Merge lp:~laurynas-biveinis/percona-server/bug905711 into lp:percona-server/5.1

[Laurynas Biveinis]

Fix bug 905711: Crash in DTCollation::set(DTCollation &set), upstream
63793.

The cause and the fix are the same as for upstream 53236 (except that
that testcase does not trigger the crash): don't call member functions
with this == NULL in sql_select.cc:change_cond_ref_to_const. If
clone_item() returns NULL, then there is no need to set the
collation.

Add new testcase bug63793.

[Alexey Kopytov (akopytov)]

Looks good to me except that if I saw the 'backport' word somewhere in the revision/MP comments, figuring out what the patch is would be a no-op. But that's a minor thing, feel free to ignore.

review: Approve

[Laurynas Biveinis (laurynas-biveinis)]

Alexey -

Thanks. I was cautious about saying "backport", as the the original testcase passes on 5.1 already and this one has a new testcase.

=== added file 'Percona-Server/mysql-test/r/bug63793.result'
--- Percona-Server/mysql-test/r/bug63793.result	1970-01-01 00:00:00 +0000
+++ Percona-Server/mysql-test/r/bug63793.result	2011-12-20 01:52:25 +0000
@@ -0,0 +1,5 @@
+DROP TABLE IF EXISTS t1;
+CREATE TABLE t1 (a VARCHAR(50));
+SELECT a FROM t1 WHERE CAST(a as binary)=x'62736D697468' AND CAST(a AS BINARY)=x'65736D697468';
+a
+DROP TABLE t1;

=== added file 'Percona-Server/mysql-test/t/bug63793.test'
--- Percona-Server/mysql-test/t/bug63793.test	1970-01-01 00:00:00 +0000
+++ Percona-Server/mysql-test/t/bug63793.test	2011-12-20 01:52:25 +0000
@@ -0,0 +1,9 @@
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+CREATE TABLE t1 (a VARCHAR(50));
+
+SELECT a FROM t1 WHERE CAST(a as binary)=x'62736D697468' AND CAST(a AS BINARY)=x'65736D697468';
+
+DROP TABLE t1;

=== modified file 'Percona-Server/sql/sql_select.cc'
--- Percona-Server/sql/sql_select.cc	2011-11-24 16:33:30 +0000
+++ Percona-Server/sql/sql_select.cc	2011-12-20 01:52:25 +0000
@@ -8580,10 +8580,10 @@
        left_item->collation.collation == value->collation.collation))
   {
     Item *tmp=value->clone_item();
-    tmp->collation.set(right_item->collation);
     
     if (tmp)
     {
+      tmp->collation.set(right_item->collation);
       thd->change_item_tree(args + 1, tmp);
       func->update_used_tables();
       if ((functype == Item_func::EQ_FUNC || functype == Item_func::EQUAL_FUNC)
@@ -8604,10 +8604,10 @@
             right_item->collation.collation == value->collation.collation))
   {
     Item *tmp= value->clone_item();
-    tmp->collation.set(left_item->collation);
     
     if (tmp)
     {
+      tmp->collation.set(left_item->collation);
       thd->change_item_tree(args, tmp);
       value= tmp;
       func->update_used_tables();