BUG#13310 incorrect user parsing by SP

 - Strip surrounding ''s from username when a new user connects. There
   is no user 'a@', it should be a@

mysql-test/r/grant2.result

@@ -356,3 +356,16 @@ insert into mysql.user select * from t1;
 drop table t1, t2;
 drop database TESTDB;
 flush privileges;
+grant all privileges on test.* to `a@`@localhost;
+grant execute on * to `a@`@localhost;
+create table t2 (s1 int);
+insert into t2 values (1);
+drop function if exists f2;
+create function f2 () returns int begin declare v int; select s1 from t2
+into v; return v; end//
+select f2();
+f2()
+1
+drop function f2;
+drop table t2;
+REVOKE ALL PRIVILEGES, GRANT OPTION FROM `a@`@localhost;

mysql-test/t/grant2.test

@@ -465,3 +465,28 @@ drop table t1, t2;
 drop database TESTDB;
 flush privileges;
 
+#
+# BUG#13310 incorrect user parsing by SP
+#
+
+grant all privileges on test.* to `a@`@localhost;
+grant execute on * to `a@`@localhost;
+connect (bug13310,localhost,'a@',,test);
+connection bug13310;
+create table t2 (s1 int);
+insert into t2 values (1);
+--disable_warnings
+drop function if exists f2;
+--enable_warnings
+delimiter //;
+create function f2 () returns int begin declare v int; select s1 from t2
+into v; return v; end//
+delimiter ;//
+select f2();
+
+drop function f2;
+drop table t2;
+disconnect bug13310;
+
+connection default;
+REVOKE ALL PRIVILEGES, GRANT OPTION FROM `a@`@localhost;

sql/sql_parse.cc

@@ -993,6 +993,7 @@ static int check_connection(THD *thd)
 
   char *user= end;
   char *passwd= strend(user)+1;
+  uint user_len= passwd - user - 1;
   char *db= passwd;
   char db_buff[NAME_LEN+1];                     // buffer to store db in utf8
   char user_buff[USERNAME_LENGTH+1];		// buffer to store user in utf8
@@ -1018,11 +1019,19 @@ static int check_connection(THD *thd)
     db= db_buff;
   }
 
-  user_buff[copy_and_convert(user_buff, sizeof(user_buff)-1,
-                             system_charset_info, user, strlen(user),
-                             thd->charset(), &dummy_errors)]= '\0';
+  user_buff[user_len= copy_and_convert(user_buff, sizeof(user_buff)-1,
+                                       system_charset_info, user, user_len,
+                                       thd->charset(), &dummy_errors)]= '\0';
   user= user_buff;
 
+  /* If username starts and ends in "'", chop them off */
+  if (user_len > 1 && user[0] == '\'' && user[user_len - 1] == '\'')
+  {
+    user[user_len-1]= 0;
+    user++;
+    user_len-= 2;
+  }
+
   if (thd->main_security_ctx.user)
     x_free(thd->main_security_ctx.user);
   if (!(thd->main_security_ctx.user= my_strdup(user, MYF(0))))