+(* For each entry which is a symlink, read the destination of the
+ * symlink. This is non-trivial because on Windows we cannot use
+ * readlink but need to instead parse the reparse data from NTFS.
+ *)
+and readlink_wrapper g dir names stats =
+ (* Is the directory on an NTFS filesystem? *)
+ let dev = get_mounted_device g dir in
+ if g#vfs_type dev <> "ntfs" then (
+ (* Not NTFS, use the fast g#readlinklist method. *)
+ let rec readlinklist_wrapper g dir = function
+ | [] -> []
+ | names ->
+ let names', names = List.take 1000 names, List.drop 1000 names in
+ let xs = g#readlinklist dir (Array.of_list names') in
+ let xs = Array.to_list xs in
+ xs @ readlinklist_wrapper g dir names
+ in
+ readlinklist_wrapper g dir names
+ )
+ else (
+ (* NTFS: look up each symlink individually. *)
+ List.map (
+ fun (name, stat) ->
+ if not (is_symlink stat.G.mode) then ""
+ else
+ let path = if dir = "/" then dir ^ name else dir ^ "/" ^ name in
+ try
+ let _, display = get_ntfs_reparse_data g path in
+ display
+ with exn ->
+ debug "get_ntfs_reparse_data: %s: failed: %s"
+ path (Printexc.to_string exn);
+ "?"
+ ) (List.combine names stats)
+ )
+
+(* See:
+ * https://bugzilla.redhat.com/show_bug.cgi?id=663407
+ * http://git.annexia.org/?p=libguestfs.git;a=commit;h=3a3836b933b80c4f9f2c767fda4f8b459f998db2
+ * http://www.tuxera.com/community/ntfs-3g-advanced/junction-points-and-symbolic-links/
+ * http://www.tuxera.com/community/ntfs-3g-advanced/extended-attributes/
+ * http://www.codeproject.com/KB/winsdk/junctionpoints.aspx
+ *)
+and get_ntfs_reparse_data g path =
+ let data = g#lgetxattr path "system.ntfs_reparse_data" in
+ let link, display =
+ bitmatch Bitstring.bitstring_of_string data with
+ (* IO_REPARSE_TAG_MOUNT_POINT *)
+ | { 0xa0000003_l : 32 : littleendian;
+ _ : 16 : littleendian; (* data length - ignore it *)
+ _ : 16 : littleendian; (* reserved *)
+ link_offset : 16 : littleendian;
+ link_len : 16 : littleendian;
+ display_offset : 16 : littleendian;
+ display_len : 16 : littleendian;
+ link : link_len * 8 :
+ string, offset (8 * (link_offset + 0x10));
+ display : display_len * 8 :
+ string, offset (8 * (display_offset + 0x10)) } ->
+ (* These strings should always be valid UTF16LE, but the caller
+ * is prepared to catch any exception if this fails.
+ *)
+ let link = windows_string_to_utf8 link in
+ let display = windows_string_to_utf8 display in
+ link, display
+ | { 0xa0000003_l : 32 : littleendian } ->
+ invalid_arg (
+ sprintf "%s: could not parse IO_REPARSE_TAG_MOUNT_POINT data" path
+ )
+
+ (* IO_REPARSE_TAG_SYMLINK *)
+ | { 0xa000000c_l : 32 : littleendian;
+ _ : 16 : littleendian; (* data length - ignore it *)
+ _ : 16 : littleendian; (* reserved *)
+ link_offset : 16 : littleendian;
+ link_len : 16 : littleendian;
+ display_offset : 16 : littleendian;
+ display_len : 16 : littleendian;
+ link : link_len * 8 :
+ string, offset (8 * (link_offset + 0x14));
+ display : display_len * 8 :
+ string, offset (8 * (display_offset + 0x14)) } ->
+ let link = windows_string_to_utf8 link in
+ let display = windows_string_to_utf8 display in
+ link, display
+ | { 0xa000000c_l : 32 : littleendian } ->
+ invalid_arg (
+ sprintf "%s: could not parse IO_REPARSE_TAG_SYMLINK data" path
+ )
+
+ | { i : 32 : littleendian } ->
+ invalid_arg (
+ sprintf "%s: reparse data of type 0x%lx is not supported" path i
+ )
+ | { _ } ->
+ invalid_arg (sprintf "%s: reparse data is too short" path) in
+
+ link, display
+
+(* Given a path which is located somewhere on a mountpoint, return the
+ * device name. This works by using g#mountpoints and then looking for
+ * the mount path with the longest match.
+ *)
+and get_mounted_device g path =
+ let mps = g#mountpoints () in
+ let mps = List.map (
+ fun (dev, mp) ->
+ if String.starts_with path mp then dev, String.length mp else dev, 0
+ ) mps in
+ let cmp (_,n1) (_,n2) = compare n2 n1 in
+ let mps = List.sort ~cmp mps in
+ match mps with
+ | [] ->
+ invalid_arg (sprintf "%s: not mounted" path)
+ | (_,0) :: _ ->
+ invalid_arg (sprintf "%s: not found on any filesystem" path)
+ | (dev,_) :: _ -> dev