source: MondoRescue/branches/stable/mindi-busybox/init/init.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * Mini init implementation for busybox
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 * Adjusted by so many folks, it's impossible to keep track.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include <paths.h>
//#include <signal.h>
//#include <sys/ioctl.h>
//#include <sys/wait.h>
#include <sys/reboot.h>

#if ENABLE_FEATURE_INIT_SYSLOG
# include <sys/syslog.h>
#endif

#define INIT_BUFFS_SIZE 256
#define CONSOLE_NAME_SIZE 32
#define MAXENV  16      /* Number of env. vars */

#if ENABLE_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>
#endif

#define INITTAB      "/etc/inittab" /* inittab file location */
#ifndef INIT_SCRIPT
#define INIT_SCRIPT  "/etc/init.d/rcS"  /* Default sysinit script. */
#endif

/* 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 {
    struct init_action *next;
    int action;
    pid_t pid;
    char command[INIT_BUFFS_SIZE];
    char terminal[CONSOLE_NAME_SIZE];
};

/* Static variables */
static struct init_action *init_action_list = NULL;

#if !ENABLE_FEATURE_INIT_SYSLOG
static const char *log_console = VC_5;
#endif
#if !ENABLE_DEBUG_INIT
static sig_atomic_t got_cont = 0;
#endif

enum {
    L_LOG = 0x1,
    L_CONSOLE = 0x2,

#if ENABLE_FEATURE_EXTRA_QUIET
    MAYBE_CONSOLE = 0x0,
#else
    MAYBE_CONSOLE = L_CONSOLE,
#endif

#ifndef RB_HALT_SYSTEM
    RB_HALT_SYSTEM = 0xcdef0123, /* FIXME: this overflows enum */
    RB_ENABLE_CAD = 0x89abcdef,
    RB_DISABLE_CAD = 0,
    RB_POWER_OFF = 0x4321fedc,
    RB_AUTOBOOT = 0x01234567,
#endif
};

static const char *const environment[] = {
    "HOME=/",
    bb_PATH_root_path,
    "SHELL=/bin/sh",
    "USER=root",
    NULL
};

/* Function prototypes */
static void delete_init_action(struct init_action *a);
static int waitfor(const struct init_action *a, pid_t pid);
#if !ENABLE_DEBUG_INIT
static void shutdown_signal(int sig);
#endif

#if !ENABLE_DEBUG_INIT
static void loop_forever(void)
{
    while (1)
        sleep(1);
}
#endif

/* Print a message to the specified device.
 * Device may be bitwise-or'd from L_LOG | L_CONSOLE */
#if ENABLE_DEBUG_INIT
#define messageD message
#else
#define messageD(...)  do {} while (0)
#endif
static void message(int device, const char *fmt, ...)
    __attribute__ ((format(printf, 2, 3)));
static void message(int device, const char *fmt, ...)
{
#if !ENABLE_FEATURE_INIT_SYSLOG
    static int log_fd = -1;
#endif

    va_list arguments;
    int l;
    char msg[128];

    msg[0] = '\r';
    va_start(arguments, fmt);
    vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
    va_end(arguments);
    msg[sizeof(msg) - 2] = '\0';
    l = strlen(msg);

#if ENABLE_FEATURE_INIT_SYSLOG
    /* Log the message to syslogd */
    if (device & L_LOG) {
        /* don't out "\r" */
        openlog(applet_name, 0, LOG_DAEMON);
        syslog(LOG_INFO, "init: %s", msg + 1);
        closelog();
    }
    msg[l++] = '\n';
    msg[l] = '\0';
#else
    msg[l++] = '\n';
    msg[l] = '\0';
    /* Take full control of the log tty, and never close it.
     * It's mine, all mine!  Muhahahaha! */
    if (log_fd < 0) {
        if (!log_console) {
            log_fd = 2;
        } else {
            log_fd = device_open(log_console, O_WRONLY | O_NONBLOCK | O_NOCTTY);
            if (log_fd < 0) {
                bb_error_msg("can't log to %s", log_console);
                device = L_CONSOLE;
            } else {
                fcntl(log_fd, F_SETFD, FD_CLOEXEC);
            }
        }
    }
    if (device & L_LOG) {
        full_write(log_fd, msg, l);
        if (log_fd == 2)
            return; /* don't print dup messages */
    }
#endif

    if (device & L_CONSOLE) {
        /* Send console messages to console so people will see them. */
        full_write(2, msg, l);
    }
}

