class Nokogiri::HTML4::EncodingReader

def read(len)
  # no support for a call without len
  unless @firstchunk
    (@firstchunk = @io.read(len)) || return
    # This implementation expects that the first call from
    # htmlReadIO() is made with a length long enough (~1KB) to
    # achieve advanced encoding detection.
    if (encoding = EncodingReader.detect_encoding(@firstchunk))
      # The first chunk is stored for the next read in retry.
      raise @encoding_found = EncodingFound.new(encoding)
    end
  end
  @encoding_found = nil
  ret = @firstchunk.slice!(0, len)
  if (len -= ret.length) > 0
    (rest = @io.read(len)) && ret << (rest)
  end
  if ret.empty?
    nil
  else
    ret
  end
end