+and parse_mft dev mft_lcn mft_size =
+ (* Read the whole of the MFT (which is an array of MFT records) ... *)
+ let bits = dev#read_bitstring mft_lcn mft_size in
+
+ (* ... and turn the MFT into records. *)
+ let records = parse_mft_records bits in
+ records
+
+and parse_mft_records bits =
+ bitmatch bits with
+ | { "FILE" : 32 : string;
+ (* Assume 3 USAs starting at offset 0x30. XXX? *)
+ 0x30 : 16 : littleendian;
+ 0x03 : 16 : littleendian;
+ _ : 64; (* lsn *)
+ _ : 16; (* sequence_number *)
+ _ : 16; (* link_count *)
+ _ : 16; (* attrs_offset *)
+ _ : 16; (* MFT_RECORD_FLAGS *)
+ bytes_in_use : 32 : littleendian;
+ record_size : 32 : littleendian;
+ _ : 64; (* base_mft_record *)
+ _ : 16; (* next_attr_instance *)
+ _ : 16; (* reserved *)
+ _ : 32; (* mft_record_number *)
+ _ : 64; (* USN, 3 * USAs -- see above. *)
+
+ (* The attributes. Subtract header size (0x30 bytes)
+ * and space for the USN/USAs (8 bytes).
+ *)
+ attrs : (Int32.to_int record_size - 0x30 - 8)*8 : bitstring;
+
+ (* Subsequent MFT records: *)
+ rest : -1 : bitstring } ->
+
+ if !debug then
+ eprintf "got an MFT record, now parsing attributes ...\n%!";
+
+ let mft_record = {
+ ntfs_filename = None;
+ ntfs_info = None;
+ ntfs_data = None
+ } in
+ let mft_record = parse_attrs attrs mft_record in
+
+ mft_record :: parse_mft_records rest (* loop rest of MFT records *)
+
+ (* Just assume that the end of the list of MFT records
+ * is marked by all zeroes. This seems to be the
+ * case, but not sure if it is generally true.
+ * XXX?
+ *)
+ | { 0x00000000_l : 32 } -> []
+
+ | { _ } -> []
+
+and parse_attrs attrs mft_record =
+ (* Parse the MFT record attributes. *)
+ bitmatch attrs with
+ | { 0xFFFFFFFF_l : 32 : littleendian } -> (* AT_END *)
+ if !debug then
+ eprintf "found AT_END, end of attributes\n%!";
+ mft_record
+
+ | { attr_type : 32 : littleendian;
+ attr_size : 32 : littleendian;
+ 0 : 8; (* means attribute is resident *)
+ _ : 24*8 - 8 - 64 : bitstring; (* actually meaningful *)
+ attr : (Int32.to_int attr_size - 24) * 8 : bitstring;
+ rest : -1 : bitstring } ->
+
+ let mft_record = parse_resident_attr attr_type attr mft_record in
+ parse_attrs rest mft_record
+
+ | { attr_type : 32 : littleendian;
+ attr_size : 32 : littleendian;
+ 1 : 8; (* non-resident attribute *)
+ 0 : 8; (* name length, assume unnamed *)
+ _ : 16; (* name offset *)
+ _ : 16; (* flags *)
+ _ : 16; (* instance number *)
+ 0L : 64 : littleendian; (* lowest VCN, assume single extent *)
+ highest_vcn : 64 : littleendian; (* size in clusters - 1 *)
+ 0x40 : 16 : littleendian; (* mapping pairs offset *)
+ 0 : 8; (* assume not compressed *)
+ _ : 40 : bitstring; (* padding *)
+ allocated_size : 64 : littleendian; (* allocate size on disk *)
+ data_size : 64 : littleendian; (* byte size of the attribute *)
+ initialized_size : 64 : littleendian;
+
+ (* Table of virtual clusters to logical clusters. *)
+ mapping_pairs : (Int32.to_int attr_size - 0x40) * 8 : bitstring;
+
+ rest : -1 : bitstring } ->
+
+ let data_size = Int63.of_int64 data_size in
+
+ let mft_record =
+ parse_nonresident_attr attr_type highest_vcn
+ allocated_size data_size initialized_size
+ mapping_pairs mft_record in
+
+ parse_attrs rest mft_record
+
+ (* Not matched above, so we don't know how to parse this attribute, but
+ * there is still enough information to skip to the next one.
+ *)
+ | { attr_type : 32 : littleendian;
+ attr_size : 32 : littleendian;
+ _ : (Int32.to_int attr_size - 8) * 8 : bitstring;
+ rest : -1 : bitstring } ->
+
+ if !debug then
+ eprintf "cannot parse MFT attribute entry, attr_type = %lx\n%!"
