Bug #39920: MySQL cannot deal with Leap Second expression in string literal.

                  
Updated MySQL time handling code to react correctly on UTC leap second additions.
MySQL functions that return the OS current time, like e.g. CURDATE(), NOW() etc
will return :59:59 instead of :59:60 or 59:61.
As a result the reader will receive :59:59 for 2 or 3 consecutive seconds 
during the leap second.
This fix will not affect the values returned by UNIX_TIMESTAMP() for leap seconds.
But note that when converting the value returned by UNIX_TIMESTAMP() to broken 
down time the correction of leap seconds will still be applied.
Note that this fix will make a difference *only* if the OS is specially configured
to return leap seconds from the OS time calls or when using a MySQL time zone 
defintion that has leap seconds.
Even after this change date/time literals (or other broken down time 
representations) with leap seconds (ending on :59:60 or 59:61) will still be 
considered illegal and discarded by the server with an error or 
a warning depending on the sql mode.
Added a test case to demonstrate the effect of the fix.

mysql-test/r/timezone3.result:
  Bug #39920: test case
mysql-test/std_data/Moscow_leap:
  Bug #39920: updated the Moscow time zone to Dr. Olson's tzdata 2008i 
  to accomodate for the 2008 leap second
mysql-test/t/timezone3.test:
  Bug #39920: test case
sql/tztime.cc:
  Bug #39920: adjust leap seconds (:60 or :61) to :59
sql/tztime.h:
  Bug #39920: adjust leap seconds (:60 or :61) to :59

1 files changed, 3 insertions, 0 deletions

diff --git a/sql/tztime.h b/sql/tztime.h
index 32a942a26e1..750b8dacbe1 100644
--- a/sql/tztime.h
+++ b/sql/tztime.h
@@ -55,6 +55,9 @@ public:
     allocated on MEM_ROOT and should not require destruction.
   */
   virtual ~Time_zone() {};
+
+protected:
+  static inline void adjust_leap_second(MYSQL_TIME *t);
 };
 
 extern Time_zone * my_tz_UTC;