xref: /dragonfly/sbin/init/init.c (revision 333227be)
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Donn Seeley at Berkeley Software Design, Inc.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  * @(#) Copyright (c) 1991, 1993 The Regents of the University of California.  All rights reserved.
37  * @(#)init.c	8.1 (Berkeley) 7/15/93
38  * $FreeBSD: src/sbin/init/init.c,v 1.38.2.8 2001/10/22 11:27:32 des Exp $
39  * $DragonFly: src/sbin/init/init.c,v 1.6 2004/11/20 04:09:34 dillon Exp $
40  */
41 
42 #include <sys/param.h>
43 #include <sys/ioctl.h>
44 #include <sys/mount.h>
45 #include <sys/sysctl.h>
46 #include <sys/wait.h>
47 #include <sys/stat.h>
48 
49 #include <db.h>
50 #include <errno.h>
51 #include <fcntl.h>
52 #include <libutil.h>
53 #include <paths.h>
54 #include <signal.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <syslog.h>
59 #include <time.h>
60 #include <ttyent.h>
61 #include <unistd.h>
62 #include <sys/reboot.h>
63 #include <err.h>
64 
65 #ifdef __STDC__
66 #include <stdarg.h>
67 #else
68 #include <varargs.h>
69 #endif
70 
71 #ifdef SECURE
72 #include <pwd.h>
73 #endif
74 
75 #ifdef LOGIN_CAP
76 #include <login_cap.h>
77 #endif
78 
79 #include "pathnames.h"
80 
81 /*
82  * Sleep times; used to prevent thrashing.
83  */
84 #define	GETTY_SPACING		 5	/* N secs minimum getty spacing */
85 #define	GETTY_SLEEP		30	/* sleep N secs after spacing problem */
86 #define GETTY_NSPACE             3      /* max. spacing count to bring reaction */
87 #define	WINDOW_WAIT		 3	/* wait N secs after starting window */
88 #define	STALL_TIMEOUT		30	/* wait N secs after warning */
89 #define	DEATH_WATCH		10	/* wait N secs for procs to die */
90 #define DEATH_SCRIPT		120	/* wait for 2min for /etc/rc.shutdown */
91 #define RESOURCE_RC		"daemon"
92 #define RESOURCE_WINDOW 	"default"
93 #define RESOURCE_GETTY		"default"
94 
95 void handle(sig_t, ...);
96 void delset(sigset_t *, ...);
97 
98 void stall(char *, ...);
99 void warning(char *, ...);
100 void emergency(char *, ...);
101 void disaster(int);
102 void badsys(int);
103 int  runshutdown(void);
104 
105 /*
106  * We really need a recursive typedef...
107  * The following at least guarantees that the return type of (*state_t)()
108  * is sufficiently wide to hold a function pointer.
109  */
110 typedef long (*state_func_t)(void);
111 typedef state_func_t (*state_t)(void);
112 
113 state_func_t single_user(void);
114 state_func_t runcom(void);
115 state_func_t read_ttys(void);
116 state_func_t multi_user(void);
117 state_func_t clean_ttys(void);
118 state_func_t catatonia(void);
119 state_func_t death(void);
120 
121 enum { AUTOBOOT, FASTBOOT } runcom_mode = AUTOBOOT;
122 #define FALSE	0
123 #define TRUE	1
124 
125 int Reboot = FALSE;
126 int howto = RB_AUTOBOOT;
127 
128 void transition(state_t);
129 state_t requested_transition = runcom;
130 
131 void setctty(char *);
132 
133 typedef struct init_session {
134 	int	se_index;		/* index of entry in ttys file */
135 	pid_t	se_process;		/* controlling process */
136 	time_t	se_started;		/* used to avoid thrashing */
137 	int	se_flags;		/* status of session */
138 #define	SE_SHUTDOWN	0x1		/* session won't be restarted */
139 #define	SE_PRESENT	0x2		/* session is in /etc/ttys */
140 	int     se_nspace;              /* spacing count */
141 	char	*se_device;		/* filename of port */
142 	char	*se_getty;		/* what to run on that port */
143 	char    *se_getty_argv_space;   /* pre-parsed argument array space */
144 	char	**se_getty_argv;	/* pre-parsed argument array */
145 	char	*se_window;		/* window system (started only once) */
146 	char    *se_window_argv_space;  /* pre-parsed argument array space */
147 	char	**se_window_argv;	/* pre-parsed argument array */
148 	char    *se_type;               /* default terminal type */
149 	struct	init_session *se_prev;
150 	struct	init_session *se_next;
151 } session_t;
152 
153 void free_session(session_t *);
154 session_t *new_session(session_t *, int, struct ttyent *);
155 session_t *sessions;
156 
157 char **construct_argv(char *);
158 void start_window_system(session_t *);
159 void collect_child(pid_t);
160 pid_t start_getty(session_t *);
161 void transition_handler(int);
162 void alrm_handler(int);
163 void setsecuritylevel(int);
164 int getsecuritylevel(void);
165 char *get_chroot(void);
166 int setupargv(session_t *, struct ttyent *);
167 #ifdef LOGIN_CAP
168 void setprocresources(const char *);
169 #endif
170 int clang;
171 
172 void clear_session_logs(session_t *);
173 
174 int start_session_db(void);
175 void add_session(session_t *);
176 void del_session(session_t *);
177 session_t *find_session(pid_t);
178 DB *session_db;
179 
180 /*
181  * The mother of all processes.
182  */
183 int
184 main(int argc, char **argv)
185 {
186 	char *init_chroot;
187 	int c;
188 	struct sigaction sa;
189 	sigset_t mask;
190 	struct stat sts;
191 
192 
193 	/* Dispose of random users. */
194 	if (getuid() != 0)
195 		errx(1, "%s", strerror(EPERM));
196 
197 	/* System V users like to reexec init. */
198 	if (getpid() != 1) {
199 #ifdef COMPAT_SYSV_INIT
200 		/* So give them what they want */
201 		if (argc > 1) {
202 			if (strlen(argv[1]) == 1) {
203 				register char runlevel = *argv[1];
204 				register int sig;
205 
206 				switch (runlevel) {
207 					case '0': /* halt + poweroff */
208 						sig = SIGUSR2;
209 						break;
210 					case '1': /* single-user */
211 						sig = SIGTERM;
212 						break;
213 					case '6': /* reboot */
214 						sig = SIGINT;
215 						break;
216 					case 'c': /* block further logins */
217 						sig = SIGTSTP;
218 						break;
219 					case 'q': /* rescan /etc/ttys */
220 						sig = SIGHUP;
221 						break;
222 					default:
223 						goto invalid;
224 				}
225 				kill(1, sig);
226 				_exit(0);
227 			} else
228 invalid:
229 				errx(1, "invalid run-level ``%s''", argv[1]);
230 		} else
231 #endif
232 			errx(1, "already running");
233 	}
234 	/*
235 	 * Note that this does NOT open a file...
