Issue #3331310: Exclude unknown paths in project base

package_manager/src/PathExcluder/UnknownPathExcluder.php

+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\package_manager\PathExcluder;
+
+use Drupal\package_manager\Event\CollectIgnoredPathsEvent;
+use Drupal\package_manager\PathLocator;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Excludes unknown paths from stage operations.
+ *
+ * Any paths in the root directory of the project that are NOT one of the
+ * following are considered unknown paths:
+ * 1. The vendor directory
+ * 2. The webroot
+ * 3. composer.json
+ * 4. composer.lock
+ * 5. Scaffold files as determined by the drupal/core-composer-scaffold plugin
+ * If web root and project root are same then nothing is excluded.
+ *
+ * @internal
+ *   This is an internal part of Package Manager and may be changed or removed
+ *   at any time without warning. External code should not interact with this
+ *   class.
+ */
+final class UnknownPathExcluder implements EventSubscriberInterface {
+
+  use PathExclusionsTrait;
+
+  /**
+   * Constructs a UnknownPathExcluder object.
+   *
+   * @param \Drupal\package_manager\PathLocator $path_locator
+   *   The path locator service.
+   */
+  public function __construct(PathLocator $path_locator) {
+    $this->pathLocator = $path_locator;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    return [
+      CollectIgnoredPathsEvent::class => 'excludeUnknownPaths',
+    ];
+  }
+
+  /**
+   * Excludes unknown paths from stage operations.
+   *
+   * @param \Drupal\package_manager\Event\CollectIgnoredPathsEvent $event
+   *   The event object.
+   */
+  public function excludeUnknownPaths(CollectIgnoredPathsEvent $event): void {
+    $project_root = $this->pathLocator->getProjectRoot();
+    $web_root = $project_root . DIRECTORY_SEPARATOR . $this->pathLocator->getWebRoot();
+    if (realpath($web_root) === $project_root) {
+      return;
+    }
+    $vendor_dir = $this->pathLocator->getVendorDirectory();
+    // @todo Refactor in https://www.drupal.org/project/automatic_updates/issues/3334994.
+    $core_packages = $event->getStage()->getActiveComposer()->getCorePackages();
+    $scaffold_files_paths = $this->getScaffoldFiles($core_packages);
+    $paths_in_project_root = glob("$project_root/*");
+    $paths = [];
+    $known_paths = array_merge([$vendor_dir, $web_root, "$project_root/composer.json", "$project_root/composer.lock"], $scaffold_files_paths);
+    foreach ($paths_in_project_root as $path_in_project_root) {
+      if (!in_array($path_in_project_root, $known_paths, TRUE)) {
+        $paths[] = $path_in_project_root;
+      }
+    }
+    $this->excludeInProjectRoot($event, $paths);
+  }
+
+  /**
+   * Gets the path of scaffold files, for example 'index.php' and 'robots.txt'.
+   *
+   * @param string[] $core_packages
+   *   The installed core packages.
+   *
+   * @return array
+   *   The array of scaffold file paths.
+   */
+  private function getScaffoldFiles(array $core_packages): array {
+    $scaffold_file_paths = [];
+    /** @var \Composer\Package\PackageInterface $package */
+    foreach ($core_packages as $package) {
+      $core_composer_extra = $package->getExtra();
+      if (array_key_exists('drupal-scaffold', $core_composer_extra)) {
+        $scaffold_file_paths = array_merge($scaffold_file_paths, array_keys($core_composer_extra['drupal-scaffold']['file-mapping']));
+      }
+    }
+    return $scaffold_file_paths;
+  }
+
+}