Changeset 44973

Timestamp:

03/21/2019 09:52:07 PM (8 years ago)

Author:

flixos90

Message:

Bootstrap/Load: Introduce a recovery mode for fixing fatal errors.

Using the new fatal handler introduced in [44962], an email is sent to the admin when a fatal error occurs. This email includes a secret link to enter recovery mode. When clicked, the link will be validated and on success a cookie will be placed on the client, enabling recovery mode for that user. This functionality is executed early before plugins and themes are loaded, in order to be unaffected by potential fatal errors these might be causing.

When in recovery mode, broken plugins and themes will be paused for that client, so that they are able to access the admin backend despite of these errors. They are notified about the broken extensions and the errors caused, and can then decide whether they would like to temporarily deactivate the extension or fix the problem and resume the extension.

A link in the admin bar allows the client to exit recovery mode.

Props timothyblynjacobs, afragen, flixos90, nerrad, miss_jwo, schlessera, spacedmonkey, swissspidy.
Fixes #46130, #44458.

Location:

trunk

Files:

• src/wp-admin/css/list-tables.css (modified) (1 diff)
• src/wp-admin/includes/admin-filters.php (modified) (1 diff)
• src/wp-admin/includes/class-wp-plugins-list-table.php (modified) (11 diffs)
• src/wp-admin/includes/plugin.php (modified) (2 diffs)
• src/wp-admin/includes/theme.php (modified) (1 diff)
• src/wp-admin/plugins.php (modified) (3 diffs)
• src/wp-admin/themes.php (modified) (5 diffs)
• src/wp-includes/admin-bar.php (modified) (1 diff)
• src/wp-includes/capabilities.php (modified) (2 diffs)
• src/wp-includes/class-wp-admin-bar.php (modified) (1 diff)
• src/wp-includes/class-wp-fatal-error-handler.php (modified) (1 diff)
• src/wp-includes/class-wp-paused-extensions-storage.php (added)
• src/wp-includes/class-wp-recovery-mode-cookie-service.php (added)
• src/wp-includes/class-wp-recovery-mode-email-service.php (added)
• src/wp-includes/class-wp-recovery-mode-key-service.php (added)
• src/wp-includes/class-wp-recovery-mode-link-service.php (added)
• src/wp-includes/class-wp-recovery-mode.php (added)
• src/wp-includes/class-wp-theme.php (modified) (1 diff)
• src/wp-includes/default-constants.php (modified) (1 diff)
• src/wp-includes/default-filters.php (modified) (1 diff)
• src/wp-includes/error-protection.php (modified) (2 diffs)
• src/wp-includes/load.php (modified) (2 diffs)
• src/wp-login.php (modified) (2 diffs)
• src/wp-settings.php (modified) (2 diffs)
• tests/phpunit/tests/error-protection (added)
• tests/phpunit/tests/error-protection/recovery-mode-cookie-service.php (added)
• tests/phpunit/tests/error-protection/recovery-mode-key-service.php (added)
• tests/phpunit/tests/user/capabilities.php (modified) (4 diffs)

trunk/src/wp-admin/css/list-tables.css

@@ -1311 +1311 @@
 }
 
+.plugins tr.paused th.check-column {
+        border-left: 4px solid #d54e21;
+}
+
+.plugins tr.paused th,
+.plugins tr.paused td {
+        background-color: #fef7f1;
+}
+
+.plugins tr.paused .plugin-title,
+.plugins .paused .dashicons-warning {
+        color: #dc3232;
+}
+
+.plugins .paused .error-display p,
+.plugins .paused .error-display code {
+        font-size: 90%;
+        font-style: italic;
+        color: rgb( 0, 0, 0, 0.7 );
+}
+
+.plugins .resume-link {
+        color: #dc3232;
+}
+
 .plugin-card .update-now:before {
         color: #f56e28;

trunk/src/wp-admin/includes/admin-filters.php

@@ -118 +118 @@
 
 add_action( 'admin_notices', 'update_nag', 3 );
+add_action( 'admin_notices', 'paused_plugins_notice', 5 );
+add_action( 'admin_notices', 'paused_themes_notice', 5 );
 add_action( 'admin_notices', 'maintenance_nag', 10 );
 

trunk/src/wp-admin/includes/class-wp-plugins-list-table.php

@@ -41 +41 @@
 
                 $status = 'all';
-                if ( isset( $_REQUEST['plugin_status'] ) && in_array( $_REQUEST['plugin_status'], array( 'active', 'inactive', 'recently_activated', 'upgrade', 'mustuse', 'dropins', 'search' ) ) ) {
+                if ( isset( $_REQUEST['plugin_status'] ) && in_array( $_REQUEST['plugin_status'], array( 'active', 'inactive', 'recently_activated', 'upgrade', 'mustuse', 'dropins', 'search', 'paused' ) ) ) {
                         $status = $_REQUEST['plugin_status'];
                 }
@@ -100 +100 @@
                         'mustuse'            => array(),
                         'dropins'            => array(),
+                        'paused'             => array(),
                 );
 
