bool date_add_interval()

in mysql_sys/my_time.cc [2290:2414]
113 lines of code
45 McCabe index (conditional complexity)

bool date_add_interval(MYSQL_TIME *ltime, interval_type int_type,
                       Interval interval, int *warnings) {
  ltime->neg = false;

  long long sign = (interval.neg ? -1 : 1);

  switch (int_type) {
    case INTERVAL_SECOND:
    case INTERVAL_SECOND_MICROSECOND:
    case INTERVAL_MICROSECOND:
    case INTERVAL_MINUTE:
    case INTERVAL_HOUR:
    case INTERVAL_MINUTE_MICROSECOND:
    case INTERVAL_MINUTE_SECOND:
    case INTERVAL_HOUR_MICROSECOND:
    case INTERVAL_HOUR_SECOND:
    case INTERVAL_HOUR_MINUTE:
    case INTERVAL_DAY_MICROSECOND:
    case INTERVAL_DAY_SECOND:
    case INTERVAL_DAY_MINUTE:
    case INTERVAL_DAY_HOUR: {
      longlong sec, days, daynr, microseconds, extra_sec;
      ltime->time_type = MYSQL_TIMESTAMP_DATETIME;  // Return full date
      microseconds = ltime->second_part + sign * interval.second_part;
      extra_sec = microseconds / 1000000L;
      microseconds = microseconds % 1000000L;

      if (interval.day > MAX_DAY_NUMBER) goto invalid_date;
      if (interval.hour > MAX_DAY_NUMBER * 24ULL) goto invalid_date;
      if (interval.minute > MAX_DAY_NUMBER * 24ULL * 60ULL) goto invalid_date;
      if (interval.second > MAX_DAY_NUMBER * 24ULL * 60ULL * 60ULL)
        goto invalid_date;
      sec =
          ((ltime->day - 1) * 3600LL * 24LL + ltime->hour * 3600LL +
           ltime->minute * 60LL + ltime->second +
           sign * static_cast<longlong>(
                      interval.day * 3600ULL * 24ULL + interval.hour * 3600ULL +
                      interval.minute * 60ULL + interval.second)) +
          extra_sec;
      if (microseconds < 0) {
        microseconds += 1000000LL;
        sec--;
      }
      days = sec / (3600 * 24LL);
      sec -= days * 3600 * 24LL;
      if (sec < 0) {
        days--;
        sec += 3600 * 24LL;
      }
      ltime->second_part = static_cast<uint>(microseconds);
      ltime->second = static_cast<uint>(sec % 60);
      ltime->minute = static_cast<uint>(sec / 60 % 60);
      ltime->hour = static_cast<uint>(sec / 3600);
      daynr = calc_daynr(ltime->year, ltime->month, 1) + days;
      /* Day number from year 0 to 9999-12-31 */
      if (daynr < 0 || daynr > MAX_DAY_NUMBER) goto invalid_date;
      get_date_from_daynr(daynr, &ltime->year, &ltime->month, &ltime->day);
      break;
    }
    case INTERVAL_DAY:
    case INTERVAL_WEEK: {
      unsigned long period;
      period = calc_daynr(ltime->year, ltime->month, ltime->day);
      if (interval.neg) {
        if (period < interval.day)  // Before 0.
          goto invalid_date;
        period -= interval.day;
      } else {
        if (period + interval.day < period)  // Overflow.
          goto invalid_date;
        if (period + interval.day > MAX_DAY_NUMBER)  // After 9999-12-31.
          goto invalid_date;
        period += interval.day;
      }
      get_date_from_daynr(period, &ltime->year, &ltime->month, &ltime->day);
    } break;
    case INTERVAL_YEAR:
      if (interval.year > 10000UL) goto invalid_date;
      ltime->year += sign * static_cast<long>(interval.year);
      if (static_cast<ulong>(ltime->year) >= 10000L) goto invalid_date;
      if (ltime->month == 2 && ltime->day == 29 &&
          calc_days_in_year(ltime->year) != 366)
        ltime->day = 28;  // Was leap-year
      break;
    case INTERVAL_YEAR_MONTH:
    case INTERVAL_QUARTER:
    case INTERVAL_MONTH: {
      unsigned long long period;

      // Simple guards against arithmetic overflow when calculating period.
      if (interval.month >= UINT_MAX / 2) goto invalid_date;
      if (interval.year >= UINT_MAX / 12) goto invalid_date;

      period = (ltime->year * 12ULL +
                sign * static_cast<unsigned long long>(interval.year) * 12ULL +
                ltime->month - 1ULL +
                sign * static_cast<unsigned long long>(interval.month));
      if (period >= 120000LL) goto invalid_date;
      ltime->year = period / 12;
      ltime->month = (period % 12L) + 1;
      /* Adjust day if the new month doesn't have enough days */
      if (ltime->day > days_in_month[ltime->month - 1]) {
        ltime->day = days_in_month[ltime->month - 1];
        if (ltime->month == 2 && calc_days_in_year(ltime->year) == 366)
          ltime->day++;  // Leap-year
      }
    } break;
    default:
      fprintf(stderr, "Unexpected interval type: %u\n",
              static_cast<unsigned int>(int_type));
      assert(false);
      goto null_date;
  }

  return false;  // Ok

invalid_date:
  if (warnings) {
    *warnings |= MYSQL_TIME_WARN_DATETIME_OVERFLOW;
  }

null_date:

  return true;
}