/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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/param.h>
#include <sys/boottrace.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/syslog.h>
#include <sys/time.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <pwd.h>
#include <setjmp.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef DEBUG
#undef _PATH_NOLOGIN
#define _PATH_NOLOGIN   "./nologin"
#endif

#define H               *60*60
#define M               *60
#define S               *1
#define NOLOG_TIME      5*60
static struct interval {
        int timeleft, timetowait;
} tlist[] = {
        { 10 H,  5 H },
        {  5 H,  3 H },
        {  2 H,  1 H },
        {  1 H, 30 M },
        { 30 M, 10 M },
        { 20 M, 10 M },
        { 10 M,  5 M },
        {  5 M,  3 M },
        {  2 M,  1 M },
        {  1 M, 30 S },
        { 30 S, 30 S },
        {  0  ,  0   }
};
#undef H
#undef M
#undef S

static time_t offset, shuttime;
static int docycle, dohalt, dopower, doreboot, ign_noshutdown,
    killflg, mbuflen, oflag;
static char mbuf[BUFSIZ];
static const char *nosync, *whom;

static void badtime(void);
static void die_you_gravy_sucking_pig_dog(void);
static void finish(int);
static void getoffset(char *);
static void loop(bool);
static void nolog(void);
static void timeout(int);
static void timewarn(int);
static void usage(const char *);

extern const char **environ;

int
main(int argc, char **argv)
{
        char *p, *endp;
        struct passwd *pw;
        struct stat st;
        int arglen, ch, len, readstdin;
        bool dowarn;

#ifndef DEBUG
        if (geteuid())
                errx(1, "NOT super-user");
#endif

        dowarn = true;
        nosync = NULL;
        readstdin = 0;

        /*
         * Test for the special case where the utility is called as
         * "poweroff", for which it runs 'shutdown -p now'.
         */
        if ((p = strrchr(argv[0], '/')) == NULL)
                p = argv[0];
        else
                ++p;
        if (strcmp(p, "poweroff") == 0) {
                if (getopt(argc, argv, "") != -1)
                        usage((char *)NULL);
                argc -= optind;
                argv += optind;
                if (argc != 0)
                        usage((char *)NULL);
                dopower = 1;
                offset = 0;
                (void)time(&shuttime);
                goto poweroff;
        }

        while ((ch = getopt(argc, argv, "-cfhknopqr")) != -1)
                switch (ch) {
                case '-':
                        readstdin = 1;
                        break;
                case 'c':
                        docycle = 1;
                        break;
                case 'f':
                        ign_noshutdown = 1;
                        break;
                case 'h':
                        dohalt = 1;
                        break;
                case 'k':
                        killflg = 1;
                        break;
                case 'n':
                        nosync = "-n";
                        break;
                case 'o':
                        oflag = 1;
                        break;
                case 'p':
                        dopower = 1;
                        break;
                case 'q':
                        dowarn = false;
                        break;
                case 'r':
                        doreboot = 1;
                        break;
                case '?':
                default:
                        usage((char *)NULL);
                }
        argc -= optind;
        argv += optind;

        if (argc < 1)
                usage((char *)NULL);

        if (killflg + doreboot + dohalt + dopower + docycle > 1)
                usage("incompatible switches -c, -h, -k, -p and -r");

        if (oflag && !(dohalt || dopower || doreboot || docycle))
                usage("-o requires -c, -h, -p or -r");

        if (nosync != NULL && !oflag)
                usage("-n requires -o");

        getoffset(*argv++);

poweroff:
        if (!dowarn && *argv != NULL)
                usage("warning-message supplied but suppressed with -q");
        if (*argv) {
                for (p = mbuf, len = sizeof(mbuf); *argv; ++argv) {
                        arglen = strlen(*argv);
                        if ((len -= arglen) <= 2)
                                break;
                        if (p != mbuf)
                                *p++ = ' ';
                        memmove(p, *argv, arglen);
                        p += arglen;
                }
                *p = '\n';
                *++p = '\0';
        }

        if (readstdin) {
                p = mbuf;
                endp = mbuf + sizeof(mbuf) - 2;
                for (;;) {
                        if (!fgets(p, endp - p + 1, stdin))
                                break;
                        for (; *p &&  p < endp; ++p);
                        if (p == endp) {
                                *p = '\n';
                                *++p = '\0';
                                break;
                        }
                }
        }
        mbuflen = strlen(mbuf);

