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 "ext2fs/ext2fs.h"
  96 #include "nls-enable.h"
  97
  98 #undef DEBUG
  99
 100 #ifdef DEBUG
 101 #define WHY(fmt, arg...) { printf("\r%Ld: " fmt, sk, ##arg) ; continue; }
 102 #else
 103 #define WHY(fmt, arg...) { continue; }
 104 #endif
 105
 106 static void usage(void)
 107 {
 108         fprintf(stderr,
 109                 _("Usage:  findsuper device [skipbytes [startkb]]\n"));
 110         exit(1);
 111 }
 112
 113
 114 int main(int argc, char *argv[])
 115 {
 116         int skiprate=512;               /* one sector */
 117         loff_t sk=0, skl=0;
 118         int fd;
 119         char *s;
 120         time_t tm, last = time(0);
 121         loff_t interval = 1024 * 1024;
 122         int c, print_jnl_copies = 0;
 123         const char * device_name;
 124         struct ext2_super_block ext2;
 125         /* interesting fields: EXT2_SUPER_MAGIC
 126          *      s_blocks_count s_log_block_size s_mtime s_magic s_lastcheck */
 127
 128 #ifdef ENABLE_NLS
 129         setlocale(LC_MESSAGES, "");
 130         setlocale(LC_CTYPE, "");
 131         bindtextdomain(NLS_CAT_NAME, LOCALEDIR);
 132         textdomain(NLS_CAT_NAME);
 133 #endif
 134
 135         while ((c = getopt (argc, argv, "j")) != EOF) {
 136                 switch (c) {
 137                 case 'j':
 138                         print_jnl_copies++;
 139                         break;
 140                 default:
 141                         usage();
 142                 }
 143         }
 144
 145         if (optind == argc)
 146                 usage();
 147
 148         device_name = argv[optind++];
 149
 150         if (optind < argc) {
 151                 skiprate = strtol(argv[optind], &s, 0);
 152                 if (s == argv[optind]) {
 153                         fprintf(stderr,_("skipbytes should be a number, not %s\n"), s);
 154                         exit(1);
 155                 }
 156                 optind++;
 157         }
 158         if (skiprate & 0x1ff) {
 159                 fprintf(stderr,
 160                         _("skipbytes must be a multiple of the sector size\n"));
 161                 exit(2);
 162         }
 163         if (optind < argc) {
 164                 sk = skl = strtoll(argv[optind], &s, 0) << 10;
 165                 if (s == argv[optind]) {
 166                         fprintf(stderr,
 167                                 _("startkb should be a number, not %s\n"), s);
 168                         exit(1);
 169                 }
 170                 optind++;
 171         }
 172         if (sk < 0) {
 173                 fprintf(stderr, _("startkb should be positive, not %Lu\n"), sk);
 174                 exit(1);
 175         }
 176
 177         fd = open(device_name, O_RDONLY);
 178         if (fd < 0) {
 179                 perror(device_name);
 180                 exit(1);
 181         }
 182
 183         /* Now, go looking for the superblock! */
 184         printf(_("starting at %Lu, with %u byte increments\n"), sk, skiprate);
 185         if (print_jnl_copies)
 186                 printf(_("[*] probably superblock written in the ext3 "
 187                          "journal superblock,\n\tso start/end/grp wrong\n"));
 188         printf(_("byte_offset  byte_start     byte_end  fs_blocks blksz  grp  last_mount_time           sb_uuid label\n"));
 189         for (; lseek64(fd, sk, SEEK_SET) != -1 &&
 190                read(fd, &ext2, 512) == 512; sk += skiprate) {
 191                 static unsigned char last_uuid[16] = "blah";
 192                 unsigned long long bsize, grpsize;
 193                 int jnl_copy, sb_offset;
 194
 195                 if (sk && !(sk & (interval - 1))) {
 196                         time_t now, diff;
 197
 198                         now = time(0);
 199                         diff = now - last;
 200
 201                         if (diff > 0) {
 202                                 s = ctime(&now);
 203                                 s[24] = 0;
 204                                 printf("\r%11Lu: %8LukB/s @ %s", sk,
 205                                        (((sk - skl)) / diff) >> 10, s);
 206                                 fflush(stdout);
 207                         }
 208                         if (diff < 5)
 209                                 interval <<= 1;
 210                         else if (diff > 20)
 211                                 interval >>= 1;
 212                         last = now;
 213                         skl = sk;
 214                 }
 215                 if (ext2.s_magic != EXT2_SUPER_MAGIC)
 216                         continue;
 217                 if (ext2.s_log_block_size > 6)
 218                         WHY("log block size > 6 (%u)\n", ext2.s_log_block_size);
 219                 if (ext2fs_r_blocks_count(&ext2) > ext2fs_blocks_count(&ext2))
 220                         WHY("r_blocks_count > blocks_count (%u > %u)\n",
 221                             ext2fs_r_blocks_count(&ext2),
 222                             ext2fs_blocks_count(&ext2));
 223                 if (ext2fs_free_blocks_count(&ext2) > ext2fs_blocks_count(&ext2))
 224                         WHY("free_blocks_count > blocks_count\n (%u > %u)\n",
 225                             ext2fs_free_blocks_count(&ext2),
 226                             ext2fs_blocks_count(&ext2));
 227                 if (ext2.s_free_inodes_count > ext2.s_inodes_count)
 228                         WHY("free_inodes_count > inodes_count (%u > %u)\n",
 229                             ext2.s_free_inodes_count, ext2.s_inodes_count);
 230
 231                 tm = ext2.s_mtime;
 232                 s = ctime(&tm);
 233                 s[24] = 0;
 234                 bsize = 1 << (ext2.s_log_block_size + 10);
 235                 grpsize = bsize * ext2.s_blocks_per_group;
 236                 if (memcmp(ext2.s_uuid, last_uuid, sizeof(last_uuid)) == 0 &&
 237                     ext2.s_rev_level > 0 && ext2.s_block_group_nr == 0) {
 238                         jnl_copy = 1;
 239                 } else {
 240                         jnl_copy = 0;
 241                         memcpy(last_uuid, ext2.s_uuid, sizeof(last_uuid));
 242                 }
 243                 if (ext2.s_block_group_nr == 0 || bsize == 1024)
 244                         sb_offset = 1024;
 245                 else
 246                         sb_offset = 0;
 247                 if (jnl_copy && !print_jnl_copies)
 248                         continue;
 249                 printf("\r%11Lu %11Lu%s %11Lu%s %9u %5Lu %4u%s %s %02x%02x%02x%02x %s\n",
 250                        sk, sk - ext2.s_block_group_nr * grpsize - sb_offset,
 251                        jnl_copy ? "*":" ",
 252                        sk + ext2fs_blocks_count(&ext2) * bsize -
 253                             ext2.s_block_group_nr * grpsize - sb_offset,
 254                        jnl_copy ? "*" : " ", ext2fs_blocks_count(&ext2), bsize,
 255                        ext2.s_block_group_nr, jnl_copy ? "*" : " ", s,
 256                        ext2.s_uuid[0], ext2.s_uuid[1],
 257                        ext2.s_uuid[2], ext2.s_uuid[3], ext2.s_volume_name);
 258         }
 259         printf(_("\n%11Lu: finished with errno %d\n"), sk, errno);
 260         close(fd);
 261
 262         return errno;
 263 }