shutdown.c

sysvinit--linux系统下的init

/*
 * shutdown.c	Shut the system down.
 *
 * Usage:	shutdown [-krhfnc] time [warning message]
 *		  -k: don't really shutdown, only warn.
 *		  -r: reboot after shutdown.
 *		  -h: halt after shutdown.
 *		  -f: do a 'fast' reboot (skip fsck).
 *		  -F: Force fsck on reboot.
 *		  -n: do not go through init but do it ourselves.
 *		  -c: cancel an already running shutdown.
 *		  -t secs: delay between SIGTERM and SIGKILL for init.
 *
 * Author:	Miquel van Smoorenburg, [e-mail]
 *
 * Version:	@(#)shutdown  2.86-1  31-Jul-2004  [e-mail]
 *
 *		This file is part of the sysvinit suite,
 *		Copyright 1991-2004 Miquel van Smoorenburg.
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h> 
#include <signal.h>
#include <fcntl.h>
#include <stdarg.h>
#include <utmp.h>
#include <syslog.h>
#include "paths.h"
#include "reboot.h"
#include "initreq.h"

char *Version = "@(#) shutdown 2.86-1 31-Jul-2004 [e-mail]";

#define MESSAGELEN	256

int dontshut = 0;	/* Don't shutdown, only warn	*/
char down_level[2];	/* What runlevel to go to.	*/
int dosync = 1;		/* Sync before reboot or halt	*/
int fastboot = 0;	/* Do a 'fast' reboot		*/
int forcefsck = 0;	/* Force fsck on reboot		*/
char message[MESSAGELEN];	/* Warning message	*/
char *sltime = 0;	/* Sleep time			*/
char newstate[64];	/* What are we gonna do		*/
int doself = 0;		/* Don't use init		*/
int got_alrm = 0;

char *clean_env[] = {
	"HOME=/",
	"PATH=/bin:/usr/bin:/sbin:/usr/sbin",
	"TERM=dumb",
	NULL,
};

/* From "wall.c" */
extern void wall(char *, int, int);

/* From "utmp.c" */
extern void write_wtmp(char *user, char *id, int pid, int type, char *line);

/*
 *	Sleep without being interrupted.
 */
void hardsleep(int secs)
{
	struct timespec ts, rem;

	ts.tv_sec = secs;
	ts.tv_nsec = 0;

	while(nanosleep(&ts, &rem) < 0 && errno == EINTR)
		ts = rem;
}

/*
 *	Break off an already running shutdown.
 */
void stopit(int sig)
{
	unlink(NOLOGIN);
	unlink(FASTBOOT);
	unlink(FORCEFSCK);
	unlink(SDPID);
	printf("\r\nShutdown cancelled.\r\n");
	exit(0);
}

/*
 *	Show usage message.
 */
void usage(void)
{
	fprintf(stderr,
	"Usage:\t  shutdown [-akrhHPfnc] [-t secs] time [warning message]\n"
	"\t\t  -a:      use /etc/shutdown.allow\n"
	"\t\t  -k:      don't really shutdown, only warn.\n"
	"\t\t  -r:      reboot after shutdown.\n"
	"\t\t  -h:      halt after shutdown.\n"
	"\t\t  -P:      halt action is to turn off power.\n"
	"\t\t  -H:      halt action is to just halt.\n"
	"\t\t  -f:      do a 'fast' reboot (skip fsck).\n"
	"\t\t  -F:      Force fsck on reboot.\n"
	"\t\t  -n:      do not go through \"init\" but go down real fast.\n"
	"\t\t  -c:      cancel a running shutdown.\n"
	"\t\t  -t secs: delay between warning and kill signal.\n"
	"\t\t  ** the \"time\" argument is mandatory! (try \"now\") **\n");
	exit(1);
}


void alrm_handler(int sig)
{
	got_alrm = sig;
}


/*
 *	Set environment variables in the init process.
 */
int init_setenv(char *name, char *value)
{
	struct init_request	request;
	struct sigaction	sa;
	int			fd;
	int			nl, vl;

	memset(&request, 0, sizeof(request));
	request.magic = INIT_MAGIC;
	request.cmd = INIT_CMD_SETENV;
	nl = strlen(name);
	vl = value ? strlen(value) : 0;

	if (nl + vl + 3 >= sizeof(request.i.data))
		return -1;

	memcpy(request.i.data, name, nl);
	if (value) {
		request.i.data[nl] = '=';
		memcpy(request.i.data + nl + 1, value, vl);
	}

        /*
	 *	Open the fifo and write the command.
         *	Make sure we don't hang on opening /dev/initctl
	 */
	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = alrm_handler;
	sigaction(SIGALRM, &sa, NULL);
	got_alrm = 0;
        alarm(3);
        if ((fd = open(INIT_FIFO, O_WRONLY)) >= 0 &&
            write(fd, &request, sizeof(request)) == sizeof(request)) {
                close(fd);
                alarm(0);
                return 0;
        }
                                                                                
        fprintf(stderr, "shutdown: ");
        if (got_alrm) {
                fprintf(stderr, "timeout opening/writing control channel %s\n",
                        INIT_FIFO);
        } else {
                perror(INIT_FIFO);
        }
        return -1;
}


