Merge branch 'master-read-only-check' into next

public/include/database.inc.php

@@ -7,6 +7,11 @@ if (!defined('SECURITY'))
 // Instantiate class, we are using mysqlng
 $mysqli = new mysqli($config['db']['host'], $config['db']['user'], $config['db']['pass'], $config['db']['name'], $config['db']['port']);
 
+// Check if read-only and quit if it is on
+if ($mysqli->query('/* MYSQLND_MS_MASTER_SWITCH */SELECT @@global.read_only AS read_only')->fetch_object()->read_only == 1) {
+  die('Database is in READ-ONLY mode');
+}
+
 /* check connection */
 if (mysqli_connect_errno()) {
   die("Failed to connect to database");