236 	 * Does 'init' deserve its own facility number?
237 	 */
238 	openlog("init", LOG_CONS|LOG_ODELAY, LOG_AUTH);
239 
240 	/*
241 	 * If chroot has been requested by the boot loader,
242 	 * do it now.  Try to be robust:  If the directory
243 	 * doesn't exist, continue anyway.
244 	 */
245 	init_chroot = get_chroot();
246 	if (init_chroot != NULL) {
247 		if (chdir(init_chroot) == -1 || chroot(".") == -1)
248 			warning("can't chroot to %s: %m", init_chroot);
249 		free(init_chroot);
250 	}
251 
252 	/*
253 	 * Create an initial session.
254 	 */
255 	if (setsid() < 0)
256 		warning("initial setsid() failed: %m");
257 
258 	/*
259 	 * Establish an initial user so that programs running
260 	 * single user do not freak out and die (like passwd).
261 	 */
262 	if (setlogin("root") < 0)
263 		warning("setlogin() failed: %m");
264 
265 	if (stat("/dev/null", &sts) < 0) {
266 		warning("/dev MAY BE CORRUPT! /dev/null is missing!\n");
267 		sleep(5);
268 	}
269 
270 	/*
271 	 * This code assumes that we always get arguments through flags,
272 	 * never through bits set in some random machine register.
273 	 */
274 	while ((c = getopt(argc, argv, "dsf")) != -1)
275 		switch (c) {
276 		case 'd':
277 			/* We don't support DEVFS. */
278 			break;
279 		case 's':
280 			requested_transition = single_user;
281 			break;
282 		case 'f':
283 			runcom_mode = FASTBOOT;
284 			break;
285 		default:
286 			warning("unrecognized flag '-%c'", c);
287 			break;
288 		}
289 
290 	if (optind != argc)
291 		warning("ignoring excess arguments");
292 
293 	/*
294 	 * We catch or block signals rather than ignore them,
295 	 * so that they get reset on exec.
296 	 */
297 	handle(badsys, SIGSYS, 0);
298 	handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV,
299 	       SIGBUS, SIGXCPU, SIGXFSZ, 0);
300 	handle(transition_handler, SIGHUP, SIGINT, SIGTERM, SIGTSTP,
301 		SIGUSR1, SIGUSR2, 0);
302 	handle(alrm_handler, SIGALRM, 0);
303 	sigfillset(&mask);
304 	delset(&mask, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGSYS,
305 		SIGXCPU, SIGXFSZ, SIGHUP, SIGINT, SIGTERM, SIGTSTP, SIGALRM,
306 		SIGUSR1, SIGUSR2, 0);
307 	sigprocmask(SIG_SETMASK, &mask, (sigset_t *) 0);
308 	sigemptyset(&sa.sa_mask);
309 	sa.sa_flags = 0;
310 	sa.sa_handler = SIG_IGN;
311 	(void) sigaction(SIGTTIN, &sa, (struct sigaction *)0);
312 	(void) sigaction(SIGTTOU, &sa, (struct sigaction *)0);
313 
314 	/*
315 	 * Paranoia.
316 	 */
317 	close(0);
318 	close(1);
319 	close(2);
320 
321 	/*
322 	 * Start the state machine.
323 	 */
324 	transition(requested_transition);
325 
326 	/*
327 	 * Should never reach here.
328 	 */
329 	return 1;
330 }
331 
332 /*
333  * Associate a function with a signal handler.
334  */
335 void
336 handle(sig_t handler, ...)
337 {
338 	int sig;
339 	struct sigaction sa;
340 	sigset_t mask_everything;
341 	va_list ap;
342 
343 	va_start(ap, handler);
344 
345 	sa.sa_handler = handler;
346 	sigfillset(&mask_everything);
347 
348 	while ((sig = va_arg(ap, int)) != NULL) {
349 		sa.sa_mask = mask_everything;
350 		/* XXX SA_RESTART? */
351 		sa.sa_flags = sig == SIGCHLD ? SA_NOCLDSTOP : 0;
352 		sigaction(sig, &sa, (struct sigaction *) 0);
353 	}
354 	va_end(ap);
355 }
356 
357 /*
358  * Delete a set of signals from a mask.
359  */
360 void
361 delset(sigset_t *maskp, ...)
362 {
363 	int sig;
364 	va_list ap;
365 
366 	va_start(ap, maskp);
367 
368 	while ((sig = va_arg(ap, int)) != NULL)
369 		sigdelset(maskp, sig);
370 	va_end(ap);
371 }
372 
373 /*
374  * Log a message and sleep for a while (to give someone an opportunity
375  * to read it and to save log or hardcopy output if the problem is chronic).
376  * NB: should send a message to the session logger to avoid blocking.
377  */
378 void
379 stall(char *message, ...)
380 {
381 	va_list ap;
382 
383 	va_start(ap, message);
384 
385 	vsyslog(LOG_ALERT, message, ap);
386 	va_end(ap);
387 	sleep(STALL_TIMEOUT);
388 }
389 
390 /*
391  * Like stall(), but doesn't sleep.
392  * If cpp had variadic macros, the two functions could be #defines for another.
393  * NB: should send a message to the session logger to avoid blocking.
394  */
395 void
396 warning(char *message, ...)
397 {
398 	va_list ap;
399 
400 	va_start(ap, message);
401 
402 	vsyslog(LOG_ALERT, message, ap);
403 	va_end(ap);
404 }
405 
406 /*
407  * Log an emergency message.
408  * NB: should send a message to the session logger to avoid blocking.
409  */
410 void
411 emergency(char *message, ...)
412 {
413 	va_list ap;
414 
415 	va_start(ap, message);
416 
417 	vsyslog(LOG_EMERG, message, ap);
418 	va_end(ap);
419 }
420 
421 /*
422  * Catch a SIGSYS signal.
423  *
424  * These may arise if a system does not support sysctl.
425  * We tolerate up to 25 of these, then throw in the towel.
426  */
427 void
428 badsys(int sig)
429 {
430 	static int badcount = 0;
431 
432 	if (badcount++ < 25)
433 		return;
434 	disaster(sig);
435 }
436 
437 /*
438  * Catch an unexpected signal.
439  */
440 void
441 disaster(int sig)
442 {
443 	emergency("fatal signal: %s",
444 		(unsigned)sig < NSIG ? sys_siglist[sig] : "unknown signal");
445 
446 	sleep(STALL_TIMEOUT);
447 	_exit(sig);		/* reboot */
448 }
449 
450 /*
451  * Get the security level of the kernel.
