initial checkin of yaulw (locally)

@integrate/Trinet.Core.IO.Ntfs/StreamName.cs

@@ -0,0 +1,134 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Trinet.Core.IO.Ntfs
+{
+	internal sealed class StreamName : IDisposable
+	{
+		#region Private Data
+
+		private static readonly SafeHGlobalHandle _invalidBlock = SafeHGlobalHandle.Invalid();
+		private SafeHGlobalHandle _memoryBlock = _invalidBlock;
+
+		#endregion
+
+		#region Constructor
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="StreamName"/> class.
+		/// </summary>
+		public StreamName()
+		{
+		}
+
+		#endregion
+
+		#region Properties
+
+		/// <summary>
+		/// Returns the handle to the block of memory.
+		/// </summary>
+		/// <value>
+		/// The <see cref="SafeHGlobalHandle"/> representing the block of memory.
+		/// </value>
+		public SafeHGlobalHandle MemoryBlock
+		{
+			get { return _memoryBlock; }
+		}
+
+		#endregion
+
+		#region Methods
+
+		/// <summary>
+		/// Performs application-defined tasks associated with freeing, 
+		/// releasing, or resetting unmanaged resources.
+		/// </summary>
+		public void Dispose()
+		{
+			if (!_memoryBlock.IsInvalid)
+			{
+				_memoryBlock.Dispose();
+				_memoryBlock = _invalidBlock;
+			}
+		}
+
+		/// <summary>
+		/// Ensures that there is sufficient memory allocated.
+		/// </summary>
+		/// <param name="capacity">
+		/// The required capacity of the block, in bytes.
+		/// </param>
+		/// <exception cref="OutOfMemoryException">
+		/// There is insufficient memory to satisfy the request.
+		/// </exception>
+		public void EnsureCapacity(int capacity)
+		{
+			int currentSize = _memoryBlock.IsInvalid ? 0 : _memoryBlock.Size;
+			if (capacity > currentSize)
+			{
+				if (0 != currentSize) currentSize <<= 1;
+				if (capacity > currentSize) currentSize = capacity;
+
+				if (!_memoryBlock.IsInvalid) _memoryBlock.Dispose();
+				_memoryBlock = SafeHGlobalHandle.Allocate(currentSize);
+			}
+		}
+
+		/// <summary>
+		/// Reads the Unicode string from the memory block.
+		/// </summary>
+		/// <param name="length">
+		/// The length of the string to read, in characters.
+		/// </param>
+		/// <returns>
+		/// The string read from the memory block.
+		/// </returns>
+		public string ReadString(int length)
+		{
+			if (0 >= length || _memoryBlock.IsInvalid) return null;
+			if (length > _memoryBlock.Size) length = _memoryBlock.Size;
+			return Marshal.PtrToStringUni(_memoryBlock.DangerousGetHandle(), length);
+		}
+
+		/// <summary>
+		/// Reads the string, and extracts the stream name.
+		/// </summary>
+		/// <param name="length">
+		/// The length of the string to read, in characters.
+		/// </param>
+		/// <returns>
+		/// The stream name.
+		/// </returns>
+		public string ReadStreamName(int length)
+		{
+			string name = this.ReadString(length);
+			if (!string.IsNullOrEmpty(name))
+			{
+				// Name is of the format ":NAME:$DATA\0"
+				int separatorIndex = name.IndexOf(SafeNativeMethods.StreamSeparator, 1);
+				if (-1 != separatorIndex)
+				{
+					name = name.Substring(1, separatorIndex - 1);
+				}
+				else
+				{
+					// Should never happen!
+					separatorIndex = name.IndexOf('\0');
+					if (1 < separatorIndex)
+					{
+						name = name.Substring(1, separatorIndex - 1);
+					}
+					else
+					{
+						name = null;
+					}
+				}
+			}
+
+			return name;
+		}
+
+		#endregion
+	}
+}