/*      $OpenBSD: init.c,v 1.72 2022/09/10 00:49:47 cheloha Exp $       */
/*      $NetBSD: init.c,v 1.22 1996/05/15 23:29:33 jtc Exp $    */

/*-
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Donn Seeley at Berkeley Software Design, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/reboot.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/tree.h>
#include <sys/wait.h>
#include <machine/cpu.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <login_cap.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <ttyent.h>
#include <unistd.h>
#include <util.h>

#ifdef SECURE
#include <pwd.h>
#include <readpassphrase.h>
#endif

#include "pathnames.h"

/*
 * Sleep times; used to prevent thrashing.
 */
#define GETTY_SPACING            5      /* N secs minimum getty spacing */
#define GETTY_SLEEP             30      /* sleep N secs after spacing problem */
#define WINDOW_WAIT              3      /* wait N secs after starting window */
#define STALL_TIMEOUT           30      /* wait N secs after warning */
#define DEATH_WATCH             10      /* wait N secs for procs to die */

/*
 * User-based resource limits.
 */
#define RESOURCE_RC             "daemon"
#define RESOURCE_WINDOW         "default"
#define RESOURCE_GETTY          "default"

#ifndef DEFAULT_STATE
#define DEFAULT_STATE           runcom
#endif

void handle(sig_t, ...);
void delset(sigset_t *, ...);

void stall(char *, ...);
void warning(char *, ...);
void emergency(char *, ...);
void disaster(int);

typedef enum {
        invalid_state,
        single_user,
        runcom,
        read_ttys,
        multi_user,
        clean_ttys,
        catatonia,
        death,
        do_reboot,
        hard_death,
        nice_death
} state_t;
typedef state_t (*state_func_t)(void);

state_t f_single_user(void);
state_t f_runcom(void);
state_t f_read_ttys(void);
state_t f_multi_user(void);
state_t f_clean_ttys(void);
state_t f_catatonia(void);
state_t f_death(void);
state_t f_do_reboot(void);
state_t f_hard_death(void);
state_t f_nice_death(void);

state_func_t state_funcs[] = {
        NULL,
        f_single_user,
        f_runcom,
        f_read_ttys,
        f_multi_user,
        f_clean_ttys,
        f_catatonia,
        f_death,
        f_do_reboot,
        f_hard_death,
        f_nice_death
};

enum { AUTOBOOT, FASTBOOT } runcom_mode = AUTOBOOT;

void transition(state_t);
volatile sig_atomic_t requested_transition = DEFAULT_STATE;

void setctty(char *);

typedef struct init_session {
        int     se_index;               /* index of entry in ttys file */
        pid_t   se_process;             /* controlling process */
        struct  timespec se_started;    /* used to avoid thrashing */
        int     se_flags;               /* status of session */
#define SE_SHUTDOWN     0x1             /* session won't be restarted */
#define SE_PRESENT      0x2             /* session is in /etc/ttys */
#define SE_DEVEXISTS    0x4             /* open does not result in ENODEV */
        char    *se_device;             /* filename of port */
        char    *se_getty;              /* what to run on that port */
        char    **se_getty_argv;        /* pre-parsed argument array */
        char    *se_window;             /* window system (started only once) */
        char    **se_window_argv;       /* pre-parsed argument array */
        struct  init_session *se_prev;
        struct  init_session *se_next;
        RB_ENTRY(init_session) se_entry;
} session_t;

static int cmp_sessions(session_t *, session_t *);
RB_HEAD(session_tree, init_session) session_tree = RB_INITIALIZER(session_tree);
RB_PROTOTYPE(session_tree, init_session, se_entry, cmp_sessions);
RB_GENERATE(session_tree, init_session, se_entry, cmp_sessions);

void free_session(session_t *);
session_t *new_session(session_t *, int, struct ttyent *);
session_t *sessions;

char **construct_argv(char *);
void start_window_system(session_t *);
void collect_child(pid_t);
pid_t start_getty(session_t *);
void transition_handler(int);
void alrm_handler(int);
void setsecuritylevel(int);
void setprocresources(char *);
int getsecuritylevel(void);
int setupargv(session_t *, struct ttyent *);

volatile sig_atomic_t clang;

void clear_session_logs(session_t *);

void add_session(session_t *);
void del_session(session_t *);
session_t *find_session(pid_t);

/*
 * The mother of all processes.
 */
int
main(int argc, char *argv[])
{
        int c, fd;
        struct sigaction sa;
        sigset_t mask;