@@ -184 +185 @@
                         // Extra info if known. array_merge() ensures $plugin_data has precedence if keys collide.
                         if ( isset( $plugin_info->response[ $plugin_file ] ) ) {
-                                $plugins['all'][ $plugin_file ] = $plugin_data = array_merge( (array) $plugin_info->response[ $plugin_file ], $plugin_data );
+                                $plugin_data                    = array_merge( (array) $plugin_info->response[ $plugin_file ], $plugin_data );
+                                $plugins['all'][ $plugin_file ] = $plugin_data;
                                 // Make sure that $plugins['upgrade'] also receives the extra info since it is used on ?plugin_status=upgrade
                                 if ( isset( $plugins['upgrade'][ $plugin_file ] ) ) {
-                                        $plugins['upgrade'][ $plugin_file ] = $plugin_data = array_merge( (array) $plugin_info->response[ $plugin_file ], $plugin_data );
+                                        $plugins['upgrade'][ $plugin_file ] = $plugin_data;
                                 }
                         } elseif ( isset( $plugin_info->no_update[ $plugin_file ] ) ) {
-                                $plugins['all'][ $plugin_file ] = $plugin_data = array_merge( (array) $plugin_info->no_update[ $plugin_file ], $plugin_data );
+                                $plugin_data                    = array_merge( (array) $plugin_info->no_update[ $plugin_file ], $plugin_data );
+                                $plugins['all'][ $plugin_file ] = $plugin_data;
                                 // Make sure that $plugins['upgrade'] also receives the extra info since it is used on ?plugin_status=upgrade
                                 if ( isset( $plugins['upgrade'][ $plugin_file ] ) ) {
-                                        $plugins['upgrade'][ $plugin_file ] = $plugin_data = array_merge( (array) $plugin_info->no_update[ $plugin_file ], $plugin_data );
+                                        $plugins['upgrade'][ $plugin_file ] = $plugin_data;
                                 }
                         }
@@ -219 +222 @@
                                 // On the network-admin screen, populate the active list with plugins that are network activated
                                 $plugins['active'][ $plugin_file ] = $plugin_data;
+
+                                if ( ! $screen->in_admin( 'network' ) && is_plugin_paused( $plugin_file ) ) {
+                                        $plugins['paused'][ $plugin_file ] = $plugin_data;
+                                }
                         } else {
                                 if ( isset( $recently_activated[ $plugin_file ] ) ) {
@@ -445 +452 @@
                                         /* translators: %s: plugin count */
                                         $text = _n( 'Drop-ins <span class="count">(%s)</span>', 'Drop-ins <span class="count">(%s)</span>', $count );
+                                        break;
+                                case 'paused':
+                                        /* translators: %s: plugin count */
+                                        $text = _n( 'Paused <span class="count">(%s)</span>', 'Paused <span class="count">(%s)</span>', $count );
                                         break;
                                 case 'upgrade':
@@ -658 +669 @@
                                                 $actions['deactivate'] = '<a href="' . wp_nonce_url( 'plugins.php?action=deactivate&amp;plugin=' . urlencode( $plugin_file ) . '&amp;plugin_status=' . $context . '&amp;paged=' . $page . '&amp;s=' . $s, 'deactivate-plugin_' . $plugin_file ) . '" aria-label="' . esc_attr( sprintf( _x( 'Deactivate %s', 'plugin' ), $plugin_data['Name'] ) ) . '">' . __( 'Deactivate' ) . '</a>';
                                         }
+                                        if ( current_user_can( 'resume_plugin', $plugin_file ) && is_plugin_paused( $plugin_file ) ) {
+                                                /* translators: %s: plugin name */
+                                                $actions['resume'] = '<a class="resume-link" href="' . wp_nonce_url( 'plugins.php?action=resume&amp;plugin=' . urlencode( $plugin_file ) . '&amp;plugin_status=' . $context . '&amp;paged=' . $page . '&amp;s=' . $s, 'resume-plugin_' . $plugin_file ) . '" aria-label="' . esc_attr( sprintf( _x( 'Resume %s', 'plugin' ), $plugin_data['Name'] ) ) . '">' . __( 'Resume' ) . '</a>';
+                                        }
                                 } else {
                                         if ( current_user_can( 'activate_plugin', $plugin_file ) ) {
@@ -764 +779 @@
                 if ( ! empty( $totals['upgrade'] ) && ! empty( $plugin_data['update'] ) ) {
                         $class .= ' update';
+                }
+
+                $paused = ! $screen->in_admin( 'network' ) && is_plugin_paused( $plugin_file );
+
+                if ( $paused ) {
+                        $class .= ' paused';
                 }
 
@@ -847 +868 @@
                                          * @param string   $status      Status of the plugin. Defaults are 'All', 'Active',
                                          *                              'Inactive', 'Recently Activated', 'Upgrade', 'Must-Use',
-                                         *                              'Drop-ins', 'Search'.
+                                         *                              'Drop-ins', 'Search', 'Paused'.
                                          */
                                         $plugin_meta = apply_filters( 'plugin_row_meta', $plugin_meta, $plugin_file, $plugin_data, $status );
@@ -853 +874 @@
 
                                         echo '</div>';
+
+                                        if ( $paused ) {
+                                                $notice_text = __( 'This plugin failed to load properly and is paused during recovery mode.' );
+
+                                                printf( '<p><span class="dashicons dashicons-warning"></span> <strong>%s</strong></p>', $notice_text );
+
+                                                $error = wp_get_plugin_error( $plugin_file );
+
+                                                if ( false !== $error ) {
+                                                        printf( '<div class="error-display"><p>%s</p></div>', wp_get_extension_error_description( $error ) );
+                                                }
+                                        }
 
