[#1925] Only expose sub-region of ByteBuf on nioBuffer(...)

buffer/src/main/java/io/netty/buffer/PooledDirectByteBuf.java

@@ -330,7 +330,7 @@ final class PooledDirectByteBuf extends PooledByteBuf<ByteBuffer> {
     public ByteBuffer nioBuffer(int index, int length) {
         checkIndex(index, length);
         index = idx(index);
-        return (ByteBuffer) memory.duplicate().position(index).limit(index + length);
+        return ((ByteBuffer) memory.duplicate().position(index).limit(index + length)).slice();
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/PooledHeapByteBuf.java

@@ -259,7 +259,8 @@ final class PooledHeapByteBuf extends PooledByteBuf<byte[]> {
     public ByteBuffer nioBuffer(int index, int length) {
         checkIndex(index, length);
         index = idx(index);
-        return (ByteBuffer) ByteBuffer.wrap(memory).position(index).limit(index + length);
+        ByteBuffer buf =  ByteBuffer.wrap(memory, index, length);
+        return buf.slice();
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/PooledUnsafeDirectByteBuf.java

@@ -339,7 +339,7 @@ final class PooledUnsafeDirectByteBuf extends PooledByteBuf<ByteBuffer> {
     public ByteBuffer nioBuffer(int index, int length) {
         checkIndex(index, length);
         index = idx(index);
-        return (ByteBuffer) memory.duplicate().position(index).limit(index + length);
+        return ((ByteBuffer) memory.duplicate().position(index).limit(index + length)).slice();
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/UnpooledDirectByteBuf.java

@@ -575,7 +575,7 @@ public class UnpooledDirectByteBuf extends AbstractReferenceCountedByteBuf {
 
     @Override
     public ByteBuffer nioBuffer(int index, int length) {
-        return (ByteBuffer) buffer.duplicate().position(index).limit(index + length);
+        return ((ByteBuffer) buffer.duplicate().position(index).limit(index + length)).slice();
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/UnpooledHeapByteBuf.java

@@ -267,7 +267,7 @@ public class UnpooledHeapByteBuf extends AbstractReferenceCountedByteBuf {
     @Override
     public ByteBuffer nioBuffer(int index, int length) {
         ensureAccessible();
-        return ByteBuffer.wrap(array, index, length);
+        return ByteBuffer.wrap(array, index, length).slice();
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/UnpooledUnsafeDirectByteBuf.java

@@ -475,7 +475,7 @@ public class UnpooledUnsafeDirectByteBuf extends AbstractReferenceCountedByteBuf
 
     @Override
     public ByteBuffer nioBuffer(int index, int length) {
-        return (ByteBuffer) buffer.duplicate().position(index).limit(index + length);
+        return ((ByteBuffer) buffer.duplicate().position(index).limit(index + length)).slice();
     }
 
     @Override

buffer/src/test/java/io/netty/buffer/AbstractByteBufTest.java

@@ -1942,6 +1942,23 @@ public abstract class AbstractByteBufTest {
         assertEquals((byte) 0 , buffer.readByte());
         buffer.readByte();
     }
+
+    @Test
+    public void testNioBufferExposeOnlyRegion() {
+        final ByteBuf buffer = freeLater(newBuffer(8));
+        byte[] data = new byte[8];
+        random.nextBytes(data);
+        buffer.writeBytes(data);
+
+        ByteBuffer nioBuf = buffer.nioBuffer(1, data.length - 2);
+        assertEquals(0, nioBuf.position());
+        assertEquals(6, nioBuf.remaining());
+
+        for (int i = 1; nioBuf.hasRemaining(); i++) {
+            assertEquals(data[i], nioBuf.get());
+        }
+    }
+
     static final class TestGatheringByteChannel implements GatheringByteChannel {
         private final ByteArrayOutputStream out = new ByteArrayOutputStream();
         private final WritableByteChannel channel = Channels.newChannel(out);

buffer/src/test/java/io/netty/buffer/SlicedByteBufTest.java

@@ -88,4 +88,10 @@ public class SlicedByteBufTest extends AbstractByteBufTest {
     public void testSliceBytesInArrayMultipleThreads() throws Exception {
         super.testSliceBytesInArrayMultipleThreads();
     }
+
+    @Test(expected = IndexOutOfBoundsException.class)
+    @Override
+    public void testNioBufferExposeOnlyRegion() {
+        super.testNioBufferExposeOnlyRegion();
+    }
 }