452  */
453 int
454 getsecuritylevel(void)
455 {
456 #ifdef KERN_SECURELVL
457 	int name[2], curlevel;
458 	size_t len;
459 
460 	name[0] = CTL_KERN;
461 	name[1] = KERN_SECURELVL;
462 	len = sizeof curlevel;
463 	if (sysctl(name, 2, &curlevel, &len, NULL, 0) == -1) {
464 		emergency("cannot get kernel security level: %s",
465 		    strerror(errno));
466 		return (-1);
467 	}
468 	return (curlevel);
469 #else
470 	return (-1);
471 #endif
472 }
473 
474 /*
475  * Get the value of the "init_chroot" variable from the
476  * kernel environment (or NULL if not set).
477  * (Most of this has been copied from src/usr.bin/kenv/kenv.c.)
478  */
479 char *
480 get_chroot(void)
481 {
482 	const char * const ichname = "init_chroot=";	/* includes '=' */
483 	const int ichlen = strlen(ichname);
484 	int real_oid[CTL_MAXNAME+4];
485 	int n2oid_oid[2];
486 	char sbuf[1024];
487 	size_t oidlen;
488 	char *name;
489 	char *res;
490 	int slen;
491 	int i;
492 
493 	n2oid_oid[0] = 0;	/* This is magic & undocumented! */
494 	n2oid_oid[1] = 3;
495 	oidlen = sizeof(real_oid);
496 	name = "kern.environment";
497 
498 	if (sysctl(n2oid_oid, 2, real_oid, &oidlen, name, strlen(name)) < 0) {
499 		warning("cannot find kern.environment base sysctl OID");
500 		return NULL;
501 	}
502 	oidlen /= sizeof(int);
503 	if (oidlen >= CTL_MAXNAME) {
504 		warning("kern.environment OID is too large!");
505 		return NULL;
506 	}
507 	res = NULL;
508 	real_oid[oidlen] = 0;
509 
510 	for (i = 0; ; i++) {
511 		real_oid[oidlen + 1] = i;
512 		slen = sizeof(sbuf);
513 		if (sysctl(real_oid, oidlen + 2, sbuf, &slen, NULL, 0) < 0) {
514 			if (errno != ENOENT)
515 				warning("sysctl kern.environment.%d: %m", i);
516 			break;
517 		}
518 
519 		/*
520 		 * slen includes the terminating \0, but do a few sanity
521 		 * checks anyway.
522 		 */
523 		if (slen == 0)
524 			continue;
525 		sbuf[slen - 1] = 0;
526 		if (strncmp(sbuf, ichname, ichlen) != 0)
527 			continue;
528 		if (sbuf[ichlen])
529 			res = strdup(sbuf + ichlen);
530 		break;
531 	}
532 	return (res);
533 }
534 
535 /*
536  * Set the security level of the kernel.
537  */
538 void
539 setsecuritylevel(int newlevel)
540 {
541 #ifdef KERN_SECURELVL
542 	int name[2], curlevel;
543 
544 	curlevel = getsecuritylevel();
545 	if (newlevel == curlevel)
546 		return;
547 	name[0] = CTL_KERN;
548 	name[1] = KERN_SECURELVL;
549 	if (sysctl(name, 2, NULL, NULL, &newlevel, sizeof newlevel) == -1) {
550 		emergency(
551 		    "cannot change kernel security level from %d to %d: %s",
552 		    curlevel, newlevel, strerror(errno));
553 		return;
554 	}
555 #ifdef SECURE
556 	warning("kernel security level changed from %d to %d",
557 	    curlevel, newlevel);
558 #endif
559 #endif
560 }
561 
562 /*
563  * Change states in the finite state machine.
564  * The initial state is passed as an argument.
565  */
566 void
567 transition(state_t s)
568 {
569 	for (;;)
570 		s = (state_t) (*s)();
571 }
572 
573 /*
574  * Close out the accounting files for a login session.
575  * NB: should send a message to the session logger to avoid blocking.
576  */
577 void
578 clear_session_logs(session_t *sp)
579 {
580 	char *line = sp->se_device + sizeof(_PATH_DEV) - 1;
581 
582 	if (logout(line))
583 		logwtmp(line, "", "");
584 }
585 
586 /*
587  * Start a session and allocate a controlling terminal.
588  * Only called by children of init after forking.
589  */
590 void
591 setctty(char *name)
592 {
593 	int fd;
594 
595 	(void) revoke(name);
596 	if ((fd = open(name, O_RDWR)) == -1) {
597 		stall("can't open %s: %m", name);
598 		_exit(1);
599 	}
600 	if (login_tty(fd) == -1) {
601 		stall("can't get %s for controlling terminal: %m", name);
602 		_exit(1);
603 	}
604 }
605 
606 /*
607  * Bring the system up single user.
608  */
609 state_func_t
610 single_user(void)
611 {
612 	pid_t pid, wpid;
613 	int status;
614 	sigset_t mask;
615 	char *shell = _PATH_BSHELL;
616 	char *argv[2];
617 #ifdef SECURE
618 	struct ttyent *typ;
619 	struct passwd *pp;
620 	static const char banner[] =
621 		"Enter root password, or ^D to go multi-user\n";
622 	char *clear, *password;
623 #endif
624 #ifdef DEBUGSHELL
625 	char altshell[128];
626 #endif
627 
628 	if (Reboot) {
629 		/* Instead of going single user, let's reboot the machine */
630 		sync();
631 		alarm(2);
632 		pause();
633 		reboot(howto);
634 		_exit(0);
635 	}
636 
637 	if ((pid = fork()) == 0) {
638 		/*
639 		 * Start the single user session.
640 		 */
641 		setctty(_PATH_CONSOLE);
642 
643 #ifdef SECURE
644 		/*
645 		 * Check the root password.
646 		 * We don't care if the console is 'on' by default;
647 		 * it's the only tty that can be 'off' and 'secure'.
648 		 */
649 		typ = getttynam("console");
650 		pp = getpwnam("root");
651 		if (typ && (typ->ty_status & TTY_SECURE) == 0 &&
652 		    pp && *pp->pw_passwd) {
653 			write(2, banner, sizeof banner - 1);
654 			for (;;) {
655 				clear = getpass("Password:");
656 				if (clear == 0 || *clear == '\0')
657 					_exit(0);
658 				password = crypt(clear, pp->pw_passwd);
659 				bzero(clear, _PASSWORD_LEN);
660 				if (strcmp(password, pp->pw_passwd) == 0)
661 					break;
662 				warning("single-user login failed\n");
663 			}
664 		}
665 		endttyent();
666 		endpwent();
667 #endif /* SECURE */
668 
669 #ifdef DEBUGSHELL
670 		{
671 			char *cp = altshell;
672 			int num;
673 
674 #define	SHREQUEST \
675 	"Enter full pathname of shell or RETURN for " _PATH_BSHELL ": "
676 			(void)write(STDERR_FILENO,
677 			    SHREQUEST, sizeof(SHREQUEST) - 1);
678 			while ((num = read(STDIN_FILENO, cp, 1)) != -1 &&
679 			    num != 0 && *cp != '\n' && cp < &altshell[127])
680 					cp++;
681 			*cp = '\0';
682 			if (altshell[0] != '\0')
683 				shell = altshell;
684 		}
685 #endif /* DEBUGSHELL */
686 
687 		/*
688 		 * Unblock signals.
