init.c

手机嵌入式Linux下可用的busybox源码

			}
			cmd[i] = NULL;
		}

		cmdpath = cmd[0];

		/*
		   Interactive shells want to see a dash in argv[0].  This
		   typically is handled by login, argv will be setup this 
		   way if a dash appears at the front of the command path 
		   (like "-/bin/sh").
		 */

		if (*cmdpath == '-') {

			/* skip over the dash */
			++cmdpath;

			/* find the last component in the command pathname */
			s = get_last_path_component(cmdpath);

			/* make a new argv[0] */
			if ((cmd[0] = malloc(strlen(s)+2)) == NULL) {
				message(LOG | CONSOLE, "malloc failed");
				cmd[0] = cmdpath;
			} else {
				cmd[0][0] = '-';
				strcpy(cmd[0]+1, s);
			}
		}

		if (a->action & ASKFIRST) {
			/*
			 * Save memory by not exec-ing anything large (like a shell)
			 * before the user wants it. This is critical if swap is not
			 * enabled and the system has low memory. Generally this will
			 * be run on the second virtual console, and the first will
			 * be allowed to start a shell or whatever an init script 
			 * specifies.
			 */
			messageND(LOG, "Waiting for enter to start '%s' (pid %d, terminal %s)\n",
					cmdpath, getpid(), a->terminal);
			fflush(stdout);
			write(fileno(stdout), press_enter, sizeof(press_enter) - 1);
			getc(stdin);
		}

		/* Log the process name and args */
		messageND(LOG, "Starting pid %d, console %s: '%s'\n",
				getpid(), a->terminal, cmdpath);

#if defined BB_FEATURE_INIT_COREDUMPS
		if (stat (CORE_ENABLE_FLAG_FILE, &sb) == 0) {
			struct rlimit limit;
			limit.rlim_cur = RLIM_INFINITY;
			limit.rlim_max = RLIM_INFINITY;
			setrlimit(RLIMIT_CORE, &limit);
		}
#endif

		/* Now run it.  The new program will take over this PID, 
		 * so nothing further in init.c should be run. */
		execve(cmdpath, cmd, environment);

		/* We're still here?  Some error happened. */
		message(LOG | CONSOLE, "\rBummer, could not run '%s': %s\n", cmdpath,
				strerror(errno));
		_exit(-1);
	}
	sigprocmask(SIG_SETMASK, &omask, NULL);
	return pid;
}

static int waitfor(struct init_action *a)
{
	int pid; 
	int status, wpid;

	pid = run(a);
	while (1) {
		wpid = wait(&status);
		if (wpid > 0 && wpid != pid) {
			continue;
		}
		if (wpid == pid)
			break;
	}
	return wpid;
}

/* Run all commands of a particular type */
static void run_actions(int action)
{
	struct init_action *a, *tmp;

	for (a = init_action_list; a; a = tmp) {
		tmp = a->next;
		if (a->action == action) {
			if (a->action & (SYSINIT|WAIT|CTRLALTDEL|SHUTDOWN|RESTART)) {
				waitfor(a);
				delete_init_action(a);
			} else if (a->action & ONCE) {
				run(a);
				delete_init_action(a);
			} else if (a->action & (RESPAWN|ASKFIRST)) {
				/* Only run stuff with pid==0.  If they have
				 * a pid, that means it is still running */
				if (a->pid == 0) {
					a->pid = run(a);
				}
			}
		}
	}
}


#ifndef DEBUG_INIT
static void shutdown_system(void)
{
	sigset_t block_signals;

	/* 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);

	/* first disable all our signals */
	sigemptyset(&block_signals);
	sigaddset(&block_signals, SIGHUP);
	sigaddset(&block_signals, SIGCHLD);
	sigaddset(&block_signals, SIGUSR1);
	sigaddset(&block_signals, SIGUSR2);
	sigaddset(&block_signals, SIGINT);
	sigaddset(&block_signals, SIGTERM);
	sigaddset(&block_signals, SIGCONT);
	sigaddset(&block_signals, SIGSTOP);
	sigaddset(&block_signals, SIGTSTP);
	sigprocmask(SIG_BLOCK, &block_signals, NULL);

	/* Allow Ctrl-Alt-Del to reboot system. */
	init_reboot(RB_ENABLE_CAD);

	message(CONSOLE|LOG, "\n\rThe system is going down NOW !!\n");
	sync();

