code: protected boolean readChunk ()
          throws IOException
      {
          int offset = _sync.buffer(BUFFER_SIZE);
          int bytes = _in.read(_sync.data, offset, BUFFER_SIZE);
          if (bytes > 0) {
              _sync.wrote(bytes);
              return true;
          }
          return false;
      }
docs: Reads in a chunk of data from the underlying input stream.
  
  @return true if a chunk was read, false if we've reached the end of the stream.