init.c

为samsung2410 ARM移植的busybox工具包

		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 (get_enter == TRUE) {
			/*
			 * 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, console %s)\n",
					cmd[0], getpid(), terminal);
			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(), terminal, command);

#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, "Bummer, could not run '%s': %s\n", cmdpath,
				strerror(errno));
		exit(-1);
	}
	return pid;
}

static int waitfor(char *command, char *terminal, int get_enter)
{
	int status, wpid;
	int pid = run(command, terminal, get_enter);

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

/* Make sure there is enough memory to do something useful. *
 * Calls "swapon -a" if needed so be sure /etc/fstab is present... */
static void check_memory()
{
	struct stat statBuf;

	if (check_free_memory() > 1000)
		return;

#if !defined(__UCLIBC__) || defined(__UCLIBC_HAS_MMU__)
	if (stat("/etc/fstab", &statBuf) == 0) {
		/* swapon -a requires /proc typically */
		waitfor("mount proc /proc -t proc", console, FALSE);
		/* Try to turn on swap */
		waitfor("swapon -a", console, FALSE);
		if (check_free_memory() < 1000)
			goto goodnight;
	} else
		goto goodnight;
	return;
#endif

  goodnight:
	message(CONSOLE,
			"Sorry, your computer does not have enough memory.\n");
	loop_forever();
}

/* Run all commands to be run right before halt/reboot */
static void run_actions(initActionEnum action)
{
	initAction *a, *tmp;
	for (a = initActionList; a; a = tmp) {
		tmp = a->nextPtr;
		if (a->action == action) {
			waitfor(a->process, a->console, FALSE);
			delete_initAction(a);
		}
	}
}


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

	/* 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);
	sigprocmask(SIG_BLOCK, &block_signals, NULL);

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

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

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

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

	/* run everything to be run at "shutdown" */
	run_actions(SHUTDOWN);

	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 halt_signal(int sig)
{
	shutdown_system();
	message(CONSOLE|LOG,
#if #cpu(s390)
			/* Seems the s390 console is Wierd(tm). */
			"The system is halted. You may reboot now.\n",
#else
			/* secondConsole is NULL for a serial console */
			"The system is halted. Press %s or turn off power\n",
			(secondConsole == NULL)? "Reset" : "CTRL-ALT-DEL"
#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, "Please 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);
}

#endif							/* ! DEBUG_INIT */

static void new_initAction(initActionEnum action, char *process, char *cons)
{
	initAction *newAction;

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

	/* If BusyBox detects that a serial console is in use, 
	 * then entries not refering to the console or null devices will _not_ be run.
	 * The exception to this rule is the null device.
	 */
	if (secondConsole == NULL && strcmp(cons, console)
		&& strcmp(cons, "/dev/null"))
		return;
	if (strcmp(cons, "/dev/null") == 0 && action == ASKFIRST)
		return;


	newAction = calloc((size_t) (1), sizeof(initAction));
	if (!newAction) {
		message(LOG | CONSOLE, "Memory allocation failure\n");
		loop_forever();
	}
	newAction->nextPtr = initActionList;
	initActionList = newAction;
	safe_strncpy(newAction->process, process, 255);
	newAction->action = action;
	safe_strncpy(newAction->console, cons, 255);
	newAction->pid = 0;
//    message(LOG|CONSOLE, "process='%s' action='%d' console='%s'\n",
//      newAction->process, newAction->action, newAction->console);
}

static void delete_initAction(initAction * action)
{
	initAction *a, *b = NULL;

