Bug#38999 valgrind warnings for update statement in function compare_record()

Valgrind warning happpens because of uninitialized null bytes.
In row_sel_push_cache_row_for_mysql() function we fill fetch cache
with necessary field values, row_sel_store_mysql_rec() is called
for this and leaves null bytes untouched.
Later row_sel_pop_cached_row_for_mysql() rewrites table record
buffer with uninited null bytes. We can see the problem from the
test case:
At 'SELECT...' we call row_sel_push...->row_sel_store...->row_sel_pop_cached...
chain which rewrites table->record[0] buffer with uninitialized null bytes.
When we call 'UPDATE...' statement, compare_record uses this buffer and
valgrind warning occurs.
The fix is to init null bytes with default values.


mysql-test/suite/innodb/r/innodb_mysql.result:
  test case
mysql-test/suite/innodb/t/innodb_mysql.test:
  test case
mysql-test/t/ps_3innodb.test:
  enable valgrind testing
storage/innobase/row/row0sel.c:
  init null bytes with default values as they might be
  left uninitialized in some cases and these uninited bytes
  might be copied into mysql record buffer that leads to
  valgrind warnings on next use of the buffer.

mysql-test/suite/innodb/r/innodb_mysql.result

@@ -2378,4 +2378,16 @@ SELECT SECOND(c)-@bug47453 FROM t1 JOIN t2 ON d=a;
 SECOND(c)-@bug47453
 0
 DROP TABLE t1, t2;
+#
+# Bug#38999 valgrind warnings for update statement in function compare_record()
+#
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+CREATE TABLE t2 (a INT PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 values (1),(2),(3),(4),(5);
+INSERT INTO t2 values (1);
+SELECT * FROM t1 WHERE a = 2;
+a
+2
+UPDATE t1,t2 SET t1.a = t1.a + 100 WHERE t1.a = 1;
+DROP TABLE t1,t2;
 End of 5.1 tests

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

@@ -618,5 +618,18 @@ SELECT SECOND(c)-@bug47453 FROM t1 JOIN t2 ON d=a;
 
 DROP TABLE t1, t2;
 
+--echo #
+--echo # Bug#38999 valgrind warnings for update statement in function compare_record()
+--echo #
+
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+CREATE TABLE t2 (a INT PRIMARY KEY) ENGINE=InnoDB;
+INSERT INTO t1 values (1),(2),(3),(4),(5);
+INSERT INTO t2 values (1);
+
+SELECT * FROM t1 WHERE a = 2;
+UPDATE t1,t2 SET t1.a = t1.a + 100 WHERE t1.a = 1;
+
+DROP TABLE t1,t2;
 
 --echo End of 5.1 tests

mysql-test/t/ps_3innodb.test

@@ -8,10 +8,6 @@
 # NOTE: PLEASE SEE ps_1general.test (bottom) 
 #       BEFORE ADDING NEW TEST CASES HERE !!!
 
-# See Bug#38999 valgrind warnings for update statement in function
-# compare_record()
--- source include/not_valgrind.inc
-
 use test;
 
 -- source include/have_innodb.inc

storage/innobase/row/row0sel.c

@@ -2621,6 +2621,12 @@ row_sel_store_mysql_rec(
 		prebuilt->blob_heap = NULL;
 	}
 
+	/* init null bytes with default values as they might be
+	left uninitialized in some cases and this uninited bytes
+	might be copied into mysql record buffer that leads to
+	valgrind warnings */
+	memcpy(mysql_rec, prebuilt->default_rec, prebuilt->null_bitmap_len);
+
 	for (i = 0; i < prebuilt->n_template; i++) {
 
 		templ = prebuilt->mysql_template + i;