Fixing #5823 - Don't fallback to 'classic'

-issue#5823: If active theme is missing ensure the fallback is not the classic theme

CHANGELOG

@@ -23,6 +23,7 @@ Cacti CHANGELOG
 -issue#5802: Cacti should not convert non-base tables as they may have an focused characters set and engine
 -issue#5806: Issues with Cacti posix_kill wrapper in Windows
 -issue#5813: Can't change password when first installing
+-issue#5823: If active theme is missing ensure the fallback is not the classic theme
 -issue#5824: Properly cache the data source information for dsstats processing
 -feature#5784: Provide a means by which a user can track Cacti connections and disconnects from the php error_log
 -feature#5796: Due to Conflicting Interpretations of TCP Ping, Introduce new Ping Method

lib/functions.php

@@ -796,23 +796,25 @@ function get_selected_theme() {
 			array($_SESSION['sess_user_id']), '', false);
 
 		// user has a theme
-		if (! empty($user_theme)) {
+		if (!empty($user_theme)) {
 			$theme = $user_theme;;
 		}
 	}
 
 	if (!file_exists($config['base_path'] . '/include/themes/' . $theme . '/main.css')) {
 		foreach($themes as $t => $name) {
-			if (file_exists($config['base_path'] . '/include/themes/' . $t . '/main.css')) {
-				$theme = $t;
+			if ($t != 'classic') {
+				if (file_exists($config['base_path'] . '/include/themes/' . $t . '/main.css')) {
+					$theme = $t;
 
-				db_execute_prepared('UPDATE settings_user
-					SET value = ?
-					WHERE user_id = ?
-					AND name="selected_theme"',
-					array($theme, $_SESSION['sess_user_id']));
+					db_execute_prepared('UPDATE settings_user
+						SET value = ?
+						WHERE user_id = ?
+						AND name = "selected_theme"',
+						array($theme, $_SESSION['sess_user_id']));
 
-				break;
+					break;
+				}
 			}
 		}
 	}