        /* Dispose of random users. */
        if (getuid() != 0)
                errc(1, EPERM, NULL);

        /* System V users like to reexec init. */
        if (getpid() != 1)
                errx(1, "already running");

        /*
         * Paranoia.
         */
        if ((fd = open(_PATH_DEVNULL, O_RDWR)) != -1) {
                (void)dup2(fd, STDIN_FILENO);
                (void)dup2(fd, STDOUT_FILENO);
                (void)dup2(fd, STDERR_FILENO);
                if (fd > 2)
                        (void)close(fd);
        }

        /*
         * Note that this does NOT open a file...
         * Does 'init' deserve its own facility number?
         */
        openlog("init", LOG_CONS|LOG_ODELAY, LOG_AUTH);

        /*
         * Create an initial session.
         */
        if (setsid() == -1)
                warning("initial setsid() failed: %m");

        /*
         * Establish an initial user so that programs running
         * single user do not freak out and die (like passwd).
         */
        if (setlogin("root") == -1)
                warning("setlogin() failed: %m");

        /*
         * This code assumes that we always get arguments through flags,
         * never through bits set in some random machine register.
         */
        while ((c = getopt(argc, argv, "sf")) != -1)
                switch (c) {
                case 's':
                        requested_transition = single_user;
                        break;
                case 'f':
                        runcom_mode = FASTBOOT;
                        break;
                default:
                        warning("unrecognized flag '-%c'", c);
                        break;
                }

        if (optind != argc)
                warning("ignoring excess arguments");

        /*
         * We catch or block signals rather than ignore them,
         * so that they get reset on exec.
         */
        handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV,
            SIGBUS, SIGSYS, SIGXCPU, SIGXFSZ, 0);
        handle(transition_handler, SIGHUP, SIGINT, SIGTERM, SIGTSTP,
            SIGUSR1, SIGUSR2, 0);
        handle(alrm_handler, SIGALRM, 0);
        sigfillset(&mask);
        delset(&mask, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGSYS,
            SIGXCPU, SIGXFSZ, SIGHUP, SIGINT, SIGTERM, SIGUSR1, SIGUSR2,
            SIGTSTP, SIGALRM, 0);
        sigprocmask(SIG_SETMASK, &mask, NULL);
        memset(&sa, 0, sizeof sa);
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = 0;
        sa.sa_handler = SIG_IGN;
        (void) sigaction(SIGTTIN, &sa, NULL);
        (void) sigaction(SIGTTOU, &sa, NULL);

        /*
         * Start the state machine.
         */
        transition(requested_transition);

        /*
         * Should never reach here.
         */
        exit(1);
}

/*
 * Associate a function with a signal handler.
 */
void
handle(sig_t handler, ...)
{
        int sig;
        struct sigaction sa;
        sigset_t mask_everything;
        va_list ap;

        va_start(ap, handler);

        memset(&sa, 0, sizeof sa);
        sa.sa_handler = handler;
        sigfillset(&mask_everything);

        while ((sig = va_arg(ap, int))) {
                sa.sa_mask = mask_everything;
                /* XXX SA_RESTART? */
                sa.sa_flags = sig == SIGCHLD ? SA_NOCLDSTOP : 0;
                sigaction(sig, &sa, NULL);
        }
        va_end(ap);
}

/*
 * Delete a set of signals from a mask.
 */
void
delset(sigset_t *maskp, ...)
{
        int sig;
        va_list ap;

        va_start(ap, maskp);
        while ((sig = va_arg(ap, int)))
                sigdelset(maskp, sig);
        va_end(ap);
}

/*
 * Log a message and sleep for a while (to give someone an opportunity
 * to read it and to save log or hardcopy output if the problem is chronic).
 * NB: should send a message to the session logger to avoid blocking.
 */
void
stall(char *message, ...)
{
        va_list ap;

        va_start(ap, message);
        vsyslog(LOG_ALERT, message, ap);
        va_end(ap);
        closelog();
        sleep(STALL_TIMEOUT);
}

/*
 * Like stall(), but doesn't sleep.
 * If cpp had variadic macros, the two functions could be #defines for another.
 * NB: should send a message to the session logger to avoid blocking.
 */
void
warning(char *message, ...)
{
        va_list ap;

        va_start(ap, message);
        vsyslog(LOG_ALERT, message, ap);
        va_end(ap);
        closelog();
}

/*
 * Log an emergency message.
 * NB: should send a message to the session logger to avoid blocking.
 */
void
emergency(char *message, ...)
{
        struct syslog_data sdata = SYSLOG_DATA_INIT;
        va_list ap;

        va_start(ap, message);
        vsyslog_r(LOG_EMERG, &sdata, message, ap);
        va_end(ap);
}

