init/init.c

/* vi: set sw=4 ts=4: */
/*
 * Mini init implementation for busybox
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 * Copyright (C) 1999-2002 by Erik Andersen <andersee@debian.org>
 * Adjusted by so many folks, it's impossible to keep track.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

/* Turn this on to disable all the dangerous 
   rebooting stuff when debugging.
#define DEBUG_INIT
*/

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <paths.h>
#include <signal.h>
#include <stdarg.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <limits.h>
#include <sys/fcntl.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "busybox.h"
#ifdef CONFIG_SYSLOGD
# include <sys/syslog.h>
#endif

#if defined(__UCLIBC__) && !defined(__UCLIBC_HAS_MMU__)
#define fork	vfork
#endif

/* From <linux/vt.h> */
struct vt_stat {
	unsigned short v_active;        /* active vt */
	unsigned short v_signal;        /* signal to send */
	unsigned short v_state;         /* vt bitmask */
};
static const int VT_GETSTATE = 0x5603;  /* get global vt state info */

/* From <linux/serial.h> */
struct serial_struct {
	int     type;
	int     line;
	int     port;
	int     irq;
	int     flags;
	int     xmit_fifo_size;
	int     custom_divisor;
	int     baud_base;
	unsigned short  close_delay;
	char    reserved_char[2];
	int     hub6;
	unsigned short  closing_wait; /* time to wait before closing */
	unsigned short  closing_wait2; /* no longer used... */
	int     reserved[4];
};


#if (__GNU_LIBRARY__ > 5) || defined(__dietlibc__) 
  #include <sys/reboot.h>
  #define init_reboot(magic) reboot(magic)
#else
  #define init_reboot(magic) reboot(0xfee1dead, 672274793, magic)
#endif

#ifndef _PATH_STDPATH
#define _PATH_STDPATH	"/usr/bin:/bin:/usr/sbin:/sbin"
#endif

#if defined CONFIG_FEATURE_INIT_COREDUMPS
/*
 * When a file named CORE_ENABLE_FLAG_FILE exists, setrlimit is called 
 * before processes are spawned to set core file size as unlimited.
 * This is for debugging only.  Don't use this is production, unless
 * you want core dumps lying about....
 */
#define CORE_ENABLE_FLAG_FILE "/.init_enable_core"
#include <sys/resource.h>
#include <sys/time.h>
#endif

#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))

#if __GNU_LIBRARY__ > 5
	#include <sys/kdaemon.h>
#else
	extern int bdflush (int func, long int data);
#endif

#define SHELL        "/bin/sh"	     /* Default shell */
#define LOGIN_SHELL  "-" SHELL	     /* Default login shell */
#define INITTAB      "/etc/inittab"  /* inittab file location */
#ifndef INIT_SCRIPT
#define INIT_SCRIPT  "/etc/init.d/rcS"   /* Default sysinit script. */
#endif

#define MAXENV	16		/* Number of env. vars */

/* Allowed init action types */
#define SYSINIT     0x001
#define RESPAWN     0x002
#define ASKFIRST    0x004
#define WAIT        0x008
#define ONCE        0x010
#define CTRLALTDEL  0x020
#define SHUTDOWN    0x040
#define RESTART     0x080

/* A mapping between "inittab" action name strings and action type codes. */
struct init_action_type {
	const char *name;
	int action;
};

static const struct init_action_type actions[] = {
	{"sysinit", SYSINIT},
	{"respawn", RESPAWN},
	{"askfirst", ASKFIRST},
	{"wait", WAIT},
	{"once", ONCE},
	{"ctrlaltdel", CTRLALTDEL},
	{"shutdown", SHUTDOWN},
	{"restart", RESTART},
	{0, 0}
};

/* Set up a linked list of init_actions, to be read from inittab */
struct init_action {
	pid_t pid;
	char command[256];
	char terminal[256];
	struct init_action *next;
	int action;
};

