extras/volume_id/volume_id/ext.c

   1 /*
   2  * volume_id - reads filesystem label and uuid
   3  *
   4  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
   5  *
   6  *      This program is free software; you can redistribute it and/or modify it
   7  *      under the terms of the GNU General Public License as published by the
   8  *      Free Software Foundation version 2 of the License.
   9  */
  10
  11 #ifndef _GNU_SOURCE
  12 #define _GNU_SOURCE 1
  13 #endif
  14
  15 #ifdef HAVE_CONFIG_H
  16 #  include <config.h>
  17 #endif
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <ctype.h>
  25
  26 #include "volume_id.h"
  27 #include "util.h"
  28 #include "logging.h"
  29 #include "ext.h"
  30
  31 struct ext2_super_block {
  32         uint32_t        inodes_count;
  33         uint32_t        blocks_count;
  34         uint32_t        r_blocks_count;
  35         uint32_t        free_blocks_count;
  36         uint32_t        free_inodes_count;
  37         uint32_t        first_data_block;
  38         uint32_t        log_block_size;
  39         uint32_t        dummy3[7];
  40         uint8_t magic[2];
  41         uint16_t        state;
  42         uint32_t        dummy5[8];
  43         uint32_t        feature_compat;
  44         uint32_t        feature_incompat;
  45         uint32_t        feature_ro_compat;
  46         uint8_t uuid[16];
  47         uint8_t volume_name[16];
  48 } __attribute__((__packed__));
  49
  50 #define EXT3_FEATURE_COMPAT_HAS_JOURNAL         0x00000004
  51 #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV       0x00000008
  52 #define EXT_SUPERBLOCK_OFFSET                   0x400
  53
  54 int volume_id_probe_ext(struct volume_id *id, uint64_t off)
  55 {
  56         struct ext2_super_block *es;
  57
  58         dbg("probing at offset 0x%llx", (unsigned long long) off);
  59
  60         es = (struct ext2_super_block *) volume_id_get_buffer(id, off + EXT_SUPERBLOCK_OFFSET, 0x200);
  61         if (es == NULL)
  62                 return -1;
  63
  64         if (es->magic[0] != 0123 ||
  65             es->magic[1] != 0357)
  66                 return -1;
  67
  68         volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
  69         volume_id_set_label_raw(id, es->volume_name, 16);
  70         volume_id_set_label_string(id, es->volume_name, 16);
  71         volume_id_set_uuid(id, es->uuid, UUID_DCE);
  72
  73         if ((le32_to_cpu(es->feature_compat) & EXT3_FEATURE_COMPAT_HAS_JOURNAL) != 0)
  74                 id->type = "ext3";
  75         else
  76                 id->type = "ext2";
  77
  78         return 0;
  79 }