init: major improvement in documentation and signal handling.
Lots of nasty, but hard to trip, races are fixed. text data bss dec hex filename 1038828 924 10932 1050684 10083c busybox_old 1038787 924 10932 1050643 100813 busybox_unstripped
This commit is contained in:
Denis Vlasenko
parent
cab28aa7de
commit
72c99af0b4
667
init/init.c
667
init/init.c
@ -15,6 +15,7 @@
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#include <sys/reboot.h>
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#include <sys/resource.h>
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/* Was a CONFIG_xxx option. A lot of people were building
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* not fully functional init by switching it on! */
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#define DEBUG_INIT 0
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@ -22,22 +23,53 @@
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#define COMMAND_SIZE 256
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#define CONSOLE_NAME_SIZE 32
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/* Default sysinit script. */
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#ifndef INIT_SCRIPT
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#define INIT_SCRIPT "/etc/init.d/rcS" /* Default sysinit script. */
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#define INIT_SCRIPT "/etc/init.d/rcS"
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#endif
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/* Allowed init action types */
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/* Each type of actions can appear many times. They will be
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* handled in order. RESTART is an exception, only 1st is used.
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*/
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/* Start these actions first and wait for completion */
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#define SYSINIT 0x01
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#define RESPAWN 0x02
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/* like respawn, but wait for <Enter> to be pressed on tty: */
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#define ASKFIRST 0x04
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#define WAIT 0x08
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#define ONCE 0x10
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/* Start these after SYSINIT and wait for completion */
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#define WAIT 0x02
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/* Start these after WAIT and *dont* wait for completion */
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#define ONCE 0x04
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/*
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* NB: while SYSINIT/WAIT/ONCE are being processed,
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* SIGHUP ("reread /etc/inittab") will be ignored.
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* Rationale: it would be ambiguous whether SYSINIT/WAIT/ONCE
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* need to be rerun or not.
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*/
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/* Start these after ONCE are started, restart on exit */
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#define RESPAWN 0x08
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/* Like RESPAWN, but wait for <Enter> to be pressed on tty */
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#define ASKFIRST 0x10
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/*
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* Start these on SIGINT, and wait for completion.
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* Then go back to respawning RESPAWN and ASKFIRST actions.
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* NB: kernel sends SIGINT to us if Ctrl-Alt-Del was pressed.
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*/
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#define CTRLALTDEL 0x20
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/*
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* Start these before killing all processes in preparation for
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* running RESTART actions or doing low-level halt/reboot/poweroff
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* (initiated by SIGUSR1/SIGTERM/SIGUSR2).
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* Wait for completion before proceeding.
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*/
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#define SHUTDOWN 0x40
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/*
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* exec() on SIGQUIT. SHUTDOWN actions are started and waited for,
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* then all processes are killed, then init exec's 1st RESTART action,
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* replacing itself by it. If no RESTART action specified,
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* SIGQUIT has no effect.
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*/
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#define RESTART 0x80
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/* Set up a linked list of init_actions, to be read from inittab */
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/* A linked list of init_actions, to be read from inittab */
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struct init_action {
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struct init_action *next;
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pid_t pid;
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@ -65,13 +97,6 @@ enum {
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static void halt_reboot_pwoff(int sig) NORETURN;
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static void loop_forever(void) NORETURN;
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static void loop_forever(void)
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{
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while (1)
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sleep(1);
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}
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/* Print a message to the specified device.
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* "where" may be bitwise-or'd from L_LOG | L_CONSOLE
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* NB: careful, we can be called after vfork!
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@ -241,6 +266,7 @@ static void open_stdio_to_tty(const char* tty_name, int exit_on_failure)
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/* empty tty_name means "use init's tty", else... */
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if (tty_name[0]) {
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int fd;
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close(STDIN_FILENO);
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/* fd can be only < 0 or 0: */
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fd = device_open(tty_name, O_RDWR);
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@ -252,7 +278,8 @@ static void open_stdio_to_tty(const char* tty_name, int exit_on_failure)
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if (DEBUG_INIT)
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_exit(2);
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/* NB: we don't reach this if we were called after vfork.
