Ticket #22704: 22704.whitescreen-rollback.diff

src/wp-admin/includes/class-wp-upgrader.php

@@ -1298 +1298 @@
 
                 $result = update_core( $working_dir, $wp_dir );
 
+                $try_rollback = false;
+                if ( is_wp_error( $result ) ) {
+                        $try_rollback = true;
+                } else {
+                        $site_test = $this->test_if_site_is_ok();
+                        if ( is_wp_error( $site_test ) ) {
+                                $result = $site_test;
+                                $try_rollback = true;
+                        }
+                }
+
                 // In the event of an error, rollback to the previous version
-                if ( is_wp_error( $result ) && $parsed_args['attempt_rollback'] && $current->packages->rollback && ! $parsed_args['do_rollback'] ) {
+                if ( $try_rollback && $parsed_args['attempt_rollback'] && $current->packages->rollback && ! $parsed_args['do_rollback'] ) {
                         apply_filters( 'update_feedback', $result );
                         apply_filters( 'update_feedback', $this->strings['start_rollback'] );
 
@@ -1339 +1350 @@
                         }
                 }
 
+                // Don't upgrade if we can't verify that the site is OK
+                if ( true !== $this->test_if_site_is_ok() )
+                        return false;
+
                 // 1: If we're already on that version, not much point in updating?
                 if ( $offered_ver == $wp_version )
                         return false;
@@ -1366 +1381 @@
                 return false;
         }
 
+        function test_if_site_is_ok() {
+                // Is the Admin ajax handler returning what we expect of it? 
+                $http_result = wp_remote_post( admin_url( 'admin-ajax.php?action=test-upgrade-OK' ), array( 'timeout' => 10 ) );
+                $admin_ok = ( 'OK' === wp_remote_retrieve_body( $http_result ) );
+
+                if ( ! $admin_ok )
+                        return new WP_Error( 'admin_check_failed', __(''), wp_remote_retrieve_body( $http_result ) );
+
+                // Is the front-end returning what we'd expect of it? (Note, This is a filter on template_redirect)
+                $http_result = wp_remote_post( site_url( '?test-upgrade-OK=1' ), array( 'timeout' => 10 ) );
+                $front_ok = ( 'OK' === wp_remote_retrieve_body( $http_result ) );
+
+                if ( ! $front_ok )
+                        return new WP_Error( 'site_check_failed', __(''), wp_remote_retrieve_body( $http_result ) );
+
+                return true;
+        }
+
         function check_files() {
                 global $wp_version;
 

src/wp-includes/update.php

@@ -521 +521 @@
         wp_update_themes();
 }
 
+function site_is_OK_callback() {
+        die( 'OK' );
+}
+
 /**
  * Schedule core, theme, and plugin update checks.
  *
@@ -562 +566 @@
 add_action( 'wp_update_themes', 'wp_update_themes' );
 add_action( 'upgrader_process_complete', 'wp_update_themes' );
 
+add_action('init', 'wp_schedule_update_checks');
+
 // Automatic Updates - Cron callback
 add_action( 'wp_auto_updates_maybe_update', 'wp_auto_updates_maybe_update' );
 
-add_action('init', 'wp_schedule_update_checks');
+// Automatic Updates - Site is OK callbacks
+if ( isset( $_GET['test-upgrade-OK'] ) )
+        add_action( 'template_redirect', 'site_is_OK_callback' );
+
+add_action( 'wp_ajax_test-upgrade-OK', 'site_is_OK_callback' );
+add_action( 'wp_ajax_nopriv_test-upgrade-OK', 'site_is_OK_callback' );