Theodore Ts'o | 7f88b04 | 1997-04-26 14:48:50 +0000 | [diff] [blame] | 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. |
| 9 | * |
| 10 | * This still doesn't handle disks >2G. |
| 11 | * |
| 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. |
| 14 | * |
| 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 |
| 20 | * of blocks... |
| 21 | * |
| 22 | * run this as (for example) |
| 23 | * findsuper /dev/hda |
| 24 | * findsuper /dev/hda 437760 1024 (my disk has cyls of 855*512) |
| 25 | * |
| 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 |
| 29 | * useful as is. |
| 30 | * |
| 31 | * Steve |
| 32 | * ssd@nevets.oau.org |
| 33 | * ssd@mae.engr.ucf.edu |
Theodore Ts'o | e2423cc | 1999-06-18 00:51:31 +0000 | [diff] [blame] | 34 | * |
Theodore Ts'o | 7f88b04 | 1997-04-26 14:48:50 +0000 | [diff] [blame] | 35 | */ |
| 36 | |
Theodore Ts'o | e2423cc | 1999-06-18 00:51:31 +0000 | [diff] [blame] | 37 | /* |
| 38 | * Documentation addendum added by Andreas dwguest@win.tue.nl/aeb@cwi.nl |
| 39 | * |
| 40 | * The program findsuper is a utility that scans a disk and finds |
| 41 | * copies of ext2 superblocks (by checking for the ext2 signature; it |
| 42 | * will occasionally find other blocks that by coincidence have this |
| 43 | * signature - often these can be recognised by their ridiculous |
| 44 | * dates). |
| 45 | * |
| 46 | * For each superblock found, it prints the offset in bytes, the |
| 47 | * offset in 1024-byte blocks, the size of ext2 partition in 1024-byte |
| 48 | * blocks, the filesystem blocksize (given as log(blocksize)-10, so |
| 49 | * that 0 means 1024), the block group number (0 for older ext2 |
| 50 | * systems), and a timestamp (s_mtime). |
| 51 | * |
| 52 | * This program can be used to retrieve partitions that have been |
| 53 | * lost. The superblock for block group 0 is found 1 block (2 |
| 54 | * sectors) after the partition start. |
| 55 | * |
| 56 | * For new systems that have a block group number in the superblock it |
| 57 | * is immediately clear which superblock is the first of a partition. |
| 58 | * For old systems where no group numbers are given, the first |
| 59 | * superblock can be recognised by the timestamp: all superblock |
| 60 | * copies have the creation time in s_mtime, except the first, which |
| 61 | * has the last time e2fsck or tune2fs wrote to the filesystem. |
| 62 | * |
| 63 | */ |
| 64 | |
| 65 | |
Theodore Ts'o | 7f88b04 | 1997-04-26 14:48:50 +0000 | [diff] [blame] | 66 | #include <stdio.h> |
| 67 | #include <stdlib.h> |
| 68 | #include <time.h> |
| 69 | |
| 70 | #include <linux/ext2_fs.h> |
| 71 | |
| 72 | |
| 73 | main(int argc, char *argv[]) |
| 74 | { |
Theodore Ts'o | 19c78dc | 1997-04-29 16:17:09 +0000 | [diff] [blame] | 75 | int i; |
| 76 | int skiprate=512; /* one sector */ |
| 77 | long sk=0; /* limited to 2G filesystems!! */ |
| 78 | FILE *f; |
| 79 | char *s; |
| 80 | time_t tm; |
Theodore Ts'o | 7f88b04 | 1997-04-26 14:48:50 +0000 | [diff] [blame] | 81 | |
Theodore Ts'o | 19c78dc | 1997-04-29 16:17:09 +0000 | [diff] [blame] | 82 | struct ext2_super_block ext2; |
| 83 | /* interesting fields: EXT2_SUPER_MAGIC |
| 84 | * s_blocks_count s_log_block_size s_mtime s_magic s_lastcheck */ |
Theodore Ts'o | 7f88b04 | 1997-04-26 14:48:50 +0000 | [diff] [blame] | 85 | |
Theodore Ts'o | 19c78dc | 1997-04-29 16:17:09 +0000 | [diff] [blame] | 86 | if (argc<2) { |
| 87 | fprintf(stderr, |
| 88 | "Usage: findsuper device [skiprate [start]]\n"); |
| 89 | exit(1); |
| 90 | } |
| 91 | if (argc>2) |
| 92 | skiprate=atoi(argv[2]); |
| 93 | if (skiprate<512) { |
| 94 | fprintf(stderr, |
| 95 | "Do you really want to skip less than a sector??\n"); |
| 96 | exit(2); |
| 97 | } |
| 98 | if (argc>3) |
| 99 | sk=atol(argv[3]); |
| 100 | if (sk<0) { |
| 101 | fprintf(stderr,"Have to start at 0 or greater,not %ld\n",sk); |
| 102 | exit(1); |
| 103 | } |
| 104 | f=fopen(argv[1],"r"); |
| 105 | if (!f) { |
| 106 | perror(argv[1]); |
| 107 | exit(1); |
| 108 | } |
Theodore Ts'o | 7f88b04 | 1997-04-26 14:48:50 +0000 | [diff] [blame] | 109 | |
Theodore Ts'o | 19c78dc | 1997-04-29 16:17:09 +0000 | [diff] [blame] | 110 | /* Now, go looking for the superblock ! */ |
Theodore Ts'o | eb5ab74 | 1998-07-04 17:47:52 +0000 | [diff] [blame] | 111 | printf(" thisoff block fs_blk_sz blksz grp last_mount\n"); |
Theodore Ts'o | 19c78dc | 1997-04-29 16:17:09 +0000 | [diff] [blame] | 112 | for (;!feof(f) && (i=fseek(f,sk,SEEK_SET))!= -1; sk+=skiprate){ |
| 113 | if (i=fread(&ext2,sizeof(ext2),1, f)!=1) { |
| 114 | perror("read failed"); |
Theodore Ts'o | 19c78dc | 1997-04-29 16:17:09 +0000 | [diff] [blame] | 115 | } |
Theodore Ts'o | e2423cc | 1999-06-18 00:51:31 +0000 | [diff] [blame] | 116 | if (ext2.s_magic != EXT2_SUPER_MAGIC) |
| 117 | continue; |
| 118 | |
| 119 | tm = ext2.s_mtime; |
| 120 | s=ctime(&tm); |
| 121 | s[24]=0; |
| 122 | printf("%9ld %9ld %9ld %5ld %4d %s\n", sk, |
| 123 | sk/1024, ext2.s_blocks_count, |
| 124 | ext2.s_log_block_size, |
| 125 | ext2.s_block_group_nr, s); |
Theodore Ts'o | 19c78dc | 1997-04-29 16:17:09 +0000 | [diff] [blame] | 126 | } |
| 127 | printf("Failed on %d at %ld\n", i, sk); |
| 128 | fclose(f); |
Theodore Ts'o | 7f88b04 | 1997-04-26 14:48:50 +0000 | [diff] [blame] | 129 | } |