689 		 * We catch all the interesting ones,
690 		 * and those are reset to SIG_DFL on exec.
691 		 */
692 		sigemptyset(&mask);
693 		sigprocmask(SIG_SETMASK, &mask, (sigset_t *) 0);
694 
695 		/*
696 		 * Fire off a shell.
697 		 * If the default one doesn't work, try the Bourne shell.
698 		 */
699 		argv[0] = "-sh";
700 		argv[1] = 0;
701 		execv(shell, argv);
702 		emergency("can't exec %s for single user: %m", shell);
703 		execv(_PATH_BSHELL, argv);
704 		emergency("can't exec %s for single user: %m", _PATH_BSHELL);
705 		sleep(STALL_TIMEOUT);
706 		_exit(1);
707 	}
708 
709 	if (pid == -1) {
710 		/*
711 		 * We are seriously hosed.  Do our best.
712 		 */
713 		emergency("can't fork single-user shell, trying again");
714 		while (waitpid(-1, (int *) 0, WNOHANG) > 0)
715 			continue;
716 		return (state_func_t) single_user;
717 	}
718 
719 	requested_transition = 0;
720 	do {
721 		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
722 			collect_child(wpid);
723 		if (wpid == -1) {
724 			if (errno == EINTR)
725 				continue;
726 			warning("wait for single-user shell failed: %m; restarting");
727 			return (state_func_t) single_user;
728 		}
729 		if (wpid == pid && WIFSTOPPED(status)) {
730 			warning("init: shell stopped, restarting\n");
731 			kill(pid, SIGCONT);
732 			wpid = -1;
733 		}
734 	} while (wpid != pid && !requested_transition);
735 
736 	if (requested_transition)
737 		return (state_func_t) requested_transition;
738 
739 	if (!WIFEXITED(status)) {
740 		if (WTERMSIG(status) == SIGKILL) {
741 			/*
742 			 *  reboot(8) killed shell?
743 			 */
744 			warning("single user shell terminated.");
745 			sleep(STALL_TIMEOUT);
746 			_exit(0);
747 		} else {
748 			warning("single user shell terminated, restarting");
749 			return (state_func_t) single_user;
750 		}
751 	}
752 
753 	runcom_mode = FASTBOOT;
754 	return (state_func_t) runcom;
755 }
756 
757 /*
758  * Run the system startup script.
759  */
760 state_func_t
761 runcom(void)
762 {
763 	pid_t pid, wpid;
764 	int status;
765 	char *argv[4];
766 	struct sigaction sa;
767 
768 	if ((pid = fork()) == 0) {
769 		sigemptyset(&sa.sa_mask);
770 		sa.sa_flags = 0;
771 		sa.sa_handler = SIG_IGN;
772 		(void) sigaction(SIGTSTP, &sa, (struct sigaction *)0);
773 		(void) sigaction(SIGHUP, &sa, (struct sigaction *)0);
774 
775 		setctty(_PATH_CONSOLE);
776 
777 		argv[0] = "sh";
778 		argv[1] = _PATH_RUNCOM;
779 		argv[2] = runcom_mode == AUTOBOOT ? "autoboot" : 0;
780 		argv[3] = 0;
781 
782 		sigprocmask(SIG_SETMASK, &sa.sa_mask, (sigset_t *) 0);
783 
784 #ifdef LOGIN_CAP
785 		setprocresources(RESOURCE_RC);
786 #endif
787 		execv(_PATH_BSHELL, argv);
788 		stall("can't exec %s for %s: %m", _PATH_BSHELL, _PATH_RUNCOM);
789 		_exit(1);	/* force single user mode */
790 	}
791 
792 	if (pid == -1) {
793 		emergency("can't fork for %s on %s: %m",
794 			_PATH_BSHELL, _PATH_RUNCOM);
795 		while (waitpid(-1, (int *) 0, WNOHANG) > 0)
796 			continue;
797 		sleep(STALL_TIMEOUT);
798 		return (state_func_t) single_user;
799 	}
800 
801 	/*
802 	 * Copied from single_user().  This is a bit paranoid.
803 	 */
804 	requested_transition = 0;
805 	do {
806 		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
807 			collect_child(wpid);
808 		if (wpid == -1) {
809 			if (requested_transition == death)
810 				return (state_func_t) death;
811 			if (errno == EINTR)
812 				continue;
813 			warning("wait for %s on %s failed: %m; going to single user mode",
814 				_PATH_BSHELL, _PATH_RUNCOM);
815 			return (state_func_t) single_user;
816 		}
817 		if (wpid == pid && WIFSTOPPED(status)) {
818 			warning("init: %s on %s stopped, restarting\n",
819 				_PATH_BSHELL, _PATH_RUNCOM);
820 			kill(pid, SIGCONT);
821 			wpid = -1;
822 		}
823 	} while (wpid != pid);
824 
825 	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM &&
826 	    requested_transition == catatonia) {
827 		/* /etc/rc executed /sbin/reboot; wait for the end quietly */
828 		sigset_t s;
829 
830 		sigfillset(&s);
831 		for (;;)
832 			sigsuspend(&s);
833 	}
834 
835 	if (!WIFEXITED(status)) {
836 		warning("%s on %s terminated abnormally, going to single user mode",
837 			_PATH_BSHELL, _PATH_RUNCOM);
838 		return (state_func_t) single_user;
839 	}
840 
841 	if (WEXITSTATUS(status))
842 		return (state_func_t) single_user;
843 
844 	runcom_mode = AUTOBOOT;		/* the default */
845 	/* NB: should send a message to the session logger to avoid blocking. */
846 	logwtmp("~", "reboot", "");
847 	return (state_func_t) read_ttys;
848 }
849 
850 /*
851  * Open the session database.
852  *
853  * NB: We could pass in the size here; is it necessary?
854  */
855 int
856 start_session_db(void)
857 {
858 	if (session_db && (*session_db->close)(session_db))
859 		emergency("session database close: %s", strerror(errno));
860 	if ((session_db = dbopen(NULL, O_RDWR, 0, DB_HASH, NULL)) == 0) {
861 		emergency("session database open: %s", strerror(errno));
862 		return (1);
863 	}
864 	return (0);
865 
866 }
867 
868 /*
869  * Add a new login session.
