
= &init_action_list
;
936 while ((a
= *nextp
) != NULL
) {
937 if ((a
->action_type
& ~SYSINIT
) == 0) {
946 /* run_actions(RESPAWN | ASKFIRST); */
947 /* - we return to main loop, which does this automagically */
951 static int check_delayed_sigs(void)
956 smallint sig
= bb_got_signal
;
962 #if ENABLE_FEATURE_USE_INITTAB
967 run_actions(CTRLALTDEL
);
971 #if DEBUG_SEGV_HANDLER
973 void handle_sigsegv(int sig
, siginfo_t
*info
, void *ucontext
)
979 ip
= uc
->uc_mcontext
.gregs
[REG_EIP
];
980 fdprintf(2, "signal:%d address:0x%lx ip:0x%lx\n",
982 /* this is void*, but using %p would print "(null)"
983 * even for ptrs which are not exactly 0, but, say, 0x123:
988 /* glibc extension */
991 size
= backtrace(array
, 50);
992 backtrace_symbols_fd(array
, size
, 2);
994 for (;;) sleep(9999);
998 int init_main(int argc
, char **argv
) MAIN_EXTERNALLY_VISIBLE
;
999 int init_main(int argc UNUSED_PARAM
, char **argv
)
1001 if (argv
[1] && strcmp(argv
[1], "-q") == 0) {
1002 return kill(1, SIGHUP
);
1005 #if DEBUG_SEGV_HANDLER
1007 struct sigaction sa
;
1008 memset(&sa
, 0, sizeof(sa
));
1009 sa
.sa_sigaction
= handle_sigsegv
;
1010 sa
.sa_flags
= SA_SIGINFO
;
1011 sigaction(SIGSEGV
, &sa
, NULL
);
1012 sigaction(SIGILL
, &sa
, NULL
);
1013 sigaction(SIGFPE
, &sa
, NULL
);
1014 sigaction(SIGBUS
, &sa
, NULL
);
1019 /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
1021 && (!ENABLE_FEATURE_INITRD
|| applet_name
[0] != 'l') /* not linuxrc? */
1023 bb_error_msg_and_die("must be run as PID 1");
1025 #ifdef RB_DISABLE_CAD
1026 /* Turn off rebooting via CTL-ALT-DEL - we get a
1027 * SIGINT on CAD so we can shut things down gracefully... */
1028 reboot(RB_DISABLE_CAD
); /* misnomer */
1032 /* If, say, xmalloc would ever die, we don't want to oops kernel
1034 * NB: we set die_sleep *after* PID 1 check and bb_show_usage.
1035 * Otherwise, for example, "init u" ("please rexec yourself"
1036 * command for sysvinit) will show help text (which isn't too bad),
1037 * *and sleep forever* (which is bad!)
