fix bug in ArrayInputStream.read()

runtime/src/main/java/org/capnproto/ArrayInputStream.java

@@ -35,7 +35,7 @@ public final class ArrayInputStream implements BufferedInputStream {
 
     public final int read(ByteBuffer dst) throws IOException {
         int available = this.buf.remaining();
-        int size = dst.remaining();
+        int size = java.lang.Math.min(dst.remaining(), available);
 
         ByteBuffer slice = this.buf.slice();
         slice.limit(size);

runtime/src/test/scala/org/capnproto/ArrayInputStreamSuite.scala

@@ -0,0 +1,34 @@
+// Copyright (c) 2018 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package org.capnproto
+
+import java.nio.ByteBuffer
+import org.scalatest.FunSuite
+import org.scalatest.Matchers._
+
+class ArrayInputStreamSuite extends FunSuite {
+  test("EmptyArray") {
+    val stream = new ArrayInputStream(ByteBuffer.allocate(0))
+    val dst = ByteBuffer.allocate(10)
+    stream.read(dst) should equal (0)
+  }
+}