From 28e5b8a7ea6dc157e890e39b953c980898b5455e Mon Sep 17 00:00:00 2001 From: "rjones@intel.home.annexia.org" Date: Tue, 13 May 2008 13:50:27 +0100 Subject: [PATCH] Implement offset_is_free for NTFS. --- lib/diskimage_ntfs.ml | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 55 insertions(+), 1 deletion(-) diff --git a/lib/diskimage_ntfs.ml b/lib/diskimage_ntfs.ml index e4e9036..d0f2f49 100644 --- a/lib/diskimage_ntfs.ml +++ b/lib/diskimage_ntfs.ml @@ -540,7 +540,61 @@ and iter_blocks { ntfs_blocksize = blocksize; ntfs_dev = dev } in loop data_size runlist -and offset_is_free _ _ = false +(* 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 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 = byte >^> (~^0x80 >^> (Int63.to_int bitoffset)) in + + bit <> ~^0 + with + Not_found -> false (* play it safe *) and callbacks = let i = ref 0 in -- 1.8.3.1