/** * Error Protection API: WP_Fatal_Error_Handler class * * @package WordPress * @since 5.2.0 */ /** * Core class used as the default shutdown handler for fatal errors. * * A drop-in 'fatal-error-handler.php' can be used to override the instance of this class and use a custom * implementation for the fatal error handler that WordPress registers. The custom class should extend this class and * can override its methods individually as necessary. The file must return the instance of the class that should be * registered. * * @since 5.2.0 */ class WP_Fatal_Error_Handler { /** * Runs the shutdown handler. * * This method is registered via `register_shutdown_function()`. * * @since 5.2.0 */ public function handle() { if ( defined( 'WP_SANDBOX_SCRAPING' ) && WP_SANDBOX_SCRAPING ) { return; } try { // Bail if no error found. $error = $this->detect_error(); if ( ! $error ) { return; } if ( ! isset( $GLOBALS['wp_locale'] ) && function_exists( 'load_default_textdomain' ) ) { load_default_textdomain(); } if ( ! is_multisite() && wp_recovery_mode()->is_initialized() ) { wp_recovery_mode()->handle_error( $error ); } // Display the PHP error template if headers not sent. if ( is_admin() || ! headers_sent() ) { $this->display_error_template( $error ); } } catch ( Exception $e ) { // Catch exceptions and remain silent. } } /** * Detects the error causing the crash if it should be handled. * * @since 5.2.0 * * @return array|null Error that was triggered, or null if no error received or if the error should not be handled. */ protected function detect_error() { $error = error_get_last(); // No error, just skip the error handling code. if ( null === $error ) { return null; } // Bail if this error should not be handled. if ( ! $this->should_handle_error( $error ) ) { return null; } return $error; } /** * Determines whether we are dealing with an error that WordPress should handle * in order to protect the admin backend against WSODs. * * @since 5.2.0 * * @param array $error Error information retrieved from error_get_last(). * @return bool Whether WordPress should handle this error. */ protected function should_handle_error( $error ) { $error_types_to_handle = array( E_ERROR, E_PARSE, E_USER_ERROR, E_COMPILE_ERROR, E_RECOVERABLE_ERROR, ); if ( isset( $error['type'] ) && in_array( $error['type'], $error_types_to_handle, true ) ) { return true; } /** * Filters whether a given thrown error should be handled by the fatal error handler. * * This filter is only fired if the error is not already configured to be handled by WordPress core. As such, * it exclusively allows adding further rules for which errors should be handled, but not removing existing * ones. * * @since 5.2.0 * * @param bool $should_handle_error Whether the error should be handled by the fatal error handler. * @param array $error Error information retrieved from error_get_last(). */ return (bool) apply_filters( 'wp_should_handle_php_error', false, $error ); } /** * Displays the PHP error template and sends the HTTP status code, typically 500. * * A drop-in 'php-error.php' can be used as a custom template. This drop-in should control the HTTP status code and * print the HTML markup indicating that a PHP error occurred. Note that this drop-in may potentially be executed * very early in the WordPress bootstrap process, so any core functions used that are not part of * `wp-includes/load.php` should be checked for before being called. * * If no such drop-in is available, this will call {@see WP_Fatal_Error_Handler::display_default_error_template()}. * * @since 5.2.0 * * @param array $error Error information retrieved from `error_get_last()`. */ protected function display_error_template( $error ) { if ( defined( 'WP_CONTENT_DIR' ) ) { // Load custom PHP error template, if present. $php_error_pluggable = WP_CONTENT_DIR . '/php-error.php'; if ( is_readable( $php_error_pluggable ) ) { require_once $php_error_pluggable; return; } } // Otherwise, display the default error template. $this->display_default_error_template( $error ); } /** * Displays the default PHP error template. * * This method is called conditionally if no 'php-error.php' drop-in is available. * * It calls {@see wp_die()} with a message indicating that the site is experiencing technical difficulties and a * login link to the admin backend. The {@see 'wp_php_error_message'} and {@see 'wp_php_error_args'} filters can * be used to modify these parameters. * * @since 5.2.0 * * @param array $error Error information retrieved from `error_get_last()`. */ protected function display_default_error_template( $error ) { if ( ! function_exists( '__' ) ) { wp_load_translations_early(); } if ( ! function_exists( 'wp_die' ) ) { require_once ABSPATH . WPINC . '/functions.php'; } if ( ! class_exists( 'WP_Error' ) ) { require_once ABSPATH . WPINC . '/class-wp-error.php'; } if ( is_protected_endpoint() ) { $message = __( 'The site is experiencing technical difficulties. Please check your site admin email inbox for instructions.' ); } else { $message = __( 'The site is experiencing technical difficulties.' ); } $args = array( 'response' => 500, 'exit' => false, ); /** * Filters the message that the default PHP error template displays. * * @since 5.2.0 * * @param string $message HTML error message to display. * @param array $error Error information retrieved from `error_get_last()`. */ $message = apply_filters( 'wp_php_error_message', $message, $error ); /** * Filters the arguments passed to {@see wp_die()} for the default PHP error template. * * @since 5.2.0 * * @param array $args Associative array of arguments passed to `wp_die()`. By default these contain a * 'response' key, and optionally 'link_url' and 'link_text' keys. * @param array $error Error information retrieved from `error_get_last()`. */ $args = apply_filters( 'wp_php_error_args', $args, $error ); $wp_error = new WP_Error( 'internal_server_error', $message, array( 'error' => $error, ) ); wp_die( $wp_error, '', $args ); } }