// parent directory retains the trailing slash.
func splitPath(s string, lastIndex bool) (string, string) {
	var i int
	if lastIndex {
		i = strings.LastIndex(s, "/")
	} else {
		i = strings.Index(s, "/")
	}
	if i == -1 {
		return s, ""
	}
	// Include the trailing slash in the parent directory.
	return s[:i+1], s[i+1:]
}