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* Thus halt_reboot_pwoff() itself need not be vfork-safe. */
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* Thus halt_reboot_pwoff() itself needs not be vfork-safe.
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*/
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halt_reboot_pwoff(SIGUSR1); /* halt the system */
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}
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dup2(STDIN_FILENO, STDOUT_FILENO);
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@ -313,89 +340,37 @@ static void init_exec(const char *command)
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static pid_t run(const struct init_action *a)
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{
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pid_t pid;
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sigset_t nmask, omask;
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/* Block sigchild while forking (why?) */
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sigemptyset(&nmask);
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sigaddset(&nmask, SIGCHLD);
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sigprocmask(SIG_BLOCK, &nmask, &omask);
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if (BB_MMU && (a->action_type & ASKFIRST))
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pid = fork();
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else
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pid = vfork();
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sigprocmask(SIG_SETMASK, &omask, NULL);
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if (pid < 0)
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message(L_LOG | L_CONSOLE, "can't fork");
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if (pid)
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return pid;
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return pid; /* Parent or error */
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/* Child */
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/* Reset signal handlers that were set by the parent process */
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//TODO: block signals across fork(), prevent them to affect child before
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//signals are reset?
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bb_signals(0
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+ (1 << SIGUSR1)
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+ (1 << SIGUSR2)
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+ (1 << SIGINT)
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+ (1 << SIGTERM)
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+ (1 << SIGHUP)
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+ (1 << SIGQUIT)
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+ (1 << SIGCONT)
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+ (1 << SIGSTOP)
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+ (1 << SIGINT)
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+ (1 << SIGHUP)
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+ (1 << SIGTSTP)
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, SIG_DFL);
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/* Create a new session and make ourself the process
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* group leader */
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/* Create a new session and make ourself the process group leader */
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setsid();
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/* Open the new terminal device */
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open_stdio_to_tty(a->terminal, 1 /* - exit if open fails */);
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// NB: do not enable unless you change vfork to fork above
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#ifdef BUT_RUN_ACTIONS_ALREADY_DOES_WAITING
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/* If the init Action requires us to wait, then force the
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* supplied terminal to be the controlling tty. */
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if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN | RESTART)) {
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/* Now fork off another process to just hang around */
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pid = fork();
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if (pid < 0) {
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message(L_LOG | L_CONSOLE, "can't fork");
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_exit(EXIT_FAILURE);
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}
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if (pid > 0) {
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/* Parent - wait till the child is done */
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bb_signals(0
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+ (1 << SIGINT)
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+ (1 << SIGTSTP)
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+ (1 << SIGQUIT)
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, SIG_IGN);
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signal(SIGCHLD, SIG_DFL);
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waitfor(pid);
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/* See if stealing the controlling tty back is necessary */
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if (tcgetpgrp(0) != getpid())
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_exit(EXIT_SUCCESS);
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/* Use a temporary process to steal the controlling tty. */
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pid = fork();
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if (pid < 0) {
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message(L_LOG | L_CONSOLE, "can't fork");
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_exit(EXIT_FAILURE);
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}
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if (pid == 0) {
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setsid();
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ioctl(0, TIOCSCTTY, 1);
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_exit(EXIT_SUCCESS);
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}
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waitfor(pid);
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_exit(EXIT_SUCCESS);
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}
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/* Child - fall though to actually execute things */
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}
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#endif
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/* NB: on NOMMU we can't wait for input in child, so
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* "askfirst" will work the same as "respawn". */
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if (BB_MMU && (a->action_type & ASKFIRST)) {
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@ -449,21 +424,32 @@ static pid_t run(const struct init_action *a)
