/*-
 * 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/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, 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;
	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, "-chknopqr")) != -1)
		switch (ch) {
		case '-':
			readstdin = 1;
			break;
		case 'c':
			docycle = 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 (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, "reboot", "-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, "halt", "-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, "halt", "-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, "halt", "-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 | -h | -p | -r | -k] [-o [-n]] [-q] time [warning-message ...]\n"
	    "       poweroff\n");
	exit(1);
}