class SymlinkValidator

final class SymlinkValidator implements EventSubscriberInterface {
    use BaseRequirementValidatorTrait;
    public function __construct(PathLocator $pathLocator, NoUnsupportedLinksExistInterface $precondition, PathFactoryInterface $pathFactory, PathListFactoryInterface $pathListFactory) {
    }
    
    /**
     * Flags errors if the project root or stage directory contain symbolic links.
     */
    public function validate(PreOperationStageEvent $event) : void {
        if ($event instanceof PreRequireEvent) {
            // We don't need to check symlinks again during PreRequireEvent; this was
            // already just validated during PreCreateEvent.
            return;
        }
        $active_dir = $this->pathFactory
            ->create($this->pathLocator
            ->getProjectRoot());
        // The precondition requires us to pass both an active and stage directory,
        // so if the stage hasn't been created or claimed yet, use the directory
        // that contains this file, which contains only a few files and no symlinks,
        // as the stage directory. The precondition itself doesn't care if the
        // directory actually exists or not.
        $stage_dir = __DIR__;
        if ($event->stage
            ->stageDirectoryExists()) {
            $stage_dir = $event->stage
                ->getStageDirectory();
        }
        $stage_dir = $this->pathFactory
            ->create($stage_dir);
        // Return early if no excluded paths were collected because this validator
        // is dependent on knowing which paths to exclude when searching for
        // symlinks.
        // @see \Drupal\package_manager\StatusCheckTrait::runStatusCheck()
        if ($event->excludedPaths === NULL) {
            return;
        }
        // The list of excluded paths is immutable, but the precondition may need to
        // mutate it, so convert it back to a normal, mutable path list.
        $exclusions = $this->pathListFactory
            ->create(...$event->excludedPaths
            ->getAll());
        try {
            $this->precondition
                ->assertIsFulfilled($active_dir, $stage_dir, $exclusions);
        } catch (PreconditionException $e) {
            $event->addErrorFromThrowable($e);
        }
    }

}