# File lib/camping/server.rb, line 239
      def call(env)
        status, headers, body = @app.call(env)
        
        if key = headers.keys.grep(/X-Sendfile/i).first
          filename = headers[key]
          content = File.read(filename)
          headers['Content-Length'] = size(content).to_s
          body = [content]
        end
        
        return status, headers, body
      end