Update release notes wrt, made small changes to fix for FasterXML#2602

Author: cowtowncoder

release-notes/CREDITS-2.x

@@ -1027,3 +1027,8 @@ Tobias Preuss (johnjohndoe@github)
   * Reported #2599: NoClassDefFoundError at DeserializationContext.<init> on Android 4.1.2
     and Jackson 2.10.0
   (2.10.3)
+
+Eduard Tudenhöfner (nastra@github)
+  * Reported #2602, contributed fix for: ByteBufferSerializer produces unexpected results with
+    a duplicated ByteBuffer and a position > 0
+  (2.10.3)

release-notes/VERSION-2.x

@@ -6,8 +6,12 @@ Project: jackson-databind
 
 2.10.3 (not yet released)
 
-#2599: NoClassDefFoundError at DeserializationContext.<init> on Android 4.1.2 and Jackson 2.10.0
+#2599: NoClassDefFoundError at DeserializationContext.<init> on Android 4.1.2
+  and Jackson 2.10.0
  (reported by Tobias P)
+#2602: ByteBufferSerializer produces unexpected results with a duplicated ByteBuffer
+  and a position > 0
+ (reported by Eduard T)
 
 2.10.2 (05-Jan-2020)
 

src/main/java/com/fasterxml/jackson/databind/ser/std/ByteBufferSerializer.java

@@ -19,16 +19,9 @@ public class ByteBufferSerializer extends StdScalarSerializer<ByteBuffer>
     public void serialize(ByteBuffer bbuf, JsonGenerator gen, SerializerProvider provider) throws IOException
     {
         // first, simple case when wrapping an array...
-        if (bbuf.hasArray())
-        {
-            if (bbuf.position() > 0)
-            {
-                gen.writeBinary(bbuf.array(), bbuf.position(), bbuf.limit() - bbuf.position());
-            }
-            else
-            {
-                gen.writeBinary(bbuf.array(), bbuf.arrayOffset(), bbuf.limit());
-            }
+        if (bbuf.hasArray()) {
+            final int pos = bbuf.position();
+            gen.writeBinary(bbuf.array(), bbuf.arrayOffset() + pos, bbuf.limit() - pos);
             return;
         }
         // the other case is more complicated however. Best to handle with InputStream wrapper.

src/test/java/com/fasterxml/jackson/databind/ser/jdk/JDKTypeSerializationTest.java

@@ -150,26 +150,36 @@ public void testByteBuffer() throws IOException
     public void testSlicedByteBuffer() throws IOException
     {
         final byte[] INPUT_BYTES = new byte[] { 1, 2, 3, 4, 5 };
-        String exp = MAPPER.writeValueAsString(new byte[] { 3, 4, 5 });
         ByteBuffer bbuf = ByteBuffer.wrap(INPUT_BYTES);
 
         bbuf.position(2);
         ByteBuffer slicedBuf = bbuf.slice();
 
-        assertEquals(exp, MAPPER.writeValueAsString(slicedBuf));
+        assertEquals(MAPPER.writeValueAsString(new byte[] { 3, 4, 5 }),
+                MAPPER.writeValueAsString(slicedBuf));
+
+        // but how about offset within?
+        slicedBuf.position(1);
+        assertEquals(MAPPER.writeValueAsString(new byte[] { 4, 5 }),
+                MAPPER.writeValueAsString(slicedBuf));
     }
 
+    // [databind#2602]: Need to consider position()
     public void testDuplicatedByteBufferWithCustomPosition() throws IOException
     {
         final byte[] INPUT_BYTES = new byte[] { 1, 2, 3, 4, 5 };
-        String exp = MAPPER.writeValueAsString(new byte[] { 3, 4, 5 });
 
+        String exp = MAPPER.writeValueAsString(new byte[] { 3, 4, 5 });
         ByteBuffer bbuf = ByteBuffer.wrap(INPUT_BYTES);
-
         bbuf.position(2);
         ByteBuffer duplicated = bbuf.duplicate();
-
         assertEquals(exp, MAPPER.writeValueAsString(duplicated));
+
+        // also check differently constructed bytebuffer (noting that
+        // offset given is the _position_ to use, NOT array offset
+        exp = MAPPER.writeValueAsString(new byte[] { 2, 3, 4 });
+        bbuf = ByteBuffer.wrap(INPUT_BYTES, 1, 3);
+        assertEquals(exp, MAPPER.writeValueAsString(bbuf.duplicate()));
     }
 
     // Verify that efficient UUID codec won't mess things up: