Changeset 1873 for trunk/eraser6/Eraser.Util/NtfsApi.cs

Timestamp:

3/1/2010 9:52:43 AM (2 years ago)

Author:

lowjoel

Message:

Don't double error-handle in VolumeInfo?: The OpenHandle? and Open functions check for a valid file handle each, which is redundant. Since OpenHandle? is supposed to be called internally from the assembly, do no error checking and assume the calling function knows what it is doing. This can be seen in NtfsApi? where an exception has been replaced with an if-statement.

File:

• trunk/eraser6/Eraser.Util/NtfsApi.cs (modified) (3 diffs)

trunk/eraser6/Eraser.Util/NtfsApi.cs

@@ -38 +38 @@
         public static long GetMftValidSize(VolumeInfo volume)
         {
-            return GetNtfsVolumeData(volume).MftValidDataLength;
+            NativeMethods.NTFS_VOLUME_DATA_BUFFER? volumeData = GetNtfsVolumeData(volume);
+            if (volumeData == null)
+                throw Win32ErrorCode.GetExceptionForWin32Error(Marshal.GetLastWin32Error());
+
+            return volumeData.Value.MftValidDataLength;
         }
 
@@ -48 +52 @@
         public static long GetMftRecordSegmentSize(VolumeInfo volume)
         {
-            try
-            {
-                return GetNtfsVolumeData(volume).BytesPerFileRecordSegment;
-            }
-            catch (UnauthorizedAccessException)
-            {
+            NativeMethods.NTFS_VOLUME_DATA_BUFFER? volumeData = GetNtfsVolumeData(volume);
+            if (volumeData == null)
                 return Math.Min(volume.ClusterSize, 1024);
-            }
+
+            return volumeData.Value.BytesPerFileRecordSegment;
         }
 
@@ -64 +65 @@
         /// <param name="volume">The volume to query.</param>
         /// <returns>The NTFS_VOLUME_DATA_BUFFER structure representing the data
-        /// file systme structures for the volume.</returns>
-        /// <exception cref="UnauthorizedAccessException">Thrown when the current user
-        /// does not have the permissions required to obtain the volume information.</exception>
-        internal static NativeMethods.NTFS_VOLUME_DATA_BUFFER GetNtfsVolumeData(VolumeInfo volume)
+        /// file system structures for the volume, or null if the data could not be
+        /// retrieved.</returns>
+        internal static NativeMethods.NTFS_VOLUME_DATA_BUFFER? GetNtfsVolumeData(VolumeInfo volume)
         {
             using (SafeFileHandle volumeHandle = volume.OpenHandle(
                 FileAccess.Read, FileShare.ReadWrite, FileOptions.None))
             {
+                if (volumeHandle.IsInvalid)
+                    return null;
+
                 uint resultSize = 0;
                 NativeMethods.NTFS_VOLUME_DATA_BUFFER volumeData =