/* Static variables */
static struct init_action *init_action_list = NULL;
static char *secondConsole = VC_2;
static char *thirdConsole  = VC_3;
static char *fourthConsole = VC_4;
static char *log           = VC_5;
static int  kernelVersion  = 0;
static char termType[32]   = "TERM=linux";
static char console[32]    = _PATH_CONSOLE;
static sig_atomic_t got_cont = 0;
static const int LOG = 0x1;
static const int CONSOLE = 0x2;
#if defined CONFIG_FEATURE_EXTRA_QUIET
static const int MAYBE_CONSOLE = 0x0;
#else
#define MAYBE_CONSOLE	CONSOLE
#endif
#ifndef RB_HALT_SYSTEM
static const int RB_HALT_SYSTEM = 0xcdef0123;
static const int RB_ENABLE_CAD = 0x89abcdef;
static const int RB_DISABLE_CAD = 0;
#define RB_POWER_OFF    0x4321fedc
static const int RB_AUTOBOOT = 0x01234567;
#endif

/* Function prototypes */
static void delete_init_action(struct init_action *a);
static int waitfor(struct init_action *a);


static void loop_forever(void)
{
	while (1)
		sleep (1);
}

/* Print a message to the specified device.
 * Device may be bitwise-or'd from LOG | CONSOLE */
#ifdef DEBUG_INIT
static inline messageND(int device, char *fmt, ...) { }
#else 
#define messageND message
#endif
static void message(int device, char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
static void message(int device, char *fmt, ...)
{
	va_list arguments;
	int fd;

#ifdef CONFIG_SYSLOGD

	/* Log the message to syslogd */
	if (device & LOG) {
		char msg[1024];

		va_start(arguments, fmt);
		vsnprintf(msg, sizeof(msg), fmt, arguments);
		va_end(arguments);
		syslog_msg(LOG_USER, LOG_INFO, msg);
	}
#else
	static int log_fd = -1;

	/* Take full control of the log tty, and never close it.
	 * It's mine, all mine!  Muhahahaha! */
	if (log_fd < 0) {
		if (log == NULL) {
			/* don't even try to log, because there is no such console */
			log_fd = -2;
			/* log to main console instead */
			device = CONSOLE;
		} else if ((log_fd = device_open(log, O_RDWR|O_NDELAY)) < 0) {
			log_fd = -2;
			fprintf(stderr, "Bummer, can't write to log on %s!\n", log);
			log = NULL;
			device = CONSOLE;
		}
	}
	if ((device & LOG) && (log_fd >= 0)) {
		va_start(arguments, fmt);
		vdprintf(log_fd, fmt, arguments);
		va_end(arguments);
	}
#endif

	if (device & CONSOLE) {
		/* Always send console messages to /dev/console so people will see them. */
		if (
			(fd =
			 device_open(_PATH_CONSOLE, O_WRONLY | O_NOCTTY | O_NDELAY)) >= 0) {
			va_start(arguments, fmt);
			vdprintf(fd, fmt, arguments);
			va_end(arguments);
			close(fd);
		} else {
			fprintf(stderr, "Bummer, can't print: ");
			va_start(arguments, fmt);
			vfprintf(stderr, fmt, arguments);
			va_end(arguments);
		}
	}
}

/* Set terminal settings to reasonable defaults */
static void set_term(int fd)
{
	struct termios tty;

	tcgetattr(fd, &tty);

	/* set control chars */
	tty.c_cc[VINTR]  = 3;	/* C-c */
	tty.c_cc[VQUIT]  = 28;	/* C-\ */
	tty.c_cc[VERASE] = 127; /* C-? */
	tty.c_cc[VKILL]  = 21;	/* C-u */
	tty.c_cc[VEOF]   = 4;	/* C-d */
	tty.c_cc[VSTART] = 17;	/* C-q */
	tty.c_cc[VSTOP]  = 19;	/* C-s */
	tty.c_cc[VSUSP]  = 26;	/* C-z */

	/* use line dicipline 0 */
	tty.c_line = 0;