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static void delete_init_action(struct init_action *action)
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{
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struct init_action *a, *b = NULL;
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struct init_action *a, **nextp;
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for (a = init_action_list; a; b = a, a = a->next) {
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nextp = &init_action_list;
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while ((a = *nextp) != NULL) {
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if (a == action) {
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if (b == NULL) {
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init_action_list = a->next;
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} else {
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b->next = a->next;
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}
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*nextp = a->next;
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free(a);
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break;
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}
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nextp = &a->next;
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}
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}
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static struct init_action *mark_terminated(int pid)
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{
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struct init_action *a;
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for (a = init_action_list; a; a = a->next) {
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if (a->pid == pid) {
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a->pid = 0;
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return a;
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}
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}
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return NULL;
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}
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static void waitfor(pid_t pid)
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{
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/* waitfor(run(x)): protect against failed fork inside run() */
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@ -472,176 +458,71 @@ static void waitfor(pid_t pid)
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/* Wait for any child (prevent zombies from exiting orphaned processes)
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* but exit the loop only when specified one has exited. */
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while (wait(NULL) != pid)
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continue;
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while (1) {
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pid_t wpid = wait(NULL);
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mark_terminated(wpid);
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/* Unsafe. SIGTSTP handler might have wait'ed it already */
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/*if (wpid == pid) break;*/
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/* More reliable */
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if (kill(pid, 0))
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break;
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}
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}
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/* Run all commands of a particular type */
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static void run_actions(int action_type)
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{
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struct init_action *a, *tmp;
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struct init_action *a;
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for (a = init_action_list; a; a = tmp) {
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tmp = a->next;
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if (a->action_type & action_type) {
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// Pointless: run() will error out if open of device fails.
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///* a->terminal of "" means "init's console" */
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//if (a->terminal[0] && access(a->terminal, R_OK | W_OK)) {
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// //message(L_LOG | L_CONSOLE, "Device %s cannot be opened in RW mode", a->terminal /*, strerror(errno)*/);
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// delete_init_action(a);
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//} else
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if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN | RESTART)) {
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waitfor(run(a));
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delete_init_action(a);
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} else if (a->action_type & ONCE) {
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run(a);
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delete_init_action(a);
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} else if (a->action_type & (RESPAWN | ASKFIRST)) {
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/* Only run stuff with pid==0. If they have
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* a pid, that means it is still running */
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if (a->pid == 0) {
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for (a = init_action_list; a; a = a->next) {
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if (!(a->action_type & action_type))
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continue;
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if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) {
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pid_t pid = run(a);
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if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN))
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waitfor(pid);
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}
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if (a->action_type & (RESPAWN | ASKFIRST)) {
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/* Only run stuff with pid == 0. If pid != 0,
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* it is already running
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*/
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if (a->pid == 0)
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a->pid = run(a);
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}
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}
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}
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}
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}
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static void low_level_reboot(unsigned long magic)
