Fixes #1297: CSRF not generated on error pages

docs/guide/error.md

@@ -22,14 +22,14 @@ return [
     ],
 ```
 
-After it is done in case of error Yii will launch `SiteController::actionError()`. Since errors are converted to
-exceptions we can get exception from error handler:
+After it is done in case of error, Yii will launch `SiteController::actionError()`:
 
 ```php
 public function actionError()
 {
-    $exception = \Yii::$app->getErrorHandler()->exception;
-    $this->render('myerror', ['message' => $exception->getMessage()]);
+    if (\Yii::$app->exception !== null) {
+        return $this->render('error', ['exception' => \Yii::$app->exception]);
+    }
 }
 ```
 
@@ -48,7 +48,7 @@ public function actions()
 ```
 
 After defining `actions` in `SiteController` as shown above you can create `views/site/error.php`. In the view there
-are three varialbes available:
+are three variables available:
 
 - `$name`: the error name
 - `$message`: the error message

framework/yii/base/Application.php

@@ -127,6 +127,11 @@ abstract class Application extends Module
 	 * ~~~
 	 */
 	public $extensions = [];
+	/**
+	 * @var \Exception the exception that is being handled currently. When this is not null,
+	 * it means the application is handling some exception and extra care should be taken.
+	 */
+	public $exception;
 
 	/**
 	 * @var string Used to reserve memory for fatal error handler.
@@ -487,6 +492,8 @@ abstract class Application extends Module
 	 */
 	public function handleException($exception)
 	{
+		$this->exception = $exception;
+
 		// disable error capturing to avoid recursive errors while handling exceptions
 		restore_error_handler();
 		restore_exception_handler();
@@ -574,6 +581,7 @@ abstract class Application extends Module
 
 		if (ErrorException::isFatalError($error)) {
 			$exception = new ErrorException($error['message'], $error['type'], $error['type'], $error['file'], $error['line']);
+			$this->exception = $exception;
 			// use error_log because it's too late to use Yii log
 			error_log($exception);
 

framework/yii/base/ErrorHandler.php

@@ -40,7 +40,7 @@ class ErrorHandler extends Component
 	/**
 	 * @var string the route (e.g. 'site/error') to the controller action that will be used
 	 * to display external errors. Inside the action, it can retrieve the error information
-	 * by Yii::$app->errorHandler->exception. This property defaults to null, meaning ErrorHandler
+	 * by Yii::$app->exception. This property defaults to null, meaning ErrorHandler
 	 * will handle the error display.
 	 */
 	public $errorAction;
@@ -96,8 +96,6 @@ class ErrorHandler extends Component
 		$response->getHeaders()->removeAll();
 
 		if ($useErrorView && $this->errorAction !== null) {
-			// disable CSRF validation so that errorAction can run in case the error is caused by CSRF validation failure
-			Yii::$app->getRequest()->enableCsrfValidation = false;
 			$result = Yii::$app->runAction($this->errorAction);
 			if ($result instanceof Response) {
 				$response = $result;

framework/yii/web/Controller.php

@@ -91,7 +91,7 @@ class Controller extends \yii\base\Controller
 	public function beforeAction($action)
 	{
 		if (parent::beforeAction($action)) {
-			if ($this->enableCsrfValidation && !Yii::$app->getRequest()->validateCsrfToken()) {
+			if ($this->enableCsrfValidation && Yii::$app->exception === null && !Yii::$app->getRequest()->validateCsrfToken()) {
 				throw new HttpException(400, Yii::t('yii', 'Unable to verify your data submission.'));
 			}
 			return true;

framework/yii/web/ErrorAction.php

@@ -69,7 +69,7 @@ class ErrorAction extends Action
 
 	public function run()
 	{
-		if (!($exception = Yii::$app->getErrorHandler()->exception)) {
+		if (($exception = Yii::$app->exception) === null) {
 			return '';
 		}