                                         echo '</td>';
@@ -887 +920 @@
                  * @param string $status      Status of the plugin. Defaults are 'All', 'Active',
                  *                            'Inactive', 'Recently Activated', 'Upgrade', 'Must-Use',
-                 *                            'Drop-ins', 'Search'.
+                 *                            'Drop-ins', 'Search', 'Paused'.
                  */
                 do_action( 'after_plugin_row', $plugin_file, $plugin_data, $status );
@@ -903 +936 @@
                  * @param string $status      Status of the plugin. Defaults are 'All', 'Active',
                  *                            'Inactive', 'Recently Activated', 'Upgrade', 'Must-Use',
-                 *                            'Drop-ins', 'Search'.
+                 *                            'Drop-ins', 'Search', 'Paused'.
                  */
                 do_action( "after_plugin_row_{$plugin_file}", $plugin_file, $plugin_data, $status );

trunk/src/wp-admin/includes/plugin.php

@@ -469 +469 @@
 function _get_dropins() {
         $dropins = array(
-                'advanced-cache.php' => array( __( 'Advanced caching plugin.' ), 'WP_CACHE' ), // WP_CACHE
-                'db.php'             => array( __( 'Custom database class.' ), true ), // auto on load
-                'db-error.php'       => array( __( 'Custom database error message.' ), true ), // auto on error
-                'install.php'        => array( __( 'Custom installation script.' ), true ), // auto on installation
-                'maintenance.php'    => array( __( 'Custom maintenance message.' ), true ), // auto on maintenance
-                'object-cache.php'   => array( __( 'External object cache.' ), true ), // auto on load
+                'advanced-cache.php'      => array( __( 'Advanced caching plugin.' ), 'WP_CACHE' ), // WP_CACHE
+                'db.php'                  => array( __( 'Custom database class.' ), true ), // auto on load
+                'db-error.php'            => array( __( 'Custom database error message.' ), true ), // auto on error
+                'install.php'             => array( __( 'Custom installation script.' ), true ), // auto on installation
+                'maintenance.php'         => array( __( 'Custom maintenance message.' ), true ), // auto on maintenance
+                'object-cache.php'        => array( __( 'External object cache.' ), true ), // auto on load
+                'php-error.php'           => array( __( 'Custom PHP error message.' ), true ), // auto on error
+                'fatal-error-handler.php' => array( __( 'Custom PHP fatal error handler.' ), true ), // auto on error
         );
 
@@ -2102 +2104 @@
         WP_Privacy_Policy_Content::add( $plugin_name, $policy_text );
 }
+
+/**
+ * Determines whether a plugin is technically active but was paused while
+ * loading.
+ *
+ * For more information on this and similar theme functions, check out
+ * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
+ * Conditional Tags} article in the Theme Developer Handbook.
+ *
+ * @since 5.2.0
+ *
+ * @param string $plugin Path to the plugin file relative to the plugins directory.
+ * @return bool True, if in the list of paused plugins. False, not in the list.
+ */
+function is_plugin_paused( $plugin ) {
+        if ( ! isset( $GLOBALS['_paused_plugins'] ) ) {
+                return false;
+        }
+
+        if ( ! is_plugin_active( $plugin ) ) {
+                return false;
+        }
+
+        list( $plugin ) = explode( '/', $plugin );
+
+        return array_key_exists( $plugin, $GLOBALS['_paused_plugins'] );
+}
+
+/**
+ * Gets the error that was recorded for a paused plugin.
+ *
+ * @since 5.2.0
+ *
+ * @param string $plugin Path to the plugin file relative to the plugins
+ *                       directory.
+ * @return array|false Array of error information as it was returned by
+ *                     `error_get_last()`, or false if none was recorded.
+ */
+function wp_get_plugin_error( $plugin ) {
+        if ( ! isset( $GLOBALS['_paused_plugins'] ) ) {
+                return false;
+        }
+
+        list( $plugin ) = explode( '/', $plugin );
+
+        if ( ! array_key_exists( $plugin, $GLOBALS['_paused_plugins'] ) ) {
+                return false;
+        }
+
+        return $GLOBALS['_paused_plugins'][ $plugin ];
+}
+
+/**
+ * Tries to resume a single plugin.
+ *
+ * If a redirect was provided, we first ensure the plugin does not throw fatal
+ * errors anymore.
+ *
+ * The way it works is by setting the redirection to the error before trying to
+ * include the plugin file. If the plugin fails, then the redirection will not
+ * be overwritten with the success message and the plugin will not be resumed.
+ *
+ * @since 5.2.0
+ *
+ * @param string $plugin       Single plugin to resume.
+ * @param string $redirect     Optional. URL to redirect to. Default empty string.
+ * @return bool|WP_Error True on success, false if `$plugin` was not paused,
+ *                       `WP_Error` on failure.
+ */
+function resume_plugin( $plugin, $redirect = '' ) {
+        /*
+         * We'll override this later if the plugin could be resumed without
+         * creating a fatal error.
+         */
+        if ( ! empty( $redirect ) ) {
+                wp_redirect(
+                        add_query_arg(
+                                '_error_nonce',
+                                wp_create_nonce( 'plugin-resume-error_' . $plugin ),
+                                $redirect
+                        )
+                );
+
+                // Load the plugin to test whether it throws a fatal error.
+                ob_start();
+                plugin_sandbox_scrape( $plugin );
+                ob_clean();
+        }
+
+        list( $extension ) = explode( '/', $plugin );
+
+        $result = wp_paused_plugins()->delete( $extension );
+
+        if ( ! $result ) {
+                return new WP_Error(
+                        'could_not_resume_plugin',
+                        __( 'Could not resume the plugin.' )
+                );
+        }
+
+        return true;
+}
+
+/**
+ * Renders an admin notice in case some plugins have been paused due to errors.
+ *
+ * @since 5.2.0
+ */
+function paused_plugins_notice() {
+        if ( 'plugins.php' === $GLOBALS['pagenow'] ) {
+                return;
+        }
+
+        if ( ! current_user_can( 'resume_plugins' ) ) {
+                return;
+        }
+
+        if ( ! isset( $GLOBALS['_paused_plugins'] ) || empty( $GLOBALS['_paused_plugins'] ) ) {
+                return;
+        }
+
+        printf(
+                '<div class="notice notice-error"><p><strong>%s</strong><br>%s</p><p><a href="%s">%s</a></p></div>',
+                __( 'One or more plugins failed to load properly.' ),
+                __( 'You can find more details and make changes on the Plugins screen.' ),
+                esc_url( admin_url( 'plugins.php?plugin_status=paused' ) ),
+                __( 'Go to the Plugins screen' )
+        );
+}