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{
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pid_t pid;
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/* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS) in
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* linux/kernel/sys.c, which can cause the machine to panic when
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* the init process is killed.... */
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pid = vfork();
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if (pid == 0) { /* child */
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reboot(magic);
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_exit(EXIT_SUCCESS);
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}
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waitfor(pid);
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}
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static void kill_all_processes(void)
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{
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/* run everything to be run at "shutdown". This is done _prior_
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* to killing everything, in case people wish to use scripts to
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* shut things down gracefully... */
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run_actions(SHUTDOWN);
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/* first disable all our signals */
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sigprocmask_allsigs(SIG_BLOCK);
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message(L_CONSOLE | L_LOG, "The system is going down NOW!");
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/* Allow Ctrl-Alt-Del to reboot system. */
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low_level_reboot(RB_ENABLE_CAD);
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/* Send signals to every process _except_ pid 1 */
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message(L_CONSOLE | L_LOG, "Sending SIG%s to all processes", "TERM");
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kill(-1, SIGTERM);
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sync();
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sleep(1);
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message(L_CONSOLE | L_LOG, "Sending SIG%s to all processes", "KILL");
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kill(-1, SIGKILL);
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sync();
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sleep(1);
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}
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static void halt_reboot_pwoff(int sig)
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{
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const char *m = "halt";
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int rb;
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kill_all_processes();
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rb = RB_HALT_SYSTEM;
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if (sig == SIGTERM) {
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m = "reboot";
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rb = RB_AUTOBOOT;
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} else if (sig == SIGUSR2) {
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m = "poweroff";
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rb = RB_POWER_OFF;
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}
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message(L_CONSOLE | L_LOG, "Requesting system %s", m);
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/* allow time for last message to reach serial console */
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sleep(2);
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low_level_reboot(rb);
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loop_forever();
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}
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/* Handler for QUIT - exec "restart" action,
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* else (no such action defined) do nothing */
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static void restart_handler(int sig UNUSED_PARAM)
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{
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struct init_action *a;
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for (a = init_action_list; a; a = a->next) {
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if (a->action_type & RESTART) {
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kill_all_processes();
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/* unblock all signals (blocked in kill_all_processes()) */
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sigprocmask_allsigs(SIG_UNBLOCK);
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/* Open the new terminal device */
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open_stdio_to_tty(a->terminal, 0 /* - halt if open fails */);
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messageD(L_CONSOLE | L_LOG, "Trying to re-exec %s", a->command);
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init_exec(a->command);
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sleep(2);
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low_level_reboot(RB_HALT_SYSTEM);
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loop_forever();
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}
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}
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}
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static void ctrlaltdel_signal(int sig UNUSED_PARAM)
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{
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run_actions(CTRLALTDEL);
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}
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/* The SIGCONT handler is set to record_signo().
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* It just sets bb_got_signal = SIGCONT. */
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/* The SIGSTOP & SIGTSTP handler */
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static void stop_handler(int sig UNUSED_PARAM)
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{
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int saved_errno = errno;
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bb_got_signal = 0;
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while (bb_got_signal == 0)
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pause();
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errno = saved_errno;
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}
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static void new_init_action(uint8_t action_type, const char *command, const char *cons)
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{
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struct init_action *a, *last;
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struct init_action *a, **nextp;
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// Why?
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// if (strcmp(cons, bb_dev_null) == 0 && (action & ASKFIRST))