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

    tcgetattr(STDIN_FILENO, &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(STDIN_FILENO, TCSANOW, &tty);
}

/* From <linux/serial.h> */
struct serial_struct {
    int type;
    int line;
    unsigned int    port;
    int irq;
    int flags;
    int xmit_fifo_size;
    int custom_divisor;
    int baud_base;
    unsigned short  close_delay;
    char    io_type;
    char    reserved_char[1];
    int hub6;
    unsigned short  closing_wait; /* time to wait before closing */
    unsigned short  closing_wait2; /* no longer used... */
    unsigned char   *iomem_base;
    unsigned short  iomem_reg_shift;
    unsigned int    port_high;
    unsigned long   iomap_base; /* cookie passed into ioremap */
    int reserved[1];
    /* Paranoia (imagine 64bit kernel overwriting 32bit userspace stack) */
    uint32_t bbox_reserved[16];
};
static void console_init(void)
{
    struct serial_struct sr;
    char *s;

    s = getenv("CONSOLE");
    if (!s) s = getenv("console");
    if (s) {
        int fd = open(s, O_RDWR | O_NONBLOCK | O_NOCTTY);
        if (fd >= 0) {
            dup2(fd, 0);
            dup2(fd, 1);
            dup2(fd, 2);
            while (fd > 2) close(fd--);
        }
        messageD(L_LOG, "console='%s'", s);
    } else {
        /* Make sure fd 0,1,2 are not closed */
        bb_sanitize_stdio();
    }

    s = getenv("TERM");
    if (ioctl(0, TIOCGSERIAL, &sr) == 0) {
        /* Force the TERM setting to vt102 for serial console --
         * if TERM is set to linux (the default) */
        if (!s || strcmp(s, "linux") == 0)
            putenv((char*)"TERM=vt102");
#if !ENABLE_FEATURE_INIT_SYSLOG
        log_console = NULL;
#endif
    } else if (!s)
        putenv((char*)"TERM=linux");
}

static void fixup_argv(char **argv)
{
    /* Fix up argv[0] to be certain we claim to be init */
    strncpy(argv[0], "init", strlen(argv[0]));

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

/* Open the new terminal device */
static void open_stdio_to_tty(const char* tty_name, int fail)
{
    /* empty tty_name means "use init's tty", else... */
    if (tty_name[0]) {
        int fd = device_open(tty_name, O_RDWR);
        if (fd < 0) {
            message(L_LOG | L_CONSOLE, "Can't open %s: %s",
                tty_name, strerror(errno));
            if (fail)
                _exit(1);
#if !ENABLE_DEBUG_INIT
            shutdown_signal(SIGUSR1);
#else
            _exit(2);
#endif
        } else {
            dup2(fd, 0);
            dup2(fd, 1);
            dup2(fd, 2);
            if (fd > 2) close(fd);
        }
    }
    set_sane_term();
}

static pid_t run(const struct init_action *a)
{
    int i;
    pid_t pid;
    char *s, *tmpCmd, *cmdpath;
    char *cmd[INIT_BUFFS_SIZE];
    char buf[INIT_BUFFS_SIZE + 6];  /* INIT_BUFFS_SIZE+strlen("exec ")+1 */
    sigset_t nmask, omask;

    /* Block sigchild while forking.  */
    sigemptyset(&nmask);
    sigaddset(&nmask, SIGCHLD);
    sigprocmask(SIG_BLOCK, &nmask, &omask);
    pid = fork();
    sigprocmask(SIG_SETMASK, &omask, NULL);

    if (pid)
        return pid;

    /* 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(SIGQUIT, SIG_DFL);
    signal(SIGCONT, SIG_DFL);
    signal(SIGSTOP, SIG_DFL);
    signal(SIGTSTP, SIG_DFL);

