From a9d1dede447ea046cdf9135a28df8c99911ad5e1 Mon Sep 17 00:00:00 2001
From: "Alexander M. Turek" <me@derrabus.de>
Date: Fri, 7 Feb 2020 15:12:51 +0100
Subject: [PATCH] [HttpKernel] Make ErrorListener unaware of the event
 dispatcher.

---
 .../EventListener/ErrorListener.php           | 22 +++++++++++--------
 .../Tests/EventListener/ErrorListenerTest.php |  1 -
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/Symfony/Component/HttpKernel/EventListener/ErrorListener.php b/src/Symfony/Component/HttpKernel/EventListener/ErrorListener.php
index 26c361f754..6192a452e3 100644
--- a/src/Symfony/Component/HttpKernel/EventListener/ErrorListener.php
+++ b/src/Symfony/Component/HttpKernel/EventListener/ErrorListener.php
@@ -14,11 +14,11 @@ namespace Symfony\Component\HttpKernel\EventListener;
 use Psr\Log\LoggerInterface;
 use Symfony\Component\Debug\Exception\FlattenException as LegacyFlattenException;
 use Symfony\Component\ErrorHandler\Exception\FlattenException;
-use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Event\ControllerArgumentsEvent;
 use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Symfony\Component\HttpKernel\Event\ResponseEvent;
 use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
 use Symfony\Component\HttpKernel\KernelEvents;
@@ -33,7 +33,7 @@ class ErrorListener implements EventSubscriberInterface
     protected $logger;
     protected $debug;
 
-    public function __construct($controller, LoggerInterface $logger = null, $debug = false)
+    public function __construct($controller, LoggerInterface $logger = null, bool $debug = false)
     {
         $this->controller = $controller;
         $this->logger = $logger;
@@ -47,7 +47,7 @@ class ErrorListener implements EventSubscriberInterface
         $this->logException($event->getThrowable(), sprintf('Uncaught PHP Exception %s: "%s" at %s line %s', $e->getClass(), $e->getMessage(), $e->getFile(), $e->getLine()));
     }
 
-    public function onKernelException(ExceptionEvent $event, string $eventName = null, EventDispatcherInterface $eventDispatcher = null)
+    public function onKernelException(ExceptionEvent $event)
     {
         if (null === $this->controller) {
             return;
@@ -79,12 +79,15 @@ class ErrorListener implements EventSubscriberInterface
 
         $event->setResponse($response);
 
-        if ($this->debug && $eventDispatcher instanceof EventDispatcherInterface) {
-            $cspRemovalListener = function ($event) use (&$cspRemovalListener, $eventDispatcher) {
-                $event->getResponse()->headers->remove('Content-Security-Policy');
-                $eventDispatcher->removeListener(KernelEvents::RESPONSE, $cspRemovalListener);
-            };
-            $eventDispatcher->addListener(KernelEvents::RESPONSE, $cspRemovalListener, -128);
+        if ($this->debug) {
+            $event->getRequest()->attributes->set('_remove_csp_headers', true);
+        }
+    }
+
+    public function removeCspHeader(ResponseEvent $event): void
+    {
+        if ($this->debug && $event->getRequest()->attributes->get('_remove_csp_headers', false)) {
+            $event->getResponse()->headers->remove('Content-Security-Policy');
         }
     }
 
@@ -114,6 +117,7 @@ class ErrorListener implements EventSubscriberInterface
                 ['logKernelException', 0],
                 ['onKernelException', -128],
             ],
+            KernelEvents::RESPONSE => ['removeCspHeader', -128],
         ];
     }
 
diff --git a/src/Symfony/Component/HttpKernel/Tests/EventListener/ErrorListenerTest.php b/src/Symfony/Component/HttpKernel/Tests/EventListener/ErrorListenerTest.php
index cdf6874f35..408b580630 100644
--- a/src/Symfony/Component/HttpKernel/Tests/EventListener/ErrorListenerTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/EventListener/ErrorListenerTest.php
@@ -155,7 +155,6 @@ class ErrorListenerTest extends TestCase
         $dispatcher->dispatch($event, KernelEvents::RESPONSE);
 
         $this->assertFalse($response->headers->has('content-security-policy'), 'CSP header has been removed');
-        $this->assertFalse($dispatcher->hasListeners(KernelEvents::RESPONSE), 'CSP removal listener has been removed');
     }
 
     /**