Bug#13002783 PARTIALLY UNINITIALIZED CASCADE UPDATE VECTOR

In the ON UPDATE CASCADE clause of FOREIGN KEY constraints, the
calculated update vector was not fully initialized. This bug was
introduced in the InnoDB Plugin when implementing support for
ROW_FORMAT=DYNAMIC.

Additionally, the data type information was not initialized, but
apparently it has never been needed in this case.  Nevertheless, it is
not good programming practice to pass uninitialized values around.

calc_row_difference(): Declare the update field uninitialized in
Valgrind. Copy the data type information as well, except when the
field is SQL NULL. In the built-in InnoDB, initialize
ufield->extern_storage = FALSE (an initialization bug that had gone
unnoticed this far). The InnoDB Plugin and later have this flag to
dfield_t and have always initialized it properly.

row_ins_cascade_calc_update_vec(): Reduce the scope of some
pointers. Initialize orig_len. (This caused the bug in InnoDB Plugin
and later.)

row_ins_foreign_check_on_constraint(): Simplify a condition. Declare
the update vector uninitialized.

rb:771 approved by Jimmy Yang

mysql-test/suite/innodb_plugin/t/innodb.test

@@ -1040,6 +1040,24 @@ update t1,t2,t3 set t3.id=5, t2.id=6, t1.id=7  where t1.id =1 and t2.id = t1.id
 update t3 set  t3.id=7  where t1.id =1 and t2.id = t1.id and t3.id = t2.id;
 drop table t3,t2,t1;
 
+# test ON UPDATE CASCADE
+CREATE TABLE t1 (
+        c1 VARCHAR(8), c2 VARCHAR(8),
+	PRIMARY KEY (c1, c2)
+) ENGINE=InnoDB;
+
+CREATE TABLE t2 (
+        c0 INT PRIMARY KEY,
+        c1 VARCHAR(8) UNIQUE,
+        FOREIGN KEY (c1) REFERENCES t1 (c1) ON UPDATE CASCADE
+) ENGINE=InnoDB;
+
+INSERT INTO t1 VALUES ('old', 'somevalu'), ('other', 'anyvalue');
+INSERT INTO t2 VALUES (10, 'old'), (20, 'other');
+-- error ER_FOREIGN_DUPLICATE_KEY
+UPDATE t1 SET c1 = 'other' WHERE c1 = 'old';
+DROP TABLE t2,t1;
+
 #
 # test for recursion depth limit
 #