	/* Send signals to every process _except_ pid 1 */
	message(CONSOLE|LOG, "\rSending SIGTERM to all processes.\n");
	kill(-1, SIGTERM);
	sleep(1);
	sync();

	message(CONSOLE|LOG, "\rSending SIGKILL to all processes.\n");
	kill(-1, SIGKILL);
	sleep(1);

	sync();
	if (kernelVersion > 0 && kernelVersion <= KERNEL_VERSION(2,2,11)) {
		/* bdflush, kupdate not needed for kernels >2.2.11 */
		bdflush(1, 0);
		sync();
	}
}

static void exec_signal(int sig)
{
	struct init_action *a, *tmp;
	sigset_t unblock_signals;
	
	for (a = init_action_list; a; a = tmp) {
		tmp = a->next;
		if (a->action & RESTART) {
			shutdown_system();

			/* unblock all signals, blocked in shutdown_system() */
			sigemptyset(&unblock_signals);
			sigaddset(&unblock_signals, SIGHUP);
			sigaddset(&unblock_signals, SIGCHLD);
			sigaddset(&unblock_signals, SIGUSR1);
			sigaddset(&unblock_signals, SIGUSR2);
			sigaddset(&unblock_signals, SIGINT);
			sigaddset(&unblock_signals, SIGTERM);
			sigaddset(&unblock_signals, SIGCONT);
			sigaddset(&unblock_signals, SIGSTOP);
			sigaddset(&unblock_signals, SIGTSTP);
			sigprocmask(SIG_UNBLOCK, &unblock_signals, NULL);

			message(CONSOLE|LOG, "\rTrying to re-exec %s\n", a->command);
			execl(a->command, a->command, NULL);
	
			message(CONSOLE|LOG, "\rexec of '%s' failed: %s\n", 
				a->command, strerror(errno));
			sync();
			sleep(2);
			init_reboot(RB_HALT_SYSTEM);
			loop_forever();
		}
	}
}

static void halt_signal(int sig)
{
	shutdown_system();
	message(CONSOLE|LOG,
#if #cpu(s390)
			/* Seems the s390 console is Wierd(tm). */
			"\rThe system is halted. You may reboot now.\n"
#else
			"\rThe system is halted. Press Reset or turn off power\n"
#endif
		   );
	sync();

	/* allow time for last message to reach serial console */
	sleep(2);

	if (sig == SIGUSR2 && kernelVersion >= KERNEL_VERSION(2,2,0))
		init_reboot(RB_POWER_OFF);
	else
		init_reboot(RB_HALT_SYSTEM);

	loop_forever();
}

static void reboot_signal(int sig)
{
	shutdown_system();
	message(CONSOLE|LOG, "\rPlease stand by while rebooting the system.\n");
	sync();

	/* allow time for last message to reach serial console */
	sleep(2);

	init_reboot(RB_AUTOBOOT);

	loop_forever();
}

static void ctrlaltdel_signal(int sig)
{
	run_actions(CTRLALTDEL);
}

/* The SIGSTOP & SIGTSTP handler */
static void stop_handler(int sig)
{
	int saved_errno = errno;

	got_cont = 0;
	while(!got_cont) pause();
	got_cont = 0;
	errno = saved_errno;
}

/* The SIGCONT handler */ 
static void cont_handler(int sig)
{
	got_cont = 1;
}

#endif							/* ! DEBUG_INIT */

static void new_init_action(int action, char *command, char *cons)
{
	struct init_action *new_action, *a;

	if (*cons == '\0')
		cons = console;

	/* do not run entries if console device is not available */
	if (access(cons, R_OK|W_OK))
		return;
	if (strcmp(cons, "/dev/null") == 0 && (action & ASKFIRST))
		return;

	new_action = calloc((size_t) (1), sizeof(struct init_action));
	if (!new_action) {
		message(LOG | CONSOLE, "\rMemory allocation failure\n");
		loop_forever();
	}

