class Gem::Package::Old

def contents
  verify
  return @contents if @contents
  @gem.with_read_io do |io|
    read_until_dashes io # spec
    header = file_list io
    @contents = header.map {|file| file["path"] }
  end
end

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

def file_list(io) # :nodoc:
  header = String.new
  read_until_dashes io do |line|
    header << line
  end
  Gem::SafeYAML.safe_load header
end

def initialize(gem, security_policy)
  require "fileutils"
  require "zlib"
  Gem.load_yaml
  @contents        = nil
  @gem             = gem
  @security_policy = security_policy
  @spec            = nil
end

def read_until_dashes(io) # :nodoc:
  while (line = io.gets) && line.chomp.strip != "---" do
    yield line if block_given?
  end
end

def skip_ruby(io) # :nodoc:
  loop do
    line = io.gets
    return if line.chomp == "__END__"
    break unless line
  end
  raise Gem::Exception, "Failed to find end of Ruby script while reading gem"
end

def spec
  verify
  return @spec if @spec
  yaml = String.new
  @gem.with_read_io do |io|
    skip_ruby io
    read_until_dashes io do |line|
      yaml << line
    end
  end
  begin
    @spec = Gem::Specification.from_yaml yaml
  rescue Psych::SyntaxError
    raise Gem::Exception, "Failed to parse gem specification out of gem file"
  end
rescue ArgumentError
  raise Gem::Exception, "Failed to parse gem specification out of gem file"
end

def verify
  return true unless @security_policy
  raise Gem::Security::Exception,
        "old format gems do not contain signatures and cannot be verified" if
    @security_policy.verify_data
  true
end