Add possibility to configure max_allowed_packet value for all database engines (#1490283)

CHANGELOG

@@ -2,6 +2,7 @@ CHANGELOG Roundcube Webmail
 ===========================
 
 - Add possibility to print contact information (of a single contact)
+- Add possibility to configure max_allowed_packet value for all database engines (#1490283)
 - Fix refreshing of drafts list when sending a message which was saved in meantime (#1490238)
 - Fix saving/sending emoticon images when assets_dir is set
 - Fix PHP fatal error when visiting Vacation interface and there's no sieve script yet

config/defaults.inc.php

@@ -51,6 +51,12 @@ $config['db_table_dsn'] = array(
 //    'cache_messages' => 'r',
 );
 
+// It is possible to specify database variable values e.g. some limits here.
+// Use them if your server is not MySQL or for better performance.
+// For example Roundcube uses max_allowed_packet value (in bytes)
+// which limits query size for database cache operations.
+$config['db_max_allowed_packet'] = 23423440;
+
 
 // ----------------------------------
 // LOGGING/DEBUGGING

program/lib/Roundcube/rcube_db.php

@@ -357,7 +357,7 @@ class rcube_db
     public function get_variable($varname, $default = null)
     {
         // to be implemented by driver class
-        return $default;
+        return rcube::get_instance()->config->get('db_' . $varname, $default);
     }
 
     /**

program/lib/Roundcube/rcube_db_mysql.php

@@ -167,6 +167,12 @@ class rcube_db_mysql extends rcube_db
             return $this->variables[$varname];
         }
 
+        // configured value has higher prio
+        $conf_value = rcube::get_instance()->config->get('db_' . $varname);
+        if ($conf_value !== null) {
+            return $this->variables[$varname] = $conf_value;
+        }
+
         $result = $this->query('SHOW VARIABLES LIKE ?', $varname);
 
         while ($row = $this->fetch_array($result)) {

program/lib/Roundcube/rcube_db_pgsql.php

@@ -139,9 +139,11 @@ class rcube_db_pgsql extends rcube_db
         // There's a known case when max_allowed_packet is queried
         // PostgreSQL doesn't have such limit, return immediately
         if ($varname == 'max_allowed_packet') {
-            return $default;
+            return rcube::get_instance()->config->get('db_' . $varname, $default);
         }
 
+        $this->variables[$varname] = rcube::get_instance()->config->get('db_' . $varname);
+
         if (!isset($this->variables)) {
             $this->variables = array();