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

    /* Open the new terminal device */
    open_stdio_to_tty(a->terminal, 1);

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

        /* Now fork off another process to just hang around */
        if ((pid = fork()) < 0) {
            message(L_LOG | L_CONSOLE, "Can't fork");
            _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);

            waitfor(NULL, pid);
            /* See if stealing the controlling tty back is necessary */
            if (tcgetpgrp(0) != getpid())
                _exit(0);

            /* Use a temporary process to steal the controlling tty. */
            if ((pid = fork()) < 0) {
                message(L_LOG | L_CONSOLE, "Can't fork");
                _exit(1);
            }
            if (pid == 0) {
                setsid();
                ioctl(0, TIOCSCTTY, 1);
                _exit(0);
            }
            waitfor(NULL, pid);
            _exit(0);
        }

        /* Now fall though to actually execute things */
    }

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

        /* make a new argv[0] */
        if ((cmd[0] = malloc(strlen(s) + 2)) == NULL) {
            message(L_LOG | L_CONSOLE, bb_msg_memory_exhausted);
            cmd[0] = cmdpath;
        } else {
            cmd[0][0] = '-';
            strcpy(cmd[0] + 1, s);
        }
#if ENABLE_FEATURE_INIT_SCTTY
        /* Establish this process as session leader and
         * (attempt) to make the tty (if any) a controlling tty.
         */
        setsid();
        ioctl(0, TIOCSCTTY, 0 /*don't steal it*/);
#endif
    }

#if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
    if (a->action & ASKFIRST) {
        static const char press_enter[] ALIGN1 =
#ifdef CUSTOMIZED_BANNER
#include CUSTOMIZED_BANNER
#endif
            "\nPlease press Enter to activate this console. ";
        char c;
        /*
         * 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.
         */
        messageD(L_LOG, "waiting for enter to start '%s'"
                    "(pid %d, tty '%s')\n",
                  cmdpath, getpid(), a->terminal);
        full_write(1, press_enter, sizeof(press_enter) - 1);
        while (read(0, &c, 1) == 1 && c != '\n')
            ;
    }
#endif
    /* Log the process name and args */
    message(L_LOG, "starting pid %d, tty '%s': '%s'",
              getpid(), a->terminal, cmdpath);

#if ENABLE_FEATURE_INIT_COREDUMPS
    {
        struct stat sb;
        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. */
    BB_EXECVP(cmdpath, cmd);

    /* We're still here?  Some error happened. */
    message(L_LOG | L_CONSOLE, "Cannot run '%s': %s",
            cmdpath, strerror(errno));
    _exit(-1);
}

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

    runpid = (NULL == a)? pid : run(a);
    while (1) {
        wpid = waitpid(runpid, &status, 0);
        if (wpid == runpid)
            break;
        if (wpid == -1 && errno == ECHILD) {
            /* we missed its termination */
            break;
        }
        /* FIXME other errors should maybe trigger an error, but allow
         * the program to continue */
    }
    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) {
            /* a->terminal of "" means "init's console" */
            if (a->terminal[0] && access(a->terminal, R_OK | W_OK)) {
                delete_init_action(a);
            } else if (a->action & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN | RESTART)) {
                waitfor(a, 0);
                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);
                }
            }
        }
    }
}

#if !ENABLE_DEBUG_INIT
static void init_reboot(unsigned long magic)
{
    pid_t pid;
    /* We have to fork here, since the kernel calls do_exit(0) in
     * linux/kernel/sys.c, which can cause the machine to panic when
     * the init process is killed.... */
    pid = vfork();
    if (pid == 0) { /* child */
        reboot(magic);
        _exit(0);
    }
    waitpid(pid, NULL, 0);
}

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, SIGQUIT);
    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);

    message(L_CONSOLE | L_LOG, "The system is going down NOW!");

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

    /* 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 | L_LOG, "Sending SIG%s to all processes", "KILL");
    kill(-1, SIGKILL);
    sync();
    sleep(1);
}

static void exec_signal(int sig ATTRIBUTE_UNUSED)
{
    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, SIGQUIT);
            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);

