* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
* Adjusted by so many folks, it's impossible to keep track.
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
+//applet:IF_INIT(APPLET(init, BB_DIR_SBIN, BB_SUID_DROP))
+//applet:IF_FEATURE_INITRD(APPLET_ODDNAME(linuxrc, init, BB_DIR_ROOT, BB_SUID_DROP, linuxrc))
+
+//kbuild:lib-$(CONFIG_INIT) += init.o
+
+//config:config INIT
+//config: bool "init"
+//config: default y
+//config: select FEATURE_SYSLOG
+//config: help
+//config: init is the first program run when the system boots.
+//config:
+//config:config FEATURE_USE_INITTAB
+//config: bool "Support reading an inittab file"
+//config: default y
+//config: depends on INIT
+//config: help
+//config: Allow init to read an inittab file when the system boot.
+//config:
+//config:config FEATURE_KILL_REMOVED
+//config: bool "Support killing processes that have been removed from inittab"
+//config: default n
+//config: depends on FEATURE_USE_INITTAB
+//config: help
+//config: When respawn entries are removed from inittab and a SIGHUP is
+//config: sent to init, this option will make init kill the processes
+//config: that have been removed.
+//config:
+//config:config FEATURE_KILL_DELAY
+//config: int "How long to wait between TERM and KILL (0 - send TERM only)" if FEATURE_KILL_REMOVED
+//config: range 0 1024
+//config: default 0
+//config: depends on FEATURE_KILL_REMOVED
+//config: help
+//config: With nonzero setting, init sends TERM, forks, child waits N
+//config: seconds, sends KILL and exits. Setting it too high is unwise
+//config: (child will hang around for too long and could actually kill
+//config: the wrong process!)
+//config:
+//config:config FEATURE_INIT_SCTTY
+//config: bool "Run commands with leading dash with controlling tty"
+//config: default y
+//config: depends on INIT
+//config: help
+//config: If this option is enabled, init will try to give a controlling
+//config: tty to any command which has leading hyphen (often it's "-/bin/sh").
+//config: More precisely, init will do "ioctl(STDIN_FILENO, TIOCSCTTY, 0)".
+//config: If device attached to STDIN_FILENO can be a ctty but is not yet
+//config: a ctty for other session, it will become this process' ctty.
+//config: This is not the traditional init behavour, but is often what you want
+//config: in an embedded system where the console is only accessed during
+//config: development or for maintenance.
+//config: NB: using cttyhack applet may work better.
+//config:
+//config:config FEATURE_INIT_SYSLOG
+//config: bool "Enable init to write to syslog"
+//config: default y
+//config: depends on INIT
+//config:
+//config:config FEATURE_EXTRA_QUIET
+//config: bool "Be _extra_ quiet on boot"
+//config: default y
+//config: depends on INIT
+//config: help
+//config: Prevent init from logging some messages to the console during boot.
+//config:
+//config:config FEATURE_INIT_COREDUMPS
+//config: bool "Support dumping core for child processes (debugging only)"
+//config: default y
+//config: depends on INIT
+//config: help
+//config: If this option is enabled and the file /.init_enable_core
+//config: exists, then init will call setrlimit() to allow unlimited
+//config: core file sizes. If this option is disabled, processes
+//config: will not generate any core files.
+//config:
+//config:config FEATURE_INITRD
+//config: bool "Support running init from within an initrd (not initramfs)"
+//config: default y
+//config: depends on INIT
+//config: help
+//config: Legacy support for running init under the old-style initrd. Allows
+//config: the name linuxrc to act as init, and it doesn't assume init is PID 1.
+//config:
+//config: This does not apply to initramfs, which runs /init as PID 1 and
+//config: requires no special support.
+//config:
+//config:config INIT_TERMINAL_TYPE
+//config: string "Initial terminal type"
+//config: default "linux"
+//config: depends on INIT
+//config: help
+//config: This is the initial value set by init for the TERM environment
+//config: variable. This variable is used by programs which make use of
+//config: extended terminal capabilities.
+//config:
+//config: Note that on Linux, init attempts to detect serial terminal and
+//config: sets TERM to "vt102" if one is found.