870  */
871 void
872 add_session(session_t *sp)
873 {
874 	DBT key;
875 	DBT data;
876 
877 	key.data = &sp->se_process;
878 	key.size = sizeof sp->se_process;
879 	data.data = &sp;
880 	data.size = sizeof sp;
881 
882 	if ((*session_db->put)(session_db, &key, &data, 0))
883 		emergency("insert %d: %s", sp->se_process, strerror(errno));
884 }
885 
886 /*
887  * Delete an old login session.
888  */
889 void
890 del_session(session_t *sp)
891 {
892 	DBT key;
893 
894 	key.data = &sp->se_process;
895 	key.size = sizeof sp->se_process;
896 
897 	if ((*session_db->del)(session_db, &key, 0))
898 		emergency("delete %d: %s", sp->se_process, strerror(errno));
899 }
900 
901 /*
902  * Look up a login session by pid.
903  */
904 session_t *
905 find_session(pid_t pid)
906 {
907 	DBT key;
908 	DBT data;
909 	session_t *ret;
910 
911 	key.data = &pid;
912 	key.size = sizeof pid;
913 	if ((*session_db->get)(session_db, &key, &data, 0) != 0)
914 		return 0;
915 	bcopy(data.data, (char *)&ret, sizeof(ret));
916 	return ret;
917 }
918 
919 /*
920  * Construct an argument vector from a command line.
921  */
922 char **
923 construct_argv(char *command)
924 {
925 	char *strk (char *);
926 	register int argc = 0;
927 	register char **argv = (char **) malloc(((strlen(command) + 1) / 2 + 1)
928 						* sizeof (char *));
929 
930 	if ((argv[argc++] = strk(command)) == 0) {
931 		free(argv);
932 		return (NULL);
933 	}
934 	while ((argv[argc++] = strk((char *) 0)) != NULL)
935 		continue;
936 	return argv;
937 }
938 
939 /*
940  * Deallocate a session descriptor.
941  */
942 void
943 free_session(register session_t *sp)
944 {
945 	free(sp->se_device);
946 	if (sp->se_getty) {
947 		free(sp->se_getty);
948 		free(sp->se_getty_argv_space);
949 		free(sp->se_getty_argv);
950 	}
951 	if (sp->se_window) {
952 		free(sp->se_window);
953 		free(sp->se_window_argv_space);
954 		free(sp->se_window_argv);
955 	}
956 	if (sp->se_type)
957 		free(sp->se_type);
958 	free(sp);
959 }
960 
961 /*
962  * Allocate a new session descriptor.
963  * Mark it SE_PRESENT.
964  */
965 session_t *
966 new_session(session_t *sprev, int session_index, register struct ttyent *typ)
967 {
968 	register session_t *sp;
969 	int fd;
970 
971 	if ((typ->ty_status & TTY_ON) == 0 ||
972 	    typ->ty_name == 0 ||
973 	    typ->ty_getty == 0)
974 		return 0;
975 
976 	sp = (session_t *) calloc(1, sizeof (session_t));
977 
978 	sp->se_index = session_index;
979 	sp->se_flags |= SE_PRESENT;
980 
981 	sp->se_device = malloc(sizeof(_PATH_DEV) + strlen(typ->ty_name));
982 	(void) sprintf(sp->se_device, "%s%s", _PATH_DEV, typ->ty_name);
983 
984 	/*
985 	 * Attempt to open the device, if we get "device not configured"
986 	 * then don't add the device to the session list.
987 	 */
988 	if ((fd = open(sp->se_device, O_RDONLY | O_NONBLOCK, 0)) < 0) {
989 		if (errno == ENXIO) {
990 			free_session(sp);
991 			return (0);
992 		}
993 	} else
994 		close(fd);
995 
996 	if (setupargv(sp, typ) == 0) {
997 		free_session(sp);
998 		return (0);
999 	}
1000 
1001 	sp->se_next = 0;
1002 	if (sprev == 0) {
1003 		sessions = sp;
1004 		sp->se_prev = 0;
1005 	} else {
1006 		sprev->se_next = sp;
1007 		sp->se_prev = sprev;
1008 	}
1009 
1010 	return sp;
1011 }
1012 
1013 /*
1014  * Calculate getty and if useful window argv vectors.
1015  */
1016 int
1017 setupargv(session_t *sp, struct ttyent *typ)
1018 {
1019 
1020 	if (sp->se_getty) {
1021 		free(sp->se_getty);
1022 		free(sp->se_getty_argv_space);
1023 		free(sp->se_getty_argv);
1024 	}
1025 	sp->se_getty = malloc(strlen(typ->ty_getty) + strlen(typ->ty_name) + 2);
1026 	(void) sprintf(sp->se_getty, "%s %s", typ->ty_getty, typ->ty_name);
1027 	sp->se_getty_argv_space = strdup(sp->se_getty);
1028 	sp->se_getty_argv = construct_argv(sp->se_getty_argv_space);
1029 	if (sp->se_getty_argv == 0) {
1030 		warning("can't parse getty for port %s", sp->se_device);
1031 		free(sp->se_getty);
1032 		free(sp->se_getty_argv_space);
1033 		sp->se_getty = sp->se_getty_argv_space = 0;
1034 		return (0);
1035 	}
1036 	if (sp->se_window) {
1037 		free(sp->se_window);
1038 		free(sp->se_window_argv_space);
1039 		free(sp->se_window_argv);
1040 	}
1041 	sp->se_window = sp->se_window_argv_space = 0;
1042 	sp->se_window_argv = 0;
1043 	if (typ->ty_window) {
1044 		sp->se_window = strdup(typ->ty_window);
1045 		sp->se_window_argv_space = strdup(sp->se_window);
1046 		sp->se_window_argv = construct_argv(sp->se_window_argv_space);
1047 		if (sp->se_window_argv == 0) {
1048 			warning("can't parse window for port %s",
1049 				sp->se_device);
1050 			free(sp->se_window_argv_space);
1051 			free(sp->se_window);
1052 			sp->se_window = sp->se_window_argv_space = 0;
1053 			return (0);
1054 		}
1055 	}
1056 	if (sp->se_type)
1057 		free(sp->se_type);
1058 	sp->se_type = typ->ty_type ? strdup(typ->ty_type) : 0;
1059 	return (1);
1060 }
1061 
1062 /*
1063  * Walk the list of ttys and create sessions for each active line.
1064  */
1065 state_func_t
1066 read_ttys(void)
1067 {
1068 	int session_index = 0;
1069 	register session_t *sp, *snext;
1070 	register struct ttyent *typ;
1071 
1072 	/*
1073 	 * Destroy any previous session state.
1074 	 * There shouldn't be any, but just in case...
1075 	 */
1076 	for (sp = sessions; sp; sp = snext) {
1077 		if (sp->se_process)
1078 			clear_session_logs(sp);
1079 		snext = sp->se_next;
1080 		free_session(sp);
1081 	}
1082 	sessions = 0;
1083 	if (start_session_db())
1084 		return (state_func_t) single_user;
1085 
1086 	/*
1087 	 * Allocate a session entry for each active port.