            /* Open the new terminal device */
            open_stdio_to_tty(a->terminal, 0);

            messageD(L_CONSOLE | L_LOG, "Trying to re-exec %s", a->command);
            BB_EXECLP(a->command, a->command, NULL);

            message(L_CONSOLE | L_LOG, "Cannot run '%s': %s",
                    a->command, strerror(errno));
            sleep(2);
            init_reboot(RB_HALT_SYSTEM);
            loop_forever();
        }
    }
}

static void shutdown_signal(int sig)
{
    const char *m;
    int rb;

    shutdown_system();

    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 | L_LOG, "Requesting system %s", m);
    /* allow time for last message to reach serial console */
    sleep(2);
    init_reboot(rb);
    loop_forever();
}

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

/* The SIGSTOP & SIGTSTP handler */
static void stop_handler(int sig ATTRIBUTE_UNUSED)
{
    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 ATTRIBUTE_UNUSED)
{
    got_cont = 1;
}

#endif  /* !ENABLE_DEBUG_INIT */

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

    if (strcmp(cons, bb_dev_null) == 0 && (action & ASKFIRST))
        return;

    /* Append to the end of the list */
    for (a = last = init_action_list; a; a = a->next) {
        /* don't enter action if it's already in the list,
         * but do overwrite existing actions */
        if ((strcmp(a->command, command) == 0)
         && (strcmp(a->terminal, cons) == 0)
        ) {
            a->action = action;
            return;
        }
        last = a;
    }

    new_action = xzalloc(sizeof(struct init_action));
    if (last) {
        last->next = new_action;
    } else {
        init_action_list = new_action;
    }
    strcpy(new_action->command, command);
    new_action->action = action;
    strcpy(new_action->terminal, cons);
    messageD(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%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)
{
#if ENABLE_FEATURE_USE_INITTAB
    FILE *file;
    char buf[INIT_BUFFS_SIZE], lineAsRead[INIT_BUFFS_SIZE];
    char tmpConsole[CONSOLE_NAME_SIZE];
    char *id, *runlev, *action, *command, *eol;
    const struct init_action_type *a = actions;

    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, "reboot", "");
        /* Umount all filesystems on halt/reboot */
        new_init_action(SHUTDOWN, "umount -a -r", "");
        /* Swapoff on halt/reboot */
        if (ENABLE_SWAPONOFF) new_init_action(SHUTDOWN, "swapoff -a", "");
        /* Prepare to restart init when a HUP is received */
        new_init_action(RESTART, "init", "");
        /* Askfirst shell on tty1-4 */
        new_init_action(ASKFIRST, bb_default_login_shell, "");
        new_init_action(ASKFIRST, bb_default_login_shell, VC_2);
        new_init_action(ASKFIRST, bb_default_login_shell, VC_3);
        new_init_action(ASKFIRST, bb_default_login_shell, VC_4);
        /* sysinit */
        new_init_action(SYSINIT, INIT_SCRIPT, "");

        return;
#if ENABLE_FEATURE_USE_INITTAB
    }

    while (fgets(buf, INIT_BUFFS_SIZE, file) != NULL) {
        /* 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 */
        //XXX: chomp() ?
        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(L_LOG | L_CONSOLE, "Bad inittab entry: %s", lineAsRead);
            continue;
        } else {
            *runlev = '\0';
            ++runlev;
        }

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

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

        /* Ok, now process it */
        for (a = actions; a->name != 0; a++) {
            if (strcmp(a->name, action) == 0) {
                if (*id != '\0') {
                    if (strncmp(id, "/dev/", 5) == 0)
                        id += 5;
                    strcpy(tmpConsole, "/dev/");
                    safe_strncpy(tmpConsole + 5, id,
                        sizeof(tmpConsole) - 5);
                    id = tmpConsole;
                }
                new_init_action(a->action, command, id);
                break;
            }
        }
        if (a->name == 0) {
            /* Choke on an unknown action */
            message(L_LOG | L_CONSOLE, "Bad inittab entry: %s", lineAsRead);
        }
    }
    fclose(file);
#endif /* FEATURE_USE_INITTAB */
}

