if hasNUL(s) || (tooLong && !allowLongGNU) {
			whyNoGNU = fmt.Sprintf("GNU cannot encode %s=%q", name, s)
			format.mustNotBe(FormatGNU)
		}
		if !isASCII(s) || tooLong {
			canSplitUSTAR := paxKey == paxPath
			if _, _, ok := splitUSTARPath(s); !canSplitUSTAR || !ok {
				whyNoUSTAR = fmt.Sprintf("USTAR cannot encode %s=%q", name, s)
				format.mustNotBe(FormatUSTAR)
			}

	return c.Err.Error()
}

// Confirm waits for a user to confirm with the supplied message.
func Confirm(msg string, writer io.Writer) bool {
	for {
		_, _ = fmt.Fprintf(writer, "%s ", msg)
		var response string
		_, err := fmt.Scanln(&response)
		if err != nil {
			return false
		}
		switch strings.ToUpper(response) {
		case "Y", "YES":
			return true
		case "N", "NO":
			return false
		}
	}