From 91ae3d067f18c648a363f5ffd33430907c387ab1 Mon Sep 17 00:00:00 2001
From: Ryan Blue <blue@apache.org>
Date: Sun, 21 Feb 2016 18:16:07 -0800
Subject: [PATCH] AVRO-1799: Fix GenericRecord#toString ByteBuffer bug.

Reading the ByteBuffer to return a string representaton modified the
buffer's position. The solution is to duplicate the buffer before
reading its content.
---
 .../src/main/java/org/apache/avro/generic/GenericData.java    | 2 +-
 .../test/java/org/apache/avro/generic/TestGenericData.java    | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java b/lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java
index 7c70631df52..2b01de408c0 100644
--- a/lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java
+++ b/lang/java/avro/src/main/java/org/apache/avro/generic/GenericData.java
@@ -547,7 +547,7 @@ protected void toString(Object datum, StringBuilder buffer) {
       buffer.append("\"");
     } else if (isBytes(datum)) {
       buffer.append("{\"bytes\": \"");
-      ByteBuffer bytes = (ByteBuffer)datum;
+      ByteBuffer bytes = ((ByteBuffer) datum).duplicate();
       writeEscapedString(StandardCharsets.ISO_8859_1.decode(bytes), buffer);
       buffer.append("\"}");
     } else if (((datum instanceof Float) &&       // quote Nan & Infinity
diff --git a/lang/java/avro/src/test/java/org/apache/avro/generic/TestGenericData.java b/lang/java/avro/src/test/java/org/apache/avro/generic/TestGenericData.java
index 68c33b61632..b8b59e244c7 100644
--- a/lang/java/avro/src/test/java/org/apache/avro/generic/TestGenericData.java
+++ b/lang/java/avro/src/test/java/org/apache/avro/generic/TestGenericData.java
@@ -321,7 +321,9 @@ public void testToStringIsJson() throws JsonParseException, IOException {
 
   @Test public void testToStringEscapesControlCharsInBytes() throws Exception {
     GenericData data = GenericData.get();
-    assertEquals("{\"bytes\": \"a\\nb\"}", data.toString(ByteBuffer.wrap(new byte[] {'a', '\n', 'b'})));
+    ByteBuffer bytes = ByteBuffer.wrap(new byte[] {'a', '\n', 'b'});
+    assertEquals("{\"bytes\": \"a\\nb\"}", data.toString(bytes));
+    assertEquals("{\"bytes\": \"a\\nb\"}", data.toString(bytes));
   }
 
   @Test public void testToStringFixed() throws Exception {