From 22c3126c1c42143940a16bc627854b36abf87a79 Mon Sep 17 00:00:00 2001
From: Andrii Vasyliev <sol@hiqdev.com>
Date: Fri, 6 Jul 2018 17:05:03 +0300
Subject: [PATCH] Fixes #16487: Added circular reference detection in DI
 container

---
 framework/CHANGELOG.md                      |  1 +
 framework/di/CircularReferenceException.php | 39 +++++++++++++++++++++++++++++
 framework/di/Container.php                  | 13 ++++++++--
 tests/framework/di/ContainerTest.php        | 21 ++++++++++++++++
 4 files changed, 72 insertions(+), 2 deletions(-)
 create mode 100644 framework/di/CircularReferenceException.php

diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index f352e8c..34027b1 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -54,6 +54,7 @@ Yii Framework 2 Change Log
 - Enh #16126: Allows to configure `Connection::dsn` by config array (leandrogehlen)
 - Chg #11397: `yii\i18n\MessageFormatter` polyfills and `yii\i18n\MessageFormatter::parse()` method were removed resulting in performance boost. See UPGRADE for compatibility notes (samdark)
 - Chg #16247: Cloning components will now clone their behaviors as well (brandonkelly)
+- Enh #16487: Added circular reference detection in DI container (hiqsol)
 
 2.0.14.2 under development
 ------------------------
diff --git a/framework/di/CircularReferenceException.php b/framework/di/CircularReferenceException.php
new file mode 100644
index 0000000..cb5ca56
--- /dev/null
+++ b/framework/di/CircularReferenceException.php
@@ -0,0 +1,39 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\di;
+
+use yii\base\InvalidConfigException;
+
+/**
+ * NotInstantiableException is thrown when container tries to resolve
+ * object having circular reference in configuration.
+ *
+ * @author Andrii Vasyliev <sol@hiqdev.com>
+ * @since 3.0.0
+ */
+class CircularReferenceException extends InvalidConfigException
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function __construct($class, $message = null, $code = 0, \Exception $previous = null)
+    {
+        if ($message === null) {
+            $message = "Circular reference in $class.";
+        }
+        parent::__construct($message, $code, $previous);
+    }
+
+    /**
+     * @return string the user-friendly name of this exception
+     */
+    public function getName()
+    {
+        return 'Circular reference';
+    }
+}
diff --git a/framework/di/Container.php b/framework/di/Container.php
index c47c32a..8310106 100644
--- a/framework/di/Container.php
+++ b/framework/di/Container.php
@@ -121,7 +121,10 @@ class Container extends Component
      * is associated with a list of constructor parameter types or default values.
      */
     private $_dependencies = [];
-
+    /**
+     * @var array used to collect classes instantiated during get to detect circular references
+     */
+    private $_getting = [];
 
     /**
      * Returns an instance of the requested class.
@@ -157,6 +160,11 @@ class Container extends Component
             return $this->build($class, $params, $config);
         }
 
+        if (isset($this->_getting[$class])) {
+            throw new CircularReferenceException($class);
+        }
+        $this->_getting[$class] = 1;
+
         $definition = $this->_definitions[$class];
 
         if (is_callable($definition, true)) {
@@ -175,7 +183,7 @@ class Container extends Component
                 $object = $this->get($concrete, $params, $config);
             }
         } elseif (is_object($definition)) {
-            return $this->_singletons[$class] = $definition;
+            $object = $this->_singletons[$class] = $definition;
         } else {
             throw new InvalidConfigException('Unexpected object definition type: ' . gettype($definition));
         }
@@ -184,6 +192,7 @@ class Container extends Component
             // singleton
             $this->_singletons[$class] = $object;
         }
+        unset($this->_getting[$class]);
 
         return $object;
     }
diff --git a/tests/framework/di/ContainerTest.php b/tests/framework/di/ContainerTest.php
index e2f6a3d..c83adfe 100644
--- a/tests/framework/di/ContainerTest.php
+++ b/tests/framework/di/ContainerTest.php
@@ -10,6 +10,7 @@ namespace yiiunit\framework\di;
 use Yii;
 use yii\di\Container;
 use yii\di\Instance;
+use yii\di\CircularReferenceException;
 use yii\validators\NumberValidator;
 use yiiunit\data\ar\Cat;
 use yiiunit\data\ar\Order;
@@ -319,4 +320,24 @@ class ContainerTest extends TestCase
 
         $this->assertTrue(true, 'Should be not exception above');
     }
+
+    public function testCircularReference()
+    {
+        $container = new Container();
+        $container->set(Bar::class, Qux::class);
+        $container->set(Qux::class, Bar::class);
+
+        $this->expectException(CircularReferenceException::class);
+        $container->get(Qux::class);
+    }
+
+    public function testCircularReferenceWithInstance()
+    {
+        $container = new Container();
+        $container->set(Bar::class, 'qux');
+        $container->set('qux', Qux::class, [Instance::of(Bar::class)]);
+
+        $this->expectException(CircularReferenceException::class);
+        $container->get(Bar::class);
+    }
 }