/* scanufs.c, http://www.bolthole.com/solaris/scanufs.c */
/* Last update, Jan 11, 2007 */

/* Solaris-specific defines, to make sure that system library calls
 * works on files larger than 2Gig in size
 */
#define _LARGEFILE_SOURCE 1
#define _FILE_OFFSET_BITS 64



#include <fcntl.h>
#include <sys/types.h>
#include <sys/dkio.h>
#include <sys/fs/ufs_fs.h>
#include <errno.h>

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/stat.h>


void 
usage()
{
	puts("Usage: ");
	puts("  scanufs /dev/name ");

}



/* Given a SPECIFIC BLOCK, scan it for vtoc */
/* its up to the caller to do the +1 for solaris irritation */
/* return 0 on fail, 1 on found */
int 
scanblock(int fd, int blocknum)
{
	struct fs      *label;
	char            buffer[2048];
	uint32_t nativemagic, crossmagic;
	uint8_t *magicptr;

	nativemagic=FS_MAGIC;
        magicptr=(uint8_t*)&nativemagic;
        crossmagic=(magicptr[0]<<24) |(magicptr[1]<<16) |(magicptr[2]<<8) |(magicptr[3]);

	if(lseek(fd, (off_t)blocknum * 512, SEEK_SET) == -1){
		perror("llseek failed");
		exit(errno);
	}

	if (read(fd, buffer, 2048) != 2048) {
		perror("err reading initial 2k");
		exit(errno);
	}
	label = (struct fs *)buffer;

	if (label->fs_magic == nativemagic) {
		fprintf(stderr, "Found ufs marker at block %d(0x%x)\n",
			blocknum, blocknum);
		return 1;
	}
	if (label->fs_magic == crossmagic) {
		fprintf(stderr, "Found NON-NATIVE ufs marker at block %d(0x%x)\n",
			blocknum, blocknum);
		return 1;
	}

	return 0;
}

int 
main(int argc, char *argv[])
{
	int             fd;
	struct stat 	buf;
	int             blocknum;

/*	printf("DEBUG: size of structfs is %d\n", sizeof(struct fs));*/

	if (argc < 2) {
		puts("Need name of  device!");
		usage();
		exit(1);
	}
	fd = open(argv[1], O_RDONLY);

	if (fd == -1 || fstat(fd, &buf) == -1) {
		perror("could not open device");
		exit(errno);
	}
	for (blocknum = 0; blocknum < buf.st_size/512; blocknum++) {
		if (scanblock(fd, blocknum) == 1) {
			fprintf(stderr,
				"FOUND ufs magic at block %d\n",
				blocknum);
			fprintf(stderr, "FS should start at block %d\n",
				blocknum-16);
		}
	}

	return 0;
}