+ attr_type;
+
+ parse_attrs rest mft_record
+
+ (* Otherwise unparsable & unskippable attribute entry. *)
+ | { _ } ->
+ if !debug then
+ eprintf "corrupt MFT attribute entry\n%!";
+ mft_record
+
+and parse_resident_attr attr_type attr mft_record =
+ match attr_type with
+ | 0x10_l -> (* AT_STANDARD_INFORMATION *)
+ (bitmatch attr with
+ | { creation_time : 64;
+ last_data_change_time : 64;
+ last_mft_change_time : 64;
+ last_access_time : 64
+ (* other stuff follows, just ignore it *) } ->
+
+ let info = {
+ ntfs_creation_time = creation_time;
+ ntfs_last_data_change_time = last_data_change_time;
+ ntfs_last_mft_change_time = last_mft_change_time;
+ ntfs_last_access_time = last_access_time
+ } in
+ { mft_record with ntfs_info = Some info }
+
+ | { _ } ->
+ if !debug then
+ eprintf "cannot parse AT_STANDARD_INFORMATION\n%!";
+ mft_record
+ );
+
+ | 0x30_l -> (* AT_FILE_NAME *)
+ (bitmatch attr with
+ | { _ : 64; (* parent directory ref *)
+ _ : 64; (* creation time *)
+ _ : 64; (* last change time *)
+ _ : 64; (* last MFT change time *)
+ _ : 64; (* last access time *)
+ _ : 64; (* allocated size *)
+ _ : 64; (* data size *)
+ _ : 32;
+ _ : 32;
+ name_len : 8;
+ name_type_flags : 8;
+ name : name_len*16 : string } ->
+
+ let name = ucs2_to_utf8 name name_len in
+ let filename = {
+ ntfs_name = name
+ } in
+ { mft_record with ntfs_filename = Some filename }
+
+ | { _ } ->
+ if !debug then
+ eprintf "cannot parse AT_FILE_NAME\n%!";
+ mft_record
+ );
+
+ | _ -> (* unknown attribute - just ignore *)
+ if !debug then
+ eprintf "unknown resident attribute %lx\n%!" attr_type;
+ mft_record
+
+and parse_nonresident_attr attr_type highest_vcn
+ allocated_size data_size initialized_size
+ mapping_pairs mft_record =
+ match attr_type with
+ | 0x80_l -> (* AT_DATA, ie. the $Data stream *)
+ let lowest_vcn = ~^0 (* see assumption above *) in
+ let runlist = parse_runlist lowest_vcn ~^0 mapping_pairs in
+ if !debug then (
+ eprintf "AT_DATA: runlist is:\n";
+ List.iter (
+ function
+ | ((vcn, deltavcn), Some lcn) ->
+ eprintf "\tVCNs %s..%s -> LCN %s\n"
+ (Int63.to_string vcn) (Int63.to_string (vcn +^ deltavcn -^ ~^1))
+ (Int63.to_string lcn)
+ | ((vcn, deltavcn), None) ->
+ eprintf "\tVCNs %s..%s -> sparse hole\n"
+ (Int63.to_string vcn) (Int63.to_string (vcn +^ deltavcn -^ ~^1))
+ ) runlist
+ );
+
+ let data = {
+ ntfs_data_size = data_size;
+ ntfs_runlist = runlist
+ } in
+ { mft_record with ntfs_data = Some data }
+
+ | _ ->
+ if !debug then
+ eprintf "unknown non-resident attribute %lx\n%!" attr_type;
+ mft_record
+
+(* mapping_pairs is not straightforward and not documented well. See
+ * ntfsprogs libntfs/runlist.c:ntfs_mapping_pairs_decompress
+ *)
+and parse_runlist vcn lcn bits =
+ bitmatch bits with
+ | { 0 : 8 } -> (* end of table *)
+ []
+
+ | { 0 : 4;
+ vcnlen : 4;
+ deltavcn : vcnlen * 8 : littleendian;
+ rest : -1 : bitstring
+ } when vcnlen >= 1 && vcnlen <= 4 ->
+
+ let deltavcn = Int63.of_int64 deltavcn in
+
+ (* This is a sparse file hole. *)
+ ((vcn, deltavcn), None) ::
+ parse_runlist (vcn +^ deltavcn) lcn rest
+
+ | { (* Really these fields are signed, but we'll just limit it to
+ * sensible values in the when clause instead.
+ *)
+ lcnlen : 4;
+ vcnlen : 4;
+ deltavcn : vcnlen * 8 : littleendian;
+ deltalcn : lcnlen * 8 : littleendian;
+ rest : -1 : bitstring
+ } when (vcnlen >= 1 && vcnlen <= 4) && (lcnlen >= 1 || lcnlen <= 4) ->
+
+ let deltavcn = Int63.of_int64 deltavcn in
+ let deltalcn = Int63.of_int64 deltalcn in (* XXX signed *)
+
+ let lcn = lcn +^ deltalcn in
+
+ ((vcn, deltavcn), Some lcn) ::
+ parse_runlist (vcn +^ deltavcn) lcn rest
+
+ | { _ } ->
+ if !debug then (
+ eprintf "unknown field in the runlist\n%!";
+ Bitmatch.hexdump_bitstring Pervasives.stderr bits
+ );
+ []