1039 die_sleep
= 30 * 24*60*60;
1041 /* Figure out where the default console should be */
1047 /* Make sure environs is set to something sane */
1048 putenv((char *) "HOME=/");
1049 putenv((char *) bb_PATH_root_path
);
1050 putenv((char *) "SHELL=/bin/sh");
1051 putenv((char *) "USER=root"); /* needed? why? */
1054 xsetenv("RUNLEVEL", argv
[1]);
1056 #if !ENABLE_FEATURE_EXTRA_QUIET
1058 message(L_CONSOLE
| L_LOG
, "init started: %s", bb_banner
);
1061 /* struct sysinfo is linux-specific */
1063 /* Make sure there is enough memory to do something useful. */
1064 if (ENABLE_SWAPONOFF
) {
1065 struct sysinfo info
;
1067 if (sysinfo(&info
) == 0
1068 && (info
.mem_unit
? info
.mem_unit
: 1) * (long long)info
.totalram
< 1024*1024
1070 message(L_CONSOLE
, "Low memory, forcing swapon");
1071 /* swapon -a requires /proc typically */
1072 new_init_action(SYSINIT
, "mount -t proc proc /proc", "");
1073 /* Try to turn on swap */
1074 new_init_action(SYSINIT
, "swapon -a", "");
1075 run_actions(SYSINIT
); /* wait and removing */
1080 /* Check if we are supposed to be in single user mode */
1082 && (strcmp(argv
[1], "single") == 0 || strcmp(argv
[1], "-s") == 0 || LONE_CHAR(argv
[1], '1'))
1084 /* ??? shouldn't we set RUNLEVEL="b" here? */
1085 /* Start a shell on console */
1086 new_init_action(RESPAWN
, bb_default_login_shell
, "");
1088 /* Not in single user mode - see what inittab says */
1090 /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
1091 * then parse_inittab() simply adds in some default
1092 * actions(i.e., INIT_SCRIPT and a pair
1093 * of "askfirst" shells */
1098 if (getenv("SELINUX_INIT") == NULL
) {
1101 putenv((char*)"SELINUX_INIT=YES");
1102 if (selinux_init_load_policy(&enforce
) == 0) {
1103 BB_EXECVP(argv
[0], argv
);
1104 } else if (enforce
> 0) {
1105 /* SELinux in enforcing mode but load_policy failed */
1106 message(L_CONSOLE
, "can't load SELinux Policy. "
1107 "Machine is in enforcing mode. Halting now.");
1108 return EXIT_FAILURE
;
1113 /* Make the command line just say "init" - thats all, nothing else */
1114 strncpy(argv
[0], "init", strlen(argv
[0]));
1115 /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
1117 memset(*argv
, 0, strlen(*argv
));
1119 /* Set up signal handlers */
1121 struct sigaction sa
;
1124 + (1 << SIGUSR1
) /* halt */
1125 + (1 << SIGTERM
) /* reboot */
1126 + (1 << SIGUSR2
) /* poweroff */
1127 , halt_reboot_pwoff
);
1128 signal(SIGQUIT
, restart_handler
); /* re-exec another init */
1130 /* Stop handler must allow only SIGCONT inside itself */
1131 memset(&sa
, 0, sizeof(sa
));
1132 sigfillset(&sa
.sa_mask
);
1133 sigdelset(&sa
.sa_mask
, SIGCONT
);
1134 sa
.sa_handler
= stop_handler
;
1135 /* NB: sa_flags doesn't have SA_RESTART.
1136 * It must be able to interrupt wait().
1138 sigaction_set(SIGTSTP
, &sa
); /* pause */
1139 /* Does not work as intended, at least in 2.6.20.
1140 * SIGSTOP is simply ignored by init:
1142 sigaction_set(SIGSTOP
, &sa
); /* pause */
1144 /* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
1145 * setting handler without SA_RESTART flag.
1147 bb_signals_recursive_norestart((1 << SIGINT
), record_signo
);
1150 /* Set up "reread /etc/inittab" handler.
1151 * Handler is set up without SA_RESTART, it will interrupt syscalls.
1153 if (!DEBUG_INIT
&& ENABLE_FEATURE_USE_INITTAB
)
1154 bb_signals_recursive_norestart((1 << SIGHUP
), record_signo
);
1156 /* Now run everything that needs to be run */
1157 /* First run the sysinit command */
1158 run_actions(SYSINIT
);
1159 check_delayed_sigs();
1160 /* Next run anything that wants to block */
1162 check_delayed_sigs();
1163 /* Next run anything to be run only once */
1166 /* Now run the looping stuff for the rest of forever.
1171 maybe_WNOHANG
= check_delayed_sigs();
1173 /* (Re)run the respawn/askfirst stuff */
1174 run_actions(RESPAWN
| ASKFIRST
);
1175 maybe_WNOHANG
|= check_delayed_sigs();
1177 /* Don't consume all CPU time - sleep a bit */
1179 maybe_WNOHANG
|= check_delayed_sigs();
1181 /* Wait for any child process(es) to exit.