1088 	 * Note that sp starts at 0.
1089 	 */
1090 	while ((typ = getttyent()) != NULL)
1091 		if ((snext = new_session(sp, ++session_index, typ)) != NULL)
1092 			sp = snext;
1093 
1094 	endttyent();
1095 
1096 	return (state_func_t) multi_user;
1097 }
1098 
1099 /*
1100  * Start a window system running.
1101  */
1102 void
1103 start_window_system(session_t *sp)
1104 {
1105 	pid_t pid;
1106 	sigset_t mask;
1107 	char term[64], *env[2];
1108 
1109 	if ((pid = fork()) == -1) {
1110 		emergency("can't fork for window system on port %s: %m",
1111 			sp->se_device);
1112 		/* hope that getty fails and we can try again */
1113 		return;
1114 	}
1115 
1116 	if (pid)
1117 		return;
1118 
1119 	sigemptyset(&mask);
1120 	sigprocmask(SIG_SETMASK, &mask, (sigset_t *) 0);
1121 
1122 	if (setsid() < 0)
1123 		emergency("setsid failed (window) %m");
1124 
1125 #ifdef LOGIN_CAP
1126 	setprocresources(RESOURCE_WINDOW);
1127 #endif
1128 	if (sp->se_type) {
1129 		/* Don't use malloc after fork */
1130 		strcpy(term, "TERM=");
1131 		strncat(term, sp->se_type, sizeof(term) - 6);
1132 		env[0] = term;
1133 		env[1] = 0;
1134 	}
1135 	else
1136 		env[0] = 0;
1137 	execve(sp->se_window_argv[0], sp->se_window_argv, env);
1138 	stall("can't exec window system '%s' for port %s: %m",
1139 		sp->se_window_argv[0], sp->se_device);
1140 	_exit(1);
1141 }
1142 
1143 /*
1144  * Start a login session running.
1145  */
1146 pid_t
1147 start_getty(session_t *sp)
1148 {
1149 	pid_t pid;
1150 	sigset_t mask;
1151 	time_t current_time = time((time_t *) 0);
1152 	int too_quick = 0;
1153 	char term[64], *env[2];
1154 
1155 	if (current_time >= sp->se_started &&
1156 	    current_time - sp->se_started < GETTY_SPACING) {
1157 		if (++sp->se_nspace > GETTY_NSPACE) {
1158 			sp->se_nspace = 0;
1159 			too_quick = 1;
1160 		}
1161 	} else
1162 		sp->se_nspace = 0;
1163 
1164 	/*
1165 	 * fork(), not vfork() -- we can't afford to block.
1166 	 */
1167 	if ((pid = fork()) == -1) {
1168 		emergency("can't fork for getty on port %s: %m", sp->se_device);
1169 		return -1;
1170 	}
1171 
1172 	if (pid)
1173 		return pid;
1174 
1175 	if (too_quick) {
1176 		warning("getty repeating too quickly on port %s, sleeping %d secs",
1177 			sp->se_device, GETTY_SLEEP);
1178 		sleep((unsigned) GETTY_SLEEP);
1179 	}
1180 
1181 	if (sp->se_window) {
1182 		start_window_system(sp);
1183 		sleep(WINDOW_WAIT);
1184 	}
1185 
1186 	sigemptyset(&mask);
1187 	sigprocmask(SIG_SETMASK, &mask, (sigset_t *) 0);
1188 
1189 #ifdef LOGIN_CAP
1190 	setprocresources(RESOURCE_GETTY);
1191 #endif
1192 	if (sp->se_type) {
1193 		/* Don't use malloc after fork */
1194 		strcpy(term, "TERM=");
1195 		strncat(term, sp->se_type, sizeof(term) - 6);
1196 		env[0] = term;
1197 		env[1] = 0;
1198 	}
1199 	else
1200 		env[0] = 0;
1201 	execve(sp->se_getty_argv[0], sp->se_getty_argv, env);
1202 	stall("can't exec getty '%s' for port %s: %m",
1203 		sp->se_getty_argv[0], sp->se_device);
1204 	_exit(1);
1205 }
1206 
1207 /*
1208  * Collect exit status for a child.
1209  * If an exiting login, start a new login running.
1210  */
1211 void
1212 collect_child(pid_t pid)
1213 {
1214 	register session_t *sp, *sprev, *snext;
1215 
1216 	if (! sessions)
1217 		return;
1218 
1219 	if (! (sp = find_session(pid)))
1220 		return;
1221 
1222 	clear_session_logs(sp);
1223 	del_session(sp);
1224 	sp->se_process = 0;
1225 
1226 	if (sp->se_flags & SE_SHUTDOWN) {
1227 		if ((sprev = sp->se_prev) != NULL)
1228 			sprev->se_next = sp->se_next;
1229 		else
1230 			sessions = sp->se_next;
1231 		if ((snext = sp->se_next) != NULL)
1232 			snext->se_prev = sp->se_prev;
1233 		free_session(sp);
1234 		return;
1235 	}
1236 
1237 	if ((pid = start_getty(sp)) == -1) {
1238 		/* serious trouble */
1239 		requested_transition = clean_ttys;
1240 		return;
1241 	}
1242 
1243 	sp->se_process = pid;
1244 	sp->se_started = time((time_t *) 0);
1245 	add_session(sp);
1246 }
1247 
1248 /*
1249  * Catch a signal and request a state transition.
1250  */
1251 void
1252 transition_handler(int sig)
1253 {
1254 
1255 	switch (sig) {
1256 	case SIGHUP:
1257 		requested_transition = clean_ttys;
1258 		break;
1259 	case SIGUSR2:
1260 		howto = RB_POWEROFF;
1261 	case SIGUSR1:
1262 		howto |= RB_HALT;
1263 	case SIGINT:
1264 		Reboot = TRUE;
1265 	case SIGTERM:
1266 		requested_transition = death;
1267 		break;
1268 	case SIGTSTP:
1269 		requested_transition = catatonia;
1270 		break;
1271 	default:
1272 		requested_transition = 0;
1273 		break;
1274 	}
1275 }
1276 
1277 /*
1278  * Take the system multiuser.
1279  */
1280 state_func_t
1281 multi_user(void)
1282 {
1283 	pid_t pid;
1284 	register session_t *sp;
1285 
1286 	requested_transition = 0;
1287 
1288 	/*
1289 	 * If the administrator has not set the security level to -1
1290 	 * to indicate that the kernel should not run multiuser in secure
1291 	 * mode, and the run script has not set a higher level of security
1292 	 * than level 1, then put the kernel into secure mode.
