Merge commit '36bca61764984ff5395653cf8377ec5daa71b709' as 'libs/protobuf'

libs/protobuf/csharp/src/Google.Protobuf/ByteStringAsync.cs

@@ -0,0 +1,62 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Google.Protobuf
+{
+    /// <summary>
+    /// SecuritySafeCritical attribute can not be placed on types with async methods.
+    /// This class has ByteString's async methods so it can be marked with SecuritySafeCritical.
+    /// </summary>
+    internal static class ByteStringAsync
+    {
+        internal static async Task<ByteString> FromStreamAsyncCore(Stream stream, CancellationToken cancellationToken)
+        {
+            int capacity = stream.CanSeek ? checked((int)(stream.Length - stream.Position)) : 0;
+            var memoryStream = new MemoryStream(capacity);
+            // We have to specify the buffer size here, as there's no overload accepting the cancellation token
+            // alone. But it's documented to use 81920 by default if not specified.
+            await stream.CopyToAsync(memoryStream, 81920, cancellationToken);
+#if NETSTANDARD1_1
+            byte[] bytes = memoryStream.ToArray();
+#else
+            // Avoid an extra copy if we can.
+            byte[] bytes = memoryStream.Length == memoryStream.Capacity ? memoryStream.GetBuffer() : memoryStream.ToArray();
+#endif
+            return ByteString.AttachBytes(bytes);
+        }
+    }
+}