Fix for bug#25026 `information_schema.KEY_COLUMN_USAGE`.`REFERENCED_TABLE_NAME` returns garbage

Unencode internal db & table name

mysql-test/r/information_schema_inno.result

@@ -56,3 +56,25 @@ test	t3	FOREIGN KEY	A2	test	t2	NONE	SET NULL	RESTRICT
 test	t4	FOREIGN KEY	A3	test	t3	NONE	NO ACTION	SET NULL
 test	t5	FOREIGN KEY	A4	test	t4	NONE	RESTRICT	CASCADE
 drop tables t5, t4, t3, t2, t1;
+create database `db-1`;
+use `db-1`;
+create table `t-2` (
+id int(10) unsigned not null auto_increment,
+primary key (id)
+) engine=innodb;
+create table `t-1` (
+id int(10) unsigned not null auto_increment,
+idtype int(10) unsigned not null,
+primary key (id),
+key fk_t1_1 (idtype),
+constraint fk_t1_1 foreign key (idtype) references `t-2` (id)
+) engine=innodb;
+use test;
+select referenced_table_schema, referenced_table_name 
+from information_schema.key_column_usage
+where constraint_schema = 'db-1';
+referenced_table_schema	referenced_table_name
+NULL	NULL
+db-1	t-2
+NULL	NULL
+drop database `db-1`;

mysql-test/t/information_schema_inno.test

+-- source include/testdb_only.inc
 -- source include/have_innodb.inc
 --disable_warnings
 DROP TABLE IF EXISTS t1,t2,t3;
@@ -53,3 +54,26 @@ from information_schema.TABLE_CONSTRAINTS a,
 where a.CONSTRAINT_SCHEMA = 'test' and a.CONSTRAINT_SCHEMA = b.CONSTRAINT_SCHEMA and
 a.CONSTRAINT_NAME = b.CONSTRAINT_NAME;
 drop tables t5, t4, t3, t2, t1;
+
+#
+# Bug#25026  `information_schema.KEY_COLUMN_USAGE`.`REFERENCED_TABLE_NAME` returns garbage
+#
+create database `db-1`;
+use `db-1`;
+create table `t-2` (
+  id int(10) unsigned not null auto_increment,
+  primary key (id)
+) engine=innodb;
+
+create table `t-1` (
+  id int(10) unsigned not null auto_increment,
+  idtype int(10) unsigned not null,
+  primary key (id),
+  key fk_t1_1 (idtype),
+  constraint fk_t1_1 foreign key (idtype) references `t-2` (id)
+) engine=innodb;
+use test;
+select referenced_table_schema, referenced_table_name 
+from information_schema.key_column_usage
+where constraint_schema = 'db-1';
+drop database `db-1`;

storage/innobase/handler/ha_innodb.cc

@@ -5933,6 +5933,9 @@ ha_innobase::get_foreign_key_list(THD *thd, List<FOREIGN_KEY_INFO> *f_key_list)
 	  uint i;
 	  FOREIGN_KEY_INFO f_key_info;
 	  LEX_STRING *name= 0;
+          uint ulen;
+          char uname[NAME_LEN*3+1];           /* Unencoded name */
+          char db_name[NAME_LEN*3+1];
 	  const char *tmp_buff;
 
 	  tmp_buff= foreign->id;
@@ -5943,14 +5946,23 @@ ha_innobase::get_foreign_key_list(THD *thd, List<FOREIGN_KEY_INFO> *f_key_list)
 	  f_key_info.forein_id= make_lex_string(thd, 0, tmp_buff,
 		  (uint) strlen(tmp_buff), 1);
 	  tmp_buff= foreign->referenced_table_name;
+
+          /* Database name */
 	  i= 0;
 	  while (tmp_buff[i] != '/')
-		  i++;
-	  f_key_info.referenced_db= make_lex_string(thd, 0,
-		  tmp_buff, i, 1);
+          {
+            db_name[i]= tmp_buff[i];
+            i++;
+          }
+          db_name[i]= 0;
+          ulen= filename_to_tablename(db_name, uname, sizeof(uname));
+          f_key_info.referenced_db= make_lex_string(thd, 0, uname, ulen, 1);
+
+          /* Table name */
 	  tmp_buff+= i + 1;
-	  f_key_info.referenced_table= make_lex_string(thd, 0, tmp_buff,
-		  (uint) strlen(tmp_buff), 1);
+          ulen= filename_to_tablename(tmp_buff, uname, sizeof(uname));
+          f_key_info.referenced_table= make_lex_string(thd, 0, uname,
+                                                       ulen, 1);
 
 	  for (i= 0;;) {
 		  tmp_buff= foreign->foreign_col_names[i];