+
#include "libbb.h"
#include <syslog.h>
#include <paths.h>
-#include <sys/reboot.h>
#include <sys/resource.h>
+#ifdef __linux__
+#include <linux/vt.h>
+#endif
+#include "reboot.h" /* reboot() constants */
+/* Used only for sanitizing purposes in set_sane_term() below. On systems where
+ * the baud rate is stored in a separate field, we can safely disable them. */
+#ifndef CBAUD
+# define CBAUD 0
+# define CBAUDEX 0
+#endif
/* Was a CONFIG_xxx option. A lot of people were building
* not fully functional init by switching it on! */
#define ONCE 0x04
/*
* NB: while SYSINIT/WAIT/ONCE are being processed,
- * SIGHUP ("reread /etc/inittab") will be ignored.
- * Rationale: it would be ambiguous whether SYSINIT/WAIT/ONCE
- * need to be rerun or not.
+ * SIGHUP ("reread /etc/inittab") will be processed only after
+ * each group of actions. If new inittab adds, say, a SYSINIT action,
+ * it will not be run, since init is already "past SYSINIT stage".
*/
/* Start these after ONCE are started, restart on exit */
#define RESPAWN 0x08
enum {
L_LOG = 0x1,
L_CONSOLE = 0x2,
- MAYBE_CONSOLE = L_CONSOLE * !ENABLE_FEATURE_EXTRA_QUIET,
-#ifndef RB_HALT_SYSTEM
- RB_HALT_SYSTEM = 0xcdef0123, /* FIXME: this overflows enum */
- RB_ENABLE_CAD = 0x89abcdef,
- RB_DISABLE_CAD = 0,
- RB_POWER_OFF = 0x4321fedc,
- RB_AUTOBOOT = 0x01234567,
-#endif
};
/* Print a message to the specified device.
msg[l] = '\0';
if (where & L_LOG) {
/* Log the message to syslogd */
- openlog("init", 0, LOG_DAEMON);
+ openlog(applet_name, 0, LOG_DAEMON);
/* don't print "\r" */
syslog(LOG_INFO, "%s", msg + 1);
closelog();
}
}
-/* From <linux/serial.h> */
-struct serial_struct {
- int type;
- int line;
- unsigned int port;
- int irq;
- int flags;
- int xmit_fifo_size;
- int custom_divisor;
- int baud_base;
- unsigned short close_delay;
- char io_type;
- char reserved_char[1];
- int hub6;
- unsigned short closing_wait; /* time to wait before closing */
- unsigned short closing_wait2; /* no longer used... */
- unsigned char *iomem_base;
- unsigned short iomem_reg_shift;
- unsigned int port_high;
- unsigned long iomap_base; /* cookie passed into ioremap */
- int reserved[1];
- /* Paranoia (imagine 64bit kernel overwriting 32bit userspace stack) */
- uint32_t bbox_reserved[16];
-};
static void console_init(void)
{
- struct serial_struct sr;
+#ifdef VT_OPENQRY
+ int vtno;
+#endif
char *s;
s = getenv("CONSOLE");
}
s = getenv("TERM");
- if (ioctl(STDIN_FILENO, TIOCGSERIAL, &sr) == 0) {
- /* Force the TERM setting to vt102 for serial console
+#ifdef VT_OPENQRY
+ if (ioctl(STDIN_FILENO, VT_OPENQRY, &vtno) != 0) {
+ /* Not a linux terminal, probably serial console.