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// return;
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/* Append to the end of the list */
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for (a = last = init_action_list; a; a = a->next) {
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/* don't enter action if it's already in the list,
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* but do overwrite existing actions */
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//BUG
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//old:
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//::shutdown:umount -a -r
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//::shutdown:swapoff -a
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//new: swapped:
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//::shutdown:swapoff -a
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//::shutdown:umount -a -r
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//on SIGHUP, new one will be loaded, but order will be wrong.
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nextp = &init_action_list;
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while ((a = *nextp) != NULL) {
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/* Don't enter action if it's already in the list,
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* just overwrite existing one's type.
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* This prevents losing running RESPAWNs.
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*/
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if ((strcmp(a->command, command) == 0)
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&& (strcmp(a->terminal, cons) == 0)
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) {
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a->action_type = action_type;
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return;
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}
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last = a;
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nextp = &a->next;
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}
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/* Append to the end of the list */
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a = xzalloc(sizeof(*a));
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if (last) {
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last->next = a;
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} else {
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init_action_list = a;
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}
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*nextp = a;
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a->action_type = action_type;
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safe_strncpy(a->command, command, sizeof(a->command));
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safe_strncpy(a->terminal, cons, sizeof(a->terminal));
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@ -665,7 +546,7 @@ static void parse_inittab(void)
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if (parser == NULL)
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#endif
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{
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/* No inittab file -- set up some default behavior */
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/* No inittab file - set up some default behavior */
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/* Reboot on Ctrl-Alt-Del */
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new_init_action(CTRLALTDEL, "reboot", "");
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/* Umount all filesystems on halt/reboot */
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@ -694,7 +575,7 @@ static void parse_inittab(void)
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PARSE_NORMAL & ~(PARSE_TRIM | PARSE_COLLAPSE))) {
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/* order must correspond to SYSINIT..RESTART constants */
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static const char actions[] ALIGN1 =
|
||||
"sysinit\0""respawn\0""askfirst\0""wait\0""once\0"
|
||||
"sysinit\0""wait\0""once\0""respawn\0""askfirst\0"
|
||||
"ctrlaltdel\0""shutdown\0""restart\0";
|
||||
int action;
|
||||
char *tty = token[0];
|
||||
@ -722,14 +603,172 @@ static void parse_inittab(void)
|
||||
#endif
|
||||
}
|
||||
|
||||
static void low_level_reboot(unsigned magic) NORETURN;
|
||||
static void low_level_reboot(unsigned magic)
|
||||
{
|
||||
pid_t pid;
|
||||
|
||||
/* Allow time for last message to reach serial console, etc */
|
||||
sleep(1);
|
||||
|
||||
/* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS)
|
||||
* in linux/kernel/sys.c, which can cause the machine to panic when
|
||||
* the init process exits... */
|
||||
pid = vfork();
|
||||
if (pid == 0) { /* child */
|
||||
reboot(magic);
|
||||
_exit(EXIT_SUCCESS);
|
||||
}
|
||||
waitfor(pid);
|
||||
while (1)
|
||||
sleep(1);
|
||||
}
|
||||
|
||||
static void kill_all_processes(void)
|
||||
{
|
||||
/* Run everything to be run at "shutdown". This is done _prior_
|
||||
* to killing everything, in case people wish to use scripts to
|
||||
* shut things down gracefully... */
|
||||
run_actions(SHUTDOWN);
|
||||
|
||||
message(L_CONSOLE | L_LOG, "The system is going down NOW!");
|
||||
|
||||
/* Allow Ctrl-Alt-Del to reboot system. */
|
||||
reboot(RB_ENABLE_CAD); /* misnomer */
|
||||
|
||||
/* Send signals to every process _except_ pid 1 */
|
||||
message(L_CONSOLE | L_LOG, "Sending SIG%s to all processes", "TERM");
|
||||
kill(-1, SIGTERM);
|
||||
sync();
|
||||
sleep(1);
|
||||
|
||||
message(L_CONSOLE, "Sending SIG%s to all processes", "KILL");
|
||||
kill(-1, SIGKILL);
|
||||
sync();
|
||||
sleep(1);
|
||||
}
|
||||
|
||||
/* Signal handling by init:
|
||||
*
|
||||
* For process with PID==1, on entry kernel sets all signals to SIG_DFL
|
||||
* and unmasks all signals. However, for process with PID==1,
|
||||
* default action (SIG_DFL) on any signal is to ignore it,
|
||||
* even for special signals SIGKILL and SIGCONT.
|
||||
* (SIGSTOP is still handled specially, at least in 2.6.20)
|
||||
* Also, any signal can be caught or blocked.
|
||||
*
|
||||
* We install two kinds of handlers, "immediate" and "delayed".
|
||||
*
|
||||
* Immediate handlers execute at any time, even while, say, sysinit
|
||||
* is running.
|
||||
*
|
||||
* Delayed handlers just set a flag variable. The variable is checked
|
||||
* in the main loop and acted upon.
|
||||
*
|
||||
* halt/poweroff/reboot and restart have immediate handlers.
|
||||
* They only traverse linked list of struct action's, never modify it,
|
||||
* this should be safe to do even in signal handler. Also they
|
||||
* never return.
|
||||
*
|
||||
* SIGSTOP and SIGTSTP have immediate handlers. They just wait
|
||||
* for SIGCONT to happen.
|
||||
*
|
||||
* SIGHUP has a delayed handler, because modifying linked list
|
||||
* of struct action's from a signal handler while it is manipulated
|
||||
* by the program may be disastrous.
|
||||
*
|
||||
* Ctrl-Alt-Del has a delayed handler. Not a must, but allowing
|
||||
* 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.
