ExceptionHandler.php

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<?php

namespace Elgg\Application;

use Elgg\Application;
use Elgg\Exceptions\Configuration\InstallationException;
use Elgg\Http\Request;
use Elgg\Traits\Loggable;
use Psr\Log\LogLevel;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\RedirectResponse;
use Symfony\Component\HttpFoundation\Response;

class ExceptionHandler {

    use Loggable;

    public function __invoke($exception) {
        $exception->timestamp = time();
        $exception->uncaught = true;

        $this->log(LogLevel::CRITICAL, $exception);

        // Wipe any existing output buffer
        ob_end_clean();

        $request = Request::createFromGlobals();
        $headers = [
            'Cache-Control' => 'no-store, must-revalidate',
            'Expires' => 'Fri, 05 Feb 1982 00:00:00 -0500',
        ];

        if ($exception instanceof InstallationException) {
            $response = new RedirectResponse('/install.php', ELGG_HTTP_TEMPORARY_REDIRECT, $headers);
            $response->prepare($request);

            $response->send();

            return;
        }

        $app = Application::$_instance;

        if (!$app || !$app->internal_services) {
            $msg = "Exception loading Elgg core. Check log at time {$exception->timestamp}";
            $response = new Response($msg, ELGG_HTTP_INTERNAL_SERVER_ERROR, $headers);
            $response->prepare($request);

            $response->send();

            return;
        }

        $services = $app->internal_services;
        if ($services->responseFactory->getSentResponse() !== null) {
            return;
        }
        
        try {
            // allow custom scripts to trigger on exception
            // value in settings.php should be a system path to a file to include
            $exception_include = $services->config->exception_include;

            if ($exception_include && is_file($exception_include)) {
                ob_start();

                // don't isolate, these scripts may use the local $exception var.
                include $exception_include;

                $exception_output = ob_get_clean();

                // if content is returned from the custom handler we will output
                // that instead of our default failsafe view
                if (!empty($exception_output)) {
                    $response = new Response($exception_output, ELGG_HTTP_INTERNAL_SERVER_ERROR, $headers);
                    $response->prepare($request);

                    $response->send();

                    return;
                }
            }

            if (Application::isCli()) {
                // An error has already been logged
                return;
            }

            if ($services->request->isXmlHttpRequest()) {
                $services->views->setViewtype('json');
                $response = new JsonResponse(null, ELGG_HTTP_INTERNAL_SERVER_ERROR, $headers);
            } else {
                $services->views->setViewtype('failsafe');
                $response = new Response('', ELGG_HTTP_INTERNAL_SERVER_ERROR, $headers);
            }

            $body = elgg_view('messages/exceptions/exception', [
                'object' => $exception,
                'ts' => $exception->timestamp,
            ]);

            $response->prepare($services->request);
            $response->setContent(elgg_view_page(elgg_echo('exception:title'), $body));
            $response->send();
        } catch (\Exception $e) {
            $timestamp = time();

            $e->timestamp = $timestamp;

            $this->log(LogLevel::CRITICAL, $e);

            $msg = "Fatal error in exception handler. Check log for Exception at time $timestamp";

            $response = new Response($msg, ELGG_HTTP_INTERNAL_SERVER_ERROR, $headers);
            $response->prepare($request);
            $response->send();
        }
    }
}