1 /* Well, here's my linux version of findsuper.
2 * I'm sure you coulda done it faster. :)
3 * IMHO there isn't as much interesting data to print in the
4 * linux superblock as there is in the SunOS superblock--disk geometry is
5 * not there...and linux seems to update the dates in all the superblocks.
6 * SunOS doesn't ever touch the backup superblocks after the fs is created,
7 * as far as I can tell, so the date is more interesting IMHO and certainly
8 * marks which superblocks are backup ones.
10 * This still doesn't handle disks >2G.
12 * I wanted to add msdos support, but I couldn't make heads or tails
13 * of the kernel include files to find anything I could look for in msdos.
15 * Reading every block of a Sun partition is fairly quick. Doing the
16 * same under linux (slower hardware I suppose) just isn't the same.
17 * It might be more useful to default to reading the first (second?) block
18 * on each cyl; however, if the disk geometry is wrong, this is useless.
19 * But ya could still get the cyl size to print the numbers as cyls instead
22 * run this as (for example)
24 * findsuper /dev/hda 437760 1024 (my disk has cyls of 855*512)
26 * I suppose the next step is to figgure out a way to determine if
27 * the block found is the first superblock somehow, and if so, build
28 * a partition table from the superblocks found... but this is still
33 * ssd@mae.engr.ucf.edu
40 #include <linux/ext2_fs.h>
43 main(int argc, char *argv[])
46 int skiprate=512; /* one sector */
47 long sk=0; /* limited to 2G filesystems!! */
52 struct ext2_super_block ext2;
53 /* interesting fields: EXT2_SUPER_MAGIC
54 * s_blocks_count s_log_block_size s_mtime s_magic s_lastcheck */
58 "Usage: findsuper device [skiprate [start]]\n");
62 skiprate=atoi(argv[2]);
65 "Do you really want to skip less than a sector??\n");
71 fprintf(stderr,"Have to start at 0 or greater,not %ld\n",sk);
80 /* Now, go looking for the superblock ! */
81 printf(" thisoff block fs_blk_sz blksz grp last_mount\n");
82 for (;!feof(f) && (i=fseek(f,sk,SEEK_SET))!= -1; sk+=skiprate){
83 if (i=fread(&ext2,sizeof(ext2),1, f)!=1) {
84 perror("read failed");
85 } else if (ext2.s_magic == EXT2_SUPER_MAGIC){
89 printf("%9ld %9ld %9ld %5ld %4d %s\n", sk,
90 sk/1024, ext2.s_blocks_count,
91 ext2.s_log_block_size,
92 ext2.s_block_group_nr, s);
95 printf("Failed on %d at %ld\n", i, sk);