/*
 * Copyright (c) 1999 Niall Smart.  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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Niall Smart, niall@pobox.com.
 *
 * THIS SOFTWARE IS PROVIDED BY NIALL SMART ``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 NIALL SMART 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/types.h>
#include <sys/param.h>
#include <ufs/ffs/fs.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdlib.h>
#include <limits.h>

int
main(int argc, char** argv)
{
	int		fd;
	int		ret;
	off_t		offset;
	u_quad_t	skip;
	char*		ptr;
	char		buf[SBSIZE];
	struct fs*	fs = (struct fs*)buf;

	if (argc != 3) {
		fprintf(stderr, "usage: %s device skip\n", argv[0]);
		exit(1);
	}

	if ( (fd = open(argv[1], O_RDONLY)) < 0) {
		perror("open");
		exit(1);
	}

	if ( (skip = strtouq(argv[2], &ptr, 0)) == QUAD_MAX || *ptr != '\0') {
		fprintf(stderr, "bad seek value: %s\n", argv[2]);
		exit(1);
	}

	if ( (skip % SBOFF) != 0)
		fprintf(stderr, "warning: %qu is not a multiple of SBOFF (%d)\n", skip, (int)SBOFF);;

	if (skip > 0) {
		fprintf(stderr, "skipping %qu bytes\n", skip);
		lseek(fd, skip, SEEK_SET);
	}

	while (1) {

		ret = read(fd, buf, sizeof(buf));

		if (ret < 0) {
			perror("read");
			exit(1);
		}

		/*
		 * based on checks in /sys/ufs/ffs/ffs_vfsops.c, line 478
		 */

		if (fs->fs_magic == FS_MAGIC &&
				fs->fs_bsize <= MAXBSIZE &&
				fs->fs_bsize >= (int32_t)sizeof(struct fs)) {

			offset = lseek(fd, 0, SEEK_CUR);

			printf("found superblock: offset=%qd, fs_size=%d, fs_fsmnt=%.*s\n",
					offset, fs->fs_size, MAXMNTLEN, fs->fs_fsmnt);

			printf("suggested disklabel entry:\n\n");
			printf("    size   offset    fstype\n");
			printf("%8d %8qd    4.2BSD\n\n", fs->fs_size * 2, (offset - 16384) / 512);


		}

	}

	printf("%d:%d\n", sizeof(struct fs), offsetof(struct fs, fs_magic));

	return 0;
}