shutdown.c

sysvinit--linux系统下的init

 */
void shutdown(char *halttype)
{
	char	*args[8];
	int	argp = 0;
	int	do_halt = (down_level[0] == '0');

	/* Warn for the last time */
	warn(0);
	if (dontshut) {
		hardsleep(1);
		stopit(0);
	}
	openlog("shutdown", LOG_PID, LOG_USER);
	if (do_halt)
  		syslog(LOG_NOTICE, "shutting down for system halt");
	else
		syslog(LOG_NOTICE, "shutting down for system reboot");
	closelog();

	/* See if we have to do it ourself. */
	if (doself) fastdown();

	/* Create the arguments for init. */
	args[argp++] = INIT;
	if (sltime) {
		args[argp++] = "-t";
		args[argp++] = sltime;
	}
	args[argp++] = down_level;
	args[argp]   = (char *)NULL;

	unlink(SDPID);
	unlink(NOLOGIN);

	/* Now execute init to change runlevel. */
	sync();
	init_setenv("INIT_HALT", halttype);
	execv(INIT, args);

	/* Oops - failed. */
	fprintf(stderr, "\rshutdown: cannot execute %s\r\n", INIT);
	unlink(FASTBOOT);
	unlink(FORCEFSCK);
	init_setenv("INIT_HALT", NULL);
	openlog("shutdown", LOG_PID, LOG_USER);
	syslog(LOG_NOTICE, "shutdown failed");
	closelog();
	exit(1);
}

/*
 *	returns if a warning is to be sent for wt
 */
static int needwarning(int wt)
{
	int ret;

	if (wt < 10)
		ret = 1;
	else if (wt < 60)
		ret = (wt % 15 == 0);
	else if (wt < 180)
		ret = (wt % 30 == 0);
	else
		ret = (wt % 60 == 0);

	return ret;
}

/*
 *	Main program.
 *	Process the options and do the final countdown.
 */
int main(int argc, char **argv)
{
	FILE			*fp;
	extern int		getopt();
	extern int		optind; 
	struct sigaction	sa;
	struct tm		*lt;
	struct stat		st;
	struct utmp		*ut;
	time_t			t;
	uid_t			realuid;
	char			*halttype;
	char			*downusers[32];
	char			buf[128];
	char			term[UT_LINESIZE + 6];
	char			*sp;
	char			*when = NULL;
	int			c, i, wt;
	int			hours, mins;
	int			didnolog = 0;
	int			cancel = 0;
	int			useacl = 0;
	int			pid = 0;
	int			user_ok = 0;

	/* We can be installed setuid root (executable for a special group) */
	realuid = getuid();
	setuid(geteuid());

	if (getuid() != 0) {
  		fprintf(stderr, "shutdown: you must be root to do that!\n");
  		exit(1);
	}
	strcpy(down_level, "1");
	halttype = NULL;

	/* Process the options. */
	while((c = getopt(argc, argv, "HPacqkrhnfFyt:g:i:")) != EOF) {
  		switch(c) {
			case 'H':
				halttype = "HALT";
				break;
			case 'P':
				halttype = "POWERDOWN";
				break;
			case 'a': /* Access control. */
				useacl = 1;
				break;
			case 'c': /* Cancel an already running shutdown. */
				cancel = 1;
				break;
  			case 'k': /* Don't really shutdown, only warn.*/
  				dontshut = 1;
  				break;
  			case 'r': /* Automatic reboot */
				down_level[0] = '6';
  				break;
  			case 'h': /* Halt after shutdown */
				down_level[0] = '0';
  				break;
  			case 'f': /* Don't perform fsck after next boot */
  				fastboot = 1;
  				break;
  			case 'F': /* Force fsck after next boot */
  				forcefsck = 1;
  				break;
			case 'n': /* Don't switch runlevels. */
				doself = 1;
				break;
			case 't': /* Delay between TERM and KILL */
				sltime = optarg;
				break;
			case 'y': /* Ignored for sysV compatibility */
				break;
			case 'g': /* sysv style to specify time. */
				when = optarg;
				break;
			case 'i': /* Level to go to. */
				if (!strchr("0156aAbBcCsS", optarg[0])) {
					fprintf(stderr,
					"shutdown: `%s': bad runlevel\n",
					optarg);
					exit(1);
				}
				down_level[0] = optarg[0];
				break;
  			default:
  				usage();
  				break;	
  		}
	}

	/* Do we need to use the shutdown.allow file ? */
	if (useacl && (fp = fopen(SDALLOW, "r")) != NULL) {

		/* Read /etc/shutdown.allow. */
		i = 0;
		while(fgets(buf, 128, fp)) {
			if (buf[0] == '#' || buf[0] == '\n') continue;
			if (i > 31) continue;
			for(sp = buf; *sp; sp++) if (*sp == '\n') *sp = 0;
			downusers[i++] = strdup(buf);
		}
		if (i < 32) downusers[i] = 0;
		fclose(fp);

		/* Now walk through /var/run/utmp to find logged in users. */
		while(!user_ok && (ut = getutent()) != NULL) {