trunk/src/wp-admin/includes/theme.php

@@ -769 +769 @@
         <?php
 }
+
+/**
+ * Determines whether a theme is technically active but was paused while
+ * loading.
+ *
+ * For more information on this and similar theme functions, check out
+ * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
+ * Conditional Tags} article in the Theme Developer Handbook.
+ *
+ * @since 5.2.0
+ *
+ * @param string $theme Path to the theme directory relative to the themes directory.
+ * @return bool True, if in the list of paused themes. False, not in the list.
+ */
+function is_theme_paused( $theme ) {
+        if ( ! isset( $GLOBALS['_paused_themes'] ) ) {
+                return false;
+        }
+
+        if ( get_stylesheet() !== $theme && get_template() !== $theme ) {
+                return false;
+        }
+
+        return array_key_exists( $theme, $GLOBALS['_paused_themes'] );
+}
+
+/**
+ * Gets the error that was recorded for a paused theme.
+ *
+ * @since 5.2.0
+ *
+ * @param string $theme Path to the theme directory relative to the themes
+ *                      directory.
+ * @return array|false Array of error information as it was returned by
+ *                     `error_get_last()`, or false if none was recorded.
+ */
+function wp_get_theme_error( $theme ) {
+        if ( ! isset( $GLOBALS['_paused_themes'] ) ) {
+                return false;
+        }
+
+        if ( ! array_key_exists( $theme, $GLOBALS['_paused_themes'] ) ) {
+                return false;
+        }
+
+        return $GLOBALS['_paused_themes'][ $theme ];
+}
+
+/**
+ * Tries to resume a single theme.
+ *
+ * If a redirect was provided and a functions.php file was found, we first ensure that
+ * functions.php file does not throw fatal errors anymore.
+ *
+ * The way it works is by setting the redirection to the error before trying to
+ * include the file. If the theme fails, then the redirection will not be overwritten
+ * with the success message and the theme will not be resumed.
+ *
+ * @since 5.2.0
+ *
+ * @param string $theme    Single theme to resume.
+ * @param string $redirect Optional. URL to redirect to. Default empty string.
+ * @return bool|WP_Error True on success, false if `$theme` was not paused,
+ *                       `WP_Error` on failure.
+ */
+function resume_theme( $theme, $redirect = '' ) {
+        list( $extension ) = explode( '/', $theme );
+
+        /*
+         * We'll override this later if the theme could be resumed without
+         * creating a fatal error.
+         */
+        if ( ! empty( $redirect ) ) {
+                $functions_path = '';
+                if ( strpos( STYLESHEETPATH, $extension ) ) {
+                        $functions_path = STYLESHEETPATH . '/functions.php';
+                } elseif ( strpos( TEMPLATEPATH, $extension ) ) {
+                        $functions_path = TEMPLATEPATH . '/functions.php';
+                }
+
+                if ( ! empty( $functions_path ) ) {
+                        wp_redirect(
+                                add_query_arg(
+                                        '_error_nonce',
+                                        wp_create_nonce( 'theme-resume-error_' . $theme ),
+                                        $redirect
+                                )
+                        );
+
+                        // Load the theme's functions.php to test whether it throws a fatal error.
+                        ob_start();
+                        include $functions_path;
+                        ob_clean();
+                }
+        }
+
+        $result = wp_paused_themes()->delete( $extension );
+
+        if ( ! $result ) {
+                return new WP_Error(
+                        'could_not_resume_theme',
+                        __( 'Could not resume the theme.' )
+                );
+        }
+
+        return true;
+}
+
+/**
+ * Renders an admin notice in case some themes have been paused due to errors.
+ *
+ * @since 5.2.0
+ */
+function paused_themes_notice() {
+        if ( 'themes.php' === $GLOBALS['pagenow'] ) {
+                return;
+        }
+
+        if ( ! current_user_can( 'resume_themes' ) ) {
+                return;
+        }
+
+        if ( ! isset( $GLOBALS['_paused_themes'] ) || empty( $GLOBALS['_paused_themes'] ) ) {
+                return;
+        }
+
+        printf(
+                '<div class="notice notice-error"><p><strong>%s</strong><br>%s</p><p><a href="%s">%s</a></p></div>',
+                __( 'One or more themes failed to load properly.' ),
+                __( 'You can find more details and make changes on the Themes screen.' ),
+                esc_url( admin_url( 'themes.php' ) ),
+                __( 'Go to the Themes screen' )
+        );
+}

trunk/src/wp-admin/plugins.php

@@ -390 +390 @@
                         break;
 
