From b06444e859384bccd65c13dc87e4afb389754947 Mon Sep 17 00:00:00 2001 From: Felix Arntz Date: Thu, 21 Mar 2019 16:02:05 +0000 Subject: [PATCH] Bootstrap/Load: Introduce fatal error handler. This changeset introduces a `WP_Fatal_Error_Handler` class that detects fatal errors and displays a more user-friendly message about the site experiencing technical difficulties. Websites that have custom requirements in that regard can implement their own fatal error handler by adding a `fatal-error-handler.php` drop-in that returns the handler instance to use, which must be based on a class that inherits `WP_Fatal_Error_Handler`. That handler will then be used in place of the default one. Alternatively, the fatal error handler feature can be completely disable through a constant `WP_DISABLE_FATAL_ERROR_HANDLER`. Websites that would like to modify specifically the error template displayed in the frontend can add a `php-error.php` drop-in that works similarly to the existing `db-error.php` drop-in. For more granular customization, the fatal error handler also includes new filters `wp_should_handle_php_error`, `wp_php_error_message` and `wp_php_error_args`. Props afragen, bradleyt, flixos90, ocean90, schlessera, SergeyBiryukov, spacedmonkey, timothyblynjacobs. See #46130, #44458. git-svn-id: https://develop.svn.wordpress.org/trunk@44962 602fd350-edb4-49c9-b593-d223f7449a82 --- .../class-wp-fatal-error-handler.php | 185 ++++++++++++++++++ src/wp-includes/error-protection.php | 54 +++++ src/wp-settings.php | 14 ++ 3 files changed, 253 insertions(+) create mode 100644 src/wp-includes/class-wp-fatal-error-handler.php create mode 100644 src/wp-includes/error-protection.php diff --git a/src/wp-includes/class-wp-fatal-error-handler.php b/src/wp-includes/class-wp-fatal-error-handler.php new file mode 100644 index 0000000000..e36a8f68e8 --- /dev/null +++ b/src/wp-includes/class-wp-fatal-error-handler.php @@ -0,0 +1,185 @@ +detect_error(); + if ( ! $error ) { + return; + } + + // Display the PHP error template. + $this->display_error_template(); + } 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 + */ + protected function display_error_template() { + 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(); + } + + /** + * 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 + */ + protected function display_default_error_template() { + if ( ! function_exists( '__' ) ) { + wp_load_translations_early(); + } + + if ( ! function_exists( 'wp_die' ) ) { + require_once ABSPATH . WPINC . '/functions.php'; + } + + $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. + */ + $message = apply_filters( 'wp_php_error_message', $message ); + + /** + * 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. + */ + $args = apply_filters( 'wp_php_error_args', $args ); + + $error = new WP_Error( 'internal_server_error', $message ); + + wp_die( $error, '', $args ); + } +} diff --git a/src/wp-includes/error-protection.php b/src/wp-includes/error-protection.php new file mode 100644 index 0000000000..abcb1f9ba7 --- /dev/null +++ b/src/wp-includes/error-protection.php @@ -0,0 +1,54 @@ +