let id = "ntfs"
-(* Private data functions. *)
-let attach_private_data, get_private_data =
- private_data_functions (fun {fs_cb = {fs_cb_uq = u}} -> u)
-
(* Type of the private data, basically all the metadata that we
* read from the NTFS volume.
*)
type ntfs_fs = {
+ ntfs_dev : device; (* Device. *)
ntfs_blocksize : int63; (* Blocksize (cluster size) *)
ntfs_mft_lcn : int63; (* MFT location (bytes) *)
ntfs_mft_size : int63; (* MFT size (bytes) *)
(* VCN start,size => LCN / None if sparse hole *)
(int63 * int63) * int63 option
+(* Private data functions. *)
+let attach_private_data, get_private_data =
+ private_data_functions (fun {fs_cb = {fs_cb_uq = u}} -> u)
+
+(* Probe for an NTFS filesystem on this device. *)
let rec probe dev =
let fs = probe_superblock dev in
fs
_ : 24;
volume_serial_number : 64 : littleendian;
checksum : 32 : littleendian; (* Boot sector checksum. *)
- code : 8 * 426 : bitstring; (* Boot code. *)
+ _ : 8 * 426 : bitstring; (* Boot code. *)
0x55AA : 16 } -> (* End of bootsector magic. *)
let blocksize = bytes_per_sector * sectors_per_cluster in
dev#name blocksize volume_serial_number;
let blocksize = Int63.of_int blocksize in
+ let number_of_sectors = Int63.of_int64 number_of_sectors in
+ let bytes_per_sector = Int63.of_int bytes_per_sector in
(* The blocksize of the filesystem is likely to be quite different
* from that of the underlying device, so create an overlay device
let mft = parse_mft dev mft_lcn mft_size in
- let priv = {
+ let ntfs = {
+ ntfs_dev = fs_dev;
ntfs_blocksize = blocksize;
ntfs_mft_lcn = mft_lcn;
ntfs_mft_size = mft_size;
ntfs_mft_records = mft
} in
- raise Not_found (* XXX *)
+ (* Query free space. I cannot find any metadata in the NTFS
+ * structures which records free space directly, so instead we
+ * need to read the $Bitmap::$Data (bitmap of allocated LCNs).
+ *)
+ let blocks_used, blocks_avail = parse_bitmap_freespace ntfs in
+
+ (* Create a filesystem structure. *)
+ let fs = {
+ fs_cb = callbacks ();
+ fs_dev = fs_dev;
+ fs_blocksize = blocksize;
+ fs_blocks_total = number_of_sectors *^ bytes_per_sector /^ blocksize;
+ fs_is_swap = false;
+ fs_blocks_reserved = ~^0; (* XXX MFT, bitmap are "reserved" *)
+ fs_blocks_avail = blocks_avail;
+ fs_blocks_used = blocks_used;
+ fs_inodes_total = ~^0; (* XXX MFT records are like inodes *)
+ fs_inodes_reserved = ~^0;
+ fs_inodes_avail = ~^0;
+ fs_inodes_used = ~^0;
+ } in
+
+ attach_private_data fs ntfs;
+ fs
| { _ } -> raise Not_found (* Not an NTFS boot sector. *)
| { attr_type : 32 : littleendian;
attr_size : 32 : littleendian;
0 : 8; (* means attribute is resident *)
- pad : 24*8 - 8 - 64 : bitstring; (* actually meaningful *)
+ _ : 24*8 - 8 - 64 : bitstring; (* actually meaningful *)
attr : (Int32.to_int attr_size - 24) * 8 : bitstring;
rest : -1 : bitstring } ->
highest_vcn : 64 : littleendian; (* size in clusters - 1 *)
0x40 : 16 : littleendian; (* mapping pairs offset *)
0 : 8; (* assume not compressed *)
- pad : 40 : bitstring; (* padding *)
+ _ : 40 : bitstring; (* padding *)
allocated_size : 64 : littleendian; (* allocate size on disk *)
data_size : 64 : littleendian; (* byte size of the attribute *)
initialized_size : 64 : littleendian;
*)
| { attr_type : 32 : littleendian;
attr_size : 32 : littleendian;
- pad : (Int32.to_int attr_size - 8) * 8 : bitstring;
+ _ : (Int32.to_int attr_size - 8) * 8 : bitstring;
rest : -1 : bitstring } ->
- if !debug then (
- eprintf "cannot parse MFT attribute entry\n%!";
- Bitmatch.hexdump_bitstring Pervasives.stderr attrs
- );
+ if !debug then
+ eprintf "cannot parse MFT attribute entry, attr_type = %lx\n%!"
+ attr_type;
parse_attrs rest mft_record
done;
outstr
-and offset_is_free _ _ = false
+(* Parse $Bitmap::$Data to get free/used. Returns (used, free) blocks. *)
+and parse_bitmap_freespace ntfs =
+ (* Can throw Not_found - allow that to escape because we don't
+ * expect an NTFS filesystem without this magic file.