+ * Force the TERM setting to vt102
* if TERM is set to linux (the default) */
if (!s || strcmp(s, "linux") == 0)
putenv((char*)"TERM=vt102");
if (!ENABLE_FEATURE_INIT_SYSLOG)
log_console = NULL;
- } else if (!s)
- putenv((char*)"TERM=linux");
+ } else
+#endif
+ if (!s)
+ putenv((char*)"TERM=" CONFIG_INIT_TERMINAL_TYPE);
}
/* Set terminal settings to reasonable defaults.
tty.c_cc[VSTOP] = 19; /* C-s */
tty.c_cc[VSUSP] = 26; /* C-z */
+#ifdef __linux__
/* use line discipline 0 */
tty.c_line = 0;
+#endif
/* Make it be sane */
- tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD;
+#ifndef CRTSCTS
+# define CRTSCTS 0
+#endif
+ /* added CRTSCTS to fix Debian bug 528560 */
+ tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD | CRTSCTS;
tty.c_cflag |= CREAD | HUPCL | CLOCAL;
/* input modes */
tty.c_oflag = OPOST | ONLCR;
/* local modes */
- tty.c_lflag =
- ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
+ tty.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;
tcsetattr_stdin_TCSANOW(&tty);
}
return 1; /* success */
}
+static void reset_sighandlers_and_unblock_sigs(void)
+{
+ bb_signals(0
+ + (1 << SIGUSR1)
+ + (1 << SIGUSR2)
+ + (1 << SIGTERM)
+ + (1 << SIGQUIT)
+ + (1 << SIGINT)
+ + (1 << SIGHUP)
+ + (1 << SIGTSTP)
+ + (1 << SIGSTOP)
+ , SIG_DFL);
+ sigprocmask_allsigs(SIG_UNBLOCK);
+}
+
/* Wrapper around exec:
* Takes string (max COMMAND_SIZE chars).
* If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'.
char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */
int dash = (command[0] == '-' /* maybe? && command[1] == '/' */);
+ command += dash;
+
/* See if any special /bin/sh requiring characters are present */
if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
- strcpy(buf, "exec ");
- strcpy(buf + 5, command + dash); /* excluding "-" */
+ sprintf(buf, "exec %s", command); /* excluding "-" */
/* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */
cmd[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL + !dash);
cmd[1] = (char*)"-c";
cmd[2] = buf;
cmd[3] = NULL;
+ command = LIBBB_DEFAULT_LOGIN_SHELL + 1;
} else {
/* Convert command (char*) into cmd (char**, one word per string) */
char *word, *next;
int i = 0;
- next = strcpy(buf, command); /* including "-" */
+ next = strcpy(buf, command - dash); /* command including "-" */
while ((word = strsep(&next, " \t")) != NULL) {
if (*word != '\0') { /* not two spaces/tabs together? */
cmd[i] = word;
}
/* If we saw leading "-", it is interactive shell.
* Try harder to give it a controlling tty.
- * And skip "-" in actual exec call. */
- if (dash) {
+ */
+ if (ENABLE_FEATURE_INIT_SCTTY && dash) {
/* _Attempt_ to make stdin a controlling tty. */
- if (ENABLE_FEATURE_INIT_SCTTY)
- ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/);
+ ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/);
}
- BB_EXECVP(cmd[0] + dash, cmd);
- message(L_LOG | L_CONSOLE, "cannot run '%s': %s", cmd[0], strerror(errno));
+ /* Here command never contains the dash, cmd[0] might */
+ BB_EXECVP(command, cmd);
+ message(L_LOG | L_CONSOLE, "can't run '%s': %s", command, strerror(errno));
/* returns if execvp fails */
}
{
pid_t pid;
+ /* Careful: don't be affected by a signal in vforked child */
+ sigprocmask_allsigs(SIG_BLOCK);
if (BB_MMU && (a->action_type & ASKFIRST))
pid = fork();
else
pid = vfork();
if (pid < 0)
message(L_LOG | L_CONSOLE, "can't fork");
- if (pid)
+ if (pid) {
+ sigprocmask_allsigs(SIG_UNBLOCK);
return pid; /* Parent or error */
+ }
/* Child */
/* Reset signal handlers that were set by the parent process */
-//TODO: block signals across fork(), prevent them to affect child before
-//signals are reset?
- bb_signals(0
- + (1 << SIGUSR1)
- + (1 << SIGUSR2)
- + (1 << SIGTERM)
- + (1 << SIGQUIT)
- + (1 << SIGINT)
- + (1 << SIGHUP)
- + (1 << SIGTSTP)
- , SIG_DFL);
+ reset_sighandlers_and_unblock_sigs();
/* Create a new session and make ourself the process group leader */
setsid();
return a;
}
}
+ update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL,
+ /*username:*/ NULL,
+ /*hostname:*/ NULL);
}
return NULL;
}
/* Don't enter action if it's already in the list,
* This prevents losing running RESPAWNs.