	/* Make it be sane */
	tty.c_cflag &= CBAUD|CBAUDEX|CSIZE|CSTOPB|PARENB|PARODD;
	tty.c_cflag |= CREAD|HUPCL|CLOCAL;


	/* input modes */
	tty.c_iflag = ICRNL | IXON | IXOFF;

	/* output modes */
	tty.c_oflag = OPOST | ONLCR;

	/* local modes */
	tty.c_lflag =
		ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;

	tcsetattr(fd, TCSANOW, &tty);
}

/* How much memory does this machine have?
   Units are kBytes to avoid overflow on 4GB machines */
static int check_free_memory(void)
{
	struct sysinfo info;
	unsigned int result, u, s=10;

	if (sysinfo(&info) != 0) {
		perror_msg("Error checking free memory");
		return -1;
	}

	/* Kernels 2.0.x and 2.2.x return info.mem_unit==0 with values in bytes.
	 * Kernels 2.4.0 return info.mem_unit in bytes. */
	u = info.mem_unit;
	if (u==0) u=1;
	while ( (u&1) == 0 && s > 0 ) { u>>=1; s--; }
	result = (info.totalram>>s) + (info.totalswap>>s);
	result = result*u;
	if (result < 0) result = INT_MAX;
	return result;
}

static void console_init(void)
{
	int fd;
	int tried_devcons = 0;
	int tried_vtprimary = 0;
	struct vt_stat vt;
	struct serial_struct sr;
	char *s;

	if ((s = getenv("TERM")) != NULL) {
		snprintf(termType, sizeof(termType) - 1, "TERM=%s", s);
	}

	if ((s = getenv("CONSOLE")) != NULL) {
		safe_strncpy(console, s, sizeof(console));
	}
#if #cpu(sparc)
	/* sparc kernel supports console=tty[ab] parameter which is also 
	 * passed to init, so catch it here */
	else if ((s = getenv("console")) != NULL) {
		/* remap tty[ab] to /dev/ttyS[01] */
		if (strcmp(s, "ttya") == 0)
			safe_strncpy(console, SC_0, sizeof(console));
		else if (strcmp(s, "ttyb") == 0)
			safe_strncpy(console, SC_1, sizeof(console));
	}
#endif
	else {
		/* 2.2 kernels: identify the real console backend and try to use it */
		if (ioctl(0, TIOCGSERIAL, &sr) == 0) {
			/* this is a serial console */
			snprintf(console, sizeof(console) - 1, SC_FORMAT, sr.line);
		} else if (ioctl(0, VT_GETSTATE, &vt) == 0) {
			/* this is linux virtual tty */
			snprintf(console, sizeof(console) - 1, VC_FORMAT, vt.v_active);
		} else {
			safe_strncpy(console, _PATH_CONSOLE, sizeof(console));
			tried_devcons++;
		}
	}

	while ((fd = open(console, O_RDONLY | O_NONBLOCK)) < 0) {
		/* Can't open selected console -- try /dev/console */
		if (!tried_devcons) {
			tried_devcons++;
			safe_strncpy(console, _PATH_CONSOLE, sizeof(console));
			continue;
		}
		/* Can't open selected console -- try vt1 */
		if (!tried_vtprimary) {
			tried_vtprimary++;
			safe_strncpy(console, VC_1, sizeof(console));
			continue;
		}
		break;
	}
	if (fd < 0) {
		/* Perhaps we should panic here? */
		safe_strncpy(console, "/dev/null", sizeof(console));
	} else {
		/* check for serial console and disable logging to tty5 & 
		 * running a shell to tty2-4 */
		if (ioctl(0, TIOCGSERIAL, &sr) == 0) {
			log = NULL;
			secondConsole = NULL;
			thirdConsole = NULL;
			fourthConsole = NULL;
			/* Force the TERM setting to vt102 for serial console --
			 * iff TERM is set to linux (the default) */
			if (strcmp( termType, "TERM=linux" ) == 0)
				safe_strncpy(termType, "TERM=vt102", sizeof(termType));
			message(LOG | CONSOLE,
					"\rserial console detected.  Disabling virtual terminals.\n");
		}
		close(fd);
	}
	message(LOG, "console=%s\n", console);
}
	
static void fixup_argv(int argc, char **argv, char *new_argv0)
{
	int len;
	/* Fix up argv[0] to be certain we claim to be init */
	len = strlen(argv[0]);
	memset(argv[0], 0, len);
	safe_strncpy(argv[0], new_argv0, len + 1);