1293 	 */
1294 	if (getsecuritylevel() == 0)
1295 		setsecuritylevel(1);
1296 
1297 	for (sp = sessions; sp; sp = sp->se_next) {
1298 		if (sp->se_process)
1299 			continue;
1300 		if ((pid = start_getty(sp)) == -1) {
1301 			/* serious trouble */
1302 			requested_transition = clean_ttys;
1303 			break;
1304 		}
1305 		sp->se_process = pid;
1306 		sp->se_started = time((time_t *) 0);
1307 		add_session(sp);
1308 	}
1309 
1310 	while (!requested_transition)
1311 		if ((pid = waitpid(-1, (int *) 0, 0)) != -1)
1312 			collect_child(pid);
1313 
1314 	return (state_func_t) requested_transition;
1315 }
1316 
1317 /*
1318  * This is an (n*2)+(n^2) algorithm.  We hope it isn't run often...
1319  */
1320 state_func_t
1321 clean_ttys(void)
1322 {
1323 	register session_t *sp, *sprev;
1324 	register struct ttyent *typ;
1325 	register int session_index = 0;
1326 	register int devlen;
1327 	char *old_getty, *old_window, *old_type;
1328 
1329 	if (! sessions)
1330 		return (state_func_t) multi_user;
1331 
1332 	/*
1333 	 * mark all sessions for death, (!SE_PRESENT)
1334 	 * as we find or create new ones they'll be marked as keepers,
1335 	 * we'll later nuke all the ones not found in /etc/ttys
1336 	 */
1337 	for (sp = sessions; sp != NULL; sp = sp->se_next)
1338 		sp->se_flags &= ~SE_PRESENT;
1339 
1340 	devlen = sizeof(_PATH_DEV) - 1;
1341 	while ((typ = getttyent()) != NULL) {
1342 		++session_index;
1343 
1344 		for (sprev = 0, sp = sessions; sp; sprev = sp, sp = sp->se_next)
1345 			if (strcmp(typ->ty_name, sp->se_device + devlen) == 0)
1346 				break;
1347 
1348 		if (sp) {
1349 			/* we want this one to live */
1350 			sp->se_flags |= SE_PRESENT;
1351 			if (sp->se_index != session_index) {
1352 				warning("port %s changed utmp index from %d to %d",
1353 				       sp->se_device, sp->se_index,
1354 				       session_index);
1355 				sp->se_index = session_index;
1356 			}
1357 			if ((typ->ty_status & TTY_ON) == 0 ||
1358 			    typ->ty_getty == 0) {
1359 				sp->se_flags |= SE_SHUTDOWN;
1360 				kill(sp->se_process, SIGHUP);
1361 				continue;
1362 			}
1363 			sp->se_flags &= ~SE_SHUTDOWN;
1364 			old_getty = sp->se_getty ? strdup(sp->se_getty) : 0;
1365 			old_window = sp->se_window ? strdup(sp->se_window) : 0;
1366 			old_type = sp->se_type ? strdup(sp->se_type) : 0;
1367 			if (setupargv(sp, typ) == 0) {
1368 				warning("can't parse getty for port %s",
1369 					sp->se_device);
1370 				sp->se_flags |= SE_SHUTDOWN;
1371 				kill(sp->se_process, SIGHUP);
1372 			}
1373 			else if (   !old_getty
1374 				 || (!old_type && sp->se_type)
1375 				 || (old_type && !sp->se_type)
1376 				 || (!old_window && sp->se_window)
1377 				 || (old_window && !sp->se_window)
1378 				 || (strcmp(old_getty, sp->se_getty) != 0)
1379 				 || (old_window && strcmp(old_window, sp->se_window) != 0)
1380 				 || (old_type && strcmp(old_type, sp->se_type) != 0)
1381 				) {
1382 				/* Don't set SE_SHUTDOWN here */
1383 				sp->se_nspace = 0;
1384 				sp->se_started = 0;
1385 				kill(sp->se_process, SIGHUP);
1386 			}
1387 			if (old_getty)
1388 				free(old_getty);
1389 			if (old_window)
1390 				free(old_window);
1391 			if (old_type)
1392 				free(old_type);
1393 			continue;
1394 		}
1395 
1396 		new_session(sprev, session_index, typ);
1397 	}
1398 
1399 	endttyent();
1400 
1401 	/*
1402 	 * sweep through and kill all deleted sessions
1403 	 * ones who's /etc/ttys line was deleted (SE_PRESENT unset)
1404 	 */
1405 	for (sp = sessions; sp != NULL; sp = sp->se_next) {
1406 		if ((sp->se_flags & SE_PRESENT) == 0) {
1407 			sp->se_flags |= SE_SHUTDOWN;
1408 			kill(sp->se_process, SIGHUP);
1409 		}
1410 	}
1411 
1412 	return (state_func_t) multi_user;
1413 }
1414 
1415 /*
1416  * Block further logins.
1417  */
1418 state_func_t
1419 catatonia(void)
1420 {
1421 	register session_t *sp;
1422 
1423 	for (sp = sessions; sp; sp = sp->se_next)
1424 		sp->se_flags |= SE_SHUTDOWN;
1425 
1426 	return (state_func_t) multi_user;
1427 }
1428 
1429 /*
1430  * Note SIGALRM.
1431  */
1432 void
1433 alrm_handler(int sig)
1434 {
1435 	(void)sig;
1436 	clang = 1;
1437 }
1438 
1439 /*
1440  * Bring the system down to single user.
1441  */
1442 state_func_t
1443 death(void)
1444 {
1445 	register session_t *sp;
1446 	register int i;
1447 	pid_t pid;
1448 	static const int death_sigs[2] = { SIGTERM, SIGKILL };
1449 
1450 	/* NB: should send a message to the session logger to avoid blocking. */
1451 	logwtmp("~", "shutdown", "");
1452 
1453 	for (sp = sessions; sp; sp = sp->se_next) {
1454 		sp->se_flags |= SE_SHUTDOWN;
1455 		kill(sp->se_process, SIGHUP);
1456 	}
1457 
1458 	/* Try to run the rc.shutdown script within a period of time */
1459 	(void) runshutdown();
1460 
1461 	for (i = 0; i < 2; ++i) {
1462 		if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
1463 			return (state_func_t) single_user;
1464 
1465 		clang = 0;
1466 		alarm(DEATH_WATCH);
1467 		do
1468 			if ((pid = waitpid(-1, (int *)0, 0)) != -1)
1469 				collect_child(pid);
1470 		while (clang == 0 && errno != ECHILD);
1471 
1472 		if (errno == ECHILD)
1473 			return (state_func_t) single_user;
1474 	}
1475 
1476 	warning("some processes would not die; ps axl advised");
1477 
1478 	return (state_func_t) single_user;
1479 }
1480 
1481 /*
1482  * Run the system shutdown script.
