Bug #56595 RENAME TABLE causes assert on OS X

The problem was that RENAME TABLE caused an assert if the system variable
lower_case_table_names was 2 (default on Mac OS X) and the old table name
was given in upper case. This caused lowercase_table2.test to fail.

The assert checks that an exclusive metadata lock is held by the connection
trying to do RENAME TABLE - specificially during updates of table triggers.
The assert was triggered since the check is case sensitive and the lock
was held on the normalized (lower case) version of the table name.

This patch fixes the problem by making sure a normalized version of the
table name is used for the metadata lock check, while using a non-normalized
version of the table name for the rename of trigger files. The same is done
for ALTER TABLE ... RENAME.

Regression testing for the bug itself is already covered by
lowercase_table2.test. Additional coverage added to lowercase_fs_off.test.

mysql-test/r/lowercase_fs_off.result

@@ -55,3 +55,11 @@ DROP USER user_1@localhost;
 DROP USER USER_1@localhost;
 DROP DATABASE db1;
 use test;
+#
+# Extra test coverage for Bug#56595 RENAME TABLE causes assert on OS X
+#
+CREATE TABLE t1(a INT);
+CREATE TRIGGER t1_bi BEFORE INSERT ON t1 FOR EACH ROW SET new.a= 1;
+RENAME TABLE t1 TO T1;
+ALTER TABLE T1 RENAME t1;
+DROP TABLE t1;

mysql-test/t/lowercase_fs_off.test

@@ -91,3 +91,14 @@ DROP DATABASE db1;
 use test;
 
 # End of 5.0 tests
+
+
+--echo #
+--echo # Extra test coverage for Bug#56595 RENAME TABLE causes assert on OS X
+--echo #
+
+CREATE TABLE t1(a INT);
+CREATE TRIGGER t1_bi BEFORE INSERT ON t1 FOR EACH ROW SET new.a= 1;
+RENAME TABLE t1 TO T1;
+ALTER TABLE T1 RENAME t1;
+DROP TABLE t1;

sql/sql_rename.cc

@@ -285,6 +285,7 @@ do_rename(THD *thd, TABLE_LIST *ren_table, char *new_db, char *new_table_name,
         {
           if ((rc= Table_triggers_list::change_table_name(thd, ren_table->db,
                                                           old_alias,
+                                                          ren_table->table_name,
                                                           new_db,
                                                           new_alias)))
           {

sql/sql_table.cc

@@ -5918,7 +5918,8 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
         *fn_ext(new_name)=0;
         if (mysql_rename_table(old_db_type,db,table_name,new_db,new_alias, 0))
           error= -1;
-        else if (Table_triggers_list::change_table_name(thd, db, table_name,
+        else if (Table_triggers_list::change_table_name(thd, db,
+                                                        alias, table_name,
                                                         new_db, new_alias))
         {
           (void) mysql_rename_table(old_db_type, new_db, new_alias, db,
@@ -6555,7 +6556,7 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
            (need_copy_table != ALTER_TABLE_METADATA_ONLY ||
             mysql_rename_table(save_old_db_type, db, table_name, new_db,
                                new_alias, NO_FRM_RENAME)) &&
-           Table_triggers_list::change_table_name(thd, db, table_name,
+           Table_triggers_list::change_table_name(thd, db, alias, table_name,
                                                   new_db, new_alias)))
   {
     /* Try to get everything back. */

sql/sql_trigger.cc

@@ -1874,6 +1874,7 @@ Table_triggers_list::change_table_name_in_trignames(const char *old_db_name,
 
   @param[in,out] thd Thread context
   @param[in] db Old database of subject table
+  @param[in] old_alias Old alias of subject table
   @param[in] old_table Old name of subject table
   @param[in] new_db New database for subject table
   @param[in] new_table New name of subject table
@@ -1890,6 +1891,7 @@ Table_triggers_list::change_table_name_in_trignames(const char *old_db_name,
 */
 
 bool Table_triggers_list::change_table_name(THD *thd, const char *db,
+                                            const char *old_alias,
                                             const char *old_table,
                                             const char *new_db,
                                             const char *new_table)
@@ -1911,7 +1913,7 @@ bool Table_triggers_list::change_table_name(THD *thd, const char *db,
                                              MDL_EXCLUSIVE));
 
   DBUG_ASSERT(my_strcasecmp(table_alias_charset, db, new_db) ||
-              my_strcasecmp(table_alias_charset, old_table, new_table));
+              my_strcasecmp(table_alias_charset, old_alias, new_table));
 
   if (Table_triggers_list::check_n_load(thd, db, old_table, &table, TRUE))
   {
@@ -1920,7 +1922,7 @@ bool Table_triggers_list::change_table_name(THD *thd, const char *db,
   }
   if (table.triggers)
   {
-    LEX_STRING old_table_name= { (char *) old_table, strlen(old_table) };
+    LEX_STRING old_table_name= { (char *) old_alias, strlen(old_alias) };
     LEX_STRING new_table_name= { (char *) new_table, strlen(new_table) };
     /*
       Since triggers should be in the same schema as their subject tables

sql/sql_trigger.h

@@ -157,6 +157,7 @@ public:
                            TABLE *table, bool names_only);
   static bool drop_all_triggers(THD *thd, char *db, char *table_name);
   static bool change_table_name(THD *thd, const char *db,
+                                const char *old_alias,
                                 const char *old_table,
                                 const char *new_db,
                                 const char *new_table);