endrun_atoi
int endrun_atoi(char *s, int len);
if ((n = endrun_atoi(y, 4)) == -1)
if ((n = endrun_atoi(doy, 3)) == -1 || n == 0 || n > year_days)
if ((n = endrun_atoi(&s[0], 2)) == -1 || n > 23)
if ((n = endrun_atoi(&s[3], 2)) == -1 || n > 59)
if ((n = endrun_atoi(&s[6], 2)) == -1 || n > 60)
if ((n = endrun_atoi(&s[1], 2)) == -1)