extras/volume_id/lib/ntfs.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 "libvolume_id.h"
  27 #include "util.h"
  28
  29 static struct ntfs_super_block {
  30         uint8_t         jump[3];
  31         uint8_t         oem_id[8];
  32         uint16_t        bytes_per_sector;
  33         uint8_t         sectors_per_cluster;
  34         uint16_t        reserved_sectors;
  35         uint8_t         fats;
  36         uint16_t        root_entries;
  37         uint16_t        sectors;
  38         uint8_t         media_type;
  39         uint16_t        sectors_per_fat;
  40         uint16_t        sectors_per_track;
  41         uint16_t        heads;
  42         uint32_t        hidden_sectors;
  43         uint32_t        large_sectors;
  44         uint16_t        unused[2];
  45         uint64_t        number_of_sectors;
  46         uint64_t        mft_cluster_location;
  47         uint64_t        mft_mirror_cluster_location;
  48         int8_t          cluster_per_mft_record;
  49         uint8_t         reserved1[3];
  50         int8_t          cluster_per_index_record;
  51         uint8_t         reserved2[3];
  52         uint8_t         volume_serial[8];
  53         uint16_t        checksum;
  54 } PACKED *ns;
  55
  56 static struct master_file_table_record {
  57         uint8_t         magic[4];
  58         uint16_t        usa_ofs;
  59         uint16_t        usa_count;
  60         uint64_t        lsn;
  61         uint16_t        sequence_number;
  62         uint16_t        link_count;
  63         uint16_t        attrs_offset;
  64         uint16_t        flags;
  65         uint32_t        bytes_in_use;
  66         uint32_t        bytes_allocated;
  67 } PACKED *mftr;
  68
  69 static struct file_attribute {
  70         uint32_t        type;
  71         uint32_t        len;
  72         uint8_t         non_resident;
  73         uint8_t         name_len;
  74         uint16_t        name_offset;
  75         uint16_t        flags;
  76         uint16_t        instance;
  77         uint32_t        value_len;
  78         uint16_t        value_offset;
  79 } PACKED *attr;
  80
  81 static struct volume_info {
  82         uint64_t        reserved;
  83         uint8_t         major_ver;
  84         uint8_t         minor_ver;
  85 } PACKED *info;
  86
  87 #define MFT_RECORD_VOLUME                       3
  88 #define MFT_RECORD_ATTR_VOLUME_NAME             0x60
  89 #define MFT_RECORD_ATTR_VOLUME_INFO             0x70
  90 #define MFT_RECORD_ATTR_OBJECT_ID               0x40
  91 #define MFT_RECORD_ATTR_END                     0xffffffffu
  92
  93 int volume_id_probe_ntfs(struct volume_id *id, uint64_t off, uint64_t size)
  94 {
  95         unsigned int sector_size;
  96         unsigned int cluster_size;
  97         uint64_t mft_cluster;
  98         uint64_t mft_off;
  99         unsigned int mft_record_size;
 100         unsigned int attr_type;
 101         unsigned int attr_off;
 102         unsigned int attr_len;
 103         unsigned int val_off;
 104         unsigned int val_len;
 105         const uint8_t *buf;
 106         const uint8_t *val;
 107
 108         info("probing at offset 0x%llx\n", (unsigned long long) off);
 109
 110         ns = (struct ntfs_super_block *) volume_id_get_buffer(id, off, 0x200);
 111         if (ns == NULL)
 112                 return -1;
 113
 114         if (memcmp(ns->oem_id, "NTFS", 4) != 0)
 115                 return -1;
 116
 117         volume_id_set_uuid(id, ns->volume_serial, 0, UUID_64BIT_LE);
 118
 119         sector_size = le16_to_cpu(ns->bytes_per_sector);
 120         if (sector_size < 0x200)
 121                 return -1;
 122
 123         cluster_size = ns->sectors_per_cluster * sector_size;
 124         mft_cluster = le64_to_cpu(ns->mft_cluster_location);
 125         mft_off = mft_cluster * cluster_size;
 126
 127         if (ns->cluster_per_mft_record < 0)
 128                 /* size = -log2(mft_record_size); normally 1024 Bytes */
 129                 mft_record_size = 1 << -ns->cluster_per_mft_record;
 130         else
 131                 mft_record_size = ns->cluster_per_mft_record * cluster_size;
 132
 133         dbg("sectorsize  0x%x\n", sector_size);
 134         dbg("clustersize 0x%x\n", cluster_size);
 135         dbg("mftcluster  %llu\n", (unsigned long long) mft_cluster);
 136         dbg("mftoffset  0x%llx\n", (unsigned long long) mft_off);
 137         dbg("cluster per mft_record  %i\n", ns->cluster_per_mft_record);
 138         dbg("mft record size  %i\n", mft_record_size);
 139
 140         buf = volume_id_get_buffer(id, off + mft_off + (MFT_RECORD_VOLUME * mft_record_size),
 141                          mft_record_size);
 142         if (buf == NULL)
 143                 return -1;
 144
 145         mftr = (struct master_file_table_record*) buf;
 146         dbg("mftr->magic '%c%c%c%c'\n", mftr->magic[0], mftr->magic[1], mftr->magic[2], mftr->magic[3]);
 147         if (memcmp(mftr->magic, "FILE", 4) != 0)
 148                 return -1;
 149
 150         attr_off = le16_to_cpu(mftr->attrs_offset);
 151         dbg("file $Volume's attributes are at offset %i\n", attr_off);
 152
 153         while (1) {
 154                 attr = (struct file_attribute*) &buf[attr_off];
 155                 attr_type = le32_to_cpu(attr->type);
 156                 attr_len = le16_to_cpu(attr->len);
 157                 val_off = le16_to_cpu(attr->value_offset);
 158                 val_len = le32_to_cpu(attr->value_len);
 159                 attr_off += attr_len;
 160
 161                 if (attr_len == 0)
 162                         break;
 163
 164                 if (attr_off >= mft_record_size)
 165                         break;
 166
 167                 if (attr_type == MFT_RECORD_ATTR_END)
 168                         break;
 169
 170                 dbg("found attribute type 0x%x, len %i, at offset %i\n",
 171                     attr_type, attr_len, attr_off);
 172
 173                 if (attr_type == MFT_RECORD_ATTR_VOLUME_INFO) {
 174                         dbg("found info, len %i\n", val_len);
 175                         info = (struct volume_info*) (((uint8_t *) attr) + val_off);
 176                         snprintf(id->type_version, sizeof(id->type_version)-1,
 177                                  "%u.%u", info->major_ver, info->minor_ver);
 178                 }
 179
 180                 if (attr_type == MFT_RECORD_ATTR_VOLUME_NAME) {
 181                         dbg("found label, len %i\n", val_len);
 182                         if (val_len > VOLUME_ID_LABEL_SIZE)
 183                                 val_len = VOLUME_ID_LABEL_SIZE;
 184
 185                         val = ((uint8_t *) attr) + val_off;
 186                         volume_id_set_label_raw(id, val, val_len);
 187                         volume_id_set_label_unicode16(id, val, LE, val_len);
 188                 }
 189         }
 190
 191         volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
 192         id->type = "ntfs";
 193
 194         return 0;
 195 }