			/* See if this is a user process on a VC. */
			if (ut->ut_type != USER_PROCESS) continue;
			sprintf(term, "/dev/%.*s", UT_LINESIZE, ut->ut_line);
			if (stat(term, &st) < 0) continue;
#ifdef major /* glibc */
			if (major(st.st_rdev) != 4 ||
			    minor(st.st_rdev) > 63) continue;
#else
			if ((st.st_rdev & 0xFFC0) != 0x0400) continue;
#endif
			/* Root is always OK. */
			if (strcmp(ut->ut_user, "root") == 0) {
				user_ok++;
				break;
			}

			/* See if this is an allowed user. */
			for(i = 0; i < 32 && downusers[i]; i++)
				if (!strncmp(downusers[i], ut->ut_user,
				    UT_NAMESIZE)) {
					user_ok++;
					break;
				}
		}
		endutent();

		/* See if user was allowed. */
		if (!user_ok) {
			if ((fp = fopen(CONSOLE, "w")) != NULL) {
				fprintf(fp, "\rshutdown: no authorized users "
						"logged in.\r\n");
				fclose(fp);
			}
			exit(1);
		}
	}

	/* Read pid of running shutdown from a file */
	if ((fp = fopen(SDPID, "r")) != NULL) {
		fscanf(fp, "%d", &pid);
		fclose(fp);
	}

	/* Read remaining words, skip time if needed. */
	message[0] = 0;
	for(c = optind + (!cancel && !when); c < argc; c++) {
		if (strlen(message) + strlen(argv[c]) + 4 > MESSAGELEN)
			break;
  		strcat(message, argv[c]);
  		strcat(message, " ");
	}
	if (message[0]) strcat(message, "\r\n");

	/* See if we want to run or cancel. */
	if (cancel) {
		if (pid <= 0) {
			fprintf(stderr, "shutdown: cannot find pid "
					"of running shutdown.\n");
			exit(1);
		}
		init_setenv("INIT_HALT", NULL);
		if (kill(pid, SIGINT) < 0) {
			fprintf(stderr, "shutdown: not running.\n");
			exit(1);
		}
		if (message[0]) wall(message, 1, 0);
		exit(0);
	}
  
	/* Check syntax. */
	if (when == NULL) {
		if (optind == argc) usage();
		when = argv[optind++];
	}

	/* See if we are already running. */
	if (pid > 0 && kill(pid, 0) == 0) {
		fprintf(stderr, "\rshutdown: already running.\r\n");
		exit(1);
	}

	/* Extra check. */
	if (doself && down_level[0] != '0' && down_level[0] != '6') {
		fprintf(stderr,
		"shutdown: can use \"-n\" for halt or reboot only.\r\n");
		exit(1);
	}

	/* Tell users what we're gonna do. */
	switch(down_level[0]) {
		case '0':
			strcpy(newstate, "for system halt");
			break;
		case '6':
			strcpy(newstate, "for reboot");
			break;
		case '1':
			strcpy(newstate, "to maintenance mode");
			break;
		default:
			sprintf(newstate, "to runlevel %s", down_level);
			break;
	}

	/* Create a new PID file. */
	unlink(SDPID);
	umask(022);
	if ((fp = fopen(SDPID, "w")) != NULL) {
		fprintf(fp, "%d\n", getpid());
		fclose(fp);
	} else if (errno != EROFS)
		fprintf(stderr, "shutdown: warning: cannot open %s\n", SDPID);

	/*
	 *	Catch some common signals.
	 */
	signal(SIGQUIT, SIG_IGN);
	signal(SIGCHLD, SIG_IGN);
	signal(SIGHUP,  SIG_IGN);
	signal(SIGTSTP, SIG_IGN);
	signal(SIGTTIN, SIG_IGN);
	signal(SIGTTOU, SIG_IGN);

	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = stopit;
	sigaction(SIGINT, &sa, NULL);

	/* Go to the root directory */
	chdir("/");
	if (fastboot)  close(open(FASTBOOT,  O_CREAT | O_RDWR, 0644));
	if (forcefsck) close(open(FORCEFSCK, O_CREAT | O_RDWR, 0644));

	/* Alias now and take care of old '+mins' notation. */
	if (!strcmp(when, "now")) strcpy(when, "0");
	if (when[0] == '+') when++;

	/* Decode shutdown time. */
	for (sp = when; *sp; sp++) {
		if (*sp != ':' && (*sp < '0' || *sp > '9'))
			usage();
	}
	if (strchr(when, ':') == NULL) {
		/* Time in minutes. */
		wt = atoi(when);
		if (wt == 0 && when[0] != '0') usage();
	} else {
		/* Time in hh:mm format. */
		if (sscanf(when, "%d:%2d", &hours, &mins) != 2) usage();
		if (hours > 23 || mins > 59) usage();
		time(&t);
		lt = localtime(&t);
		wt = (60*hours + mins) - (60*lt->tm_hour + lt->tm_min);
		if (wt < 0) wt += 1440;
	}
	/* Shutdown NOW if time == 0 */
	if (wt == 0) shutdown(halttype);

	/* Give warnings on regular intervals and finally shutdown. */
	if (wt < 15 && !needwarning(wt)) warn(wt);
	while(wt) {
		if (wt <= 5 && !didnolog) {
			donologin(wt);
			didnolog++;
		}
		if (needwarning(wt)) warn(wt);
		hardsleep(60);
		wt--;
	}
	shutdown(halttype);

	return 0; /* Never happens */
}