/*
 * Catch an unexpected signal.
 */
void
disaster(int sig)
{
        emergency("fatal signal: %s", strsignal(sig));

        sleep(STALL_TIMEOUT);
        _exit(sig);             /* reboot */
}

/*
 * Get the security level of the kernel.
 */
int
getsecuritylevel(void)
{
#ifdef KERN_SECURELVL
        int name[2], curlevel;
        size_t len;

        name[0] = CTL_KERN;
        name[1] = KERN_SECURELVL;
        len = sizeof curlevel;
        if (sysctl(name, 2, &curlevel, &len, NULL, 0) == -1) {
                emergency("cannot get kernel security level: %s",
                    strerror(errno));
                return (-1);
        }
        return (curlevel);
#else
        return (-1);
#endif
}

/*
 * Set the security level of the kernel.
 */
void
setsecuritylevel(int newlevel)
{
#ifdef KERN_SECURELVL
        int name[2], curlevel;

        curlevel = getsecuritylevel();
        if (newlevel == curlevel)
                return;
        name[0] = CTL_KERN;
        name[1] = KERN_SECURELVL;
        if (sysctl(name, 2, NULL, NULL, &newlevel, sizeof newlevel) == -1) {
                emergency(
                    "cannot change kernel security level from %d to %d: %s",
                    curlevel, newlevel, strerror(errno));
                return;
        }
#ifdef SECURE
        warning("kernel security level changed from %d to %d",
            curlevel, newlevel);
#endif
#endif
}

/*
 * Change states in the finite state machine.
 * The initial state is passed as an argument.
 */
void
transition(state_t s)
{
        for (;;)
                s = (*state_funcs[s])();
}

/*
 * Close out the accounting files for a login session.
 * NB: should send a message to the session logger to avoid blocking.
 */
void
clear_session_logs(session_t *sp)
{
        char *line = sp->se_device + sizeof(_PATH_DEV) - 1;

        if (logout(line))
                logwtmp(line, "", "");
}

/*
 * Start a session and allocate a controlling terminal.
 * Only called by children of init after forking.
 */
void
setctty(char *name)
{
        int fd;

        (void) revoke(name);
        sleep(2);                       /* leave DTR low */
        if ((fd = open(name, O_RDWR)) == -1) {
                stall("can't open %s: %m", name);
                _exit(1);
        }
        if (login_tty(fd) == -1) {
                stall("can't get %s for controlling terminal: %m", name);
                _exit(1);
        }
}

/*
 * Bring the system up single user.
 */
state_t
f_single_user(void)
{
        pid_t pid, wpid;
        int status;
        sigset_t mask;
        char shell[PATH_MAX];           /* Allocate space here */
        char name[PATH_MAX];            /* Name (argv[0]) of shell */
        char *argv[2];
#ifdef SECURE
        struct ttyent *typ;
        struct passwd *pp;
        static const char banner[] =
                "Enter root password, or ^D to go multi-user\n";
        char *clear;
        char pbuf[1024];
#endif

        /* Init shell and name */
        strlcpy(shell, _PATH_BSHELL, sizeof shell);
        strlcpy(name, "-sh", sizeof name);

        /*
         * If the kernel is in secure mode, downgrade it to insecure mode.
         */
        if (getsecuritylevel() > 0)
                setsecuritylevel(0);

        if ((pid = fork()) == 0) {
                /*
                 * Start the single user session.
                 */
                setctty(_PATH_CONSOLE);

#ifdef SECURE
                /*
                 * Check the root password.
                 * We don't care if the console is 'on' by default;
                 * it's the only tty that can be 'off' and 'secure'.
                 */
                typ = getttynam("console");
                pp = getpwnam_shadow("root");
                if (typ && (typ->ty_status & TTY_SECURE) == 0 && pp &&
                    *pp->pw_passwd) {
                        write(STDERR_FILENO, banner, sizeof banner - 1);
                        for (;;) {
                                int ok = 0;
                                clear = readpassphrase("Password:", pbuf,
                                    sizeof(pbuf), RPP_ECHO_OFF);
                                if (clear == NULL || *clear == '\0')
                                        _exit(0);
                                if (crypt_checkpass(clear, pp->pw_passwd) == 0)
                                        ok = 1;
                                explicit_bzero(pbuf, sizeof(pbuf));
                                if (ok)
                                        break;
                                warning("single-user login failed\n");
                        }
                }
                endttyent();
                endpwent();
#endif /* SECURE */

