code: @Override
    public int read(byte []buf, int offset, int length)
      throws IOException
    {
      int sublen = _pageReader.read(_offset, buf, offset, length);
      
      if (sublen > 0) {
        _offset += sublen;
        
        return sublen;
      }
      else {
        return sublen;
      }
    }
docs: Reads a buffer.