Gem::Package#extract_files

# File tmp/rubies/ruby-3.0.5/lib/rubygems/package.rb, line 380
def extract_files(destination_dir, pattern = "*")
  verify unless @spec

  FileUtils.mkdir_p destination_dir, :mode => dir_mode && 0755

  @gem.with_read_io do |io|
    reader = Gem::Package::TarReader.new io

    reader.each do |entry|
      next unless entry.full_name == 'data.tar.gz'

      extract_tar_gz entry, destination_dir, pattern

      return # ignore further entries
    end
  end
end