#ifdef DEBUGSHELL
                {
                        char altshell[128], *cp = altshell;
                        int num;

#define SHREQUEST \
        "Enter pathname of shell or RETURN for sh: "

                        (void)write(STDERR_FILENO,
                            SHREQUEST, sizeof(SHREQUEST) - 1);
                        while ((num = read(STDIN_FILENO, cp, 1)) != -1 &&
                            num != 0 && *cp != '\n' && cp < &altshell[127])
                                cp++;
                        *cp = '\0';

                        /* Copy in alternate shell */
                        if (altshell[0] != '\0'){
                                char *p;

                                /* Binary to exec */
                                strlcpy(shell, altshell, sizeof shell);

                                /* argv[0] */
                                p = strrchr(altshell, '/');
                                if(p == NULL) p = altshell;
                                else p++;

                                name[0] = '-';
                                strlcpy(&name[1], p, sizeof name -1);
                        }
                }
#endif /* DEBUGSHELL */

                /*
                 * Unblock signals.
                 * We catch all the interesting ones,
                 * and those are reset to SIG_DFL on exec.
                 */
                sigemptyset(&mask);
                sigprocmask(SIG_SETMASK, &mask, NULL);

                /*
                 * Fire off a shell.
                 * If the default one doesn't work, try the Bourne shell.
                 */
                argv[0] = name;
                argv[1] = NULL;
                setenv("PATH", _PATH_STDPATH, 1);
                execv(shell, argv);
                emergency("can't exec %s for single user: %m", shell);

                argv[0] = "-sh";
                argv[1] = NULL;
                execv(_PATH_BSHELL, argv);
                emergency("can't exec %s for single user: %m", _PATH_BSHELL);
                sleep(STALL_TIMEOUT);
                _exit(1);
        }

        if (pid == -1) {
                /*
                 * We are seriously hosed.  Do our best.
                 */
                emergency("can't fork single-user shell, trying again");
                while (waitpid(-1, NULL, WNOHANG) > 0)
                        continue;
                return single_user;
        }

        requested_transition = 0;
        do {
                if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
                        collect_child(wpid);
                if (wpid == -1) {
                        if (errno == EINTR)
                                continue;
                        warning("wait for single-user shell failed: %m; restarting");
                        return single_user;
                }
                if (wpid == pid && WIFSTOPPED(status)) {
                        warning("init: shell stopped, restarting\n");
                        kill(pid, SIGCONT);
                        wpid = -1;
                }
        } while (wpid != pid && !requested_transition);

        if (requested_transition)
                return requested_transition;

        if (!WIFEXITED(status)) {
                if (WTERMSIG(status) == SIGKILL) {
                        /*
                         *  reboot(8) killed shell?
                         */
                        warning("single user shell terminated.");
                        sleep(STALL_TIMEOUT);
                        _exit(0);
                } else {
                        warning("single user shell terminated, restarting");
                        return single_user;
                }
        }

        runcom_mode = FASTBOOT;
        return runcom;
}

/*
 * Run the system startup script.
 */
state_t
f_runcom(void)
{
        pid_t pid, wpid;
        int status;
        char *argv[4];
        struct sigaction sa;

        if ((pid = fork()) == 0) {
                memset(&sa, 0, sizeof sa);
                sigemptyset(&sa.sa_mask);
                sa.sa_flags = 0;
                sa.sa_handler = SIG_IGN;
                (void) sigaction(SIGTSTP, &sa, NULL);
                (void) sigaction(SIGHUP, &sa, NULL);

                setctty(_PATH_CONSOLE);

                argv[0] = "sh";
                argv[1] = _PATH_RUNCOM;
                argv[2] = runcom_mode == AUTOBOOT ? "autoboot" : NULL;
                argv[3] = NULL;

                sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);

                setprocresources(RESOURCE_RC);

                execv(_PATH_BSHELL, argv);
                stall("can't exec %s for %s: %m", _PATH_BSHELL, _PATH_RUNCOM);
                _exit(1);       /* force single user mode */
        }

        if (pid == -1) {
                emergency("can't fork for %s on %s: %m",
                        _PATH_BSHELL, _PATH_RUNCOM);
                while (waitpid(-1, NULL, WNOHANG) > 0)
                        continue;
                sleep(STALL_TIMEOUT);
                return single_user;
        }