	/* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
	len = 1;
	while (argc > len) {
		memset(argv[len], 0, strlen(argv[len]));
		len++;
	}
}

/* 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(void)
{
	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 */
		system("/bin/mount -t proc proc /proc");
		/* Try to turn on swap */
		system("/sbin/swapon -a");
		if (check_free_memory() < 1000)
			goto goodnight;
	} else
		goto goodnight;
	return;
#endif

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

static pid_t run(struct init_action *a)
{
	struct stat sb;
	int i, j, fd, junk; 
	pid_t pid, pgrp, tmp_pid;
	char *s, *tmpCmd, *cmd[255], *cmdpath, buf[255];
	sigset_t nmask, omask;
	char *environment[MAXENV+1] = {
		termType,
		"HOME=/",
		"PATH=" _PATH_STDPATH,
		"SHELL=" SHELL,
		"USER=root",
		NULL
	};
	static const char press_enter[] =
#ifdef CUSTOMIZED_BANNER
#include CUSTOMIZED_BANNER
#endif
		"\nPlease press Enter to activate this console. ";

	/* inherit environment to the child, merging our values -andy */
	for (i=0; environ[i]; i++) {
		for (j=0; environment[j]; j++) {
			s = strchr(environment[j], '=');
			if (!strncmp(environ[i], environment[j], s - environment[j]))
				break;
		}
		if (!environment[j]) {
			environment[j++] = environ[i];
			environment[j] = NULL;
		}
	}

	/* Block sigchild while forking.  */
	sigemptyset(&nmask);
	sigaddset(&nmask, SIGCHLD);
	sigprocmask(SIG_BLOCK, &nmask, &omask);

	if ((pid = fork()) == 0) 
	{
		/* Clean up */
		ioctl(0, TIOCNOTTY, 0);
		close(0);
		close(1);
		close(2);
		sigprocmask(SIG_SETMASK, &omask, NULL);

		/* Create a new session and make ourself the process group leader */
		setsid();

		/* Reset signal handlers that were set by the parent process */
		signal(SIGUSR1, SIG_DFL);
		signal(SIGUSR2, SIG_DFL);
		signal(SIGINT,  SIG_DFL);
		signal(SIGTERM, SIG_DFL);
		signal(SIGHUP,  SIG_DFL);
		signal(SIGCONT, SIG_DFL);
		signal(SIGSTOP, SIG_DFL);
		signal(SIGTSTP, SIG_DFL);

		/* Open the new terminal device */
		if ((fd = device_open(a->terminal, O_RDWR|O_NOCTTY)) < 0) {
			if (stat(a->terminal, &sb) != 0) {
				message(LOG | CONSOLE, "\rdevice '%s' does not exist.\n",
						a->terminal);
				_exit(1);
			}
			message(LOG | CONSOLE, "\rBummer, can't open %s\n", a->terminal);
			_exit(1);
		}
		/* Make sure the terminal will act fairly normal for us */
		set_term(0);

		/* If the init Action requires up to wait, then force the
		 * supplied terminal to be the controlling tty. */
		if (a->action & (SYSINIT|WAIT|CTRLALTDEL|SHUTDOWN|RESTART|ASKFIRST)) {

			/* Take over the controlling tty */
			ioctl(fd, TIOCSCTTY, 1);
			/* Setup stdin, stdout, stderr for the new process so 
			 * they point to the supplied terminal */
			dup(fd);
			dup(fd);

