Issue #3245996: Move basic exclusions and test coverage into Package Manager

package_manager/src/EventSubscriber/ExcludedPathsSubscriber.php

+<?php
+
+namespace Drupal\package_manager\EventSubscriber;
+
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\StreamWrapper\LocalStream;
+use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
+use Drupal\package_manager\Event\PreApplyEvent;
+use Drupal\package_manager\Event\PreCreateEvent;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Defines an event subscriber to exclude certain paths from staging areas.
+ */
+class ExcludedPathsSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The Drupal root.
+   *
+   * @var string
+   */
+  protected $appRoot;
+
+  /**
+   * The current site path, relative to the Drupal root.
+   *
+   * @var string
+   */
+  protected $sitePath;
+
+  /**
+   * The file system service.
+   *
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  protected $fileSystem;
+
+  /**
+   * The stream wrapper manager service.
+   *
+   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
+   */
+  protected $streamWrapperManager;
+
+  /**
+   * Constructs an UpdateSubscriber.
+   *
+   * @param string $app_root
+   *   The Drupal root.
+   * @param string $site_path
+   *   The current site path, relative to the Drupal root.
+   * @param \Drupal\Core\File\FileSystemInterface $file_system
+   *   The file system service.
+   * @param \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrapper_manager
+   *   The stream wrapper manager service.
+   */
+  public function __construct(string $app_root, string $site_path, FileSystemInterface $file_system, StreamWrapperManagerInterface $stream_wrapper_manager) {
+    $this->appRoot = $app_root;
+    $this->sitePath = $site_path;
+    $this->fileSystem = $file_system;
+    $this->streamWrapperManager = $stream_wrapper_manager;
+  }
+
+  /**
+   * Reacts before staged changes are committed the active directory.
+   *
+   * @param \Drupal\package_manager\Event\PreApplyEvent $event
+   *   The event object.
+   */
+  public function preApply(PreApplyEvent $event): void {
+    // Don't copy anything from the staging area's sites/default.
+    // @todo Make this a lot smarter in https://www.drupal.org/i/3228955.
+    $event->excludePath('sites/default');
+
+    // If the core-vendor-hardening plugin (used in the legacy-project template)
+    // is present, it may have written a web.config file into the vendor
+    // directory. We don't want to copy that.
+    $event->excludePath('web.config');
+  }
+
+  /**
+   * Excludes paths from a staging area before it is created.
+   *
+   * @param \Drupal\package_manager\Event\PreCreateEvent $event
+   *   The event object.
+   */
+  public function preCreate(PreCreateEvent $event): void {
+    // Automated test site directories should never be staged.
+    $event->excludePath('sites/simpletest');
+
+    // Windows server configuration files, like web.config, should never be
+    // staged either. (These can be written in the vendor directory by the
+    // core-vendor-hardening plugin, which is used in the drupal/legacy-project
+    // template.)
+    $event->excludePath('web.config');
+
+    if ($public = $this->getFilesPath('public')) {
+      $event->excludePath($public);
+    }
+    if ($private = $this->getFilesPath('private')) {
+      $event->excludePath($private);
+    }
+
+    // Exclude site-specific settings files.
+    $settings_files = [
+      'settings.php',
+      'settings.local.php',
+      'services.yml',
+    ];
+    $default_site = 'sites' . DIRECTORY_SEPARATOR . 'default';
+
+    foreach ($settings_files as $settings_file) {
+      $event->excludePath($this->sitePath . DIRECTORY_SEPARATOR . $settings_file);
+      $event->excludePath($default_site . DIRECTORY_SEPARATOR . $settings_file);
+    }
+  }
+
+  /**
+   * Returns the storage path for a stream wrapper.
+   *
+   * This will only work for stream wrappers that extend
+   * \Drupal\Core\StreamWrapper\LocalStream, which includes the stream wrappers
+   * for public and private files.
+   *
+   * @param string $scheme
+   *   The stream wrapper scheme.
+   *
+   * @return string|null
+   *   The storage path for files using the given scheme, relative to the Drupal
+   *   root, or NULL if the stream wrapper does not extend
+   *   \Drupal\Core\StreamWrapper\LocalStream.
+   */
+  private function getFilesPath(string $scheme): ?string {
+    $wrapper = $this->streamWrapperManager->getViaScheme($scheme);
+    if ($wrapper instanceof LocalStream) {
+      return $wrapper->getDirectoryPath();
+    }
+    return NULL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    return [
+      PreCreateEvent::class => 'preCreate',
+      PreApplyEvent::class => 'preApply',
+    ];
+  }
+
+}