difftm
if (tsp[0].tv_sec == NO_TIME || difftm(t, &tm))
if (tsp[0].tv_sec == NO_TIME || difftm(t, &tm))
if ((errno != 0 && tsp[1].tv_sec == NO_TIME) || difftm(&tm, &tms))
static int difftm(const struct tm *, const struct tm *);