|
||||
*/
|
||||
|
||||
static void halt_reboot_pwoff(int sig)
|
||||
{
|
||||
const char *m;
|
||||
unsigned rb;
|
||||
|
||||
kill_all_processes();
|
||||
|
||||
m = "halt";
|
||||
rb = RB_HALT_SYSTEM;
|
||||
if (sig == SIGTERM) {
|
||||
m = "reboot";
|
||||
rb = RB_AUTOBOOT;
|
||||
} else if (sig == SIGUSR2) {
|
||||
m = "poweroff";
|
||||
rb = RB_POWER_OFF;
|
||||
}
|
||||
message(L_CONSOLE, "Requesting system %s", m);
|
||||
low_level_reboot(rb);
|
||||
/* 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)
|
||||
{
|
||||
int saved_errno;
|
||||
smallint saved_bb_got_signal;
|
||||
|
||||
saved_errno = errno;
|
||||
saved_bb_got_signal = bb_got_signal;
|
||||
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);
|
||||
if (wpid > 0)
|
||||
mark_terminated(wpid);
|
||||
sleep(1);
|
||||
}
|
||||
|
||||
signal(SIGCONT, SIG_DFL);
|
||||
bb_got_signal = saved_bb_got_signal;
|
||||
errno = saved_errno;
|
||||
}
|
||||
|
||||
/* Handler for QUIT - exec "restart" action,
|
||||
* else (no such action defined) do nothing */
|
||||
static void restart_handler(int sig UNUSED_PARAM)
|
||||
{
|
||||
struct init_action *a;
|
||||
|
||||
for (a = init_action_list; a; a = a->next) {
|
||||
if (!(a->action_type & RESTART))
|
||||
continue;
|
||||
|
||||
/* Starting from here, we won't return.
|
||||
* Thus don't need to worry about preserving errno
|
||||
* and such.
|
||||
*/
|
||||
kill_all_processes();
|
||||
open_stdio_to_tty(a->terminal, 0 /* - halt if open fails */);
|
||||
messageD(L_CONSOLE, "Trying to re-exec %s", a->command);
|
||||
init_exec(a->command);
|
||||
low_level_reboot(RB_HALT_SYSTEM);
|
||||
/* not reached */
|
||||
}
|
||||
}
|
||||
|
||||
#if ENABLE_FEATURE_USE_INITTAB
|
||||
static void reload_inittab(int sig UNUSED_PARAM)
|
||||
static void reload_inittab(void)
|
||||
{
|
||||
struct init_action *a, *tmp;
|
||||
|
||||
message(L_LOG, "reloading /etc/inittab");
|
||||
|
||||
/* disable old entrys */
|
||||
/* Disable old entries */
|
||||
for (a = init_action_list; a; a = a->next) {
|
||||
a->action_type = ONCE;
|
||||
}
|
||||
@ -738,47 +777,57 @@ static void reload_inittab(int sig UNUSED_PARAM)
|
||||
|
||||
if (ENABLE_FEATURE_KILL_REMOVED) {
|
||||
/* Be nice and send SIGTERM first */
|
||||
for (a = init_action_list; a; a = a->next) {
|
||||
pid_t pid = a->pid;
|
||||
if ((a->action_type & ONCE) && pid != 0) {
|
||||
kill(pid, SIGTERM);
|
||||
}
|
||||
}
|
||||
for (a = init_action_list; a; a = a->next)
|
||||
if (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) {
|
||||
pid_t pid = a->pid;
|
||||
if ((a->action_type & ONCE) && pid != 0) {
|
||||
kill(pid, SIGKILL);
|
||||
}
|
||||
}
|
||||
for (a = init_action_list; a; a = a->next)
|
||||
if (a->pid != 0)
|
||||
kill(a->pid, SIGKILL);
|
||||
_exit(EXIT_SUCCESS);
|
||||
}
|
||||
#endif
|
||||
}
|
||||
|
||||
/* remove unused entrys */
|
||||
/* Remove old and unused entries */
|
||||
for (a = init_action_list; a; a = tmp) {
|
||||
tmp = a->next;
|
||||
if ((a->action_type & (ONCE | SYSINIT | WAIT)) && a->pid == 0) {
|
||||
if (a->action_type & (ONCE | SYSINIT | WAIT))
|
||||
delete_init_action(a);
|
||||
}
|
||||
/* Not needed: */
|
||||
/* run_actions(RESPAWN | ASKFIRST); */
|
||||
/* - we return to main loop, which does this automagically */
|
||||
}
|
||||
run_actions(RESPAWN | ASKFIRST);
|
||||
}
|
||||
#else
|
||||
void reload_inittab(int sig);
|
||||