	for (a = initActionList; a; b = a, a = a->nextPtr) {
		if (a == action) {
			if (b == NULL) {
				initActionList = a->nextPtr;
			} else {
				b->nextPtr = a->nextPtr;
			}
			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[256], lineAsRead[256], tmpConsole[256];
	char *id, *runlev, *action, *process, *eol;
	const struct initActionType *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_initAction(CTRLALTDEL, "/sbin/reboot", console);
#if !defined(__UCLIBC__) || defined(__UCLIBC_HAS_MMU__)
		/* Swapoff on halt/reboot */
		new_initAction(SHUTDOWN, "/sbin/swapoff -a", console);
#endif
		/* Umount all filesystems on halt/reboot */
		new_initAction(SHUTDOWN, "/bin/umount -a -r", console);
		/* Askfirst shell on tty1 */
		new_initAction(ASKFIRST, LOGIN_SHELL, console);
		/* Askfirst shell on tty2 */
		if (secondConsole != NULL)
			new_initAction(ASKFIRST, LOGIN_SHELL, secondConsole);
		/* Askfirst shell on tty3 */
		if (thirdConsole != NULL)
			new_initAction(ASKFIRST, LOGIN_SHELL, thirdConsole);
		/* Askfirst shell on tty4 */
		if (fourthConsole != NULL)
			new_initAction(ASKFIRST, LOGIN_SHELL, fourthConsole);
		/* sysinit */
		new_initAction(SYSINIT, INIT_SCRIPT, console);

		return;
#ifdef BB_FEATURE_USE_INITTAB
	}

	while (fgets(buf, 255, 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, "Bad 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, "Bad inittab entry: %s\n", lineAsRead);
			continue;
		} else {
			*action = '\0';
			++action;
		}

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

		/* 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, 200);
					id = tmpConsole;
				}
				new_initAction(a->action, process, id);
				foundIt = TRUE;
			}
			a++;
		}
		if (foundIt == TRUE)
			continue;
		else {
			/* Choke on an unknown action */
			message(LOG | CONSOLE, "Bad inittab entry: %s\n", lineAsRead);
		}
	}
	return;
#endif /* BB_FEATURE_USE_INITTAB */
}



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

#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(SIGUSR1, halt_signal);
	signal(SIGUSR2, halt_signal);
	signal(SIGINT, ctrlaltdel_signal);
	signal(SIGTERM, reboot_signal);

	/* 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();

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

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

	set_term(0);
	chdir("/");
	setsid();

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

	/* Hello world */
	message(MAYBE_CONSOLE|LOG, "init 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 */
		if (secondConsole != NULL)
			new_initAction(ASKFIRST, LOGIN_SHELL, secondConsole);
		if (thirdConsole != NULL)
			new_initAction(ASKFIRST, LOGIN_SHELL, thirdConsole);
		if (fourthConsole != NULL)
			new_initAction(ASKFIRST, LOGIN_SHELL, fourthConsole);
		/* Start a shell on tty1 */
		new_initAction(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 */
	for (a = initActionList; a; a = tmp) {
		tmp = a->nextPtr;
		if (a->action == ONCE) {
			run(a->process, a->console, FALSE);
			/* Now remove the "once" entry from the list */
			delete_initAction(a);
		}
	}
	/* If there is nothing else to do, stop */
	if (initActionList == NULL) {
		message(LOG | CONSOLE,
				"No more tasks for init -- sleeping forever.\n");
		loop_forever();
	}

	/* Now run the looping stuff for the rest of forever */
	while (1) {
		for (a = initActionList; a; a = a->nextPtr) {
			/* Only run stuff with pid==0.  If they have
			 * a pid, that means they are still running */
			if (a->pid == 0) {
				switch (a->action) {
				case RESPAWN:
					/* run the respawn stuff */
					a->pid = run(a->process, a->console, FALSE);
					break;
				case ASKFIRST:
					/* run the askfirst stuff */
					a->pid = run(a->process, a->console, TRUE);
					break;
					/* silence the compiler's incessant whining */
				default:
					break;
				}
			}
		}
		/* Wait for a child process to exit */
		wpid = wait(&status);
		if (wpid > 0) {
			/* Find out who died and clean up their corpse */
			for (a = initActionList; a; a = a->nextPtr) {
				if (a->pid == wpid) {
					a->pid = 0;
					message(LOG,
							"Process '%s' (pid %d) exited.  Scheduling it for restart.\n",
							a->process, wpid);
				}
			}
		}
		sleep(1);
	}
}

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