Issue #3285631: Make it impossible to call CronUpdater::begin() directly

package_manager/src/Validator/SymlinkValidator.php

+<?php
+
+namespace Drupal\package_manager\Validator;
+
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\package_manager\Event\PreApplyEvent;
+use Drupal\package_manager\Event\PreCreateEvent;
+use Drupal\package_manager\Event\PreOperationStageEvent;
+use Drupal\package_manager\PathLocator;
+use Symfony\Component\Finder\Finder;
+
+/**
+ * Flags errors if the project root or staging area contain symbolic links.
+ *
+ * @todo Remove this when Composer Stager's PHP file copier handles symlinks
+ *   without issues.
+ */
+class SymlinkValidator implements PreOperationStageValidatorInterface {
+
+  use StringTranslationTrait;
+
+  /**
+   * The path locator service.
+   *
+   * @var \Drupal\package_manager\PathLocator
+   */
+  protected $pathLocator;
+
+  /**
+   * Constructs a SymlinkValidator object.
+   *
+   * @param \Drupal\package_manager\PathLocator $path_locator
+   *   The path locator service.
+   */
+  public function __construct(PathLocator $path_locator) {
+    $this->pathLocator = $path_locator;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateStagePreOperation(PreOperationStageEvent $event): void {
+    $dir = $this->pathLocator->getProjectRoot();
+
+    if ($this->hasLinks($dir)) {
+      $event->addError([
+        $this->t('Symbolic links were found in the active directory, which are not supported at this time.'),
+      ]);
+    }
+  }
+
+  /**
+   * Checks if the staging area has any symbolic links.
+   *
+   * @param \Drupal\package_manager\Event\PreApplyEvent $event
+   *   The event object.
+   */
+  public function preApply(PreApplyEvent $event): void {
+    $dir = $event->getStage()->getStageDirectory();
+
+    if ($this->hasLinks($dir)) {
+      $event->addError([
+        $this->t('Symbolic links were found in the staging area, which are not supported at this time.'),
+      ]);
+    }
+  }
+
+  /**
+   * Recursively checks if a directory has any symbolic links.
+   *
+   * @param string $dir
+   *   The path of the directory to check.
+   *
+   * @return bool
+   *   TRUE if the directory contains any symbolic links, FALSE otherwise.
+   */
+  protected function hasLinks(string $dir): bool {
+    // Finder::filter() explicitly requires a closure, so create one from
+    // ::isLink() so that we can still override it for testing purposes.
+    $is_link = \Closure::fromCallable([$this, 'isLink']);
+
+    // Finder::hasResults() is more efficient than count() because it will
+    // return early if there is a match.
+    return Finder::create()
+      ->in($dir)
+      ->filter($is_link)
+      ->ignoreUnreadableDirs()
+      ->hasResults();
+  }
+
+  /**
+   * Checks if a file or directory is a symbolic link.
+   *
+   * @param \SplFileInfo $file
+   *   A value object for the file or directory.
+   *
+   * @return bool
+   *   TRUE if the file or directory is a symbolic link, FALSE otherwise.
+   */
+  protected function isLink(\SplFileInfo $file): bool {
+    return $file->isLink();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    return [
+      PreCreateEvent::class => 'validateStagePreOperation',
+      PreApplyEvent::class => [
+        ['validateStagePreOperation'],
+        ['preApply'],
+      ],
+    ];
+  }
+
+}