        /*
         * Copied from single_user().  This is a bit paranoid.
         */
        do {
                if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
                        collect_child(wpid);
                if (wpid == -1) {
                        if (errno == EINTR)
                                continue;
                        warning("wait for %s on %s failed: %m; going to single user mode",
                            _PATH_BSHELL, _PATH_RUNCOM);
                        return single_user;
                }
                if (wpid == pid && WIFSTOPPED(status)) {
                        warning("init: %s on %s stopped, restarting\n",
                            _PATH_BSHELL, _PATH_RUNCOM);
                        kill(pid, SIGCONT);
                        wpid = -1;
                }
        } while (wpid != pid);

        if (WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM &&
            requested_transition == catatonia) {
                /* /etc/rc executed /sbin/reboot; wait for the end quietly */
                sigset_t s;

                sigfillset(&s);
                for (;;)
                        sigsuspend(&s);
        }

        if (!WIFEXITED(status)) {
                warning("%s on %s terminated abnormally, going to single user mode",
                    _PATH_BSHELL, _PATH_RUNCOM);
                return single_user;
        }

        if (WEXITSTATUS(status))
                return single_user;

        runcom_mode = AUTOBOOT;         /* the default */
        /* NB: should send a message to the session logger to avoid blocking. */
        logwtmp("~", "reboot", "");
        return read_ttys;
}

/*
 * Compare session keys.
 */
static int
cmp_sessions(session_t *sp1, session_t *sp2)
{
        if (sp1->se_process < sp2->se_process)
                return (-1);
        if (sp1->se_process > sp2->se_process)
                return (1);
        return (0);
}

/*
 * Add a new login session.
 */
void
add_session(session_t *sp)
{
        if (RB_INSERT(session_tree, &session_tree, sp) != NULL)
                emergency("insert %d: %s", sp->se_process, strerror(errno));
}

/*
 * Delete an old login session.
 */
void
del_session(session_t *sp)
{
        RB_REMOVE(session_tree, &session_tree, sp);
}

/*
 * Look up a login session by pid.
 */
session_t *
find_session(pid_t pid)
{
        struct init_session s;

        s.se_process = pid;
        return (RB_FIND(session_tree, &session_tree, &s));
}

/*
 * Construct an argument vector from a command line.
 */
char **
construct_argv(char *command)
{
        int argc = 0;
        char **argv = calloc((strlen(command) + 1) / 2 + 1, sizeof (char *));
        static const char separators[] = " \t";

        if (argv == NULL)
                return (0);

        if ((argv[argc++] = strtok(command, separators)) == 0) {
                free(argv);
                return (0);
        }
        while ((argv[argc++] = strtok(NULL, separators)))
                continue;
        return (argv);
}

/*
 * Deallocate a session descriptor.
 */
void
free_session(session_t *sp)
{
        free(sp->se_device);
        if (sp->se_getty) {
                free(sp->se_getty);
                free(sp->se_getty_argv);
        }
        if (sp->se_window) {
                free(sp->se_window);
                free(sp->se_window_argv);
        }
        free(sp);
}

/*
 * Allocate a new session descriptor.
 */
session_t *
new_session(session_t *sprev, int session_index, struct ttyent *typ)
{
        session_t *sp;

        if ((typ->ty_status & TTY_ON) == 0 ||
            typ->ty_name == 0 ||
            typ->ty_getty == 0)
                return (0);

        sp = calloc(1, sizeof (session_t));
        if (sp == NULL)
                err(1, "calloc");

        sp->se_flags = SE_PRESENT;
        sp->se_index = session_index;

        if (asprintf(&sp->se_device, "%s%s", _PATH_DEV, typ->ty_name) == -1)
                err(1, "asprintf");

        if (setupargv(sp, typ) == 0) {
                free_session(sp);
                return (0);
        }

        sp->se_next = NULL;
        if (sprev == NULL) {
                sessions = sp;
                sp->se_prev = NULL;
        } else {
                sprev->se_next = sp;
                sp->se_prev = sprev;
        }

        return (sp);
}

/*
 * Calculate getty and if useful window argv vectors.
 */
int
setupargv(session_t *sp, struct ttyent *typ)
{
        if (sp->se_getty) {
                free(sp->se_getty);
                free(sp->se_getty_argv);
        }
        if (asprintf(&sp->se_getty, "%s %s", typ->ty_getty, typ->ty_name) == -1)
                err(1, "asprintf");
        sp->se_getty_argv = construct_argv(sp->se_getty);
        if (sp->se_getty_argv == 0) {
                warning("can't parse getty for port %s", sp->se_device);
                free(sp->se_getty);
                sp->se_getty = NULL;
                return (0);
        }
        if (typ->ty_window) {
                free(sp->se_window);
                sp->se_window = strdup(typ->ty_window);
                if (sp->se_window == NULL) {
                        warning("can't allocate window");
                        return (0);
                }
                sp->se_window_argv = construct_argv(sp->se_window);
                if (sp->se_window_argv == NULL) {
                        warning("can't parse window for port %s",
                            sp->se_device);
                        free(sp->se_window);
                        sp->se_window = NULL;
                        return (0);
                }
        }
        return (1);
}

