  function onClose() {
    if (arguments.length >= 3) {
      assert(!self.state.clientClose,
             makeMsg(self.what, 'Received multiple close events for client'));
      self.state.clientClose = true;
    } else {
      assert(!self.state.serverClose,
             makeMsg(self.what, 'Received multiple close events for server'));
      self.state.serverClose = true;
    }
    if (self.state.clientClose && self.state.serverClose)
      next();
  }
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.