*/
- if ((strcmp(a->command, command) == 0)
- && (strcmp(a->terminal, cons) == 0)
+ if (strcmp(a->command, command) == 0
+ && strcmp(a->terminal, cons) == 0
) {
/* Remove from list */
*nextp = a->next;
goto bad_entry;
/* turn .*TTY -> /dev/TTY */
if (tty[0]) {
- if (strncmp(tty, "/dev/", 5) == 0)
- tty += 5;
- tty = concat_path_file("/dev/", tty);
+ tty = concat_path_file("/dev/", skip_dev_pfx(tty));
}
new_init_action(1 << action, token[3], tty);
if (tty[0])
* it to happen even somewhere inside "sysinit" would be a bit awkward.
*
* There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide
- * and only one will be remebered and acted upon.
+ * and only one will be remembered and acted upon.
*/
+/* The SIGUSR[12]/SIGTERM handler */
static void halt_reboot_pwoff(int sig) NORETURN;
static void halt_reboot_pwoff(int sig)
{
const char *m;
unsigned rb;
+ /* We may call run() and it unmasks signals,
+ * including the one masked inside this signal handler.
+ * Testcase which would start multiple reboot scripts:
+ * while true; do reboot; done
+ * Preventing it:
+ */
+ reset_sighandlers_and_unblock_sigs();
+
run_shutdown_and_kill_processes();
m = "halt";
/* not reached */
}
-/* The SIGSTOP/SIGTSTP handler
- * NB: inside it, all signals except SIGCONT are masked
- * via appropriate setup in sigaction().
- */
-static void stop_handler(int sig UNUSED_PARAM)
-{
- smallint saved_bb_got_signal;
- int saved_errno;
-
- saved_bb_got_signal = bb_got_signal;
- saved_errno = errno;
- signal(SIGCONT, record_signo);
-
- while (1) {
- pid_t wpid;
-
- if (bb_got_signal == SIGCONT)
- break;
- /* NB: this can accidentally wait() for a process
- * which we waitfor() elsewhere! waitfor() must have
- * code which is resilient against this.
- */
- wpid = wait_any_nohang(NULL);
- mark_terminated(wpid);
- sleep(1);
- }
-
- signal(SIGCONT, SIG_DFL);
- errno = saved_errno;
- bb_got_signal = saved_bb_got_signal;
-}
-
/* Handler for QUIT - exec "restart" action,
* else (no such action defined) do nothing */
static void restart_handler(int sig UNUSED_PARAM)
* Thus don't need to worry about preserving errno
* and such.
*/
+
+ reset_sighandlers_and_unblock_sigs();
+
run_shutdown_and_kill_processes();
+#ifdef RB_ENABLE_CAD
/* Allow Ctrl-Alt-Del to reboot the system.
* This is how kernel sets it up for init, we follow suit.
*/
reboot(RB_ENABLE_CAD); /* misnomer */
+#endif
if (open_stdio_to_tty(a->terminal)) {
dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command);
}
}
+/* The SIGSTOP/SIGTSTP handler
+ * NB: inside it, all signals except SIGCONT are masked
+ * via appropriate setup in sigaction().
+ */
+static void stop_handler(int sig UNUSED_PARAM)
+{
+ smallint saved_bb_got_signal;
+ int saved_errno;
+
+ saved_bb_got_signal = bb_got_signal;
+ saved_errno = errno;
+ signal(SIGCONT, record_signo);
+
+ while (1) {
+ pid_t wpid;
+
+ if (bb_got_signal == SIGCONT)
+ break;
+ /* NB: this can accidentally wait() for a process
+ * which we waitfor() elsewhere! waitfor() must have
+ * code which is resilient against this.
