feature #27519 [HttpKernel][FrameworkBundle] Turn HTTP exceptions to HTTP status codes by default (nicolas-grekas)

This PR was merged into the 4.2-dev branch.

Discussion
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[HttpKernel][FrameworkBundle] Turn HTTP exceptions to HTTP status codes by default

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #25844
| License       | MIT
| Doc PR        | -

When an exception is thrown, *if it is not handled* then it will be reinjected as a 2nd exception event via `HttpKernel::terminateWithException()`. When this happens, this will generate a proper HTTP status code.

Commits
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80b0739fc2 [HttpKernel][FrameworkBundle] Turn HTTP exceptions to HTTP status codes by default

src/Symfony/Bundle/FrameworkBundle/Resources/config/web.xml

@@ -67,6 +67,16 @@
             <argument type="service" id="router" on-invalid="ignore" />
         </service>
 
+        <service id="http_exception_listener" class="Symfony\Component\HttpKernel\EventListener\ExceptionListener">
+            <tag name="kernel.event_listener" event="kernel.exception" method="onKernelException" priority="-2048" />
+            <tag name="kernel.reset" method="reset" />
+            <argument>null</argument>
+            <argument>null</argument>
+            <argument>%kernel.debug%</argument>
+            <argument>%kernel.charset%</argument>
+            <argument>%debug.file_link_format%</argument>
+        </service>
+
         <service id="validate_request_listener" class="Symfony\Component\HttpKernel\EventListener\ValidateRequestListener">
             <tag name="kernel.event_subscriber" />
         </service>

src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php

@@ -13,8 +13,10 @@ namespace Symfony\Component\HttpKernel\EventListener;
 
 use Psr\Log\LoggerInterface;
 use Symfony\Component\Debug\Exception\FlattenException;
+use Symfony\Component\Debug\ExceptionHandler;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
 use Symfony\Component\HttpKernel\Log\DebugLoggerInterface;
 use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
@@ -33,12 +35,17 @@ class ExceptionListener implements EventSubscriberInterface
     protected $controller;
     protected $logger;
     protected $debug;
+    private $charset;
+    private $fileLinkFormat;
+    private $isTerminating = false;
 
-    public function __construct($controller, LoggerInterface $logger = null, $debug = false)
+    public function __construct($controller, LoggerInterface $logger = null, $debug = false, string $charset = null, $fileLinkFormat = null)
     {
         $this->controller = $controller;
         $this->logger = $logger;
         $this->debug = $debug;
+        $this->charset = $charset;
+        $this->fileLinkFormat = $fileLinkFormat;
     }
 
     public function logKernelException(GetResponseForExceptionEvent $event)
@@ -50,6 +57,17 @@ class ExceptionListener implements EventSubscriberInterface
 
     public function onKernelException(GetResponseForExceptionEvent $event)
     {
+        if (null === $this->controller) {
+            if (!$event->isMasterRequest()) {
+                return;
+            }
+            if (!$this->isTerminating) {
+                $this->isTerminating = true;
+
+                return;
+            }
+            $this->isTerminating = false;
+        }
         $exception = $event->getException();
         $request = $this->duplicateRequest($exception, $event->getRequest());
         $eventDispatcher = func_num_args() > 2 ? func_get_arg(2) : null;
@@ -85,6 +103,11 @@ class ExceptionListener implements EventSubscriberInterface
         }
     }
 
+    public function reset()
+    {
+        $this->isTerminating = false;
+    }
+
     public static function getSubscribedEvents()
     {
         return array(
@@ -123,8 +146,12 @@ class ExceptionListener implements EventSubscriberInterface
     protected function duplicateRequest(\Exception $exception, Request $request)
     {
         $attributes = array(
-            '_controller' => $this->controller,
-            'exception' => FlattenException::create($exception),
+            'exception' => $exception = FlattenException::create($exception),
+            '_controller' => $this->controller ?: function () use ($exception) {
+                $handler = new ExceptionHandler($this->debug, $this->charset, $this->fileLinkFormat);
+
+                return new Response($handler->getHtml($exception), $exception->getStatusCode(), $exception->getHeaders());
+            },
             'logger' => $this->logger instanceof DebugLoggerInterface ? $this->logger : null,
         );
         $request = $request->duplicate(null, null, $attributes);

src/Symfony/Component/HttpKernel/Tests/EventListener/ExceptionListenerTest.php

@@ -155,6 +155,25 @@ class ExceptionListenerTest extends TestCase
         $this->assertFalse($response->headers->has('content-security-policy'), 'CSP header has been removed');
         $this->assertFalse($dispatcher->hasListeners(KernelEvents::RESPONSE), 'CSP removal listener has been removed');
     }
+
+    public function testNullController()
+    {
+        $listener = new ExceptionListener(null);
+        $kernel = $this->getMockBuilder(HttpKernelInterface::class)->getMock();
+        $kernel->expects($this->once())->method('handle')->will($this->returnCallback(function (Request $request) {
+            $controller = $request->attributes->get('_controller');
+
+            return $controller();
+        }));
+        $request = Request::create('/');
+        $event = new GetResponseForExceptionEvent($kernel, $request, HttpKernelInterface::MASTER_REQUEST, new \Exception('foo'));
+
+        $listener->onKernelException($event);
+        $this->assertNull($event->getResponse());
+
+        $listener->onKernelException($event);
+        $this->assertContains('Whoops, looks like something went wrong.', $event->getResponse()->getContent());
+    }
 }
 
 class TestLogger extends Logger implements DebugLoggerInterface