# File lib/rack/file.rb, line 22
    def _call(env)
      if env["PATH_INFO"].include? ".."
        return [403, {"Content-Type" => "text/plain"}, ["Forbidden\n"]]
      end

      @path = F.join(@root, Utils.unescape(env["PATH_INFO"]))
      ext = F.extname(@path)[1..-1]

      if F.file?(@path) && F.readable?(@path)
        [200, {
           "Last-Modified"  => F.mtime(@path).rfc822,
           "Content-Type"   => MIME_TYPES[ext] || "text/plain",
           "Content-Length" => F.size(@path).to_s
         }, self]
      else
        return [404, {"Content-Type" => "text/plain"},
                ["File not found: #{env["PATH_INFO"]}\n"]]
      end
    end