+ */
+ wpid = wait_any_nohang(NULL);
+ mark_terminated(wpid);
+ sleep(1);
+ }
+
+ signal(SIGCONT, SIG_DFL);
+ errno = saved_errno;
+ bb_got_signal = saved_bb_got_signal;
+}
+
#if ENABLE_FEATURE_USE_INITTAB
static void reload_inittab(void)
{
/* Disable old entries */
for (a = init_action_list; a; a = a->next)
- a->action_type = ONCE;
+ a->action_type = 0;
/* Append new entries, or modify existing entries
- * (set a->action_type) if cmd and device name
+ * (incl. setting a->action_type) if cmd and device name
* match new ones. End result: only entries with
- * a->action_type == ONCE are stale.
+ * a->action_type == 0 are stale.
*/
parse_inittab();
- if (ENABLE_FEATURE_KILL_REMOVED) {
- /* Kill stale entries */
- /* Be nice and send SIGTERM first */
- for (a = init_action_list; a; a = a->next)
- if (a->action_type == ONCE && a->pid != 0)
- kill(a->pid, SIGTERM);
- if (CONFIG_FEATURE_KILL_DELAY) {
- /* NB: parent will wait in NOMMU case */
- if ((BB_MMU ? fork() : vfork()) == 0) { /* child */
- sleep(CONFIG_FEATURE_KILL_DELAY);
- for (a = init_action_list; a; a = a->next)
- if (a->action_type == ONCE && a->pid != 0)
- kill(a->pid, SIGKILL);
- _exit(EXIT_SUCCESS);
- }
+#if ENABLE_FEATURE_KILL_REMOVED
+ /* Kill stale entries */
+ /* Be nice and send SIGTERM first */
+ for (a = init_action_list; a; a = a->next)
+ if (a->action_type == 0 && a->pid != 0)
+ kill(a->pid, SIGTERM);
+ if (CONFIG_FEATURE_KILL_DELAY) {
+ /* NB: parent will wait in NOMMU case */
+ if ((BB_MMU ? fork() : vfork()) == 0) { /* child */
+ sleep(CONFIG_FEATURE_KILL_DELAY);
+ for (a = init_action_list; a; a = a->next)
+ if (a->action_type == 0 && a->pid != 0)
+ kill(a->pid, SIGKILL);
+ _exit(EXIT_SUCCESS);
}
}
+#endif
- /* Remove stale (ONCE) and not useful (SYSINIT,WAIT) entries */
+ /* Remove stale entries and SYSINIT entries.
+ * We never rerun SYSINIT entries anyway,
+ * removing them too saves a few bytes */
nextp = &init_action_list;
while ((a = *nextp) != NULL) {
- if (a->action_type & (ONCE | SYSINIT | WAIT)) {
+ if ((a->action_type & ~SYSINIT) == 0) {
*nextp = a->next;
free(a);
} else {
int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int init_main(int argc UNUSED_PARAM, char **argv)
{
- die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */
-
- if (argv[1] && !strcmp(argv[1], "-q")) {
+ if (argv[1] && strcmp(argv[1], "-q") == 0) {
return kill(1, SIGHUP);
}
if (!DEBUG_INIT) {
/* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
if (getpid() != 1
- && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc"))
+ && (!ENABLE_FEATURE_INITRD || applet_name[0] != 'l') /* not linuxrc? */
) {
- bb_show_usage();
+ bb_error_msg_and_die("must be run as PID 1");
}
+#ifdef RB_DISABLE_CAD
/* Turn off rebooting via CTL-ALT-DEL - we get a
* SIGINT on CAD so we can shut things down gracefully... */
reboot(RB_DISABLE_CAD); /* misnomer */
+#endif
}
+ /* If, say, xmalloc would ever die, we don't want to oops kernel
+ * by exiting.
+ * NB: we set die_sleep *after* PID 1 check and bb_show_usage.
+ * Otherwise, for example, "init u" ("please rexec yourself"
+ * command for sysvinit) will show help text (which isn't too bad),
+ * *and sleep forever* (which is bad!)
