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

package_manager/src/EventSubscriber/LockFileValidator.php

+<?php
+
+namespace Drupal\package_manager\EventSubscriber;
+
+use Drupal\Core\State\StateInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\package_manager\Event\PostDestroyEvent;
+use Drupal\package_manager\Event\PreApplyEvent;
+use Drupal\package_manager\Event\PreCreateEvent;
+use Drupal\package_manager\Event\PreRequireEvent;
+use Drupal\package_manager\Event\StageEvent;
+use Drupal\package_manager\PathLocator;
+use Drupal\package_manager\ValidationResult;
+
+/**
+ * Checks that the active lock file is unchanged during stage operations.
+ */
+class LockFileValidator implements StageValidatorInterface {
+
+  use StringTranslationTrait;
+
+  /**
+   * The state key under which to store the hash of the active lock file.
+   *
+   * @var string
+   */
+  protected const STATE_KEY = 'package_manager.lock_hash';
+
+  /**
+   * The state service.
+   *
+   * @var \Drupal\Core\State\StateInterface
+   */
+  protected $state;
+
+  /**
+   * The path locator service.
+   *
+   * @var \Drupal\package_manager\PathLocator
+   */
+  protected $pathLocator;
+
+  /**
+   * Constructs a LockFileValidator object.
+   *
+   * @param \Drupal\Core\State\StateInterface $state
+   *   The state service.
+   * @param \Drupal\package_manager\PathLocator $path_locator
+   *   The path locator service.
+   * @param \Drupal\Core\StringTranslation\TranslationInterface $translation
+   *   The string translation service.
+   */
+  public function __construct(StateInterface $state, PathLocator $path_locator, TranslationInterface $translation) {
+    $this->state = $state;
+    $this->pathLocator = $path_locator;
+    $this->setStringTranslation($translation);
+  }
+
+  /**
+   * Returns the current hash of the active directory's lock file.
+   *
+   * @return string|false
+   *   The hash of the active directory's lock file, or FALSE if the lock file
+   *   does not exist.
+   */
+  protected function getHash() {
+    $file = $this->pathLocator->getActiveDirectory() . DIRECTORY_SEPARATOR . 'composer.lock';
+    // We want to directly hash the lock file itself, rather than look at its
+    // content-hash value, which is actually a hash of the relevant parts of
+    // composer.json. We're trying to verify that the actual installed packages
+    // have not changed; we don't care about the constraints in composer.json.
+    try {
+      return hash_file('sha256', $file);
+    }
+    catch (\Throwable $exception) {
+      return FALSE;
+    }
+  }
+
+  /**
+   * Stores the current lock file hash.
+   */
+  public function storeHash(PreCreateEvent $event): void {
+    $hash = $this->getHash();
+    if ($hash) {
+      $this->state->set(static::STATE_KEY, $hash);
+    }
+    else {
+      $result = ValidationResult::createError([
+        $this->t('Could not hash the active lock file.'),
+      ]);
+      $event->addValidationResult($result);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateStage(StageEvent $event): void {
+    // Ensure we can get a current hash of the lock file.
+    $hash = $this->getHash();
+    if (empty($hash)) {
+      $error = $this->t('Could not hash the active lock file.');
+    }
+
+    // Ensure we also have a stored hash of the lock file.
+    $stored_hash = $this->state->get(static::STATE_KEY);
+    if (empty($stored_hash)) {
+      $error = $this->t('Could not retrieve stored hash of the active lock file.');
+    }
+
+    // If we have both hashes, ensure they match.
+    if ($hash && $stored_hash && hash_equals($stored_hash, $hash) == FALSE) {
+      $error = $this->t('Stored lock file hash does not match the active lock file.');
+    }
+
+    // @todo Let the validation result carry all the relevant messages in
+    //   https://www.drupal.org/i/3247479.
+    if (isset($error)) {
+      $result = ValidationResult::createError([$error]);
+      $event->addValidationResult($result);
+    }
+  }
+
+  /**
+   * Deletes the stored lock file hash.
+   */
+  public function deleteHash(): void {
+    $this->state->delete(static::STATE_KEY);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    return [
+      PreCreateEvent::class => 'storeHash',
+      PreRequireEvent::class => 'validateStage',
+      PreApplyEvent::class => 'validateStage',
+      PostDestroyEvent::class => 'deleteHash',
+    ];
+  }
+
+}