+ *)
+ let file = find_system_file ntfs "$Bitmap" in
+
+ (* Count used/free bits. *)
+ let used = ref ~^0 and free = ref ~^0 in
+ iter_blocks ntfs file (
+ fun lcn vcn data ->
+ for i = 0 to String.length data - 1 do
+ let c = Char.code data.[i] in
+ if c = 0 then (* common cases *)
+ free := !free +^ ~^8
+ else if c = 0xff then
+ used := !used +^ ~^8
+ else ( (* uncommon case: count the bits *)
+ let m = ref 0x80 in
+ while !m > 0 do
+ if c land !m <> 0 then
+ used := !used +^ ~^1
+ else
+ free := !free +^ ~^1;
+ m := !m lsr 1
+ done
+ )
+ done
+ );
+ (!used, !free)
+
+and find_system_file { ntfs_mft_records = mft_records } fname =
+ let rec loop =
+ function
+ | [] -> raise Not_found
+ | ({ ntfs_filename = Some { ntfs_name = name } } as file) :: _
+ when name = fname ->
+ file
+ | _ :: rest -> loop rest
+ in
+ loop mft_records
+
+and iter_blocks { ntfs_blocksize = blocksize; ntfs_dev = dev }
+ { ntfs_data = data } f =
+ match data with
+ | None -> () (* No $Data attribute. *)
+ | Some { ntfs_data_size = data_size; ntfs_runlist = runlist } ->
+ let rec loop data_size = function
+ | [] -> ()
+
+ (* Run of vcnsize clusters. *)
+ | ((vcnstart, vcnsize), Some lcn) :: rest ->
+ let data_size = ref data_size in
+ let lcn = ref lcn in
+ let vcn = ref vcnstart in
+ let vcnsize = ref vcnsize in
+ while !vcnsize > ~^0 && !data_size > ~^0 do
+ let size = min blocksize !data_size in
+ let data = dev#read (!lcn *^ blocksize) size in
+ f (Some !lcn) !vcn data;
+ lcn := !lcn +^ ~^1;
+ vcn := !vcn +^ ~^1;
+ vcnsize := !vcnsize -^ ~^1;
+ data_size := !data_size -^ size
+ done;
+ loop !data_size rest
+
+ (* Sparse hole. *)
+ | ((vcnstart, vcnsize), None) :: rest ->
+ let data_size = ref data_size in
+ let vcn = ref vcnstart in
+ let vcnsize = ref vcnsize in
+ while !vcnsize > ~^0 && !data_size > ~^0 do
+ let size = min blocksize !data_size in
+ let data = String.make (Int63.to_int size) '\000' in
+ f None !vcn data;
+ vcn := !vcn +^ ~^1;
+ vcnsize := !vcnsize -^ ~^1;
+ data_size := !data_size -^ size
+ done;
+ loop !data_size rest
+ in
+ loop data_size runlist
+
+(* This is a bit limited at the moment because it can only read from
+ * a contiguous part of the file. System files are usually contiguous
+ * so this is OK for us.
+ *)
+and read_file { ntfs_blocksize = blocksize; ntfs_dev = dev }
+ { ntfs_data = data } offset size =
+ match data with
+ | None -> raise Not_found (* No $Data attribute. *)
+ | Some { ntfs_data_size = data_size; ntfs_runlist = runlist } ->
+ if offset < ~^0 || size < ~^0 || offset +^ size >= data_size then
+ invalid_arg "ntfs: read_file: tried to read outside file";
+
+ (* Get the first and last VCNs containing the data. *)
+ let vcn = offset /^ blocksize in
+ let vcnoffset = offset %^ blocksize in
+ let vcnend = (offset +^ size -^ ~^1) /^ blocksize in
+
+ (* Find the run containing this VCN. *)
+ let rec find = function
+ | [] -> raise Not_found
+ | ((vcnstart, vcnsize), lcn) :: _
+ when vcnstart <= vcn && vcn < vcnstart +^ vcnsize &&
+ vcnstart <= vcnend && vcnend < vcnstart +^ vcnsize ->
+ lcn
+ | _ :: rest -> find rest
+ in
+ let lcn = find runlist in
+
+ (* Read the LCNs. *)
+ let data =
+ match lcn with
+ | Some lcn -> dev#read (lcn *^ blocksize +^ vcnoffset) size
+ | None -> String.make (Int63.to_int size) '\000' (* sparse hole *) in
+ data
+
+(* This is easy: just look at the bitmap. *)
+and offset_is_free fs offset =
+ try
+ let ntfs = get_private_data fs in
+ let blocksize = ntfs.ntfs_blocksize in
+
+ (* Get the $Bitmap file. *)
+ let file = find_system_file ntfs "$Bitmap" in
+
+ let lcn = offset /^ blocksize in
+
+ (* Read the byte in the bitmap corresponding to this LCN. *)
+ let byteoffset = lcn >^> 3 and bitoffset = lcn &^ ~^7 in
+ let byte = read_file ntfs file byteoffset ~^1 in
+ let byte = Char.code byte.[0] in
+ let bit = Int63.of_int byte >^> (0x80 lsr Int63.to_int bitoffset) in
+
+ bit <> ~^0
+ with
+ Not_found -> false (* play it safe *)
and callbacks =
let i = ref 0 in
git.annexia.org / virt-df.git / blobdiff