Bug#18997: DATE_ADD and DATE_SUB perform year2K autoconversion magic on 4-digit year value

if input year for date_add() / date_sub() with INTERVAL is low enough for
calc_daynr() to possibly return incorrect results (calc_daynr() has no information
on whether the year is low because it was a two-digit year ('77) or because it
was a really low four-digit year (0077) and will indiscriminately try to turn the
value into a four-digit year by adding 1900 or 2000 respectively), the functions
will now throw NULL.


include/my_time.h:
  new define YY_MAGIC_BELOW: if year is below this threshold, magic kicks in in
  calc_daynr(). the idea is to convert two-digit years to four-digit ones, adding
  1900 to values >= YY_PART_YEAR or adding 2000 otherwise.
  current value of YY_MAGIC_BELOW derived from original code in calc_daynr()
mysql-test/r/func_time.result:
  test where 2 digit -> 4 digit year magic kicks in, and whether we throw NULL when
  it happens
mysql-test/t/func_time.test:
  test where 2 digit -> 4 digit year magic kicks in, and whether we throw NULL when
  it happens
sql-common/my_time.c:
  use new const YY_MAGIC_BELOW, apply 2-digit -> 4-digit magic only to years
  below this threshold.
sql/item_timefunc.cc:
  throw NULL when year in date_add() / date_sub() would be affected by
  2 digit -> 4 digit magic.

include/my_time.h

@@ -38,7 +38,10 @@ typedef long my_time_t;
 #define MY_TIME_T_MAX LONG_MAX
 #define MY_TIME_T_MIN LONG_MIN
 
+/* two-digit years < this are 20..; >= this are 19.. */
 #define YY_PART_YEAR	   70
+/* apply above magic to years < this */
+#define YY_MAGIC_BELOW     200
 
 /* Flags to str_to_datetime */
 #define TIME_FUZZY_DATE		1

mysql-test/r/func_time.result

@@ -736,42 +736,28 @@ select last_day('2005-00-00');
 last_day('2005-00-00')
 NULL
 Warnings:
-Warning	1292	Truncated incorrect datetime value: '2005-00-00'
+Warning	1292	Incorrect datetime value: '2005-00-00'
 select last_day('2005-00-01');
 last_day('2005-00-01')
 NULL
 Warnings:
-Warning	1292	Truncated incorrect datetime value: '2005-00-01'
+Warning	1292	Incorrect datetime value: '2005-00-01'
 select last_day('2005-01-00');
 last_day('2005-01-00')
 NULL
 Warnings:
-Warning	1292	Truncated incorrect datetime value: '2005-01-00'
+Warning	1292	Incorrect datetime value: '2005-01-00'
 select monthname(str_to_date(null, '%m')), monthname(str_to_date(null, '%m')),
 monthname(str_to_date(1, '%m')), monthname(str_to_date(0, '%m'));
 monthname(str_to_date(null, '%m'))	monthname(str_to_date(null, '%m'))	monthname(str_to_date(1, '%m'))	monthname(str_to_date(0, '%m'))
 NULL	NULL	January	NULL
+End of 4.1 tests
 explain extended select timestampdiff(SQL_TSI_WEEK, '2001-02-01', '2001-05-01') as a1,
 timestampdiff(SQL_TSI_FRAC_SECOND, '2001-02-01 12:59:59.120000', '2001-05-01 12:58:58.119999') as a2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 Warnings:
 Note	1003	select timestampdiff(WEEK,_latin1'2001-02-01',_latin1'2001-05-01') AS `a1`,timestampdiff(SECOND_FRAC,_latin1'2001-02-01 12:59:59.120000',_latin1'2001-05-01 12:58:58.119999') AS `a2`
-select last_day('2005-00-00');
-last_day('2005-00-00')
-NULL
-Warnings:
-Warning	1292	Incorrect datetime value: '2005-00-00'
-select last_day('2005-00-01');
-last_day('2005-00-01')
-NULL
-Warnings:
-Warning	1292	Incorrect datetime value: '2005-00-01'
-select last_day('2005-01-00');
-last_day('2005-01-00')
-NULL
-Warnings:
-Warning	1292	Incorrect datetime value: '2005-01-00'
 select time_format('100:00:00', '%H %k %h %I %l');
 time_format('100:00:00', '%H %k %h %I %l')
 100 100 04 04 4
@@ -891,3 +877,38 @@ id	day	id	day
 1	2005-06-01	3	2005-07-15
 3	2005-07-01	3	2005-07-15
 DROP TABLE t1,t2;
+End of 5.0 tests
+select date_sub("0050-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("0050-01-01 00:00:01",INTERVAL 2 SECOND)
+NULL
+select date_sub("0199-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("0199-01-01 00:00:01",INTERVAL 2 SECOND)
+NULL
+select date_add("0199-12-31 23:59:59",INTERVAL 2 SECOND);
+date_add("0199-12-31 23:59:59",INTERVAL 2 SECOND)
+NULL
+select date_sub("0200-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("0200-01-01 00:00:01",INTERVAL 2 SECOND)
+0199-12-31 23:59:59
+select date_sub("0200-01-01 00:00:01",INTERVAL 1 SECOND);
+date_sub("0200-01-01 00:00:01",INTERVAL 1 SECOND)
+0200-01-01 00:00:00
+select date_sub("0200-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("0200-01-01 00:00:01",INTERVAL 2 SECOND)
+0199-12-31 23:59:59
+select date_add("2001-01-01 23:59:59",INTERVAL -2000 YEAR);
+date_add("2001-01-01 23:59:59",INTERVAL -2000 YEAR)
+0001-01-01 23:59:59
+select date_sub("50-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("50-01-01 00:00:01",INTERVAL 2 SECOND)
+2049-12-31 23:59:59
+select date_sub("90-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("90-01-01 00:00:01",INTERVAL 2 SECOND)
+1989-12-31 23:59:59
+select date_sub("0069-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("0069-01-01 00:00:01",INTERVAL 2 SECOND)
+NULL
+select date_sub("0169-01-01 00:00:01",INTERVAL 2 SECOND);
+date_sub("0169-01-01 00:00:01",INTERVAL 2 SECOND)
+NULL
+End of 5.1 tests