+ */
+ die_sleep = 30 * 24*60*60;
+
/* Figure out where the default console should be */
console_init();
set_sane_term();
if (argv[1])
xsetenv("RUNLEVEL", argv[1]);
+#if !ENABLE_FEATURE_EXTRA_QUIET
/* Hello world */
- message(MAYBE_CONSOLE | L_LOG, "init started: %s", bb_banner);
+ message(L_CONSOLE | L_LOG, "init started: %s", bb_banner);
+#endif
+/* struct sysinfo is linux-specific */
+#ifdef __linux__
/* Make sure there is enough memory to do something useful. */
if (ENABLE_SWAPONOFF) {
struct sysinfo info;
if (sysinfo(&info) == 0
- && (info.mem_unit ? : 1) * (long long)info.totalram < 1024*1024
+ && (info.mem_unit ? info.mem_unit : 1) * (long long)info.totalram < 1024*1024
) {
message(L_CONSOLE, "Low memory, forcing swapon");
/* swapon -a requires /proc typically */
run_actions(SYSINIT); /* wait and removing */
}
}
+#endif
/* Check if we are supposed to be in single user mode */
if (argv[1]
- && (!strcmp(argv[1], "single") || !strcmp(argv[1], "-s") || LONE_CHAR(argv[1], '1'))
+ && (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 || LONE_CHAR(argv[1], '1'))
) {
/* ??? shouldn't we set RUNLEVEL="b" here? */
/* Start a shell on console */
BB_EXECVP(argv[0], argv);
} else if (enforce > 0) {
/* SELinux in enforcing mode but load_policy failed */
- message(L_CONSOLE, "cannot load SELinux Policy. "
+ message(L_CONSOLE, "can't load SELinux Policy. "
"Machine is in enforcing mode. Halting now.");
- exit(EXIT_FAILURE);
+ return EXIT_FAILURE;
}
}
#endif
bb_signals_recursive_norestart((1 << SIGINT), record_signo);
}
+ /* Set up "reread /etc/inittab" handler.
+ * Handler is set up without SA_RESTART, it will interrupt syscalls.
+ */
+ if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
+ bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
+
/* Now run everything that needs to be run */
/* First run the sysinit command */
run_actions(SYSINIT);
/* Next run anything to be run only once */
run_actions(ONCE);
- /* Set up "reread /etc/inittab" handler.
- * Handler is set up without SA_RESTART, it will interrupt syscalls.
- */
- if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB)
- bb_signals_recursive_norestart((1 << SIGHUP), record_signo);
-
/* Now run the looping stuff for the rest of forever.
- * NB: if delayed signal happened, avoid blocking in wait().
*/
while (1) {
- pid_t wpid;
- int got_sigs;
+ int maybe_WNOHANG;
- got_sigs = check_delayed_sigs();
+ maybe_WNOHANG = check_delayed_sigs();
/* (Re)run the respawn/askfirst stuff */
run_actions(RESPAWN | ASKFIRST);
-
- got_sigs |= check_delayed_sigs();
+ maybe_WNOHANG |= check_delayed_sigs();
/* Don't consume all CPU time - sleep a bit */
sleep(1);
-
- got_sigs |= check_delayed_sigs();
-
- if (got_sigs)
- goto dont_block;
- /* Wait for any child process to exit.
- * NB: "delayed" signals will also interrupt this wait(),
- * bb_signals_recursive_norestart() set them up for that.
- * This guarantees we won't be stuck here
- * till next orphan dies.
+ maybe_WNOHANG |= check_delayed_sigs();
+
+ /* Wait for any child process(es) to exit.
+ *
+ * If check_delayed_sigs above reported that a signal
+ * was caught, wait will be nonblocking. This ensures
+ * that if SIGHUP has reloaded inittab, respawn and askfirst
+ * actions will not be delayed until next child death.
