extras/volume_id/libvolume_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
  30 struct ext2_super_block {
  31         uint32_t        s_inodes_count;
  32         uint32_t        s_blocks_count;
  33         uint32_t        s_r_blocks_count;
  34         uint32_t        s_free_blocks_count;
  35         uint32_t        s_free_inodes_count;
  36         uint32_t        s_first_data_block;
  37         uint32_t        s_log_block_size;
  38         uint32_t        s_log_frag_size;
  39         uint32_t        s_blocks_per_group;
  40         uint32_t        s_frags_per_group;
  41         uint32_t        s_inodes_per_group;
  42         uint32_t        s_mtime;
  43         uint32_t        s_wtime;
  44         uint16_t        s_mnt_count;
  45         uint16_t        s_max_mnt_count;
  46         uint16_t        s_magic;
  47         uint16_t        s_state;
  48         uint16_t        s_errors;
  49         uint16_t        s_minor_rev_level;
  50         uint32_t        s_lastcheck;
  51         uint32_t        s_checkinterval;
  52         uint32_t        s_creator_os;
  53         uint32_t        s_rev_level;
  54         uint16_t        s_def_resuid;
  55         uint16_t        s_def_resgid;
  56         uint32_t        s_first_ino;
  57         uint16_t        s_inode_size;
  58         uint16_t        s_block_group_nr;
  59         uint32_t        s_feature_compat;
  60         uint32_t        s_feature_incompat;
  61         uint32_t        s_feature_ro_compat;
  62         uint8_t         s_uuid[16];
  63         uint8_t         s_volume_name[16];
  64 } __attribute__((__packed__));
  65
  66 #define EXT_SUPER_MAGIC                         0xEF53
  67 #define EXT3_FEATURE_COMPAT_HAS_JOURNAL         0x00000004
  68 #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV       0x00000008
  69 #define EXT_SUPERBLOCK_OFFSET                   0x400
  70
  71 #define EXT3_MIN_BLOCK_SIZE                     0x400
  72 #define EXT3_MAX_BLOCK_SIZE                     0x1000
  73
  74 int volume_id_probe_ext(struct volume_id *id, uint64_t off)
  75 {
  76         struct ext2_super_block *es;
  77         size_t bsize;
  78
  79         dbg("probing at offset 0x%llx", (unsigned long long) off);
  80
  81         es = (struct ext2_super_block *) volume_id_get_buffer(id, off + EXT_SUPERBLOCK_OFFSET, 0x200);
  82         if (es == NULL)
  83                 return -1;
  84
  85         if (es->s_magic != cpu_to_le16(EXT_SUPER_MAGIC))
  86                 return -1;
  87
  88         bsize = 0x400 << le32_to_cpu(es->s_log_block_size);
  89         dbg("ext blocksize 0x%zx", bsize);
  90         if (bsize < EXT3_MIN_BLOCK_SIZE || bsize > EXT3_MAX_BLOCK_SIZE) {
  91                 dbg("invalid ext blocksize");
  92                 return -1;
  93         }
  94
  95         volume_id_set_label_raw(id, es->s_volume_name, 16);
  96         volume_id_set_label_string(id, es->s_volume_name, 16);
  97         volume_id_set_uuid(id, es->s_uuid, UUID_DCE);
  98         snprintf(id->type_version, sizeof(id->type_version)-1,
  99                  "%u.%u", es->s_rev_level, es->s_minor_rev_level);
 100
 101         /* check for external journal device */
 102         if ((le32_to_cpu(es->s_feature_incompat) & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) != 0) {
 103                 volume_id_set_usage(id, VOLUME_ID_OTHER);
 104                 id->type = "jbd";
 105                 return 0;
 106         }
 107
 108         /* check for ext2 / ext3 */
 109         volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
 110         if ((le32_to_cpu(es->s_feature_compat) & EXT3_FEATURE_COMPAT_HAS_JOURNAL) != 0)
 111                 id->type = "ext3";
 112         else
 113                 id->type = "ext2";
 114
 115         return 0;
 116 }