MDEV-8609 Server crashes in is_invalid_role_name on reloading ACL with a blank role name

strip endspaces from the role name in the parser
because they'll be lost anyway when the name is stored
in the mysql.user.user column (of type CHAR)

mysql-test/suite/roles/create_and_drop_role.result

@@ -36,6 +36,10 @@ select user, host, is_role from user where user like 'test%';
 user	host	is_role
 create role '';
 ERROR OP000: Invalid role specification ``.
+create role ' ';
+ERROR OP000: Invalid role specification ``.
+create role 'foo  ';
+drop role foo;
 create role r1;
 drop user r1;
 ERROR HY000: Operation DROP USER failed for 'r1'@'%'

mysql-test/suite/roles/create_and_drop_role.test

@@ -52,6 +52,14 @@ connection default;
 --error ER_INVALID_ROLE
 create role '';
 
+#
+# MDEV-8609 Server crashes in is_invalid_role_name on reloading ACL with a blank role name
+#
+--error ER_INVALID_ROLE
+create role ' ';
+create role 'foo  ';
+drop role foo;
+
 #
 # MDEV-5523 Server crashes on DROP USER <rolename>
 #

sql/sql_yacc.yy

@@ -15170,6 +15170,9 @@ current_role:
 grant_role:
           ident_or_text
           {
+            CHARSET_INFO *cs= system_charset_info;
+            /* trim end spaces (as they'll be lost in mysql.user anyway) */
+            $1.length= cs->cset->lengthsp(cs, $1.str, $1.length);
             if ($1.length == 0)
             {
               my_error(ER_INVALID_ROLE, MYF(0), "");
@@ -15184,8 +15187,7 @@ grant_role:
             $$->auth= empty_lex_str;
 
             if (check_string_char_length(&$$->user, ER(ER_USERNAME),
-                                         username_char_length,
-                                         system_charset_info, 0))
+                                         username_char_length, cs, 0))
               MYSQL_YYABORT;
           }
         | current_role