+                case 'resume':
+                        if ( is_multisite() ) {
+                                return;
+                        }
+
+                        if ( ! current_user_can( 'resume_plugin', $plugin ) ) {
+                                wp_die( __( 'Sorry, you are not allowed to resume this plugin.' ) );
+                        }
+
+                        check_admin_referer( 'resume-plugin_' . $plugin );
+
+                        $result = resume_plugin( $plugin, self_admin_url( "plugins.php?error=resuming&plugin_status=$status&paged=$page&s=$s" ) );
+
+                        if ( is_wp_error( $result ) ) {
+                                wp_die( $result );
+                        }
+
+                        wp_redirect( self_admin_url( "plugins.php?resume=true&plugin_status=$status&paged=$page&s=$s" ) );
+                        exit;
+
                 default:
                         if ( isset( $_POST['checked'] ) ) {
@@ -489 +509 @@
                 );
                 $errmsg .= ' ' . __( 'If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.' );
+        } elseif ( 'resuming' === $_GET['error'] ) {
+                $errmsg = __( 'Plugin could not be resumed because it triggered a <strong>fatal error</strong>.' );
         } else {
                 $errmsg = __( 'Plugin could not be activated because it triggered a <strong>fatal error</strong>.' );
@@ -542 +564 @@
 <?php elseif ( 'update-selected' == $action ) : ?>
         <div id="message" class="updated notice is-dismissible"><p><?php _e( 'All selected plugins are up to date.' ); ?></p></div>
+<?php elseif ( isset( $_GET['resume'] ) ) : ?>
+        <div id="message" class="updated notice is-dismissible"><p><?php _e( 'Plugin <strong>resumed</strong>.' ); ?></p></div>
 <?php endif; ?>
 

trunk/src/wp-admin/themes.php

@@ -33 +33 @@
                 switch_theme( $theme->get_stylesheet() );
                 wp_redirect( admin_url( 'themes.php?activated=true' ) );
+                exit;
+        } elseif ( 'resume' === $_GET['action'] ) {
+                check_admin_referer( 'resume-theme_' . $_GET['stylesheet'] );
+                $theme = wp_get_theme( $_GET['stylesheet'] );
+
+                if ( ! current_user_can( 'resume_theme', $_GET['stylesheet'] ) ) {
+                        wp_die(
+                                '<h1>' . __( 'You need a higher level of permission.' ) . '</h1>' .
+                                '<p>' . __( 'Sorry, you are not allowed to resume this theme.' ) . '</p>',
+                                403
+                        );
+                }
+
+                $result = resume_theme( $theme->get_stylesheet(), self_admin_url( 'themes.php?error=resuming' ) );
+
+                if ( is_wp_error( $result ) ) {
+                        wp_die( $result );
+                }
+
+                wp_redirect( admin_url( 'themes.php?resumed=true' ) );
                 exit;
         } elseif ( 'delete' == $_GET['action'] ) {
@@ -196 +216 @@
         <div id="message4" class="error"><p><?php _e( 'You cannot delete a theme while it has an active child theme.' ); ?></p></div>
         <?php
+} elseif ( isset( $_GET['resumed'] ) ) {
+        ?>
+        <div id="message5" class="updated notice is-dismissible"><p><?php _e( 'Theme resumed.' ); ?></p></div>
+        <?php
+} elseif ( isset( $_GET['error'] ) && 'resuming' === $_GET['error'] ) {
+        ?>
+        <div id="message6" class="error"><p><?php _e( 'Theme could not be resumed because it triggered a <strong>fatal error</strong>.' ); ?></p></div>
+        <?php
 }
 
@@ -349 +377 @@
 
         <?php
+        $can_resume  = current_user_can( 'resume_themes' );
         $can_delete  = current_user_can( 'delete_themes' );
         $can_install = current_user_can( 'install_themes' );
@@ -356 +385 @@
                 <th><?php _ex( 'Name', 'theme name' ); ?></th>
                 <th><?php _e( 'Description' ); ?></th>
+                <?php if ( $can_resume ) { ?>
+                        <td></td>
+                <?php } ?>
                 <?php if ( $can_delete ) { ?>
                         <td></td>
@@ -368 +400 @@
                         <td><?php echo $broken_theme->errors()->get_error_message(); ?></td>
                         <?php
+                        if ( $can_resume ) {
+                                if ( 'theme_paused' === $broken_theme->errors()->get_error_code() ) {
+                                        $stylesheet = $broken_theme->get_stylesheet();
+                                        $resume_url = add_query_arg(
+                                                array(
+                                                        'action'     => 'resume',
+                                                        'stylesheet' => urlencode( $stylesheet ),
+                                                ),
+                                                admin_url( 'themes.php' )
+                                        );
+                                        $resume_url = wp_nonce_url( $resume_url, 'resume-theme_' . $stylesheet );
+                                        ?>
+                                        <td><a href="<?php echo esc_url( $resume_url ); ?>" class="button resume-theme"><?php _e( 'Resume' ); ?></a></td>
+                                        <?php
+                                } else {
+                                        ?>
+                                        <td></td>
+                                        <?php
+                                }
+                        }
+
                         if ( $can_delete ) {
                                 $stylesheet = $broken_theme->get_stylesheet();

