Changeset 1530

Timestamp:

1/15/2010 4:19:35 AM (3 years ago)

Author:

lowjoel

Message:

Replaced the call to Marshal.AllocHGlobal to use the managed StringBuilder? class for automatic buffer marshalling. Addresses #284: Eraser.Util rewrite

Location:

branches/eraser6/CodeReview/Eraser.Util

Files:

• KernelApi.cs (modified) (1 diff)
• VolumeInfo.cs (modified) (1 diff)

branches/eraser6/CodeReview/Eraser.Util/KernelApi.cs

@@ -1152 +1152 @@
             [return: MarshalAs(UnmanagedType.Bool)]
             public static extern bool GetVolumePathNamesForVolumeName(
-                string lpszVolumeName, IntPtr lpszVolumePathNames, uint cchBufferLength,
+                string lpszVolumeName, StringBuilder lpszVolumePathNames, uint cchBufferLength,
                 out uint lpcchReturnLength);
 

branches/eraser6/CodeReview/Eraser.Util/VolumeInfo.cs

@@ -44 +44 @@
 
             //Get the paths of the said volume
-            IntPtr pathNamesBuffer = IntPtr.Zero;
-            string pathNames = string.Empty;
-            try
-            {
-                uint currentBufferSize = KernelApi.NativeMethods.MaxPath;
+            string pathNames;
+            {
                 uint returnLength = 0;
-                pathNamesBuffer = Marshal.AllocHGlobal((int)(currentBufferSize * sizeof(char)));
+                StringBuilder pathNamesBuffer = new StringBuilder();
+                pathNamesBuffer.EnsureCapacity(KernelApi.NativeMethods.MaxPath);
                 while (!KernelApi.NativeMethods.GetVolumePathNamesForVolumeName(VolumeId,
-                    pathNamesBuffer, currentBufferSize, out returnLength))
-                {
-                    if (Marshal.GetLastWin32Error() == 234/*ERROR_MORE_DATA*/)
-                    {
-                        Marshal.FreeHGlobal(pathNamesBuffer);
-                        currentBufferSize *= 2;
-                        pathNamesBuffer = Marshal.AllocHGlobal((int)(currentBufferSize * sizeof(char)));
-                    }
+                    pathNamesBuffer, (uint)pathNamesBuffer.Capacity, out returnLength))
+                {
+                    if (Marshal.GetLastWin32Error() == 234 /*ERROR_MORE_DATA*/)
+                        pathNamesBuffer.EnsureCapacity((int)returnLength);
                     else
                         throw Marshal.GetExceptionForHR(Marshal.GetHRForLastWin32Error());
                 }
 
-                pathNames = Marshal.PtrToStringUni(pathNamesBuffer, (int)returnLength);
-            }
-            finally
-            {
-                if (pathNamesBuffer != IntPtr.Zero)
-                    Marshal.FreeHGlobal(pathNamesBuffer);
+                if (pathNamesBuffer.Length < returnLength)
+                    pathNamesBuffer.Length = (int)returnLength;
+                pathNames = pathNamesBuffer.ToString().Substring(0, (int)returnLength);
             }