#endif
|
||||
|
||||
static int check_delayed_sigs(void)
|
||||
{
|
||||
int sigs_seen = 0;
|
||||
|
||||
while (1) {
|
||||
smallint sig = bb_got_signal;
|
||||
|
||||
if (!sig)
|
||||
return sigs_seen;
|
||||
bb_got_signal = 0;
|
||||
sigs_seen = 1;
|
||||
#if ENABLE_FEATURE_USE_INITTAB
|
||||
if (sig == SIGHUP)
|
||||
reload_inittab();
|
||||
#endif
|
||||
if (sig == SIGINT)
|
||||
run_actions(CTRLALTDEL);
|
||||
}
|
||||
}
|
||||
|
||||
int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
||||
int init_main(int argc UNUSED_PARAM, char **argv)
|
||||
{
|
||||
struct init_action *a;
|
||||
pid_t wpid;
|
||||
|
||||
die_sleep = 30 * 24*60*60; /* if xmalloc will ever die... */
|
||||
die_sleep = 30 * 24*60*60; /* if xmalloc would ever die... */
|
||||
|
||||
if (argv[1] && !strcmp(argv[1], "-q")) {
|
||||
return kill(1, SIGHUP);
|
||||
@ -791,28 +840,9 @@ int init_main(int argc UNUSED_PARAM, char **argv)
|
||||
) {
|
||||
bb_show_usage();
|
||||
}
|
||||
/* Set up sig handlers -- be sure to
|
||||
* clear all of these in run() */
|
||||
// TODO: handlers should just set a flag variable.
|
||||
// Move signal handling from handlers to main loop -
|
||||
// we have bad races otherwise.
|
||||
// E.g. parse_inittab() vs. delete_init_action()...
|
||||
signal(SIGQUIT, restart_handler);
|
||||
bb_signals(0
|
||||
+ (1 << SIGUSR1) /* halt */
|
||||
+ (1 << SIGUSR2) /* poweroff */
|
||||
+ (1 << SIGTERM) /* reboot */
|
||||
, halt_reboot_pwoff);
|
||||
signal(SIGINT, ctrlaltdel_signal);
|
||||
signal(SIGCONT, record_signo);
|
||||
bb_signals(0
|
||||
+ (1 << SIGSTOP)
|
||||
+ (1 << SIGTSTP)
|
||||
, stop_handler);
|
||||
|
||||
/* Turn off rebooting via CTL-ALT-DEL -- we get a
|
||||
/* Turn off rebooting via CTL-ALT-DEL - we get a
|
||||
* SIGINT on CAD so we can shut things down gracefully... */
|
||||
low_level_reboot(RB_DISABLE_CAD);
|
||||
reboot(RB_DISABLE_CAD); /* misnomer */
|
||||
}
|
||||
|
||||
/* Figure out where the default console should be */
|
||||
@ -857,11 +887,11 @@ int init_main(int argc UNUSED_PARAM, char **argv)
|
||||
/* Start a shell on console */
|
||||
new_init_action(RESPAWN, bb_default_login_shell, "");
|
||||
} else {
|
||||
/* Not in single user mode -- see what inittab says */
|
||||
/* Not in single user mode - see what inittab says */
|
||||
|
||||
/* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined,
|
||||
* then parse_inittab() simply adds in some default
|
||||
* actions(i.e., runs INIT_SCRIPT and then starts a pair
|
||||
* actions(i.e., INIT_SCRIPT and a pair
|
||||
* of "askfirst" shells */
|
||||
parse_inittab();
|
||||
}
|
||||
@ -888,44 +918,91 @@ int init_main(int argc UNUSED_PARAM, char **argv)
|
||||
while (*++argv)
|
||||
memset(*argv, 0, strlen(*argv));
|
||||
|
||||
/* Now run everything that needs to be run */
|
||||
/* Set up signal handlers */
|
||||
if (!DEBUG_INIT) {
|
||||
struct sigaction sa;
|
||||
|
||||
bb_signals(0
|
||||
+ (1 << SIGUSR1) /* halt */
|
||||
+ (1 << SIGTERM) /* reboot */
|
||||
+ (1 << SIGUSR2) /* poweroff */
|
||||
, halt_reboot_pwoff);
|
||||
signal(SIGQUIT, restart_handler); /* re-exec another init */
|
||||
|
||||
/* Stop handler must allow only SIGCONT inside itself */
|
||||
memset(&sa, 0, sizeof(sa));
|
||||
sigfillset(&sa.sa_mask);
|
||||
sigdelset(&sa.sa_mask, SIGCONT);
|
||||
sa.sa_handler = stop_handler;
|
||||
/* NB: sa_flags doesn't have SA_RESTART.
