From 28e5b8a7ea6dc157e890e39b953c980898b5455e Mon Sep 17 00:00:00 2001
From: "rjones@intel.home.annexia.org" <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