Imported Upstream version 2.0.0.11353upstream/2.0.0.11353

1 files changed, 46 insertions, 0 deletions

diff --git a/src/mscorlib/shared/System/IO/StreamHelpers.CopyValidation.cs b/src/mscorlib/shared/System/IO/StreamHelpers.CopyValidation.cs
new file mode 100644
index 0000000000..45bbd816df
--- /dev/null
+++ b/src/mscorlib/shared/System/IO/StreamHelpers.CopyValidation.cs
@@ -0,0 +1,46 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.IO
+{
+    /// <summary>Provides methods to help in the implementation of Stream-derived types.</summary>
+    internal static partial class StreamHelpers
+    {
+        /// <summary>Validate the arguments to CopyTo, as would Stream.CopyTo.</summary>
+        public static void ValidateCopyToArgs(Stream source, Stream destination, int bufferSize)
+        {
+            if (destination == null)
+            {
+                throw new ArgumentNullException(nameof(destination));
+            }
+
+            if (bufferSize <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(bufferSize), bufferSize, SR.ArgumentOutOfRange_NeedPosNum);
+            }
+
+            bool sourceCanRead = source.CanRead;
+            if (!sourceCanRead && !source.CanWrite)
+            {
+                throw new ObjectDisposedException(null, SR.ObjectDisposed_StreamClosed);
+            }
+
+            bool destinationCanWrite = destination.CanWrite;
+            if (!destinationCanWrite && !destination.CanRead)
+            {
+                throw new ObjectDisposedException(nameof(destination), SR.ObjectDisposed_StreamClosed);
+            }
+
+            if (!sourceCanRead)
+            {
+                throw new NotSupportedException(SR.NotSupported_UnreadableStream);
+            }
+
+            if (!destinationCanWrite)
+            {
+                throw new NotSupportedException(SR.NotSupported_UnwritableStream);
+            }
+        }
+    }
+}