|
||||
* It must be able to interrupt wait().
|
||||
*/
|
||||
sigaction_set(SIGTSTP, &sa); /* pause */
|
||||
/* Does not work as intended, at least in 2.6.20.
|
||||
* SIGSTOP is simply ignored by init:
|
||||
*/
|
||||
sigaction_set(SIGSTOP, &sa); /* pause */
|
||||
|
||||
/* SIGINT (Ctrl-Alt-Del) must interrupt wait(),
|
||||
* setting handler without SA_RESTART flag.
|
||||
*/
|
||||
bb_signals_recursive_norestart((1 << SIGINT), record_signo);
|
||||
}
|
||||
|
||||
/* Now run everything that needs to be run */
|
||||
/* First run the sysinit command */
|
||||
run_actions(SYSINIT);
|
||||
|
||||
check_delayed_sigs();
|
||||
/* Next run anything that wants to block */
|
||||
run_actions(WAIT);
|
||||
|
||||
check_delayed_sigs();
|
||||
/* Next run anything to be run only once */
|
||||
run_actions(ONCE);
|
||||
|
||||
/* Redefine SIGHUP to reread /etc/inittab */
|
||||
signal(SIGHUP, ENABLE_FEATURE_USE_INITTAB ? reload_inittab : SIG_IGN);
|
||||
/* 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 */
|
||||
/* Now run the looping stuff for the rest of forever.
|
||||
* NB: if delayed signal happened, avoid blocking in wait().
|
||||
*/
|
||||
while (1) {
|
||||
/* run the respawn/askfirst stuff */
|
||||
pid_t wpid;
|
||||
int got_sigs;
|
||||
|
||||
got_sigs = check_delayed_sigs();
|
||||
|
||||
/* (Re)run the respawn/askfirst stuff */
|
||||
run_actions(RESPAWN | ASKFIRST);
|
||||
|
||||
/* Don't consume all CPU time -- sleep a bit */
|
||||
got_sigs |= check_delayed_sigs();
|
||||
|
||||
/* Don't consume all CPU time - sleep a bit */
|
||||
sleep(1);
|
||||
|
||||
/* Wait for any child process to exit */
|
||||
got_sigs |= check_delayed_sigs();
|
||||
|
||||
/* 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.
|
||||
*/
|
||||
if (got_sigs)
|
||||
goto dont_block;
|
||||
wpid = wait(NULL);
|
||||
while (wpid > 0) {
|
||||
/* Find out who died and clean up their corpse */
|
||||
for (a = init_action_list; a; a = a->next) {
|
||||
if (a->pid == wpid) {
|
||||
/* Set the pid to 0 so that the process gets
|
||||
* restarted by run_actions() */
|
||||
a->pid = 0;
|
||||
struct init_action *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 */
|
||||
/* See if anyone else is waiting to be reaped */
|
||||
dont_block:
|
||||
wpid = wait_any_nohang(NULL);
|
||||
}
|
||||
}
|
||||
} /* while (1) */
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user