Ensure leaveOpen is true when writing to a buffer

Note that the compatibility tests have had to cahnge as well, to
cope with internal changes. (The test project has access to
internals in the main project.)

Fixes #3209.

csharp/compatibility_tests/v3.0.0/src/Google.Protobuf.Test/CodedInputStreamTest.cs

@@ -403,7 +403,7 @@ namespace Google.Protobuf
                 output.Flush();
 
                 ms.Position = 0;
-                CodedInputStream input = new CodedInputStream(ms, new byte[ms.Length / 2], 0, 0);
+                CodedInputStream input = new CodedInputStream(ms, new byte[ms.Length / 2], 0, 0, false);
 
                 uint tag = input.ReadTag();
                 Assert.AreEqual(1, WireFormat.GetTagFieldNumber(tag));

csharp/compatibility_tests/v3.0.0/src/Google.Protobuf.Test/CodedOutputStreamTest.cs

@@ -334,7 +334,7 @@ namespace Google.Protobuf
             }
             // Now test Input stream:
             {
-                CodedInputStream cin = new CodedInputStream(new MemoryStream(bytes), new byte[50], 0, 0);
+                CodedInputStream cin = new CodedInputStream(new MemoryStream(bytes), new byte[50], 0, 0, false);
                 Assert.AreEqual(0, cin.Position);
                 // Field 1:
                 uint tag = cin.ReadTag();

csharp/src/Google.Protobuf.Test/CodedInputStreamTest.cs

@@ -403,7 +403,7 @@ namespace Google.Protobuf
                 output.Flush();
 
                 ms.Position = 0;
-                CodedInputStream input = new CodedInputStream(ms, new byte[ms.Length / 2], 0, 0);
+                CodedInputStream input = new CodedInputStream(ms, new byte[ms.Length / 2], 0, 0, false);
 
                 uint tag = input.ReadTag();
                 Assert.AreEqual(1, WireFormat.GetTagFieldNumber(tag));
@@ -594,5 +594,12 @@ namespace Google.Protobuf
             }
             Assert.IsTrue(memoryStream.CanRead); // We left the stream open
         }
+
+        [Test]
+        public void Dispose_FromByteArray()
+        {
+            var stream = new CodedInputStream(new byte[10]);
+            stream.Dispose();
+        }
     }
 }
\ No newline at end of file

csharp/src/Google.Protobuf.Test/CodedOutputStreamTest.cs

@@ -334,7 +334,7 @@ namespace Google.Protobuf
             }
             // Now test Input stream:
             {
-                CodedInputStream cin = new CodedInputStream(new MemoryStream(bytes), new byte[50], 0, 0);
+                CodedInputStream cin = new CodedInputStream(new MemoryStream(bytes), new byte[50], 0, 0, false);
                 Assert.AreEqual(0, cin.Position);
                 // Field 1:
                 uint tag = cin.ReadTag();
@@ -415,5 +415,12 @@ namespace Google.Protobuf
             Assert.AreEqual(1, memoryStream.Position); // Flushed data from CodedOutputStream to MemoryStream
             Assert.IsTrue(memoryStream.CanWrite); // We left the stream open
         }
+
+        [Test]
+        public void Dispose_FromByteArray()
+        {
+            var stream = new CodedOutputStream(new byte[10]);
+            stream.Dispose();
+        }
     }
 }
\ No newline at end of file

csharp/src/Google.Protobuf/CodedInputStream.cs

@@ -121,7 +121,7 @@ namespace Google.Protobuf
         /// <summary>
         /// Creates a new CodedInputStream reading data from the given byte array.
         /// </summary>
-        public CodedInputStream(byte[] buffer) : this(null, ProtoPreconditions.CheckNotNull(buffer, "buffer"), 0, buffer.Length)
+        public CodedInputStream(byte[] buffer) : this(null, ProtoPreconditions.CheckNotNull(buffer, "buffer"), 0, buffer.Length, true)
         {            
         }
 
@@ -129,7 +129,7 @@ namespace Google.Protobuf
         /// Creates a new <see cref="CodedInputStream"/> that reads from the given byte array slice.
         /// </summary>
         public CodedInputStream(byte[] buffer, int offset, int length)
-            : this(null, ProtoPreconditions.CheckNotNull(buffer, "buffer"), offset, offset + length)
+            : this(null, ProtoPreconditions.CheckNotNull(buffer, "buffer"), offset, offset + length, true)
         {            
             if (offset < 0 || offset > buffer.Length)
             {
@@ -158,16 +158,15 @@ namespace Google.Protobuf
         /// <c cref="CodedInputStream"/> is disposed; <c>false</c> to dispose of the given stream when the
         /// returned object is disposed.</param>
         public CodedInputStream(Stream input, bool leaveOpen)
-            : this(ProtoPreconditions.CheckNotNull(input, "input"), new byte[BufferSize], 0, 0)
+            : this(ProtoPreconditions.CheckNotNull(input, "input"), new byte[BufferSize], 0, 0, leaveOpen)
         {
-            this.leaveOpen = leaveOpen;
         }
         
         /// <summary>
         /// Creates a new CodedInputStream reading data from the given
         /// stream and buffer, using the default limits.
         /// </summary>
-        internal CodedInputStream(Stream input, byte[] buffer, int bufferPos, int bufferSize)
+        internal CodedInputStream(Stream input, byte[] buffer, int bufferPos, int bufferSize, bool leaveOpen)
         {
             this.input = input;
             this.buffer = buffer;
@@ -175,6 +174,7 @@ namespace Google.Protobuf
             this.bufferSize = bufferSize;
             this.sizeLimit = DefaultSizeLimit;
             this.recursionLimit = DefaultRecursionLimit;
+            this.leaveOpen = leaveOpen;
         }
 
         /// <summary>
@@ -185,8 +185,8 @@ namespace Google.Protobuf
         /// This chains to the version with the default limits instead of vice versa to avoid
         /// having to check that the default values are valid every time.
         /// </remarks>
-        internal CodedInputStream(Stream input, byte[] buffer, int bufferPos, int bufferSize, int sizeLimit, int recursionLimit)
-            : this(input, buffer, bufferPos, bufferSize)
+        internal CodedInputStream(Stream input, byte[] buffer, int bufferPos, int bufferSize, int sizeLimit, int recursionLimit, bool leaveOpen)
+            : this(input, buffer, bufferPos, bufferSize, leaveOpen)
         {
             if (sizeLimit <= 0)
             {
@@ -217,7 +217,8 @@ namespace Google.Protobuf
         /// and recursion limits.</returns>
         public static CodedInputStream CreateWithLimits(Stream input, int sizeLimit, int recursionLimit)
         {
-            return new CodedInputStream(input, new byte[BufferSize], 0, 0, sizeLimit, recursionLimit);
+            // Note: we may want an overload accepting leaveOpen
+            return new CodedInputStream(input, new byte[BufferSize], 0, 0, sizeLimit, recursionLimit, false);
         }
 
         /// <summary>