misc/findsuper.c

   1 /*
   2  * findsuper --- quick hacked up program to find ext2 superblocks.
   3  *
   4  * This is a hack, and really shouldn't be installed anywhere.  If you
   5  * need a program which does this sort of functionality, please try
   6  * using gpart program.
   7  *
   8  * Portions Copyright 1998-2000, Theodore Ts'o.
   9  *
  10  * Well, here's my linux version of findsuper.
  11  * I'm sure you coulda done it faster.  :)
  12  * IMHO there isn't as much interesting data to print in the
  13  * linux superblock as there is in the SunOS superblock--disk geometry is
  14  * not there...and linux seems to update the dates in all the superblocks.
  15  * SunOS doesn't ever touch the backup superblocks after the fs is created,
  16  * as far as I can tell, so the date is more interesting IMHO and certainly
  17  * marks which superblocks are backup ones.
  18  *
  19  * I wanted to add msdos support, but I couldn't make heads or tails
  20  * of the kernel include files to find anything I could look for in msdos.
  21  *
  22  * Reading every block of a Sun partition is fairly quick.  Doing the
  23  * same under linux (slower hardware I suppose) just isn't the same.
  24  * It might be more useful to default to reading the first (second?) block
  25  * on each cyl; however, if the disk geometry is wrong, this is useless.
  26  * But ya could still get the cyl size to print the numbers as cyls instead
  27  * of blocks...
  28  *
  29  * run this as (for example)
  30  *   findsuper /dev/hda
  31  *   findsuper /dev/hda 437760 1024   (my disk has cyls of 855*512)
  32  *
  33  * I suppose the next step is to figgure out a way to determine if
  34  * the block found is the first superblock somehow, and if so, build
  35  * a partition table from the superblocks found... but this is still
  36  * useful as is.
  37  *
  38  *              Steve
  39  * ssd@nevets.oau.org
  40  * ssd@mae.engr.ucf.edu
  41  *
  42  * Additional notes by Andreas Dilger <adilger@turbolinux.com>:
  43  * - fixed to support > 2G devices by using lseek64
  44  * - add reliability checking for the superblock to avoid random garbage
  45  * - add adaptive progress meter
  46  *
  47  * It _should_ also handle signals and tell you the ending block, so
  48  * that you can resume at a later time, but it doesn't yet...
  49  *
  50  * Note that gpart does not appear to find all superblocks that aren't aligned
  51  * with the start of a possible partition, so it is not useful in systems
  52  * with LVM or similar setups which don't use fat partition alignment.
  53  *
  54  * %Begin-Header%
  55  * This file may be redistributed under the terms of the GNU Public
  56  * License.
  57  * %End-Header%
  58  */
  59
  60 /*
  61  * Documentation addendum added by Andreas dwguest@win.tue.nl/aeb@cwi.nl
  62  *
  63  * The program findsuper is a utility that scans a disk and finds
  64  * copies of ext2 superblocks (by checking for the ext2 signature).
  65  *
  66  * For each superblock found, it prints the offset in bytes, the
  67  * offset in 1024-byte blocks, the size of the ext2 partition in fs
  68  * blocks, the filesystem blocksize (in bytes), the block group number
  69  * (always 0 for older ext2 systems), and a timestamp (s_mtime).
  70  *
  71  * This program can be used to retrieve partitions that have been
  72  * lost.  The superblock for block group 0 is found 1 block (2
  73  * sectors) after the partition start.
  74  *
  75  * For new systems that have a block group number in the superblock it
  76  * is immediately clear which superblock is the first of a partition.
  77  * For old systems where no group numbers are given, the first
  78  * superblock can be recognised by the timestamp: all superblock
  79  * copies have the creation time in s_mtime, except the first, which
  80  * has the last time e2fsck or tune2fs wrote to the filesystem.
