class Gem::Package::Old

def extract_files(destination_dir)
  verify
  errstr = "Error reading files from gem"
  @gem.with_read_io do |io|
    read_until_dashes io # spec
    header = file_list io
    raise Gem::Exception, errstr unless header
    header.each do |entry|
      full_name = entry["path"]
      destination = install_location full_name, destination_dir
      file_data = String.new
      read_until_dashes io do |line|
        file_data << line
      end
      file_data = file_data.strip.unpack1("m")
      file_data = Zlib::Inflate.inflate file_data
      raise Gem::Package::FormatError, "#{full_name} in #{@gem} is corrupt" if
        file_data.length != entry["size"].to_i
      FileUtils.rm_rf destination
      FileUtils.mkdir_p File.dirname(destination), mode: dir_mode && 0o755
      File.open destination, "wb", file_mode(entry["mode"]) do |out|
        out.write file_data
      end
      verbose destination
    end
  end
rescue Zlib::DataError
  raise Gem::Exception, errstr
end