debt: Own the handling of the is-encrypted DAV property

Signed-off-by: Louis Chemineau <louis@chmn.me>

lib/Connector/Sabre/PropFindPlugin.php

@@ -37,6 +37,8 @@
 use Sabre\HTTP\RequestInterface;
 
 class PropFindPlugin extends APlugin {
+	public const IS_ENCRYPTED_PROPERTYNAME = '{http://nextcloud.org/ns}is-encrypted';
+
 	private UserAgentManager $userAgentManager;
 	private IRequest $request;
 	protected ?Server $server = null;
@@ -58,10 +60,20 @@ public function initialize(Server $server) {
 		parent::initialize($server);
 
 		$this->server = $server;
+		$this->server->on('propFind', [$this, 'setEncryptedProperty']);
 		$this->server->on('afterMethod:PROPFIND', [$this, 'checkAccess'], 50);
 		$this->server->on('propFind', [$this, 'updateProperty'], 105);
 	}
 
+	public function setEncryptedProperty(PropFind $propFind, \Sabre\DAV\INode $node) {
+		// Only folders can be e2e encrypted, so we only respond for directories.
+		if ($node instanceof Directory) {
+			$propFind->handle(self::IS_ENCRYPTED_PROPERTYNAME, function () use ($node) {
+				return $node->getFileInfo()->isEncrypted() ? '1' : '0';
+			});
+		}
+	}
+
 	/**
 	 * Remove permissions of end-to-end encrypted files for unsupported clients
 	 *