trunk/src/wp-includes/admin-bar.php

@@ -1049 +1049 @@
 
 /**
+ * Add a link to exit recovery mode when Recovery Mode is active.
+ *
+ * @since 5.2.0
+ *
+ * @param WP_Admin_Bar $wp_admin_bar
+ */
+function wp_admin_bar_recovery_mode_menu( $wp_admin_bar ) {
+        if ( ! wp_is_recovery_mode() ) {
+                return;
+        }
+
+        $url = wp_login_url();
+        $url = add_query_arg( 'action', WP_Recovery_Mode::EXIT_ACTION, $url );
+        $url = wp_nonce_url( $url, WP_Recovery_Mode::EXIT_ACTION );
+
+        $wp_admin_bar->add_menu(
+                array(
+                        'parent' => 'top-secondary',
+                        'id'     => 'recovery-mode',
+                        'title'  => __( 'Exit Recovery Mode' ),
+                        'href'   => $url,
+                        'meta'   => array(
+                                'title' => __( 'Exit Recovery Mode' ),
+                        ),
+                )
+        );
+}
+
+/**
  * Add secondary menus.
  *

trunk/src/wp-includes/capabilities.php

@@ -465 +465 @@
                         }
                         break;
+                case 'resume_plugin':
+                        $caps[] = 'resume_plugins';
+                        break;
+                case 'resume_theme':
+                        $caps[] = 'resume_themes';
+                        break;
                 case 'delete_user':
                 case 'delete_users':
@@ -951 +957 @@
         return $allcaps;
 }
+
+/**
+ * Filters the user capabilities to grant the 'resume_plugins' and 'resume_themes' capabilities as necessary.
+ *
+ * @since 5.2.0
+ *
+ * @param bool[] $allcaps An array of all the user's capabilities.
+ * @return bool[] Filtered array of the user's capabilities.
+ */
+function wp_maybe_grant_resume_extensions_caps( $allcaps ) {
+        // Even in a multisite, regular administrators should be able to resume plugins.
+        if ( ! empty( $allcaps['activate_plugins'] ) ) {
+                $allcaps['resume_plugins'] = true;
+        }
+
+        // Even in a multisite, regular administrators should be able to resume themes.
+        if ( ! empty( $allcaps['switch_themes'] ) ) {
+                $allcaps['resume_themes'] = true;
+        }
+
+        return $allcaps;
+}

trunk/src/wp-includes/class-wp-admin-bar.php

@@ -597 +597 @@
                 add_action( 'admin_bar_menu', 'wp_admin_bar_search_menu', 4 );
                 add_action( 'admin_bar_menu', 'wp_admin_bar_my_account_item', 7 );
+                add_action( 'admin_bar_menu', 'wp_admin_bar_recovery_mode_menu', 8 );
 
                 // Site related.

trunk/src/wp-includes/class-wp-fatal-error-handler.php

@@ -37 +37 @@
                         if ( ! $error ) {
                                 return;
+                        }
+
+                        if ( ! is_multisite() && wp_recovery_mode()->is_initialized() ) {
+                                wp_recovery_mode()->handle_error( $error );
                         }
 

trunk/src/wp-includes/class-wp-theme.php

@@ -370 +370 @@
                         // Set the parent. Pass the current instance so we can do the crazy checks above and assess errors.
                         $this->parent = new WP_Theme( $this->template, isset( $theme_root_template ) ? $theme_root_template : $this->theme_root, $this );
+                }
+
+                if ( wp_paused_themes()->get( $this->stylesheet ) && ( ! is_wp_error( $this->errors ) || ! isset( $this->errors->errors['theme_paused'] ) ) ) {
+                        $this->errors = new WP_Error( 'theme_paused', __( 'This theme failed to load properly and was paused within the admin backend.' ) );
                 }
 

trunk/src/wp-includes/default-constants.php

@@ -303 +303 @@
                 define( 'COOKIE_DOMAIN', false );
         }
+
+        if ( ! defined( 'RECOVERY_MODE_COOKIE' ) ) {
+                /**
+                 * @since 5.2.0
+                 */
+                define( 'RECOVERY_MODE_COOKIE', 'wordpress_rec_' . COOKIEHASH );
+        }
 }
 

trunk/src/wp-includes/default-filters.php

@@ -580 +580 @@
 // Capabilities
 add_filter( 'user_has_cap', 'wp_maybe_grant_install_languages_cap', 1 );
+add_filter( 'user_has_cap', 'wp_maybe_grant_resume_extensions_caps', 1 );
 
 unset( $filter, $action );

trunk/src/wp-includes/error-protection.php

@@ -6 +6 @@
  * @since   5.2.0
  */
+
+/**
+ * Get the instance for storing paused plugins.
+ *
+ * @return WP_Paused_Extensions_Storage
+ */
+function wp_paused_plugins() {
+        static $storage = null;
+
+        if ( null === $storage ) {
+                $storage = new WP_Paused_Extensions_Storage( 'plugin' );
+        }
+
+        return $storage;
+}
+
+/**
+ * Get the instance for storing paused extensions.
+ *
+ * @return WP_Paused_Extensions_Storage
+ */
+function wp_paused_themes() {
+        static $storage = null;
+
+        if ( null === $storage ) {
+                $storage = new WP_Paused_Extensions_Storage( 'theme' );
+        }
+
+        return $storage;
+}
+
+/**
+ * Get a human readable description of an extension's error.
+ *
+ * @since 5.2.0
+ *
+ * @param array $error Error details {@see error_get_last()}
+ *
+ * @return string Formatted error description.
+ */
+function wp_get_extension_error_description( $error ) {
+        $constants   = get_defined_constants( true );
+        $constants   = isset( $constants['Core'] ) ? $constants['Core'] : $constants['internal'];
+        $core_errors = array();
+
+        foreach ( $constants as $constant => $value ) {
+                if ( 0 === strpos( $constant, 'E_' ) ) {
+                        $core_errors[ $value ] = $constant;
+                }
+        }
+
+        if ( isset( $core_errors[ $error['type'] ] ) ) {
+                $error['type'] = $core_errors[ $error['type'] ];
+        }
+
+        /* translators: 1: error type, 2: error line number, 3: error file name, 4: error message */
+        $error_message = __( 'An error of type %1$s was caused in line %2$s of the file %3$s. Error message: %4$s' );
+
+        return sprintf(
+                $error_message,
+                "<code>{$error['type']}</code>",
+                "<code>{$error['line']}</code>",
+                "<code>{$error['file']}</code>",
+                "<code>{$error['message']}</code>"
+        );
+}
 
