Fixed derickr#19: Inefficient algorithm for calculating dates far in …

…the past.

Also related to PHP bug #75088.

tests/c/issues.cpp

@@ -46,3 +46,87 @@ TEST(issues, issue0017_test3)
 
 	timelib_time_dtor(t);
 }
+
+TEST(issues, issue0019_test1)
+{
+	timelib_sll   ts = -172800;
+	timelib_time *t  = timelib_time_ctor();
+
+	timelib_set_timezone_from_offset(t, 0);
+	timelib_unixtime2local(t, ts);
+	LONGS_EQUAL(1969, t->y);
+	LONGS_EQUAL(12, t->m);
+	LONGS_EQUAL(30, t->d);
+
+	timelib_time_dtor(t);
+}
+
+TEST(issues, issue0019_test2)
+{
+	timelib_sll   ts = -86400;
+	timelib_time *t  = timelib_time_ctor();
+
+	timelib_set_timezone_from_offset(t, 0);
+	timelib_unixtime2local(t, ts);
+	LONGS_EQUAL(1969, t->y);
+	LONGS_EQUAL(12, t->m);
+	LONGS_EQUAL(31, t->d);
+
+	timelib_time_dtor(t);
+}
+
+TEST(issues, issue0019_test3)
+{
+	timelib_sll   ts = 0;
+	timelib_time *t  = timelib_time_ctor();
+
+	timelib_set_timezone_from_offset(t, 0);
+	timelib_unixtime2local(t, ts);
+	LONGS_EQUAL(1970, t->y);
+	LONGS_EQUAL(1, t->m);
+	LONGS_EQUAL(1, t->d);
+
+	timelib_time_dtor(t);
+}
+
+TEST(issues, issue0019_test4)
+{
+	timelib_sll   ts = -12622953600;
+	timelib_time *t  = timelib_time_ctor();
+
+	timelib_set_timezone_from_offset(t, 0);
+	timelib_unixtime2local(t, ts);
+	LONGS_EQUAL(1569, t->y);
+	LONGS_EQUAL(12, t->m);
+	LONGS_EQUAL(30, t->d);
+
+	timelib_time_dtor(t);
+}
+
+TEST(issues, issue0019_test5)
+{
+	timelib_sll   ts = -12622867200;
+	timelib_time *t  = timelib_time_ctor();
+
+	timelib_set_timezone_from_offset(t, 0);
+	timelib_unixtime2local(t, ts);
+	LONGS_EQUAL(1569, t->y);
+	LONGS_EQUAL(12, t->m);
+	LONGS_EQUAL(31, t->d);
+
+	timelib_time_dtor(t);
+}
+
+TEST(issues, issue0019_test6)
+{
+	timelib_sll   ts = -12622780800;
+	timelib_time *t  = timelib_time_ctor();
+
+	timelib_set_timezone_from_offset(t, 0);
+	timelib_unixtime2local(t, ts);
+	LONGS_EQUAL(1570, t->y);
+	LONGS_EQUAL(1, t->m);
+	LONGS_EQUAL(1, t->d);
+
+	timelib_time_dtor(t);
+}

unixtime2tm.c

@@ -48,46 +48,35 @@ void timelib_unixtime2gmt(timelib_time* tm, timelib_sll ts)
 
 	if (ts >= 0) {
 		tmp_days = days + 1;
+	} else {
+		tmp_days = days;
+	}
 
-		if (tmp_days > DAYS_PER_LYEAR_PERIOD || tmp_days <= -DAYS_PER_LYEAR_PERIOD) {
-			cur_year += YEARS_PER_LYEAR_PERIOD * (tmp_days / DAYS_PER_LYEAR_PERIOD);
-			tmp_days -= DAYS_PER_LYEAR_PERIOD * (tmp_days / DAYS_PER_LYEAR_PERIOD);
-		}
+	if (tmp_days > DAYS_PER_LYEAR_PERIOD || tmp_days <= -DAYS_PER_LYEAR_PERIOD) {
+		cur_year += YEARS_PER_LYEAR_PERIOD * (tmp_days / DAYS_PER_LYEAR_PERIOD);
+		tmp_days -= DAYS_PER_LYEAR_PERIOD * (tmp_days / DAYS_PER_LYEAR_PERIOD);
+	}
+	TIMELIB_DEBUG(printf("tmp_days=%lld, year=%lld\n", tmp_days, cur_year););
 
+	if (ts >= 0) {
 		while (tmp_days >= DAYS_PER_LYEAR) {
 			cur_year++;
 			if (timelib_is_leap(cur_year)) {
 				tmp_days -= DAYS_PER_LYEAR;
 			} else {
 				tmp_days -= DAYS_PER_YEAR;
 			}
+			TIMELIB_DEBUG(printf("tmp_days=%lld, year=%lld\n", tmp_days, cur_year););
 		}
 	} else {
-		tmp_days = days;
-
-		/* Guess why this might be for, it has to do with a pope ;-). It's also
-		 * only valid for Great Brittain and it's colonies. It needs fixing for
-		 * other locales. *sigh*, why is this crap so complex! */
-		/*
-		if (ts <= TIMELIB_LL_CONST(-6857352000)) {
-			tmp_days -= 11;
-		}
-		*/
-
 		while (tmp_days <= 0) {
-			if (tmp_days < -1460970) {
-				cur_year -= 4000;
-				TIMELIB_DEBUG(printf("tmp_days=%lld, year=%lld\n", tmp_days, cur_year););
-				tmp_days += 1460970;
+			cur_year--;
+			if (timelib_is_leap(cur_year)) {
+				tmp_days += DAYS_PER_LYEAR;
 			} else {
-				cur_year--;
-				TIMELIB_DEBUG(printf("tmp_days=%lld, year=%lld\n", tmp_days, cur_year););
-				if (timelib_is_leap(cur_year)) {
-					tmp_days += DAYS_PER_LYEAR;
-				} else {
-					tmp_days += DAYS_PER_YEAR;
-				}
+				tmp_days += DAYS_PER_YEAR;
 			}
+			TIMELIB_DEBUG(printf("tmp_days=%lld, year=%lld\n", tmp_days, cur_year););
 		}
 		remainder += SECS_PER_DAY;
 	}