Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.ServiceModel/System/ServiceModel/Channels/DetectEofStream.cs

@@ -0,0 +1,70 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+namespace System.ServiceModel.Channels
+{
+    using System.IO;
+
+    abstract class DetectEofStream : DelegatingStream
+    {
+        bool isAtEof;
+
+        protected DetectEofStream(Stream stream)
+            : base(stream)
+        {
+            this.isAtEof = false;
+        }
+
+        protected bool IsAtEof
+        {
+            get { return this.isAtEof; }
+        }
+
+        public override int EndRead(IAsyncResult result)
+        {
+            int returnValue = base.EndRead(result);
+            if (returnValue == 0)
+            {
+                ReceivedEof();
+            }
+            return returnValue;
+        }
+
+        public override int ReadByte()
+        {
+            int returnValue = base.ReadByte();
+            if (returnValue == -1)
+            {
+                ReceivedEof();
+            }
+            return returnValue;
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            if (isAtEof)
+            {
+                return 0;
+            }
+            int returnValue = base.Read(buffer, offset, count);
+            if (returnValue == 0)
+            {
+                ReceivedEof();
+            }
+            return returnValue;
+        }
+
+        void ReceivedEof()
+        {
+            if (!isAtEof)
+            {
+                this.isAtEof = true;
+                this.OnReceivedEof();
+            }
+        }
+
+        protected virtual void OnReceivedEof()
+        {
+        }
+    }
+}