# File lib/rack/utils.rb, line 486
        def initialize(path, content_type = "text/plain", binary = false)
          raise "#{path} file does not exist" unless ::File.exist?(path)
          @content_type = content_type
          @original_filename = ::File.basename(path)
          @tempfile = Tempfile.new(@original_filename)
          @tempfile.set_encoding(Encoding::BINARY) if @tempfile.respond_to?(:set_encoding)
          @tempfile.binmode if binary
          FileUtils.copy_file(path, @tempfile.path)
        end