#if ENABLE_FEATURE_USE_INITTAB
static void reload_signal(int sig ATTRIBUTE_UNUSED)
{
    struct init_action *a, *tmp;

    message(L_LOG, "reloading /etc/inittab");

    /* disable old entrys */
    for (a = init_action_list; a; a = a->next ) {
        a->action = ONCE;
    }

    parse_inittab();

    /* remove unused entrys */
    for (a = init_action_list; a; a = tmp) {
        tmp = a->next;
        if ((a->action & (ONCE | SYSINIT | WAIT)) && a->pid == 0) {
            delete_init_action(a);
        }
    }
    run_actions(RESPAWN);
}
#endif  /* FEATURE_USE_INITTAB */

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

    die_sleep = 30 * 24*60*60; /* if xmalloc will ever die... */

    if (argc > 1 && !strcmp(argv[1], "-q")) {
        return kill(1, SIGHUP);
    }
#if !ENABLE_DEBUG_INIT
    /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
    if (getpid() != 1
     && (!ENABLE_FEATURE_INITRD || !strstr(applet_name, "linuxrc"))
    ) {
        bb_show_usage();
    }
    /* Set up sig handlers  -- be sure to
     * clear all of these in run() */
    signal(SIGHUP, exec_signal);
    signal(SIGQUIT, exec_signal);
    signal(SIGUSR1, shutdown_signal);
    signal(SIGUSR2, shutdown_signal);
    signal(SIGINT, ctrlaltdel_signal);
    signal(SIGTERM, shutdown_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 where the default console should be */
    console_init();
    set_sane_term();
    chdir("/");
    setsid();
    {
        const char *const *e;
        /* Make sure environs is set to something sane */
        for (e = environment; *e; e++)
            putenv((char *) *e);
    }

    if (argc > 1) setenv("RUNLEVEL", argv[1], 1);

    /* Hello world */
    message(MAYBE_CONSOLE | L_LOG, "init started: %s", bb_banner);

    /* Make sure there is enough memory to do something useful. */
    if (ENABLE_SWAPONOFF) {
        struct sysinfo info;

        if (!sysinfo(&info) &&
            (info.mem_unit ? : 1) * (long long)info.totalram < 1024*1024)
        {
            message(L_CONSOLE, "Low memory, forcing swapon");
            /* swapon -a requires /proc typically */
            new_init_action(SYSINIT, "mount -t proc proc /proc", "");
            /* Try to turn on swap */
            new_init_action(SYSINIT, "swapon -a", "");
            run_actions(SYSINIT);   /* wait and removing */
        }
    }

    /* Check if we are supposed to be in single user mode */
    if (argc > 1
     && (!strcmp(argv[1], "single") || !strcmp(argv[1], "-s") || LONE_CHAR(argv[1], '1'))
    ) {
        /* Start a shell on console */
        new_init_action(RESPAWN, bb_default_login_shell, "");
    } 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();
    }

#if ENABLE_SELINUX
    if (getenv("SELINUX_INIT") == NULL) {
        int enforce = 0;

        putenv((char*)"SELINUX_INIT=YES");
        if (selinux_init_load_policy(&enforce) == 0) {
            BB_EXECVP(argv[0], argv);
        } else if (enforce > 0) {
            /* SELinux in enforcing mode but load_policy failed */
            /* At this point, we probably can't open /dev/console, so log() won't work */
            message(L_CONSOLE, "Cannot load SELinux Policy. "
                "Machine is in enforcing mode. Halting now.");
            exit(1);
        }
    }
#endif /* CONFIG_SELINUX */

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

    /* 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 ENABLE_FEATURE_USE_INITTAB
    /* Redefine SIGHUP to reread /etc/inittab */
    signal(SIGHUP, reload_signal);
#else
    signal(SIGHUP, SIG_IGN);
#endif /* FEATURE_USE_INITTAB */

    /* 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(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;
                    message(L_LOG, "process '%s' (pid %d) exited. "
                            "Scheduling it for restart.",
                            a->command, wpid);
                }
            }
            /* see if anyone else is waiting to be reaped */
            wpid = waitpid(-1, NULL, WNOHANG);
        }
    }
}