/*
 *	Tell everyone the system is going down in 'mins' minutes.
 */
void warn(int mins)
{
	char buf[MESSAGELEN + sizeof(newstate)];
	int len;

	buf[0] = 0;
	strncat(buf, message, sizeof(buf) - 1);
	len = strlen(buf);

	if (mins == 0)
		snprintf(buf + len, sizeof(buf) - len,
			"\rThe system is going down %s NOW!\r\n",
			newstate);
	else
  		snprintf(buf + len, sizeof(buf) - len,
			"\rThe system is going DOWN %s in %d minute%s!\r\n",
				newstate, mins, mins == 1 ? "" : "s");
	wall(buf, 1, 0);
}

/*
 *	Create the /etc/nologin file.
 */
void donologin(int min)
{
	FILE *fp;
	time_t t;

	time(&t);
	t += 60 * min;

	if ((fp = fopen(NOLOGIN, "w")) != NULL) {
  		fprintf(fp, "\rThe system is going down on %s\r\n", ctime(&t));
  		if (message[0]) fputs(message, fp);
  		fclose(fp);
	}
}

/*
 *	Spawn an external program.
 */
int spawn(int noerr, char *prog, ...)
{
	va_list	ap;
	pid_t	pid, rc;
	int	i;
	char	*argv[8];

	i = 0;
	while ((pid = fork()) < 0 && i < 10) {
		perror("fork");
		sleep(5);
		i++;
	}

	if (pid < 0) return -1;

	if (pid > 0) {
		while((rc = wait(&i)) != pid)
			if (rc < 0 && errno == ECHILD)
				break;
		return (rc == pid) ? WEXITSTATUS(i) : -1;
	}

	if (noerr) fclose(stderr);

	argv[0] = prog;
	va_start(ap, prog);
	for (i = 1; i < 7 && (argv[i] = va_arg(ap, char *)) != NULL; i++)
		;
	argv[i] = NULL;
	va_end(ap);

	chdir("/");
	environ = clean_env;

	execvp(argv[0], argv);
	perror(argv[0]);
	exit(1);

	/*NOTREACHED*/
	return 0;
}

/*
 *	Kill all processes, call /etc/init.d/halt (if present)
 */
void fastdown()
{
	int do_halt = (down_level[0] == '0');
	int i;
#if 0
	char cmd[128];
	char *script;

	/*
	 *	Currently, the halt script is either init.d/halt OR rc.d/rc.0,
	 *	likewise for the reboot script. Test for the presence
	 *	of either.
	 */
	if (do_halt) {
		if (access(HALTSCRIPT1, X_OK) == 0)
			script = HALTSCRIPT1;
		else
			script = HALTSCRIPT2;
	} else {
		if (access(REBOOTSCRIPT1, X_OK) == 0)
			script = REBOOTSCRIPT1;
		else
			script = REBOOTSCRIPT2;
	}
#endif

	/* First close all files. */
	for(i = 0; i < 3; i++)
		if (!isatty(i)) {
			close(i);
			open("/dev/null", O_RDWR);
		}
	for(i = 3; i < 20; i++) close(i);
	close(255);

	/* First idle init. */
	if (kill(1, SIGTSTP) < 0) {
		fprintf(stderr, "shutdown: can't idle init.\r\n");
		exit(1);
	}

	/* Kill all processes. */
	fprintf(stderr, "shutdown: sending all processes the TERM signal...\r\n");
	kill(-1, SIGTERM);
	sleep(sltime ? atoi(sltime) : 3);
	fprintf(stderr, "shutdown: sending all processes the KILL signal.\r\n");
	(void) kill(-1, SIGKILL);

#if 0
	/* See if we can run /etc/init.d/halt */
	if (access(script, X_OK) == 0) {
		spawn(1, cmd, "fast", NULL);
		fprintf(stderr, "shutdown: %s returned - falling back "
				"on default routines\r\n", script);
	}
#endif

	/* script failed or not present: do it ourself. */
	sleep(1); /* Give init the chance to collect zombies. */

	/* Record the fact that we're going down */
	write_wtmp("shutdown", "~~", 0, RUN_LVL, "~~");

	/* This is for those who have quota installed. */
	spawn(1, "accton", NULL);
	spawn(1, "quotaoff", "-a", NULL);

	sync();
	fprintf(stderr, "shutdown: turning off swap\r\n");
	spawn(0, "swapoff", "-a", NULL);
	fprintf(stderr, "shutdown: unmounting all file systems\r\n");
	spawn(0, "umount", "-a", NULL);

	/* We're done, halt or reboot now. */
	if (do_halt) {
		fprintf(stderr, "The system is halted. Press CTRL-ALT-DEL "
				"or turn off power\r\n");
		init_reboot(BMAGIC_HALT);
		exit(0);
	}

	fprintf(stderr, "Please stand by while rebooting the system.\r\n");
	init_reboot(BMAGIC_REBOOT);
	exit(0);
}

/*
 *	Go to runlevel 0, 1 or 6.