  function onclose(er) {
    er = er || err;
    cb(er);
    stream.closed = true;
    if (!er)
      stream.emit('close');
  }
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.