        if (!ign_noshutdown && stat(_PATH_NOSHUTDOWN, &st) == 0) {
                (void)printf("Shutdown cannot be done, " _PATH_NOSHUTDOWN
                    " is present\n");
                exit(2);
        }

        if (offset) {
                BOOTTRACE("Shutdown at %s", ctime(&shuttime));
                (void)printf("Shutdown at %.24s.\n", ctime(&shuttime));
        } else {
                BOOTTRACE("Shutdown NOW!");
                (void)printf("Shutdown NOW!\n");
        }

        if (!(whom = getlogin()))
                whom = (pw = getpwuid(getuid())) ? pw->pw_name : "???";

#ifdef DEBUG
        (void)putc('\n', stdout);
#else
        (void)setpriority(PRIO_PROCESS, 0, PRIO_MIN);
        {
                int forkpid;

                forkpid = fork();
                if (forkpid == -1)
                        err(1, "fork");
                if (forkpid)
                        errx(0, "[pid %d]", forkpid);
        }
        setsid();
#endif
        openlog("shutdown", LOG_CONS, LOG_AUTH);
        loop(dowarn);
        return(0);
}

static void
loop(bool dowarn)
{
        struct interval *tp;
        u_int sltime;
        int logged;

        if (offset <= NOLOG_TIME) {
                logged = 1;
                nolog();
        }
        else
                logged = 0;
        tp = tlist;
        if (tp->timeleft < offset)
                (void)sleep((u_int)(offset - tp->timeleft));
        else {
                while (tp->timeleft && offset < tp->timeleft)
                        ++tp;
                /*
                 * Warn now, if going to sleep more than a fifth of
                 * the next wait time.
                 */
                if ((sltime = offset - tp->timeleft)) {
                        if (dowarn && sltime > (u_int)(tp->timetowait / 5))
                                timewarn(offset);
                        (void)sleep(sltime);
                }
        }
        for (;; ++tp) {
                if (dowarn)
                        timewarn(tp->timeleft);
                if (!logged && tp->timeleft <= NOLOG_TIME) {
                        logged = 1;
                        nolog();
                }
                (void)sleep((u_int)tp->timetowait);
                if (!tp->timeleft)
                        break;
        }
        die_you_gravy_sucking_pig_dog();
}

static jmp_buf alarmbuf;

static const char *restricted_environ[] = {
        "PATH=" _PATH_STDPATH,
        NULL
};

static void
timewarn(int timeleft)
{
        static int first;
        static char hostname[MAXHOSTNAMELEN + 1];
        FILE *pf;
        char wcmd[MAXPATHLEN + 4];

        if (!first++)
                (void)gethostname(hostname, sizeof(hostname));

        /* undoc -n option to wall suppresses normal wall banner */
        (void)snprintf(wcmd, sizeof(wcmd), "%s -n", _PATH_WALL);
        environ = restricted_environ;
        if (!(pf = popen(wcmd, "w"))) {
                syslog(LOG_ERR, "shutdown: can't find %s: %m", _PATH_WALL);
                return;
        }

        (void)fprintf(pf,
            "\007*** %sSystem shutdown message from %s@%s ***\007\n",
            timeleft ? "": "FINAL ", whom, hostname);

        if (timeleft > 10*60)
                (void)fprintf(pf, "System going down at %5.5s\n\n",
                    ctime(&shuttime) + 11);
        else if (timeleft > 59)
                (void)fprintf(pf, "System going down in %d minute%s\n\n",
                    timeleft / 60, (timeleft > 60) ? "s" : "");
        else if (timeleft)
                (void)fprintf(pf, "System going down in %s30 seconds\n\n",
                    (offset > 0 && offset < 30 ? "less than " : ""));
        else
                (void)fprintf(pf, "System going down IMMEDIATELY\n\n");

        if (mbuflen)
                (void)fwrite(mbuf, sizeof(*mbuf), mbuflen, pf);

