`[[:punct:]]pod(?P<poduid>[[:xdigit:]]{8}[[:punct:]]?[[:xdigit:]]{4}[[:punct:]]?[[:xdigit:]]{4}[[:punct:]]?[[:xdigit:]]{4}[[:punct:]]?[[:xdigit:]]{12})[[:punct:]]` +
		// zero or more punctuation separated "segments" (e.g. "docker-")
		`(?:[[:^punct:]]+[[:punct:]])*` +
		// non-punctuation end of string, i.e., the container ID
		`(?P<containerid>[[:^punct:]]+)$`),

	_ = w.w.CloseWithError(err)
	_ = w.r.CloseWithError(err)
	w.err = err
}

func (w *writerAt) Close() (err error) {
	switch {
	case len(w.buffer) > 0:
		err = errors.New("some file segments were not flushed from the queue")
		_ = w.w.CloseWithError(err)
	case w.err != nil:
		// No need to close here since both pipes were
		// closing inside TransferError()
		err = w.err
	default: