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<?php
/**
* 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;
}
// Do not trigger the fatal error handler while updates are being installed.
if ( wp_is_maintenance_mode() ) {
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();
}
$handled = false;
if ( ! is_multisite() && wp_recovery_mode()->is_initialized() ) {
$handled = 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, $handled );
}
} 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, $error );
}
/**
* Displays the PHP error template and sends the HTTP status code, typically 500.
*
* A drop-in 'php-error.php' can be used as a custom template. This drop-in should control the HTTP status code and
* print the HTML markup indicating that a PHP error occurred. Note that this drop-in may potentially be executed
* very early in the WordPress bootstrap process, so any core functions used that are not part of
* `wp-includes/load.php` should be checked for before being called.
*
* If no such drop-in is available, this will call {@see WP_Fatal_Error_Handler::display_default_error_template()}.
*
* @since 5.2.0
* @since 5.3.0 The `$handled` parameter was added.
*
* @param array $error Error information retrieved from `error_get_last()`.
* @param true|WP_Error $handled Whether Recovery Mode handled the fatal error.
*/
protected function display_error_template( $error, $handled ) {
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, $handled );
}
/**
* Displays the default PHP error template.
*
* This method is called conditionally if no 'php-error.php' drop-in is available.
*
* It calls {@see wp_die()} with a message indicating that the site is experiencing technical difficulties and a
* login link to the admin backend. The {@see 'wp_php_error_message'} and {@see 'wp_php_error_args'} filters can
* be used to modify these parameters.
*
* @since 5.2.0
* @since 5.3.0 The `$handled` parameter was added.
*
* @param array $error Error information retrieved from `error_get_last()`.
* @param true|WP_Error $handled Whether Recovery Mode handled the fatal error.
*/
protected function display_default_error_template( $error, $handled ) {
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 ( true === $handled && wp_is_recovery_mode() ) {
$message = __( 'There has been a critical error on this website, putting it in recovery mode. Please check the Themes and Plugins screens for more details. If you just installed or updated a theme or plugin, check the relevant page for that first.' );
} elseif ( is_protected_endpoint() ) {
$message = __( 'There has been a critical error on this website. Please check your site admin email inbox for instructions.' );
} else {
$message = __( 'There has been a critical error on this website.' );
}
$message = sprintf(
'<p>%s</p><p><a href="%s">%s</a></p>',
$message,
/* translators: Documentation explaining debugging in WordPress. */
__( 'https://wordpress.org/support/article/debugging-in-wordpress/' ),
__( 'Learn more about debugging in WordPress.' )
);
$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 );
}
}
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