1483  *
1484  * Exit codes:      XXX I should document more
1485  * -2       shutdown script terminated abnormally
1486  * -1       fatal error - can't run script
1487  * 0        good.
1488  * >0       some error (exit code)
1489  */
1490 int
1491 runshutdown(void)
1492 {
1493 	pid_t pid, wpid;
1494 	int status;
1495 	int shutdowntimeout;
1496 	size_t len;
1497 	char *argv[4];
1498 	struct sigaction sa;
1499 	struct stat sb;
1500 
1501 	/*
1502 	 * rc.shutdown is optional, so to prevent any unnecessary
1503 	 * complaints from the shell we simply don't run it if the
1504 	 * file does not exist. If the stat() here fails for other
1505 	 * reasons, we'll let the shell complain.
1506 	 */
1507 	if (stat(_PATH_RUNDOWN, &sb) == -1 && errno == ENOENT)
1508 		return 0;
1509 
1510 	if ((pid = fork()) == 0) {
1511 		int	fd;
1512 
1513 		/* Assume that init already grab console as ctty before */
1514 
1515 		sigemptyset(&sa.sa_mask);
1516 		sa.sa_flags = 0;
1517 		sa.sa_handler = SIG_IGN;
1518 		(void) sigaction(SIGTSTP, &sa, (struct sigaction *)0);
1519 		(void) sigaction(SIGHUP, &sa, (struct sigaction *)0);
1520 
1521 		if ((fd = open(_PATH_CONSOLE, O_RDWR)) == -1)
1522 		    warning("can't open %s: %m", _PATH_CONSOLE);
1523 		else {
1524 		    (void) dup2(fd, 0);
1525 		    (void) dup2(fd, 1);
1526 		    (void) dup2(fd, 2);
1527 		    if (fd > 2)
1528 			close(fd);
1529 		}
1530 
1531 		/*
1532 		 * Run the shutdown script.
1533 		 */
1534 		argv[0] = "sh";
1535 		argv[1] = _PATH_RUNDOWN;
1536 		if (Reboot)
1537 			argv[2] = "reboot";
1538 		else
1539 			argv[2] = "single";
1540 		argv[3] = 0;
1541 
1542 		sigprocmask(SIG_SETMASK, &sa.sa_mask, (sigset_t *) 0);
1543 
1544 #ifdef LOGIN_CAP
1545 		setprocresources(RESOURCE_RC);
1546 #endif
1547 		execv(_PATH_BSHELL, argv);
1548 		warning("can't exec %s for %s: %m", _PATH_BSHELL, _PATH_RUNDOWN);
1549 		_exit(1);	/* force single user mode */
1550 	}
1551 
1552 	if (pid == -1) {
1553 		emergency("can't fork for %s on %s: %m",
1554 			_PATH_BSHELL, _PATH_RUNDOWN);
1555 		while (waitpid(-1, (int *) 0, WNOHANG) > 0)
1556 			continue;
1557 		sleep(STALL_TIMEOUT);
1558 		return -1;
1559 	}
1560 
1561 	len = sizeof(shutdowntimeout);
1562 	if (sysctlbyname("kern.shutdown_timeout",
1563 			 &shutdowntimeout,
1564 			 &len, NULL, 0) == -1 || shutdowntimeout < 2)
1565 	    shutdowntimeout = DEATH_SCRIPT;
1566 	alarm(shutdowntimeout);
1567 	clang = 0;
1568 	/*
1569 	 * Copied from single_user().  This is a bit paranoid.
1570 	 * Use the same ALRM handler.
1571 	 */
1572 	do {
1573 		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
1574 			collect_child(wpid);
1575 		if (clang == 1) {
1576 			/* we were waiting for the sub-shell */
1577 			kill(wpid, SIGTERM);
1578 			warning("timeout expired for %s on %s: %m; going to single user mode",
1579 				_PATH_BSHELL, _PATH_RUNDOWN);
1580 			return -1;
1581 		}
1582 		if (wpid == -1) {
1583 			if (errno == EINTR)
1584 				continue;
1585 			warning("wait for %s on %s failed: %m; going to single user mode",
1586 				_PATH_BSHELL, _PATH_RUNDOWN);
1587 			return -1;
1588 		}
1589 		if (wpid == pid && WIFSTOPPED(status)) {
1590 			warning("init: %s on %s stopped, restarting\n",
1591 				_PATH_BSHELL, _PATH_RUNDOWN);
1592 			kill(pid, SIGCONT);
1593 			wpid = -1;
1594 		}
1595 	} while (wpid != pid && !clang);
1596 
1597 	/* Turn off the alarm */
1598 	alarm(0);
1599 
1600 	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM &&
1601 	    requested_transition == catatonia) {
1602 		/*
1603 		 * /etc/rc.shutdown executed /sbin/reboot;
1604 		 * wait for the end quietly
1605 		 */
1606 		sigset_t s;
1607 
1608 		sigfillset(&s);
1609 		for (;;)
1610 			sigsuspend(&s);
1611 	}
1612 
1613 	if (!WIFEXITED(status)) {
1614 		warning("%s on %s terminated abnormally, going to single user mode",
1615 			_PATH_BSHELL, _PATH_RUNDOWN);
1616 		return -2;
1617 	}
1618 
1619 	if ((status = WEXITSTATUS(status)) != 0)
1620 		warning("%s returned status %d", _PATH_RUNDOWN, status);
1621 
1622 	return status;
1623 }
1624 
1625 char *
1626 strk (char *p)
1627 {
1628     static char *t;
1629     char *q;
1630     int c;
1631 
1632     if (p)
1633 	t = p;
1634     if (!t)
1635 	return 0;
1636 
1637     c = *t;
1638     while (c == ' ' || c == '\t' )
1639 	c = *++t;
1640     if (!c) {
1641 	t = 0;
1642 	return 0;
1643     }
1644     q = t;
1645     if (c == '\'') {
1646 	c = *++t;
1647 	q = t;
1648 	while (c && c != '\'')
1649 	    c = *++t;
1650 	if (!c)  /* unterminated string */
1651 	    q = t = 0;
1652 	else
1653 	    *t++ = 0;
1654     } else {
1655 	while (c && c != ' ' && c != '\t' )
1656 	    c = *++t;
1657 	*t++ = 0;
1658 	if (!c)
1659 	    t = 0;
1660     }
1661     return q;
1662 }
1663 
1664 #ifdef LOGIN_CAP
1665 void
1666 setprocresources(const char *cname)
1667 {
1668 	login_cap_t *lc;
1669 	if ((lc = login_getclassbyname(cname, NULL)) != NULL) {
1670 		setusercontext(lc, (struct passwd*)NULL, 0, LOGIN_SETPRIORITY|LOGIN_SETRESOURCES);
1671 		login_close(lc);
1672 	}
1673 }
1674 #endif
1675