        /*
         * play some games, just in case wall doesn't come back
         * probably unnecessary, given that wall is careful.
         */
        if (!setjmp(alarmbuf)) {
                (void)signal(SIGALRM, timeout);
                (void)alarm((u_int)30);
                (void)pclose(pf);
                (void)alarm((u_int)0);
                (void)signal(SIGALRM, SIG_DFL);
        }
}

static void
timeout(int signo __unused)
{
        longjmp(alarmbuf, 1);
}

static void
die_you_gravy_sucking_pig_dog(void)
{
        char *empty_environ[] = { NULL };

        BOOTTRACE("%s by %s",
            doreboot ? "reboot" : dohalt ? "halt" : dopower ? "power-down" :
            docycle ? "power-cycle" : "shutdown", whom);
        syslog(LOG_NOTICE, "%s by %s: %s",
            doreboot ? "reboot" : dohalt ? "halt" : dopower ? "power-down" :
            docycle ? "power-cycle" : "shutdown", whom, mbuf);

        (void)printf("\r\nSystem shutdown time has arrived\007\007\r\n");
        if (killflg) {
                BOOTTRACE("fake shutdown...");
                (void)printf("\rbut you'll have to do it yourself\r\n");
                exit(0);
        }
#ifdef DEBUG
        if (doreboot)
                (void)printf("reboot");
        else if (docycle)
                (void)printf("power-cycle");
        else if (dohalt)
                (void)printf("halt");
        else if (dopower)
                (void)printf("power-down");
        if (nosync != NULL)
                (void)printf(" no sync");
        (void)printf("\nkill -HUP 1\n");
#else
        if (!oflag) {
                BOOTTRACE("signal to init(8)...");
                (void)kill(1, doreboot ? SIGINT :       /* reboot */
                              dohalt ? SIGUSR1 :        /* halt */
                              dopower ? SIGUSR2 :       /* power-down */
                              docycle ? SIGWINCH :      /* power-cycle */
                              SIGTERM);                 /* single-user */
        } else {
                if (doreboot) {
                        BOOTTRACE("exec reboot(8) -l...");
                        execle(_PATH_REBOOT, "fastboot", "-l", nosync,
                                (char *)NULL, empty_environ);
                        syslog(LOG_ERR, "shutdown: can't exec %s: %m.",
                                _PATH_REBOOT);
                        warn(_PATH_REBOOT);
                }
                else if (dohalt) {
                        BOOTTRACE("exec halt(8) -l...");
                        execle(_PATH_HALT, "fasthalt", "-l", nosync,
                                (char *)NULL, empty_environ);
                        syslog(LOG_ERR, "shutdown: can't exec %s: %m.",
                                _PATH_HALT);
                        warn(_PATH_HALT);
                }
                else if (dopower) {
                        BOOTTRACE("exec halt(8) -l -p...");
                        execle(_PATH_HALT, "fasthalt", "-l", "-p", nosync,
                                (char *)NULL, empty_environ);
                        syslog(LOG_ERR, "shutdown: can't exec %s: %m.",
                                _PATH_HALT);
                        warn(_PATH_HALT);
                }
                else if (docycle) {
                        execle(_PATH_HALT, "fasthalt", "-l", "-c", nosync,
                                (char *)NULL, empty_environ);
                        syslog(LOG_ERR, "shutdown: can't exec %s: %m.",
                                _PATH_HALT);
                        warn(_PATH_HALT);
                }
                BOOTTRACE("SIGTERM to init(8)...");
                (void)kill(1, SIGTERM);         /* to single-user */
        }
#endif
        finish(0);
}

#define ATOI2(p)        (p[0] - '0') * 10 + (p[1] - '0'); p += 2;

static void
getoffset(char *timearg)
{
        struct tm *lt;
        char *p;
        time_t now;
        int maybe_today, this_year;
        char *timeunit;

        (void)time(&now);

        if (!strcasecmp(timearg, "now")) {              /* now */
                offset = 0;
                shuttime = now;
                return;
        }

        if (*timearg == '+') {                          /* +minutes */
                if (!isdigit(*++timearg))
                        badtime();
                errno = 0;
                offset = strtol(timearg, &timeunit, 10);
                if (offset < 0 || offset == LONG_MAX || errno != 0)
                        badtime();
                if (timeunit[0] == '\0' || strcasecmp(timeunit, "m") == 0 ||
                    strcasecmp(timeunit, "min") == 0 ||
                    strcasecmp(timeunit, "mins") == 0) {
                        offset *= 60;
                } else if (strcasecmp(timeunit, "h") == 0 ||
                    strcasecmp(timeunit, "hour") == 0 ||
                    strcasecmp(timeunit, "hours") == 0) {
                        offset *= 60 * 60;
                } else if (strcasecmp(timeunit, "s") == 0 ||
                    strcasecmp(timeunit, "sec") == 0 ||
                    strcasecmp(timeunit, "secs") == 0) {
                        offset *= 1;
                } else {
                        badtime();
                }
                shuttime = now + offset;
                return;
        }