*/
- wpid = wait(NULL);
- while (wpid > 0) {
- struct init_action *a = mark_terminated(wpid);
+ if (maybe_WNOHANG)
+ maybe_WNOHANG = WNOHANG;
+ while (1) {
+ pid_t wpid;
+ struct init_action *a;
+
+ /* If signals happen _in_ the wait, they interrupt it,
+ * bb_signals_recursive_norestart set them up that way
+ */
+ wpid = waitpid(-1, NULL, maybe_WNOHANG);
+ if (wpid <= 0)
+ break;
+
+ a = mark_terminated(wpid);
if (a) {
message(L_LOG, "process '%s' (pid %d) exited. "
"Scheduling for restart.",
a->command, wpid);
}
/* See if anyone else is waiting to be reaped */
- dont_block:
- wpid = wait_any_nohang(NULL);
+ maybe_WNOHANG = WNOHANG;
}
} /* while (1) */
}
+
+//usage:#define linuxrc_trivial_usage NOUSAGE_STR
+//usage:#define linuxrc_full_usage ""
+
+//usage:#define init_trivial_usage
+//usage: ""
+//usage:#define init_full_usage "\n\n"
+//usage: "Init is the parent of all processes"
+//usage:
+//usage:#define init_notes_usage
+//usage: "This version of init is designed to be run only by the kernel.\n"
+//usage: "\n"
+//usage: "BusyBox init doesn't support multiple runlevels. The runlevels field of\n"
+//usage: "the /etc/inittab file is completely ignored by BusyBox init. If you want\n"
+//usage: "runlevels, use sysvinit.\n"
+//usage: "\n"
+//usage: "BusyBox init works just fine without an inittab. If no inittab is found,\n"
+//usage: "it has the following default behavior:\n"
+//usage: "\n"
+//usage: " ::sysinit:/etc/init.d/rcS\n"
+//usage: " ::askfirst:/bin/sh\n"
+//usage: " ::ctrlaltdel:/sbin/reboot\n"
+//usage: " ::shutdown:/sbin/swapoff -a\n"
+//usage: " ::shutdown:/bin/umount -a -r\n"
+//usage: " ::restart:/sbin/init\n"
+//usage: "\n"
+//usage: "if it detects that /dev/console is _not_ a serial console, it will also run:\n"
+//usage: "\n"
+//usage: " tty2::askfirst:/bin/sh\n"
+//usage: " tty3::askfirst:/bin/sh\n"
+//usage: " tty4::askfirst:/bin/sh\n"
+//usage: "\n"
+//usage: "If you choose to use an /etc/inittab file, the inittab entry format is as follows:\n"
+//usage: "\n"
+//usage: " <id>:<runlevels>:<action>:<process>\n"
+//usage: "\n"
+//usage: " <id>:\n"
+//usage: "\n"
+//usage: " WARNING: This field has a non-traditional meaning for BusyBox init!\n"
+//usage: " The id field is used by BusyBox init to specify the controlling tty for\n"
+//usage: " the specified process to run on. The contents of this field are\n"
+//usage: " appended to \"/dev/\" and used as-is. There is no need for this field to\n"
+//usage: " be unique, although if it isn't you may have strange results. If this\n"
+//usage: " field is left blank, the controlling tty is set to the console. Also\n"
+//usage: " note that if BusyBox detects that a serial console is in use, then only\n"
+//usage: " entries whose controlling tty is either the serial console or /dev/null\n"
+//usage: " will be run. BusyBox init does nothing with utmp. We don't need no\n"
+//usage: " stinkin' utmp.\n"
+//usage: "\n"
+//usage: " <runlevels>:\n"
+//usage: "\n"
+//usage: " The runlevels field is completely ignored.\n"
+//usage: "\n"
+//usage: " <action>:\n"
+//usage: "\n"
+//usage: " Valid actions include: sysinit, respawn, askfirst, wait,\n"
+//usage: " once, restart, ctrlaltdel, and shutdown.\n"
+//usage: "\n"
+//usage: " The available actions can be classified into two groups: actions\n"
+//usage: " that are run only once, and actions that are re-run when the specified\n"
+//usage: " process exits.\n"
+//usage: "\n"
+//usage: " Run only-once actions:\n"
+//usage: "\n"
+//usage: " 'sysinit' is the first item run on boot. init waits until all\n"