mysql-test/t/func_time.test

@@ -367,19 +367,11 @@ select last_day('2005-01-00');
 select monthname(str_to_date(null, '%m')), monthname(str_to_date(null, '%m')),
        monthname(str_to_date(1, '%m')), monthname(str_to_date(0, '%m'));
 
-# End of 4.1 tests
+--echo End of 4.1 tests
 
 explain extended select timestampdiff(SQL_TSI_WEEK, '2001-02-01', '2001-05-01') as a1,
 			timestampdiff(SQL_TSI_FRAC_SECOND, '2001-02-01 12:59:59.120000', '2001-05-01 12:58:58.119999') as a2;
 
-#
-# Bug #10568
-#
-
-select last_day('2005-00-00');
-select last_day('2005-00-01');
-select last_day('2005-01-00');
-
 #
 # Bug #10590: %h, %I, and %l format specifies should all return results in
 # the 0-11 range
@@ -482,4 +474,23 @@ SELECT * FROM t1, t2
  
 DROP TABLE t1,t2;
 
-# End of 5.0 tests
+--echo End of 5.0 tests
+
+#
+# Bug #18997
+#
+
+select date_sub("0050-01-01 00:00:01",INTERVAL 2 SECOND);
+select date_sub("0199-01-01 00:00:01",INTERVAL 2 SECOND);
+select date_add("0199-12-31 23:59:59",INTERVAL 2 SECOND);
+select date_sub("0200-01-01 00:00:01",INTERVAL 2 SECOND);
+select date_sub("0200-01-01 00:00:01",INTERVAL 1 SECOND);
+select date_sub("0200-01-01 00:00:01",INTERVAL 2 SECOND);
+select date_add("2001-01-01 23:59:59",INTERVAL -2000 YEAR);
+select date_sub("50-01-01 00:00:01",INTERVAL 2 SECOND);
+select date_sub("90-01-01 00:00:01",INTERVAL 2 SECOND);
+select date_sub("0069-01-01 00:00:01",INTERVAL 2 SECOND);
+select date_sub("0169-01-01 00:00:01",INTERVAL 2 SECOND);
+
+
+--echo End of 5.1 tests

sql-common/my_time.c

@@ -689,7 +689,7 @@ long calc_daynr(uint year,uint month,uint day)
 
   if (year == 0 && month == 0 && day == 0)
     DBUG_RETURN(0);				/* Skip errors */
-  if (year < 200)
+  if (year < YY_MAGIC_BELOW)
   {
     if ((year=year+1900) < 1900+YY_PART_YEAR)
       year+=100;

sql/item_timefunc.cc

@@ -1963,6 +1963,9 @@ bool Item_date_add_interval::get_date(TIME *ltime, uint fuzzy_date)
   if (date_sub_interval)
     interval.neg = !interval.neg;
 
+  if (ltime->year < YY_MAGIC_BELOW)
+    return (null_value=1);
+
   return (null_value= date_add_interval(ltime, int_type, interval));
 }