Bug #19929435 DROP DATABASE HANGS WITH MALFORMED TABLE

Note: Backporting the patch from mysql-5.6.

Problem:

A CREATE TABLE with an invalid table name is detected
at SQL layer. So the table name is reset to an empty
string.  But the storage engine is called with this
empty table name.  The table name is specified as
"database/table".  So, in the given scenario we get
only "database/".

Solution:

Within InnoDB, detect this error and report it to
higher layer.

rb#9274 approved by jimmy.

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

+#
+# Bug #19929435 DROP DATABASE HANGS WITH MALFORMED TABLE
+#
+set session default_storage_engine=innodb;
+create database `b`;
+use `b`;
+create table `#mysql50#q.q` select 1;
+ERROR HY000: Can't create table 'b.#mysql50#q.q' (errno: 1103)
+drop database `b`;

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

+--source include/have_innodb.inc
+
+--echo #
+--echo # Bug #19929435 DROP DATABASE HANGS WITH MALFORMED TABLE
+--echo #
+
+set session default_storage_engine=innodb;
+create database `b`;
+use `b`;
+--error ER_CANT_CREATE_TABLE
+create table `#mysql50#q.q` select 1;
+drop database `b`;

storage/innobase/handler/ha_innodb.cc

@@ -6529,7 +6529,8 @@ create_table_def(
 
 	/* MySQL does the name length check. But we do additional check
 	on the name length here */
-	if (strlen(table_name) > MAX_FULL_NAME_LEN) {
+	const size_t	table_name_len = strlen(table_name);
+	if (table_name_len > MAX_FULL_NAME_LEN) {
 		push_warning_printf(
 			(THD*) trx->mysql_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
 			ER_TABLE_NAME,
@@ -6538,6 +6539,15 @@ create_table_def(
 		DBUG_RETURN(ER_TABLE_NAME);
 	}
 
+	if (table_name[table_name_len - 1] == '/') {
+		push_warning_printf(
+			(THD*) trx->mysql_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
+			ER_TABLE_NAME,
+			"InnoDB: Table name is empty");
+
+		DBUG_RETURN(ER_WRONG_TABLE_NAME);
+	}
+
 	n_cols = form->s->fields;
 
 	/* We pass 0 as the space id, and determine at a lower level the space