+//usage: " sysinit actions are completed before continuing. Following the\n"
+//usage: " completion of all sysinit actions, all 'wait' actions are run.\n"
+//usage: " 'wait' actions, like 'sysinit' actions, cause init to wait until\n"
+//usage: " the specified task completes. 'once' actions are asynchronous,\n"
+//usage: " therefore, init does not wait for them to complete. 'restart' is\n"
+//usage: " the action taken to restart the init process. By default this should\n"
+//usage: " simply run /sbin/init, but can be a script which runs pivot_root or it\n"
+//usage: " can do all sorts of other interesting things. The 'ctrlaltdel' init\n"
+//usage: " actions are run when the system detects that someone on the system\n"
+//usage: " console has pressed the CTRL-ALT-DEL key combination. Typically one\n"
+//usage: " wants to run 'reboot' at this point to cause the system to reboot.\n"
+//usage: " Finally the 'shutdown' action specifies the actions to taken when\n"
+//usage: " init is told to reboot. Unmounting filesystems and disabling swap\n"
+//usage: " is a very good here.\n"
+//usage: "\n"
+//usage: " Run repeatedly actions:\n"
+//usage: "\n"
+//usage: " 'respawn' actions are run after the 'once' actions. When a process\n"
+//usage: " started with a 'respawn' action exits, init automatically restarts\n"
+//usage: " it. Unlike sysvinit, BusyBox init does not stop processes from\n"
+//usage: " respawning out of control. The 'askfirst' actions acts just like\n"
+//usage: " respawn, except that before running the specified process it\n"
+//usage: " displays the line \"Please press Enter to activate this console.\"\n"
+//usage: " and then waits for the user to press enter before starting the\n"
+//usage: " specified process.\n"
+//usage: "\n"
+//usage: " Unrecognized actions (like initdefault) will cause init to emit an\n"
+//usage: " error message, and then go along with its business. All actions are\n"
+//usage: " run in the order they appear in /etc/inittab.\n"
+//usage: "\n"
+//usage: " <process>:\n"
+//usage: "\n"
+//usage: " Specifies the process to be executed and its command line.\n"
+//usage: "\n"
+//usage: "Example /etc/inittab file:\n"
+//usage: "\n"
+//usage: " # This is run first except when booting in single-user mode\n"
+//usage: " #\n"
+//usage: " ::sysinit:/etc/init.d/rcS\n"
+//usage: " \n"
+//usage: " # /bin/sh invocations on selected ttys\n"
+//usage: " #\n"
+//usage: " # Start an \"askfirst\" shell on the console (whatever that may be)\n"
+//usage: " ::askfirst:-/bin/sh\n"
+//usage: " # Start an \"askfirst\" shell on /dev/tty2-4\n"
+//usage: " tty2::askfirst:-/bin/sh\n"
+//usage: " tty3::askfirst:-/bin/sh\n"
+//usage: " tty4::askfirst:-/bin/sh\n"
+//usage: " \n"
+//usage: " # /sbin/getty invocations for selected ttys\n"
+//usage: " #\n"
+//usage: " tty4::respawn:/sbin/getty 38400 tty4\n"
+//usage: " tty5::respawn:/sbin/getty 38400 tty5\n"
+//usage: " \n"
+//usage: " \n"
+//usage: " # Example of how to put a getty on a serial line (for a terminal)\n"
+//usage: " #\n"
+//usage: " #::respawn:/sbin/getty -L ttyS0 9600 vt100\n"
+//usage: " #::respawn:/sbin/getty -L ttyS1 9600 vt100\n"
+//usage: " #\n"
+//usage: " # Example how to put a getty on a modem line\n"
+//usage: " #::respawn:/sbin/getty 57600 ttyS2\n"
+//usage: " \n"
+//usage: " # Stuff to do when restarting the init process\n"
+//usage: " ::restart:/sbin/init\n"
+//usage: " \n"
+//usage: " # Stuff to do before rebooting\n"
+//usage: " ::ctrlaltdel:/sbin/reboot\n"
+//usage: " ::shutdown:/bin/umount -a -r\n"
+//usage: " ::shutdown:/sbin/swapoff -a\n"
projects / oweals / busybox.git / blobdiff