        /* handle hh:mm by getting rid of the colon */
        for (p = timearg; *p; ++p)
                if (!isascii(*p) || !isdigit(*p)) {
                        if (*p == ':' && strlen(p) == 3) {
                                p[0] = p[1];
                                p[1] = p[2];
                                p[2] = '\0';
                        }
                        else
                                badtime();
                }

        unsetenv("TZ");                                 /* OUR timezone */
        lt = localtime(&now);                           /* current time val */
        maybe_today = 1;

        switch(strlen(timearg)) {
        case 10:
                this_year = lt->tm_year;
                lt->tm_year = ATOI2(timearg);
                /*
                 * check if the specified year is in the next century.
                 * allow for one year of user error as many people will
                 * enter n - 1 at the start of year n.
                 */
                if (lt->tm_year < (this_year % 100) - 1)
                        lt->tm_year += 100;
                /* adjust for the year 2000 and beyond */
                lt->tm_year += (this_year - (this_year % 100));
                /* FALLTHROUGH */
        case 8:
                lt->tm_mon = ATOI2(timearg);
                if (--lt->tm_mon < 0 || lt->tm_mon > 11)
                        badtime();
                /* FALLTHROUGH */
        case 6:
                maybe_today = 0;
                lt->tm_mday = ATOI2(timearg);
                if (lt->tm_mday < 1 || lt->tm_mday > 31)
                        badtime();
                /* FALLTHROUGH */
        case 4:
                lt->tm_hour = ATOI2(timearg);
                if (lt->tm_hour < 0 || lt->tm_hour > 23)
                        badtime();
                lt->tm_min = ATOI2(timearg);
                if (lt->tm_min < 0 || lt->tm_min > 59)
                        badtime();
                lt->tm_sec = 0;
                if ((shuttime = mktime(lt)) == -1)
                        badtime();

                if ((offset = shuttime - now) < 0) {
                        if (!maybe_today)
                                errx(1, "that time is already past.");

                        /*
                         * If the user only gave a time, assume that
                         * any time earlier than the current time
                         * was intended to be that time tomorrow.
                         */
                        lt->tm_mday++;
                        if ((shuttime = mktime(lt)) == -1)
                                badtime();
                        if ((offset = shuttime - now) < 0) {
                                errx(1, "tomorrow is before today?");
                        }
                }
                break;
        default:
                badtime();
        }
}

#define NOMSG   "\n\nNO LOGINS: System going down at "
static void
nolog(void)
{
        int logfd;
        char *ct;

        (void)unlink(_PATH_NOLOGIN);    /* in case linked to another file */
        (void)signal(SIGINT, finish);
        (void)signal(SIGHUP, finish);
        (void)signal(SIGQUIT, finish);
        (void)signal(SIGTERM, finish);
        if ((logfd = open(_PATH_NOLOGIN, O_WRONLY|O_CREAT|O_TRUNC,
            0664)) >= 0) {
                (void)write(logfd, NOMSG, sizeof(NOMSG) - 1);
                ct = ctime(&shuttime);
                (void)write(logfd, ct + 11, 5);
                (void)write(logfd, "\n\n", 2);
                (void)write(logfd, mbuf, strlen(mbuf));
                (void)close(logfd);
        }
}

static void
finish(int signo __unused)
{
        if (!killflg)
                (void)unlink(_PATH_NOLOGIN);
        exit(0);
}

static void
badtime(void)
{
        errx(1, "bad time format");
}

static void
usage(const char *cp)
{
        if (cp != NULL)
                warnx("%s", cp);
        (void)fprintf(stderr,
            "usage: shutdown [-] [-c | -f | -h | -p | -r | -k] [-o [-n]] [-q] time [warning-message ...]\n"
            "       poweroff\n");
        exit(1);
}