NettyDataBuffer#toByteBuffer fails if readPosition > 0

[chringwer]

NettyDataBuffer uses this.byteBuf.nioBuffer() internally which will allocates fewer bytes if readPosition is greater than 0. The following checks are then failing with an IndexOutOfBoundsException.

spring-framework/spring-core/src/main/java/org/springframework/core/io/buffer/NettyDataBuffer.java

Line 316 in 2b7a920

dest.put(destPos, this.byteBuf.nioBuffer(), srcPos, length);

Here is a simple repro case (which passes for DefaultDataBufferFactory):

@Test
void shouldHonorSourceBuffersReadPosition() {
  DataBufferFactory bufferFactory = new NettyDataBufferFactory(ByteBufAllocator.DEFAULT);

  DataBuffer sourceBuffer = bufferFactory.wrap("Hello World".getBytes(UTF_8));

  sourceBuffer.readPosition("Hello ".getBytes(UTF_8).length);
  ByteBuffer targetBuffer = ByteBuffer.allocate(sourceBuffer.readableByteCount());

  sourceBuffer.toByteBuffer(targetBuffer);

  assertThat(new String(targetBuffer.array(), UTF_8)).isEqualTo("World");
}

[poutsma]

Thanks for spotting this, fixed!