			/* Now fork off another process to just hang around */
			if ((pid = fork()) < 0) {
				message(LOG | CONSOLE, "Can't fork!\n");
				_exit(1);
			}

			if (pid > 0) {

				/* We are the parent -- wait till the child is done */
				signal(SIGINT, SIG_IGN);
				signal(SIGTSTP, SIG_IGN);
				signal(SIGQUIT, SIG_IGN);
				signal(SIGCHLD, SIG_DFL);

				/* Wait for child to exit */
				while ((tmp_pid = waitpid(pid, &junk, 0)) != pid) {
					if (tmp_pid < 0 && errno == ECHILD)
						break;
				}

				/* See if stealing the controlling tty back is necessary */
				pgrp = tcgetpgrp(tmp_pid);
				if (pgrp != getpid())
					_exit(0);

				/* Use a temporary process to steal the controlling tty. */
				if ((pid = fork()) < 0) {
					message(LOG | CONSOLE, "\rCan't fork!\n");
					_exit(1);
				}       
				if (pid == 0) {
					setsid();
					ioctl(tmp_pid, TIOCSCTTY, 1);
					_exit(0);
				}       
				while((tmp_pid = waitpid(pid, &junk, 0)) != pid) {
					if (tmp_pid < 0 && errno == ECHILD)
						break;
				}
				_exit(0);
			}

			/* Now fall though to actually execute things */
		} else {
			dup(fd);
			dup(fd);
		}

		/* See if any special /bin/sh requiring characters are present */
		if (strpbrk(a->command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
			cmd[0] = SHELL;
			cmd[1] = "-c";
			snprintf(buf, sizeof(buf), "exec %s", a->command);
			cmd[2] = buf;
			cmd[3] = NULL;
		} else {
			/* Convert command (char*) into cmd (char**, one word per string) */
			safe_strncpy(buf, a->command, sizeof(buf));
			s = buf;
			for (tmpCmd = buf, i = 0;
					(tmpCmd = strsep(&s, " \t")) != NULL;) {
				if (*tmpCmd != '\0') {
					cmd[i] = tmpCmd;
					tmpCmd++;
					i++;
				}
			}
			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);
			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 CONFIG_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;

	/* 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);

	/* 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 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, sys_errlist[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
			/* secondConsole is NULL for a serial console */
			"\rThe 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, "\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;

	/* 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;

	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;
	}
	safe_strncpy(new_action->command, command, 255);
	new_action->action = action;
	safe_strncpy(new_action->terminal, cons, 255);
	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 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 
 * of "askfirst" shells).  If CONFIG_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 CONFIG_FEATURE_USE_INITTAB
	FILE *file;
	char buf[256], lineAsRead[256], tmpConsole[256];
	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 */
		new_init_action(ASKFIRST, LOGIN_SHELL, console);
		/* Askfirst shell on tty2 */
		if (secondConsole != NULL)
			new_init_action(ASKFIRST, LOGIN_SHELL, secondConsole);
		/* Askfirst shell on tty3 */
		if (thirdConsole != NULL)
			new_init_action(ASKFIRST, LOGIN_SHELL, thirdConsole);
		/* Askfirst shell on tty4 */
		if (fourthConsole != NULL)
			new_init_action(ASKFIRST, LOGIN_SHELL, fourthConsole);
		/* sysinit */
		new_init_action(SYSINIT, INIT_SCRIPT, console);

		return;
#ifdef CONFIG_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, "\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, 200);
					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 /* CONFIG_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 CONFIG_FEATURE_INITRD
			&& 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();

	/* 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, "\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 */
		if (secondConsole != NULL)
			new_init_action(ASKFIRST, LOGIN_SHELL, secondConsole);
		if (thirdConsole != NULL)
			new_init_action(ASKFIRST, LOGIN_SHELL, thirdConsole);
		if (fourthConsole != NULL)
			new_init_action(ASKFIRST, LOGIN_SHELL, fourthConsole);
		/* 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 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 
		 * 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);
		if (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);
				}
			}
		}
	}
}

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