/*
 * Walk the list of ttys and create sessions for each active line.
 */
state_t
f_read_ttys(void)
{
        int session_index = 0;
        session_t *sp, *snext;
        struct ttyent *typ;

        /*
         * Destroy any previous session state.
         * There shouldn't be any, but just in case...
         */
        for (sp = sessions; sp; sp = snext) {
                if (sp->se_process)
                        clear_session_logs(sp);
                snext = sp->se_next;
                free_session(sp);
        }
        sessions = NULL;

        /*
         * Allocate a session entry for each active port.
         * Note that sp starts at 0.
         */
        while ((typ = getttyent()))
                if ((snext = new_session(sp, ++session_index, typ)))
                        sp = snext;

        endttyent();

        return multi_user;
}

/*
 * Start a window system running.
 */
void
start_window_system(session_t *sp)
{
        pid_t pid;
        sigset_t mask;

        if ((pid = fork()) == -1) {
                emergency("can't fork for window system on port %s: %m",
                    sp->se_device);
                /* hope that getty fails and we can try again */
                return;
        }

        if (pid)
                return;

        sigemptyset(&mask);
        sigprocmask(SIG_SETMASK, &mask, NULL);

        if (setsid() == -1)
                emergency("setsid failed (window) %m");

        setprocresources(RESOURCE_WINDOW);

        execv(sp->se_window_argv[0], sp->se_window_argv);
        stall("can't exec window system '%s' for port %s: %m",
            sp->se_window_argv[0], sp->se_device);
        _exit(1);
}

/*
 * Start a login session running.
 * For first open, man-handle tty directly to determine if it
 * really exists. It is not efficient to spawn gettys on devices
 * that do not exist.
 */
pid_t
start_getty(session_t *sp)
{
        pid_t pid;
        sigset_t mask;
        struct timespec current_time, elapsed;
        int p[2], new = 1;

        if (sp->se_flags & SE_DEVEXISTS)
                new = 0;

        if (new) {
                if (pipe(p) == -1)
                        return (-1);
        }

        /*
         * fork(), not vfork() -- we can't afford to block.
         */
        if ((pid = fork()) == -1) {
                emergency("can't fork for getty on port %s: %m", sp->se_device);
                return (-1);
        }

        if (pid) {
                if (new) {
                        char c;

                        close(p[1]);
                        if (read(p[0], &c, 1) != 1) {
                                close(p[0]);
                                return (-1);
                        }
                        close(p[0]);
                        if (c == '1')
                                sp->se_flags |= SE_DEVEXISTS;
                        else
                                sp->se_flags |= SE_SHUTDOWN;
                }
                return (pid);
        }
        if (new) {
                int fd;

                close(p[0]);
                fd = open(sp->se_device, O_RDONLY | O_NONBLOCK);
                if (fd == -1 && (errno == ENXIO || errno == ENOENT ||
                    errno == EISDIR)) {
                        (void)write(p[1], "0", 1);
                        close(p[1]);
                        _exit(1);
                }
                (void)write(p[1], "1", 1);
                close(p[1]);
                close(fd);
                sleep(1);
        }

        if (timespecisset(&sp->se_started)) {
                clock_gettime(CLOCK_MONOTONIC, &current_time);
                timespecsub(&current_time, &sp->se_started, &elapsed);
                if (elapsed.tv_sec < GETTY_SPACING) {
                        warning(
                            "getty repeating too quickly on port %s, sleeping",
                            sp->se_device);
                        sleep(GETTY_SLEEP);
                }
        }

        if (sp->se_window) {
                start_window_system(sp);
                sleep(WINDOW_WAIT);
        }

        sigemptyset(&mask);
        sigprocmask(SIG_SETMASK, &mask, NULL);

        setprocresources(RESOURCE_GETTY);

        execv(sp->se_getty_argv[0], sp->se_getty_argv);
        stall("can't exec getty '%s' for port %s: %m",
            sp->se_getty_argv[0], sp->se_device);
        _exit(1);
}

