Issue #3432476 add ConsoleUserValidator

Closes #3432476

src/Validator/ConsoleUserValidator.php

+<?php
+
+namespace Drupal\automatic_updates\Validator;
+
+use Drupal\automatic_updates\ConsoleUpdateStage;
+use Drupal\package_manager\Event\PreCreateEvent;
+use Drupal\package_manager\Event\StatusCheckEvent;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Validates that the `auto-update` script is not run as the root user.
+ *
+ * @todo Remove this validator in favor of exiting the `auto-update` script as
+ *   early as possible if run as root in https://www.drupal.org/i/3432496.
+ */
+class ConsoleUserValidator implements EventSubscriberInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    return [
+      StatusCheckEvent::class => ['validateConsoleUser'],
+      PreCreateEvent::class => ['validateConsoleUser'],
+    ];
+  }
+
+  /**
+   * Adds a warning if the `auto-update` script is run as the root user.
+   *
+   * @param \Drupal\package_manager\Event\StatusCheckEvent|\Drupal\package_manager\Event\PreCreateEvent $event
+   *   The stage event.
+   */
+  public function validateConsoleUser(StatusCheckEvent|PreCreateEvent $event) {
+    if ($event->stage instanceof ConsoleUpdateStage && function_exists('posix_getuid') && posix_getuid() === 0) {
+      $event->addWarning([t('The `auto-update` script should not be run as the root user. Please run it as a less privileged user. In 3.1.0 if this script is run as the root user updates will not be preformed.')]);
+    }
+  }
+
+}