//
// Keys and values should be UTF-8, but the number of bad writers out there
// forces us to be a more liberal.
// Thus, we only reject all keys with NUL, and only reject NULs in values
// for the PAX version of the USTAR string fields.
// The key must not contain an '=' character.
func validPAXRecord(k, v string) bool {
	if k == "" || strings.Contains(k, "=") {
		return false
	}
	switch k {