1183 * If check_delayed_sigs above reported that a signal
1184 * was caught, wait will be nonblocking. This ensures
1185 * that if SIGHUP has reloaded inittab, respawn and askfirst
1186 * actions will not be delayed until next child death.
1189 maybe_WNOHANG
= WNOHANG
;
1192 struct init_action
*a
;
1194 /* If signals happen _in_ the wait, they interrupt it,
1195 * bb_signals_recursive_norestart set them up that way
1197 wpid
= waitpid(-1, NULL
, maybe_WNOHANG
);
1201 a
= mark_terminated(wpid
);
1203 message(L_LOG
, "process '%s' (pid %d) exited. "
1204 "Scheduling for restart.",
1207 /* See if anyone else is waiting to be reaped */
1208 maybe_WNOHANG
= WNOHANG
;
1213 //usage:#define linuxrc_trivial_usage NOUSAGE_STR
1214 //usage:#define linuxrc_full_usage ""
1216 //usage:#define init_trivial_usage
1218 //usage:#define init_full_usage "\n\n"
1219 //usage: "Init is the parent of all processes"
1221 //usage:#define init_notes_usage
1222 //usage: "This version of init is designed to be run only by the kernel.\n"
1224 //usage: "BusyBox init doesn't support multiple runlevels. The runlevels field of\n"
1225 //usage: "the /etc/inittab file is completely ignored by BusyBox init. If you want\n"
1226 //usage: "runlevels, use sysvinit.\n"
1228 //usage: "BusyBox init works just fine without an inittab. If no inittab is found,\n"
1229 //usage: "it has the following default behavior:\n"
1231 //usage: " ::sysinit:/etc/init.d/rcS\n"
1232 //usage: " ::askfirst:/bin/sh\n"
1233 //usage: " ::ctrlaltdel:/sbin/reboot\n"
1234 //usage: " ::shutdown:/sbin/swapoff -a\n"
1235 //usage: " ::shutdown:/bin/umount -a -r\n"
1236 //usage: " ::restart:/sbin/init\n"
1238 //usage: "if it detects that /dev/console is _not_ a serial console, it will also run:\n"
1240 //usage: " tty2::askfirst:/bin/sh\n"
1241 //usage: " tty3::askfirst:/bin/sh\n"
1242 //usage: " tty4::askfirst:/bin/sh\n"
1244 //usage: "If you choose to use an /etc/inittab file, the inittab entry format is as follows:\n"
1246 //usage: " <id>:<runlevels>:<action>:<process>\n"
1250 //usage: " WARNING: This field has a non-traditional meaning for BusyBox init!\n"
1251 //usage: " The id field is used by BusyBox init to specify the controlling tty for\n"
1252 //usage: " the specified process to run on. The contents of this field are\n"
1253 //usage: " appended to \"/dev/\" and used as-is. There is no need for this field to\n"
1254 //usage: " be unique, although if it isn't you may have strange results. If this\n"
1255 //usage: " field is left blank, the controlling tty is set to the console. Also\n"
1256 //usage: " note that if BusyBox detects that a serial console is in use, then only\n"
1257 //usage: " entries whose controlling tty is either the serial console or /dev/null\n"
1258 //usage: " will be run. BusyBox init does nothing with utmp. We don't need no\n"
1259 //usage: " stinkin' utmp.\n"
1261 //usage: " <runlevels>:\n"
1263 //usage: " The runlevels field is completely ignored.\n"
1265 //usage: " <action>:\n"
1267 //usage: " Valid actions include: sysinit, respawn, askfirst, wait,\n"
1268 //usage: " once, restart, ctrlaltdel, and shutdown.\n"
1270 //usage: " The available actions can be classified into two groups: actions\n"
1271 //usage: " that are run only once, and actions that are re-run when the specified\n"
1272 //usage: " process exits.\n"
1274 //usage: " Run only-once actions:\n"
1276 //usage: " 'sysinit' is the first item run on boot. init waits until all\n"
