Patch for Bug 12652769 - 61470: CASE OPERATOR IN STORED ROUTINE RETAINS

OLD VALUE OF INPUT PARAMETER.

The user-visible problem was that CASE-control-flow function
(not CASE-statement) misbehaved in stored routines under some
circumstances. The problem resulted in a crash or wrong data
returned. The error happened when expressions in CASE-function
were not of the same character set.

A CASE-function should return values of the same character set
for all branches. Internally, that means a new Item-instance
for the CONVERT(... USING <some charset>)-function is added
to the item tree when needed. The problem was that such changes
were not properly recorded using THD::change_item_tree(),
thus dangling pointers remain in the item tree after
THD::rollback_item_tree_changes(), which lead to undefined
behavior (i.e. crash / wrong data) for subsequent executions of
the stored routine.

This bug was introduced by a patch for Bug 11753363
(44793 - CHARACTER SETS: CASE CLAUSE, UCS2 OR UTF32, FAILURE).

The fixed function is Item_func_case::fix_length_and_dec().
New CONVERT-items are added in agg_item_set_converter(),
which calls THD::change_item_tree().

The problem was that an intermediate array was passed
to agg_item_set_converter(). Thus, THD::change_item_tree() there
was called on intermediate objects.

Note: those intermediate objects are allocated on THD's
memory root, so it's Ok to put them into "changed item lists".

The fix is to track changes on the correct objects.

1 files changed, 56 insertions, 0 deletions

diff --git a/mysql-test/t/sp.test b/mysql-test/t/sp.test
index b052b181d70..a9220aa04e6 100644
--- a/mysql-test/t/sp.test
+++ b/mysql-test/t/sp.test
@@ -8778,4 +8778,60 @@ DROP TABLE t1, t2, t3;
 DROP PROCEDURE p1;
 --echo
 
+
+--echo
+--echo # --
+--echo # -- Bug#12652769 - 61470: case operator in stored routine retains old
+--echo # -- value of input parameter
+--echo # --- 
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP PROCEDURE IF EXISTS p1;
+--enable_warnings
+
+CREATE TABLE t1 (s1 CHAR(5) CHARACTER SET utf8);
+INSERT INTO t1 VALUES ('a');
+
+delimiter |;
+
+CREATE PROCEDURE p1(dt DATETIME, i INT)
+BEGIN
+  SELECT
+    CASE
+      WHEN i = 1 THEN 2
+      ELSE dt
+    END AS x1;
+
+  SELECT
+    CASE _latin1'a'
+      WHEN _utf8'a' THEN 'A'
+    END AS x2;
+
+  SELECT
+    CASE _utf8'a'
+      WHEN _latin1'a' THEN _utf8'A'
+    END AS x3;
+
+  SELECT
+    CASE s1
+      WHEN _latin1'a' THEN _latin1'b'
+      ELSE _latin1'c'
+    END AS x4
+  FROM t1;
+END|
+
+delimiter ;|
+
+--echo
+CALL p1('2011-04-03 05:14:10', 1);
+CALL p1('2011-04-03 05:14:11', 2);
+CALL p1('2011-04-03 05:14:12', 2);
+CALL p1('2011-04-03 05:14:13', 2);
+
+--echo
+DROP TABLE t1;
+DROP PROCEDURE p1;
+--echo
+
 --echo # End of 5.5 test