PreviewController: Indicate symlinks via preview icon in web ui

core/Controller/PreviewController.php

@@ -27,6 +27,7 @@
  */
 namespace OC\Core\Controller;
 
+use OC\Files\SymlinkManager;
 use OCA\Files_Sharing\SharedStorage;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
@@ -42,6 +43,12 @@
 use OCP\Preview\IMimeIconProvider;
 
 class PreviewController extends Controller {
+	private const SYMLINK_PREVIEW_ICON_PATH = '/core/img/filetypes/link.svg';
+	/**
+	 * @var SymlinkManager
+	 */
+	private $symlinkManager;
+
 	public function __construct(
 		string $appName,
 		IRequest $request,
@@ -51,6 +58,8 @@ public function __construct(
 		private IMimeIconProvider $mimeIconProvider,
 	) {
 		parent::__construct($appName, $request);
+
+		$this->symlinkManager = new SymlinkManager();
 	}
 
 	/**
@@ -169,6 +178,14 @@ private function fetchPreview(
 			}
 		}
 
+		if ($this->symlinkManager->isSymlink($node)) {
+			if ($url = \OC::$server->get(\OCP\IURLGenerator::class)->getAbsoluteURL(
+				self::SYMLINK_PREVIEW_ICON_PATH
+			)) {
+				return new RedirectResponse($url);
+			}
+		}
+
 		try {
 			$f = $this->preview->getPreview($node, $x, $y, !$a, $mode);
 			$response = new FileDisplayResponse($f, Http::STATUS_OK, [