update.c

/* vi: set sw=4 ts=4: */
/*
 * Mini update implementation for busybox; much pasted from update-2.11
 *
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 * Copyright (c) 1996, 1997, 1999 Torsten Poulin.
 * Copyright (c) 2000 by Karl M. Hegbloom <karlheg@debian.org>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

/*
 * Note: This program is only necessary if you are running a 2.0.x (or
 * earlier) kernel. 2.2.x and higher flush filesystem buffers automatically.
 */

#include <sys/param.h>
#include <sys/syslog.h>
#include <unistd.h> /* for getopt() */
#include <stdlib.h>

#if __GNU_LIBRARY__ > 5
	#include <sys/kdaemon.h>
#else
	extern int bdflush (int func, long int data);
#endif

#include "busybox.h"

static unsigned int sync_duration = 30;
static unsigned int flush_duration = 5;
static int use_sync = 0;

extern int update_main(int argc, char **argv)
{
	int pid;
	int opt;

	while ((opt = getopt(argc, argv, "Ss:f:")) > 0) {
		switch (opt) {
			case 'S':
				use_sync = 1;
				break;
			case 's':
				sync_duration = atoi(optarg);
				break;
			case 'f':
				flush_duration = atoi(optarg);
				break;
			default:
				show_usage();
		}
	}
	
	if (daemon(0, 1) < 0)
		perror_msg_and_die("daemon");

#ifdef OPEN_MAX
	for (pid = 0; pid < OPEN_MAX; pid++) close(pid);
#else
	/* glibc 2.1.92 requires using sysconf(_SC_OPEN_MAX) */
	for (pid = 0; pid < sysconf(_SC_OPEN_MAX); pid++) close(pid);
#endif

	/* This is no longer necessary since 1.3.5x, but it will harmlessly
	 * exit if that is the case.
	 */

	/* set the program name that will show up in a 'ps' listing */
	argv[0] = "bdflush (update)";
	argv[1] = NULL;
	argv[2] = NULL;
	for (;;) {
		if (use_sync) {
			sleep(sync_duration);
			sync();
		} else {
			sleep(flush_duration);
			if (bdflush(1, 0) < 0) {
				openlog("update", LOG_CONS, LOG_DAEMON);
				syslog(LOG_INFO,
						"This kernel does not need update(8). Exiting.");
				closelog();
				return EXIT_SUCCESS;
			}
		}
	}

	return EXIT_SUCCESS;
}

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