 /**
@@ -53 +119 @@
         return apply_filters( 'wp_fatal_error_handler_enabled', $enabled );
 }
+
+/**
+ * Access the WordPress Recovery Mode instance.
+ *
+ * @since 5.2.0
+ *
+ * @return WP_Recovery_Mode
+ */
+function wp_recovery_mode() {
+        static $wp_recovery_mode;
+
+        if ( ! $wp_recovery_mode ) {
+                $wp_recovery_mode = new WP_Recovery_Mode();
+        }
+
+        return $wp_recovery_mode;
+}

trunk/src/wp-includes/load.php

@@ -698 +698 @@
         }
 
+        /*
+         * Remove plugins from the list of active plugins when we're on an endpoint
+         * that should be protected against WSODs and the plugin is paused.
+         */
+        if ( wp_is_recovery_mode() ) {
+                $plugins = wp_skip_paused_plugins( $plugins );
+        }
+
+        return $plugins;
+}
+
+/**
+ * Filters a given list of plugins, removing any paused plugins from it.
+ *
+ * @since 5.2.0
+ *
+ * @param array $plugins List of absolute plugin main file paths.
+ * @return array Filtered value of $plugins, without any paused plugins.
+ */
+function wp_skip_paused_plugins( array $plugins ) {
+        $paused_plugins = wp_paused_plugins()->get_all();
+
+        if ( empty( $paused_plugins ) ) {
+                return $plugins;
+        }
+
+        foreach ( $plugins as $index => $plugin ) {
+                list( $plugin ) = explode( '/', plugin_basename( $plugin ) );
+
+                if ( array_key_exists( $plugin, $paused_plugins ) ) {
+                        unset( $plugins[ $index ] );
+
+                        // Store list of paused plugins for displaying an admin notice.
+                        $GLOBALS['_paused_plugins'][ $plugin ] = $paused_plugins[ $plugin ];
+                }
+        }
+
         return $plugins;
 }
@@ -726 +763 @@
         $themes[] = TEMPLATEPATH;
 
+        /*
+         * Remove themes from the list of active themes when we're on an endpoint
+         * that should be protected against WSODs and the theme is paused.
+         */
+        if ( wp_is_recovery_mode() ) {
+                $themes = wp_skip_paused_themes( $themes );
+
+                // If no active and valid themes exist, skip loading themes.
+                if ( empty( $themes ) ) {
+                        add_filter( 'wp_using_themes', '__return_false' );
+                }
+        }
+
         return $themes;
+}
+
+/**
+ * Filters a given list of themes, removing any paused themes from it.
+ *
+ * @since 5.2.0
+ *
+ * @param array $themes List of absolute theme directory paths.
+ * @return array Filtered value of $themes, without any paused themes.
+ */
+function wp_skip_paused_themes( array $themes ) {
+        $paused_themes = wp_paused_themes()->get_all();
+
+        if ( empty( $paused_themes ) ) {
+                return $themes;
+        }
+
+        foreach ( $themes as $index => $theme ) {
+                $theme = basename( $theme );
+
+                if ( array_key_exists( $theme, $paused_themes ) ) {
+                        unset( $themes[ $index ] );
+
+                        // Store list of paused themes for displaying an admin notice.
+                        $GLOBALS['_paused_themes'][ $theme ] = $paused_themes[ $theme ];
+                }
+        }
+
+        return $themes;
+}
+
+/**
+ * Is WordPress in Recovery Mode.
+ *
+ * In this mode, plugins or themes that cause WSODs will be paused.
+ *
+ * @since 5.2.0
+ *
+ * @return bool
+ */
+function wp_is_recovery_mode() {
+        return wp_recovery_mode()->is_active();
+}
+
+/**
+ * Determines whether we are currently on an endpoint that should be protected against WSODs.
+ *
+ * @since 5.2.0
+ *
+ * @return bool True if the current endpoint should be protected.
+ */
+function is_protected_endpoint() {
+        // Protect login pages.
+        if ( isset( $GLOBALS['pagenow'] ) && 'wp-login.php' === $GLOBALS['pagenow'] ) {
+                return true;
+        }
+
+        // Protect the admin backend.
+        if ( is_admin() && ! wp_doing_ajax() ) {
+                return true;
+        }
+
+        // Protect AJAX actions that could help resolve a fatal error should be available.
+        if ( is_protected_ajax_action() ) {
+                return true;
+        }
+
+        /**
+         * Filters whether the current request is against a protected endpoint.
+         *
+         * This filter is only fired when an endpoint is requested which is not already protected by
+         * WordPress core. As such, it exclusively allows providing further protected endpoints in
+         * addition to the admin backend, login pages and protected AJAX actions.
+         *
+         * @since 5.2.0
+         *
+         * @param bool $is_protected_endpoint Whether the currently requested endpoint is protected. Default false.
+         */
+        return (bool) apply_filters( 'is_protected_endpoint', false );
+}
+
+/**
+ * Determines whether we are currently handling an AJAX action that should be protected against WSODs.
+ *
+ * @since 5.2.0
+ *
+ * @return bool True if the current AJAX action should be protected.
+ */
+function is_protected_ajax_action() {
+        if ( ! wp_doing_ajax() ) {
+                return false;
+        }
+
+        if ( ! isset( $_REQUEST['action'] ) ) {
+                return false;
+        }
+
+        $actions_to_protect = array(
+                'edit-theme-plugin-file', // Saving changes in the core code editor.
+                'heartbeat',              // Keep the heart beating.
+                'install-plugin',         // Installing a new plugin.
+                'install-theme',          // Installing a new theme.
+                'search-plugins',         // Searching in the list of plugins.
+                'search-install-plugins', // Searching for a plugin in the plugin install screen.
+                'update-plugin',          // Update an existing plugin.
+                'update-theme',           // Update an existing theme.
+        );
+
+        /**
+         * Filters the array of protected AJAX actions.
+         *
+         * This filter is only fired when doing AJAX and the AJAX request has an 'action' property.
+         *
+         * @since 5.2.0
+         *
+         * @param array $actions_to_protect Array of strings with AJAX actions to protect.
+         */
+        $actions_to_protect = (array) apply_filters( 'wp_protected_ajax_actions', $actions_to_protect );
+
+        if ( ! in_array( $_REQUEST['action'], $actions_to_protect, true ) ) {
+                return false;
+        }
+
+        return true;
 }
 

