# File lib/rack/file.rb, line 25
    def _call(env)
      @path_info = Utils.unescape(env["PATH_INFO"])
      return forbidden  if @path_info.include? ".."

      @path = F.join(@root, @path_info)

      begin
        if F.file?(@path) && F.readable?(@path)
          serving
        else
          raise Errno::EPERM
        end
      rescue SystemCallError
        not_found
      end
    end