	/* Append to the end of the list */
	for (a = init_action_list; a && a->next; a = a->next) ;
	if (a) {
		a->next = new_action;
	} else {
		init_action_list = new_action;
	}
	strcpy(new_action->command, command);
	new_action->action = action;
	strcpy(new_action->terminal, cons);
	new_action->pid = 0;
//    message(LOG|CONSOLE, "command='%s' action='%d' terminal='%s'\n",
//      new_action->command, new_action->action, new_action->terminal);
}

static void delete_init_action(struct init_action * action)
{
	struct init_action *a, *b = NULL;

	for (a = init_action_list; a; b = a, a = a->next) {
		if (a == action) {
			if (b == NULL) {
				init_action_list = a->next;
			} else {
				b->next = a->next;
			}
			free(a);
			break;
		}
	}
}

/* NOTE that if BB_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 
 * of "askfirst" shells).  If BB_FEATURE_USE_INITTAB 
 * _is_ defined, but /etc/inittab is missing, this 
 * results in the same set of default behaviors.
 * */
static void parse_inittab(void)
{
#ifdef BB_FEATURE_USE_INITTAB
	FILE *file;
	char buf[INIT_BUFFS_SIZE], lineAsRead[INIT_BUFFS_SIZE], tmpConsole[INIT_BUFFS_SIZE];
	char *id, *runlev, *action, *command, *eol;
	const struct init_action_type *a = actions;
	int foundIt;


	file = fopen(INITTAB, "r");
	if (file == NULL) {
		/* No inittab file -- set up some default behavior */
#endif
		/* Reboot on Ctrl-Alt-Del */
		new_init_action(CTRLALTDEL, "/sbin/reboot", console);
		/* Umount all filesystems on halt/reboot */
		new_init_action(SHUTDOWN, "/bin/umount -a -r", console);
#if !defined(__UCLIBC__) || defined(__UCLIBC_HAS_MMU__)
		/* Swapoff on halt/reboot */
		new_init_action(SHUTDOWN, "/sbin/swapoff -a", console);
#endif
		/* Prepare to restart init when a HUP is received */
		new_init_action(RESTART, "/sbin/init", console);
		/* Askfirst shell on tty1-4 */
		new_init_action(ASKFIRST, LOGIN_SHELL, console);
		new_init_action(ASKFIRST, LOGIN_SHELL, VC_2);
		new_init_action(ASKFIRST, LOGIN_SHELL, VC_3);
		new_init_action(ASKFIRST, LOGIN_SHELL, VC_4);
		/* sysinit */
		new_init_action(SYSINIT, INIT_SCRIPT, console);

		return;
#ifdef BB_FEATURE_USE_INITTAB
	}

	while (fgets(buf, INIT_BUFFS_SIZE, file) != NULL) {
		foundIt = FALSE;
		/* Skip leading spaces */
		for (id = buf; *id == ' ' || *id == '\t'; id++);

		/* Skip the line if it's a comment */
		if (*id == '#' || *id == '\n')
			continue;

		/* Trim the trailing \n */
		eol = strrchr(id, '\n');
		if (eol != NULL)
			*eol = '\0';

		/* Keep a copy around for posterity's sake (and error msgs) */
		strcpy(lineAsRead, buf);

		/* Separate the ID field from the runlevels */
		runlev = strchr(id, ':');
		if (runlev == NULL || *(runlev + 1) == '\0') {
			message(LOG | CONSOLE, "\rBad inittab entry: %s\n", lineAsRead);
			continue;
		} else {
			*runlev = '\0';
			++runlev;
		}

		/* Separate the runlevels from the action */
		action = strchr(runlev, ':');
		if (action == NULL || *(action + 1) == '\0') {
			message(LOG | CONSOLE, "\rBad inittab entry: %s\n", lineAsRead);
			continue;
		} else {
			*action = '\0';
			++action;
		}

		/* Separate the action from the command */
		command = strchr(action, ':');
		if (command == NULL || *(command + 1) == '\0') {
			message(LOG | CONSOLE, "\rBad inittab entry: %s\n", lineAsRead);
			continue;
		} else {
			*command = '\0';
			++command;
		}