/*
 * Collect exit status for a child.
 * If an exiting login, start a new login running.
 */
void
collect_child(pid_t pid)
{
        session_t *sp, *sprev, *snext;

        if (sessions == NULL)
                return;

        if ((sp = find_session(pid)) == NULL)
                return;

        clear_session_logs(sp);
        login_fbtab(sp->se_device + sizeof(_PATH_DEV) - 1, 0, 0);
        del_session(sp);
        sp->se_process = 0;

        if (sp->se_flags & SE_SHUTDOWN) {
                if ((sprev = sp->se_prev))
                        sprev->se_next = sp->se_next;
                else
                        sessions = sp->se_next;
                if ((snext = sp->se_next))
                        snext->se_prev = sp->se_prev;
                free_session(sp);
                return;
        }

        if ((pid = start_getty(sp)) == -1) {
                /* serious trouble */
                requested_transition = clean_ttys;
                return;
        }

        sp->se_process = pid;
        clock_gettime(CLOCK_MONOTONIC, &sp->se_started);
        add_session(sp);
}

/*
 * Catch a signal and request a state transition.
 */
void
transition_handler(int sig)
{

        switch (sig) {
        case SIGHUP:
                requested_transition = clean_ttys;
                break;
        case SIGINT:
                requested_transition = do_reboot;
                break;
        case SIGTERM:
                requested_transition = death;
                break;
        case SIGUSR1:
                requested_transition = nice_death;
                break;
        case SIGUSR2:
                requested_transition = hard_death;
                break;
        case SIGTSTP:
                requested_transition = catatonia;
                break;
        default:
                requested_transition = 0;
                break;
        }
}

/*
 * Take the system multiuser.
 */
state_t
f_multi_user(void)
{
        pid_t pid;
        session_t *sp;

        /*
         * If the administrator has not set the security level to -1
         * to indicate that the kernel should not run multiuser in secure
         * mode, and the run script has not set a higher level of security
         * than level 1, then put the kernel into secure mode.
         */
        if (requested_transition != catatonia) {
                if (getsecuritylevel() == 0)
                        setsecuritylevel(1);
        }

        requested_transition = 0;

        for (sp = sessions; sp; sp = sp->se_next) {
                if (sp->se_process)
                        continue;
                if ((pid = start_getty(sp)) == -1) {
                        /* serious trouble */
                        requested_transition = clean_ttys;
                        break;
                }
                sp->se_process = pid;
                clock_gettime(CLOCK_MONOTONIC, &sp->se_started);
                add_session(sp);
        }

        while (!requested_transition)
                if ((pid = waitpid(-1, NULL, 0)) != -1)
                        collect_child(pid);

        return requested_transition;
}

/*
 * This is an n-squared algorithm.  We hope it isn't run often...
 */
state_t
f_clean_ttys(void)
{
        session_t *sp, *sprev;
        struct ttyent *typ;
        int session_index = 0;
        int devlen;

        for (sp = sessions; sp; sp = sp->se_next)
                sp->se_flags &= ~SE_PRESENT;

        devlen = sizeof(_PATH_DEV) - 1;
        while ((typ = getttyent())) {
                ++session_index;

                for (sprev = NULL, sp = sessions; sp; sprev = sp, sp = sp->se_next)
                        if (strcmp(typ->ty_name, sp->se_device + devlen) == 0)
                                break;

                if (sp) {
                        sp->se_flags |= SE_PRESENT;
                        if (sp->se_index != session_index) {
                                warning("port %s changed utmp index from %d to %d",
                                    sp->se_device, sp->se_index,
                                    session_index);
                                sp->se_index = session_index;
                        }
                        if ((typ->ty_status & TTY_ON) == 0 ||
                            typ->ty_getty == 0) {
                                sp->se_flags |= SE_SHUTDOWN;
                                kill(sp->se_process, SIGHUP);
                                continue;
                        }
                        sp->se_flags &= ~SE_SHUTDOWN;
                        if (setupargv(sp, typ) == 0) {
                                warning("can't parse getty for port %s",
                                    sp->se_device);
                                sp->se_flags |= SE_SHUTDOWN;
                                kill(sp->se_process, SIGHUP);
                        }
                        continue;
                }

                new_session(sprev, session_index, typ);
        }

        endttyent();

        for (sp = sessions; sp; sp = sp->se_next)
                if ((sp->se_flags & SE_PRESENT) == 0) {
                        sp->se_flags |= SE_SHUTDOWN;
                        kill(sp->se_process, SIGHUP);
                }

        return multi_user;
}

/*
 * Block further logins.
 */
state_t
f_catatonia(void)
{
        session_t *sp;

        for (sp = sessions; sp; sp = sp->se_next)
                sp->se_flags |= SE_SHUTDOWN;

        return multi_user;
}

/*
 * Note SIGALRM.
 */
void
alrm_handler(int sig)
{
        clang = 1;
}

int death_howto = RB_HALT;

