bug #18908 [DependencyInjection] force enabling the external XML entity loaders (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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[DependencyInjection] force enabling the external XML entity loaders

| Q             | A
| ------------- | ---
| Branch?       | 2.3
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #18876
| License       | MIT
| Doc PR        |

Commits
-------

142b1a4 force enabling the external XML entity loaders

Author: nicolas-grekas

Loader/XmlFileLoader.php

@@ -333,7 +333,9 @@ public function validateSchema(\DOMDocument $dom)
 EOF
         ;
 
+        $disableEntities = libxml_disable_entity_loader(false);
         $valid = @$dom->schemaValidateSource($source);
+        libxml_disable_entity_loader($disableEntities);
 
         foreach ($tmpfiles as $tmpfile) {
             @unlink($tmpfile);

Tests/Loader/XmlFileLoaderTest.php

@@ -83,6 +83,19 @@ public function testParseFile()
         $this->assertInstanceOf('Symfony\\Component\\DependencyInjection\\SimpleXMLElement', $xml, '->parseFile() returns an SimpleXMLElement object');
     }
 
+    public function testLoaderTurnsOnEntityLoaderIfNecessary()
+    {
+        $oldValue = libxml_disable_entity_loader(true);
+
+        $containerBuilder = new ContainerBuilder();
+        $loader = new XmlFileLoader($containerBuilder, new FileLocator(self::$fixturesPath.'/xml'));
+        $loader->load('services2.xml');
+
+        libxml_disable_entity_loader($oldValue);
+
+        $this->assertTrue(count($containerBuilder->getParameterBag()->all()) > 0, 'Parameters can be read from the config file.');
+    }
+
     public function testLoadParameters()
     {
         $container = new ContainerBuilder();