trunk/src/wp-login.php

@@ -440 +440 @@
 
 // Validate action so as to default to the login screen.
-if ( ! in_array( $action, array( 'postpass', 'logout', 'lostpassword', 'retrievepassword', 'resetpass', 'rp', 'register', 'login', 'confirmaction' ), true ) && false === has_filter( 'login_form_' . $action ) ) {
+if ( ! in_array( $action, array( 'postpass', 'logout', 'lostpassword', 'retrievepassword', 'resetpass', 'rp', 'register', 'login', 'confirmaction', WP_Recovery_Mode_Link_Service::LOGIN_ACTION_ENTERED ), true ) && false === has_filter( 'login_form_' . $action ) ) {
         $action = 'login';
 }
@@ -1029 +1029 @@
                         } elseif ( strpos( $redirect_to, 'about.php?updated' ) ) {
                                 $errors->add( 'updated', __( '<strong>You have successfully updated WordPress!</strong> Please log back in to see what&#8217;s new.' ), 'message' );
+                        } elseif ( WP_Recovery_Mode_Link_Service::LOGIN_ACTION_ENTERED === $action ) {
+                                $errors->add( 'enter_recovery_mode', __( 'Recovery Mode Initialized. Please log in to continue.' ), 'message' );
                         }
                 }

trunk/src/wp-settings.php

@@ -18 +18 @@
 // Include files required for initialization.
 require( ABSPATH . WPINC . '/load.php' );
+require( ABSPATH . WPINC . '/class-wp-paused-extensions-storage.php' );
 require( ABSPATH . WPINC . '/class-wp-fatal-error-handler.php' );
+require( ABSPATH . WPINC . '/class-wp-recovery-mode-cookie-service.php' );
+require( ABSPATH . WPINC . '/class-wp-recovery-mode-key-service.php' );
+require( ABSPATH . WPINC . '/class-wp-recovery-mode-link-service.php' );
+require( ABSPATH . WPINC . '/class-wp-recovery-mode-email-service.php' );
+require( ABSPATH . WPINC . '/class-wp-recovery-mode.php' );
 require( ABSPATH . WPINC . '/error-protection.php' );
 require( ABSPATH . WPINC . '/default-constants.php' );
@@ -346 +352 @@
 register_theme_directory( get_theme_root() );
 
+if ( ! is_multisite() ) {
+        // Handle users requesting a recovery mode link and initiating recovery mode.
+        wp_recovery_mode()->initialize();
+}
+
 // Load active plugins.
 foreach ( wp_get_active_and_valid_plugins() as $plugin ) {

trunk/tests/phpunit/tests/user/capabilities.php

@@ -102 +102 @@
                         'switch_themes'          => array( 'administrator' ),
                         'edit_dashboard'         => array( 'administrator' ),
+                        'resume_plugins'         => array( 'administrator' ),
+                        'resume_themes'          => array( 'administrator' ),
 
                         'moderate_comments'      => array( 'administrator', 'editor' ),
@@ -182 +184 @@
                         'switch_themes'          => array( 'administrator' ),
                         'edit_dashboard'         => array( 'administrator' ),
+                        'resume_plugins'         => array( 'administrator' ),
+                        'resume_themes'          => array( 'administrator' ),
 
                         'moderate_comments'      => array( 'administrator', 'editor' ),
@@ -393 +397 @@
                         $actual['author'],
                         $actual['subscriber'],
-                        $actual['contributor']
+                        $actual['contributor'],
+                        // the following two are granted via `user_has_cap`:
+                        $actual['resume_plugins'],
+                        $actual['resume_themes']
                 );
 
@@ -455 +462 @@
                         $expected['activate_plugin'],
                         $expected['deactivate_plugin'],
+                        $expected['resume_plugin'],
+                        $expected['resume_theme'],
                         $expected['remove_user'],
                         $expected['promote_user'],