		/* Ok, now process it */
		a = actions;
		while (a->name != 0) {
			if (strcmp(a->name, action) == 0) {
				if (*id != '\0') {
					strcpy(tmpConsole, "/dev/");
					strncat(tmpConsole, id, INIT_BUFFS_SIZE-6);
					id = tmpConsole;
				}
				new_init_action(a->action, command, id);
				foundIt = TRUE;
			}
			a++;
		}
		if (foundIt == TRUE)
			continue;
		else {
			/* Choke on an unknown action */
			message(LOG | CONSOLE, "\rBad inittab entry: %s\n", lineAsRead);
		}
	}
	fclose(file);
	return;
#endif /* BB_FEATURE_USE_INITTAB */
}



extern int init_main(int argc, char **argv)
{
	struct init_action *a;
	pid_t wpid;
	int status;

	if (argc > 1 && !strcmp(argv[1], "-q")) {
		/* don't assume init's pid == 1 */
		long *pid = find_pid_by_name("init");
		if (!pid || *pid<=0) {
			pid = find_pid_by_name("linuxrc");
			if (!pid || *pid<=0)
				error_msg_and_die("no process killed");
		}
		kill(*pid, SIGHUP);
		exit(0);
	}

#ifndef DEBUG_INIT
	/* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
	if (getpid() != 1
#ifdef BB_FEATURE_LINUXRC
			&& strstr(applet_name, "linuxrc") == NULL
#endif
	                  )
	{
			show_usage();
	}
	/* Set up sig handlers  -- be sure to
	 * clear all of these in run() */
	signal(SIGHUP,  exec_signal);
	signal(SIGUSR1, halt_signal);
	signal(SIGUSR2, halt_signal);
	signal(SIGINT,  ctrlaltdel_signal);
	signal(SIGTERM, reboot_signal);
	signal(SIGCONT, cont_handler);
	signal(SIGSTOP, stop_handler);
	signal(SIGTSTP, stop_handler);

	/* Turn off rebooting via CTL-ALT-DEL -- we get a 
	 * SIGINT on CAD so we can shut things down gracefully... */
	init_reboot(RB_DISABLE_CAD);
#endif

	/* Figure out what kernel this is running */
	kernelVersion = get_kernel_revision();

	/* Figure out where the default console should be */
	console_init();

	/* Close whatever files are open, and reset the console. */
	close(0);
	close(1);
	close(2);

	if(device_open(console, O_RDWR|O_NOCTTY)==0) {
	set_term(0);
		close(0);
	}

	chdir("/");
	setsid();

	/* Make sure PATH is set to something sane */
	putenv("PATH="_PATH_STDPATH);

	/* Hello world */
	message(MAYBE_CONSOLE|LOG, "\rinit started:  %s\n", full_version);

	/* Make sure there is enough memory to do something useful. */
	check_memory();

	/* Check if we are supposed to be in single user mode */
	if (argc > 1 && (!strcmp(argv[1], "single") ||
					 !strcmp(argv[1], "-s") || !strcmp(argv[1], "1"))) {
		/* Ask first then start a shell on tty2-4 */
		new_init_action(ASKFIRST, LOGIN_SHELL, VC_2);
		new_init_action(ASKFIRST, LOGIN_SHELL, VC_3);
		new_init_action(ASKFIRST, LOGIN_SHELL, VC_4);
		/* Start a shell on tty1 */
		new_init_action(RESPAWN, LOGIN_SHELL, console);
	} else {
		/* Not in single user mode -- see what inittab says */

		/* NOTE that if BB_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 
		 * of "askfirst" shells */
		parse_inittab();
	}

	/* Make the command line just say "init"  -- thats all, nothing else */
	fixup_argv(argc, argv, "init");

	/* Now run everything that needs to be run */

	/* First run the sysinit command */
	run_actions(SYSINIT);

	/* Next run anything that wants to block */
	run_actions(WAIT);

	/* Next run anything to be run only once */
	run_actions(ONCE);

	/* If there is nothing else to do, stop */
	if (init_action_list == NULL) {
		message(LOG | CONSOLE, "\rNo more tasks for init -- sleeping forever.\n");
		loop_forever();
	}

	/* Now run the looping stuff for the rest of forever */
	while (1) {
		/* run the respawn stuff */
		run_actions(RESPAWN);

		/* run the askfirst stuff */
		run_actions(ASKFIRST);

		/* Don't consume all CPU time -- sleep a bit */
		sleep(1);

		/* Wait for a child process to exit */
		wpid = wait(&status);
		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;
					message(LOG, "Process '%s' (pid %d) exited.  "
							"Scheduling it for restart.\n", a->command, wpid);
				}
			}
			/* see if anyone else is waiting to be reaped */
			wpid = waitpid (-1, &status, WNOHANG);
		}
	}
}

/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/