1 files changed, 63 insertions, 31 deletions
diff --git a/upgrade.php b/upgrade.php
index ac4cb57ca..d07b2a1da 100644
--- a/upgrade.php
+++ b/upgrade.php
@@ -1,35 +1,67 @@
 <?php
-	/**
-	 * Elgg upgrade script.
-	 * 
-	 * This script triggers any upgrades necessary, ensuring that upgrades are triggered deliberately by a single
-	 * user.
-	 * 
-	 * @package Elgg
-	 * @subpackage Core
-	 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
-	 * @author Curverider Ltd
-	 * @copyright Curverider Ltd 2008-2009
-	 * @link http://elgg.org/
-	 */
+/**
+ * Elgg upgrade script.
+ *
+ * This script triggers any necessary upgrades. If the site has been upgraded
+ * to the most recent version of the code, no upgrades are run and the caches
+ * are flushed. If you would prefer that this script is not accessible to others
+ * after an upgrade, you can delete it. Future versions of Elgg will include a
+ * new version of the script. Deleting the script is not a requirement and
+ * leaving it behind does not affect the security of the site.
+ *
+ * Upgrades use a table {db_prefix}upgrade_lock as a mutex to prevent concurrent upgrades.
+ *
+ * @package Elgg.Core
+ * @subpackage Upgrade
+ */
 
-	// Include elgg engine
-	define('upgrading','upgrading');
-	define('externalpage',true);
-	require_once(dirname(__FILE__) . "/engine/start.php");
-	
-	if (get_input('upgrade') == 'upgrade') {
-		if (version_upgrade_check()) {
-			version_upgrade();
-		}
-		datalist_set('simplecache_lastupdate',0);
-		
-		elgg_filepath_cache_reset();
-	} else {
-		global $CONFIG;
-		echo elgg_view('settings/upgrading');
-		exit;
+// we want to know if an error occurs
+ini_set('display_errors', 1);
+
+define('UPGRADING', 'upgrading');
+require_once(dirname(__FILE__) . "/engine/start.php");
+
+if (get_input('upgrade') == 'upgrade') {
+	// prevent someone from running the upgrade script in parallel (see #4643)
+	if (!_elgg_upgrade_lock()) {
+		register_error(elgg_echo('upgrade:locked'));
+		forward();
+	}
+	
+	// disable the system log for upgrades to avoid exceptions when the schema changes.
+	elgg_unregister_event_handler('log', 'systemlog', 'system_log_default_logger');
+	elgg_unregister_event_handler('all', 'all', 'system_log_listener');
+	
+	if (elgg_get_unprocessed_upgrades()) {
+		version_upgrade();
 	}
+
+	// turn off time limit so plugins that have upgrade scripts aren't interrupted
+	set_time_limit(0);
+	elgg_trigger_event('upgrade', 'system', null);
+	elgg_invalidate_simplecache();
+	elgg_reset_system_cache();
+	
+	_elgg_upgrade_unlock();
 	
-	forward();
-?>
-\ No newline at end of file
+} else {
+	// if upgrading from < 1.8.0, check for the core view 'welcome' and bail if it's found.
+	// see https://github.com/elgg/elgg/issues/3064
+	// we're not checking the view itself because it's likely themes will override this view.
+	// we're only concerned with core files.
+	$welcome = dirname(__FILE__) . '/views/default/welcome.php';
+	if (file_exists($welcome)) {
+		elgg_set_viewtype('failsafe');
+		// can't have pretty messages because we don't know the state of the views.
+		$content = elgg_echo('upgrade:unable_to_upgrade_info');
+		$title = elgg_echo('upgrade:unable_to_upgrade');
+		
+		echo elgg_view_page($title, $content);
+		exit;
+	}
+
+	echo elgg_view_page(elgg_echo('upgrading'), '', 'upgrade');
+	exit;
+}
+
+forward();