Bug#26703: DROP DATABASE fails if database contains a #mysql50# \

	table with backticks

(Thanks to Lu Jingdong, though I did not take his patch directly, as
it contained a significant flaw.)

It wasn't a backtick/parsing problem.  We merely didn't anticipate
and allocate enough space to handle the optional "#mysql50#" table-
name prefix. 

Now, allocate that extra space in case we need it when we look up 
a legacy table to get its file's name.

mysql-test/r/drop.result

@@ -91,4 +91,15 @@ create table mysql_test.`#sql-347f_7` (f1 int);
 create table mysql_test.`#sql-347f_8` (f1 int);
 drop table mysql_test.`#sql-347f_8`;
 drop database mysql_test;
+create database mysqltestbug26703;
+use mysqltestbug26703;
+create table `#mysql50#abc``def` ( id int );
+create table `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+ERROR 42000: Incorrect table name 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
+create table `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+create table `#mysql50#aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+create table `#mysql50#aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+ERROR 42000: Incorrect table name '#mysql50#aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
+use test;
+drop database mysqltestbug26703;
 End of 5.1 tests

mysql-test/t/drop.test

@@ -134,4 +134,19 @@ drop table mysql_test.`#sql-347f_8`;
 copy_file $MYSQLTEST_VARDIR/master-data/mysql_test/t1.frm $MYSQLTEST_VARDIR/master-data/mysql_test/#sql-347f_6.frm;
 drop database mysql_test;
 
+#
+# Bug#26703: DROP DATABASE fails if database contains a #mysql50# table with backticks
+#
+create database mysqltestbug26703;
+use mysqltestbug26703;
+create table `#mysql50#abc``def` ( id int );
+--error ER_WRONG_TABLE_NAME
+create table `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+create table `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+create table `#mysql50#aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+--error ER_WRONG_TABLE_NAME
+create table `#mysql50#aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` (a int);
+use test;
+drop database mysqltestbug26703;
+
 --echo End of 5.1 tests

sql/sql_db.cc

@@ -1111,12 +1111,17 @@ static long mysql_rm_known_files(THD *thd, MY_DIR *dirp, const char *db,
       /* Drop the table nicely */
       *extension= 0;			// Remove extension
       TABLE_LIST *table_list=(TABLE_LIST*)
-	thd->calloc(sizeof(*table_list)+ strlen(db)+strlen(file->name)+2);
+                              thd->calloc(sizeof(*table_list) + 
+                                          strlen(db) + 1 +
+                                          MYSQL50_TABLE_NAME_PREFIX_LENGTH + 
+                                          strlen(file->name) + 1);
+
       if (!table_list)
         goto err;
       table_list->db= (char*) (table_list+1);
       table_list->table_name= strmov(table_list->db, db) + 1;
       VOID(filename_to_tablename(file->name, table_list->table_name,
+                                 MYSQL50_TABLE_NAME_PREFIX_LENGTH +
                                  strlen(file->name) + 1));
       table_list->alias= table_list->table_name;	// If lower_case_table_names=2
       table_list->internal_tmp_table= is_prefix(file->name, tmp_file_prefix);