Define a helper class to allow for saving sql_mode using RAII

On construction the Sql_mode_save class stores the current THD's
sql_mode. On destruction, the THD's mode is restored.

sql/sql_acl.cc

@@ -1198,11 +1198,10 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
 {
   TABLE *table;
   READ_RECORD read_record_info;
-  bool return_val= TRUE;
   bool check_no_resolve= specialflag & SPECIAL_NO_RESOLVE;
   char tmp_name[SAFE_NAME_LEN+1];
   int password_length;
-  sql_mode_t old_sql_mode= thd->variables.sql_mode;
+  Sql_mode_save old_mode_save(thd);
   DBUG_ENTER("acl_load");
 
   thd->variables.sql_mode&= ~MODE_PAD_CHAR_TO_FULL_LENGTH;
@@ -1214,7 +1213,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
   {
     if (init_read_record(&read_record_info, thd, table, NULL, NULL,
                          1, 1, FALSE))
-      goto end;
+      DBUG_RETURN(TRUE);
     table->use_all_columns();
     while (!(read_record_info.read_record(&read_record_info)))
     {
@@ -1269,7 +1268,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
 
   if (init_read_record(&read_record_info, thd, table=tables[USER_TABLE].table,
                        NULL, NULL, 1, 1, FALSE))
-    goto end;
+    DBUG_RETURN(TRUE);
   table->use_all_columns();
 
   username_char_length= MY_MIN(table->field[1]->char_length(),
@@ -1280,7 +1279,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
   {
     sql_print_error("Fatal error: mysql.user table is damaged or in "
                     "unsupported 3.20 format.");
-    goto end;
+    DBUG_RETURN(TRUE);
   }
 
   DBUG_PRINT("info",("user table fields: %d, password length: %d",
@@ -1294,7 +1293,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
       mysql_mutex_unlock(&LOCK_global_system_variables);
       sql_print_error("Fatal error: mysql.user table is in old format, "
                       "but server started with --secure-auth option.");
-      goto end;
+      DBUG_RETURN(TRUE);
     }
     mysql_user_table_is_in_short_password_format= true;
     if (global_system_variables.old_passwords)
@@ -1527,7 +1526,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
 
   if (init_read_record(&read_record_info, thd, table=tables[DB_TABLE].table,
                        NULL, NULL, 1, 1, FALSE))
-    goto end;
+    DBUG_RETURN(TRUE);
   table->use_all_columns();
   while (!(read_record_info.read_record(&read_record_info)))
   {
@@ -1594,7 +1593,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
   {
     if (init_read_record(&read_record_info, thd, table,
                          NULL, NULL, 1, 1, FALSE))
-      goto end;
+      DBUG_RETURN(TRUE);
     table->use_all_columns();
     while (!(read_record_info.read_record(&read_record_info)))
     {
@@ -1603,10 +1602,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
       if (proxy.check_validity(check_no_resolve))
         continue;
       if (push_dynamic(&acl_proxy_users, (uchar*) &proxy))
-      {
-        end_read_record(&read_record_info);
-        goto end;
-      }
+        DBUG_RETURN(TRUE);
     }
     my_qsort((uchar*) dynamic_element(&acl_proxy_users, 0, ACL_PROXY_USER*),
              acl_proxy_users.elements,
@@ -1624,7 +1620,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
   {
     if (init_read_record(&read_record_info, thd, table, NULL, NULL, 1, 1,
                          FALSE))
-      goto end;
+      DBUG_RETURN(TRUE);
     table->use_all_columns();
 
     MEM_ROOT temp_root;
@@ -1662,12 +1658,7 @@ static bool acl_load(THD *thd, TABLE_LIST *tables)
   init_check_host();
 
   initialized=1;
-  return_val= FALSE;
-
-end:
-  end_read_record(&read_record_info);
-  thd->variables.sql_mode= old_sql_mode;
-  DBUG_RETURN(return_val);
+  DBUG_RETURN(FALSE);
 }
 
 

sql/sql_class.h

@@ -5712,6 +5712,22 @@ inline bool binlog_should_compress(ulong len)
     len >= opt_bin_log_compress_min_len;
 }
 
+
+/**
+   Save thd sql_mode on instantiation.
+   On destruction it resets the mode to the previously stored value.
+*/
+class Sql_mode_save
+{
+ public:
+  Sql_mode_save(THD *thd) : thd(thd), old_mode(thd->variables.sql_mode) {}
+  ~Sql_mode_save() { thd->variables.sql_mode = old_mode; }
+
+ private:
+  THD *thd;
+  sql_mode_t old_mode; // SQL mode saved at construction time.
+};
+
 #endif /* MYSQL_SERVER */
 
 #endif /* SQL_CLASS_INCLUDED */