  81  *
  82  */
  83
  84 #define _FILE_OFFSET_BITS 64
  85
  86 #include <stdio.h>
  87 #include <stdlib.h>
  88 #include <string.h>
  89 #include <unistd.h>
  90 #include <errno.h>
  91 #include <fcntl.h>
  92 #include <time.h>
  93
  94 #include "ext2fs/ext2_fs.h"
  95 #include "nls-enable.h"
  96
  97 #undef DEBUG
  98
  99 #ifdef DEBUG
 100 #define WHY(fmt, arg...) { printf("\r%Ld: " fmt, sk, ##arg) ; continue; }
 101 #else
 102 #define WHY(fmt, arg...) { continue; }
 103 #endif
 104
 105 int main(int argc, char *argv[])
 106 {
 107         int skiprate=512;               /* one sector */
 108         loff_t sk=0, skl=0;
 109         int fd;
 110         char *s;
 111         time_t tm, last = time(0);
 112         loff_t interval = 1024 * 1024;
 113
 114         struct ext2_super_block ext2;
 115         /* interesting fields: EXT2_SUPER_MAGIC
 116          *      s_blocks_count s_log_block_size s_mtime s_magic s_lastcheck */
 117
 118 #ifdef ENABLE_NLS
 119         setlocale(LC_MESSAGES, "");
 120         setlocale(LC_CTYPE, "");
 121         bindtextdomain(NLS_CAT_NAME, LOCALEDIR);
 122         textdomain(NLS_CAT_NAME);
 123 #endif
 124         if (argc<2) {
 125                 fprintf(stderr,
 126                         _("Usage:  findsuper device [skipbytes [startkb]]\n"));
 127                 exit(1);
 128         }
 129         if (argc>2)
 130                 skiprate = strtol(argv[2], &s, 0);
 131         if (s == argv[2]) {
 132                 fprintf(stderr,_("skipbytes should be a number, not %s\n"), s);
 133                 exit(1);
 134         }
 135         if (skiprate & 0x1ff) {
 136                 fprintf(stderr,
 137                         _("skipbytes must be a multiple of the sector size\n"));
 138                 exit(2);
 139         }
 140         if (argc>3)
 141                 sk = skl = strtoll(argv[3], &s, 0) << 10;
 142         if (s == argv[3]) {
 143                 fprintf(stderr,_("startkb should be a number, not %s\n"), s);
 144                 exit(1);
 145         }
 146         if (sk < 0) {
 147                 fprintf(stderr,_("startkb should be positive, not %Ld\n"), sk);
 148                 exit(1);
 149         }
 150         fd = open(argv[1], O_RDONLY);
 151         if (fd < 0) {
 152                 perror(argv[1]);
 153                 exit(1);
 154         }
 155
 156         /* Now, go looking for the superblock! */
 157         printf(_("starting at %Ld, with %d byte increments\n"), sk, skiprate);
 158         printf(_("       thisoff     block fs_blk_sz  blksz grp last_mount\n"));
 159         for (; lseek64(fd, sk, SEEK_SET) != -1 &&
 160                read(fd, &ext2, 512) == 512; sk += skiprate) {
 161
 162                 if (sk && !(sk & (interval - 1))) {
 163                         time_t now, diff;
 164
 165                         now = time(0);
 166                         diff = now - last;
 167
 168                         if (diff > 0) {
 169                                 s = ctime(&now);
 170                                 s[24] = 0;
 171                                 printf("\r%14Ld: %8LdkB/s @ %s", sk,
 172                                        (((sk - skl)) / diff) >> 10, s);
 173                                 fflush(stdout);
 174                         }
 175                         if (diff < 5)
 176                                 interval <<= 1;
 177                         else if (diff > 20)
 178                                 interval >>= 1;
 179                         last = now;
 180                         skl = sk;
 181                 }
 182                 if (ext2.s_magic != EXT2_SUPER_MAGIC)
 183                         continue;
 184                 if (ext2.s_log_block_size > 4)
 185                         WHY("log block size > 4 (%u)\n", ext2.s_log_block_size);
 186                 if (ext2.s_r_blocks_count > ext2.s_blocks_count)
 187                         WHY("r_blocks_count > blocks_count (%u > %u)\n",
 188                             ext2.s_r_blocks_count, ext2.s_blocks_count);
 189                 if (ext2.s_free_blocks_count > ext2.s_blocks_count)
 190                         WHY("free_blocks_count > blocks_count\n (%u > %u)\n",
 191                             ext2.s_free_blocks_count, ext2.s_blocks_count);
 192                 if (ext2.s_free_inodes_count > ext2.s_inodes_count)
 193                         WHY("free_inodes_count > inodes_count (%u > %u)\n",
 194                             ext2.s_free_inodes_count, ext2.s_inodes_count);
 195
 196                 tm = ext2.s_mtime;
 197                 s=ctime(&tm);
 198                 s[24]=0;
 199                 printf("\r%14Ld %9Ld %9d %5d %4d %s\n",
 200                        sk, sk >> 10, ext2.s_blocks_count,
 201                        1 << (ext2.s_log_block_size + 10),
 202                        ext2.s_block_group_nr, s);
 203         }
 204         printf(_("\n%14Ld: finished with errno %d\n"), sk, errno);
 205         close(fd);
 206
 207         return errno;
 208 }