1 files changed, 78 insertions, 0 deletions
diff --git a/csharp/src/ProtocolBuffers/LimitedInputStream.cs b/csharp/src/ProtocolBuffers/LimitedInputStream.cs
new file mode 100644
index 00000000..cfbf47de
--- /dev/null
+++ b/csharp/src/ProtocolBuffers/LimitedInputStream.cs
@@ -0,0 +1,78 @@
+using System;
+using System.IO;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// Stream implementation which proxies another stream, only allowing a certain amount
+    /// of data to be read. Note that this is only used to read delimited streams, so it
+    /// doesn't attempt to implement everything.
+    /// </summary>
+    internal sealed class LimitedInputStream : Stream
+    {
+        private readonly Stream proxied;
+        private int bytesLeft;
+
+        internal LimitedInputStream(Stream proxied, int size)
+        {
+            this.proxied = proxied;
+            bytesLeft = size;
+        }
+
+        public override bool CanRead
+        {
+            get { return true; }
+        }
+
+        public override bool CanSeek
+        {
+            get { return false; }
+        }
+
+        public override bool CanWrite
+        {
+            get { return false; }
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override long Length
+        {
+            get { throw new NotSupportedException(); }
+        }
+
+        public override long Position
+        {
+            get { throw new NotSupportedException(); }
+            set { throw new NotSupportedException(); }
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            if (bytesLeft > 0)
+            {
+                int bytesRead = proxied.Read(buffer, offset, Math.Min(bytesLeft, count));
+                bytesLeft -= bytesRead;
+                return bytesRead;
+            }
+            return 0;
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}