Fix incorrect behavior of ReadOnlyByteBufferBuf.getBytes(int,ByteBuffer) (#9125)

* Fix incorrect behavior of ReadOnlyByteBufferBuf.getBytes(int,ByteBuffer)

Motivation

It currently will succeed when the destination is larger than the source
range, but the ByteBuf javadoc states this should be a failure, as is
the case with all the other implementations.

Modifications

- Fix logic to fail the bounds check in this case
- Remove explicit null check which isn't done in any equivalent method
- Add unit test

Result

More correct/consistent behaviour

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

@@ -208,14 +208,10 @@ class ReadOnlyByteBufferBuf extends AbstractReferenceCountedByteBuf {
 
     @Override
     public ByteBuf getBytes(int index, ByteBuffer dst) {
-        checkIndex(index);
-        if (dst == null) {
-            throw new NullPointerException("dst");
-        }
+        checkIndex(index, dst.remaining());
 
-        int bytesToCopy = Math.min(capacity() - index, dst.remaining());
         ByteBuffer tmpBuf = internalNioBuffer();
-        tmpBuf.clear().position(index).limit(index + bytesToCopy);
+        tmpBuf.clear().position(index).limit(index + dst.remaining());
         dst.put(tmpBuf);
         return this;
     }

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

@@ -96,20 +96,6 @@ final class ReadOnlyUnsafeDirectByteBuf extends ReadOnlyByteBufferBuf {
         return this;
     }
 
-    @Override
-    public ByteBuf getBytes(int index, ByteBuffer dst) {
-        checkIndex(index);
-        if (dst == null) {
-            throw new NullPointerException("dst");
-        }
-
-        int bytesToCopy = Math.min(capacity() - index, dst.remaining());
-        ByteBuffer tmpBuf = internalNioBuffer();
-        tmpBuf.clear().position(index).limit(index + bytesToCopy);
-        dst.put(tmpBuf);
-        return this;
-    }
-
     @Override
     public ByteBuf copy(int index, int length) {
         checkIndex(index, length);

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

@@ -236,6 +236,20 @@ public class ReadOnlyDirectByteBufferBufTest {
         buf.release();
     }
 
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void testGetBytesByteBuffer() {
+        byte[] bytes = {'a', 'b', 'c', 'd', 'e', 'f', 'g'};
+        // Ensure destination buffer is bigger then what is in the ByteBuf.
+        ByteBuffer nioBuffer = ByteBuffer.allocate(bytes.length + 1);
+        ByteBuf buffer = buffer(((ByteBuffer) allocate(bytes.length)
+                .put(bytes).flip()).asReadOnlyBuffer());
+        try {
+            buffer.getBytes(buffer.readerIndex(), nioBuffer);
+        } finally {
+            buffer.release();
+        }
+    }
+
     @Test
     public void testCopy() {
         ByteBuf buf = buffer(((ByteBuffer) allocate(16).putLong(1).putLong(2).flip()).asReadOnlyBuffer());