1277 //usage: " sysinit actions are completed before continuing. Following the\n"
1278 //usage: " completion of all sysinit actions, all 'wait' actions are run.\n"
1279 //usage: " 'wait' actions, like 'sysinit' actions, cause init to wait until\n"
1280 //usage: " the specified task completes. 'once' actions are asynchronous,\n"
1281 //usage: " therefore, init does not wait for them to complete. 'restart' is\n"
1282 //usage: " the action taken to restart the init process. By default this should\n"
1283 //usage: " simply run /sbin/init, but can be a script which runs pivot_root or it\n"
1284 //usage: " can do all sorts of other interesting things. The 'ctrlaltdel' init\n"
1285 //usage: " actions are run when the system detects that someone on the system\n"
1286 //usage: " console has pressed the CTRL-ALT-DEL key combination. Typically one\n"
1287 //usage: " wants to run 'reboot' at this point to cause the system to reboot.\n"
1288 //usage: " Finally the 'shutdown' action specifies the actions to taken when\n"
1289 //usage: " init is told to reboot. Unmounting filesystems and disabling swap\n"
1290 //usage: " is a very good here.\n"
1292 //usage: " Run repeatedly actions:\n"
1294 //usage: " 'respawn' actions are run after the 'once' actions. When a process\n"
1295 //usage: " started with a 'respawn' action exits, init automatically restarts\n"
1296 //usage: " it. Unlike sysvinit, BusyBox init does not stop processes from\n"
1297 //usage: " respawning out of control. The 'askfirst' actions acts just like\n"
1298 //usage: " respawn, except that before running the specified process it\n"
1299 //usage: " displays the line \"Please press Enter to activate this console.\"\n"
1300 //usage: " and then waits for the user to press enter before starting the\n"
1301 //usage: " specified process.\n"
1303 //usage: " Unrecognized actions (like initdefault) will cause init to emit an\n"
1304 //usage: " error message, and then go along with its business. All actions are\n"
1305 //usage: " run in the order they appear in /etc/inittab.\n"
1307 //usage: " <process>:\n"
1309 //usage: " Specifies the process to be executed and its command line.\n"
1311 //usage: "Example /etc/inittab file:\n"
1313 //usage: " # This is run first except when booting in single-user mode\n"
1315 //usage: " ::sysinit:/etc/init.d/rcS\n"
1317 //usage: " # /bin/sh invocations on selected ttys\n"
1319 //usage: " # Start an \"askfirst\" shell on the console (whatever that may be)\n"
1320 //usage: " ::askfirst:-/bin/sh\n"
1321 //usage: " # Start an \"askfirst\" shell on /dev/tty2-4\n"
1322 //usage: " tty2::askfirst:-/bin/sh\n"
1323 //usage: " tty3::askfirst:-/bin/sh\n"
1324 //usage: " tty4::askfirst:-/bin/sh\n"
1326 //usage: " # /sbin/getty invocations for selected ttys\n"
1328 //usage: " tty4::respawn:/sbin/getty 38400 tty4\n"
1329 //usage: " tty5::respawn:/sbin/getty 38400 tty5\n"
1332 //usage: " # Example of how to put a getty on a serial line (for a terminal)\n"
1334 //usage: " #::respawn:/sbin/getty -L ttyS0 9600 vt100\n"
1335 //usage: " #::respawn:/sbin/getty -L ttyS1 9600 vt100\n"
1337 //usage: " # Example how to put a getty on a modem line\n"
1338 //usage: " #::respawn:/sbin/getty 57600 ttyS2\n"
1340 //usage: " # Stuff to do when restarting the init process\n"
1341 //usage: " ::restart:/sbin/init\n"
1343 //usage: " # Stuff to do before rebooting\n"
1344 //usage: " ::ctrlaltdel:/sbin/reboot\n"
1345 //usage: " ::shutdown:/bin/umount -a -r\n"
1346 //usage: " ::shutdown:/sbin/swapoff -a\n"