/*
 * Reboot the system.
 */
state_t
f_do_reboot(void)
{
        death_howto = RB_AUTOBOOT;
        return nice_death;
}

/*
 * Bring the system down nicely, then we must powerdown because something
 * is very wrong.
 */
state_t
f_hard_death(void)
{
        death_howto |= RB_POWERDOWN;    
        return nice_death;
}

/*
 * Bring the system down to single user nicely, after run the shutdown script.
 */
state_t
f_nice_death(void)
{
        session_t *sp;
        int i;
        pid_t pid;
        static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };
        int status;

#ifdef CPU_LIDACTION
        int mib[] = {CTL_MACHDEP, CPU_LIDACTION};
        int lidaction = 0;

        if ((death_howto & RB_POWERDOWN) &&
            (sysctl(mib, 2, NULL, NULL, &lidaction,
                    sizeof(lidaction)) == -1) && (errno != EOPNOTSUPP))
                        warning("cannot disable lid action");
#endif

        for (sp = sessions; sp; sp = sp->se_next) {
                sp->se_flags &= ~SE_PRESENT;
                sp->se_flags |= SE_SHUTDOWN;
                kill(sp->se_process, SIGHUP);
        }

        /* terminate the accounting process */
        acct(NULL);

        /* NB: should send a message to the session logger to avoid blocking. */
        logwtmp("~", "shutdown", "");

        if (access(_PATH_RUNCOM, R_OK) != -1) {
                struct sigaction sa;

                switch ((pid = fork())) {
                case -1:
                        break;
                case 0:

                        memset(&sa, 0, sizeof sa);
                        sigemptyset(&sa.sa_mask);
                        sa.sa_flags = 0;
                        sa.sa_handler = SIG_IGN;
                        (void) sigaction(SIGTSTP, &sa, NULL);
                        (void) sigaction(SIGHUP, &sa, NULL);

                        setctty(_PATH_CONSOLE);

                        sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);

                        execl(_PATH_BSHELL, "sh", _PATH_RUNCOM, "shutdown",
                            (char *)NULL);
                        stall("can't exec %s for %s %s: %m", _PATH_BSHELL,
                            _PATH_RUNCOM, "shutdown");
                        _exit(1);
                default:
                        waitpid(pid, &status, 0);
                        if (WIFEXITED(status) && WEXITSTATUS(status) == 2)
                                death_howto |= RB_POWERDOWN;
                }
        }

        for (i = 0; i < 3; ++i) {
                if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
                        goto die;

                clang = 0;
                alarm(DEATH_WATCH);
                do {
                        if ((pid = waitpid(-1, NULL, 0)) != -1)
                                collect_child(pid);
                } while (clang == 0 && errno != ECHILD);

                if (errno == ECHILD)
                        goto die;
        }

        warning("some processes would not die; ps axl advised");

die:
        reboot(death_howto);

        /* ... and if that fails.. oh well */
        return single_user;
}

/*
 * Bring the system down to single user.
 */
state_t
f_death(void)
{
        session_t *sp;
        int i;
        pid_t pid;
        static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };

        /* terminate the accounting process */
        acct(NULL);

        for (sp = sessions; sp; sp = sp->se_next)
                sp->se_flags |= SE_SHUTDOWN;

        /* NB: should send a message to the session logger to avoid blocking. */
        logwtmp("~", "shutdown", "");

        for (i = 0; i < 3; ++i) {
                if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
                        return single_user;

                clang = 0;
                alarm(DEATH_WATCH);
                do {
                        if ((pid = waitpid(-1, NULL, 0)) != -1)
                                collect_child(pid);
                } while (clang == 0 && errno != ECHILD);

                if (errno == ECHILD)
                        return single_user;
        }

        warning("some processes would not die; ps axl advised");

        return single_user;
}

void
setprocresources(char *class)
{
        login_cap_t *lc;

        if ((lc = login_getclass(class)) != NULL) {
                setusercontext(lc, NULL, 0,
                    LOGIN_SETPRIORITY|LOGIN_SETRESOURCES|LOGIN_SETUMASK);
                login_close(lc);
        }
}