Add system principal to cal of each card

apps/dav/lib/carddav/addressbook.php

@@ -3,6 +3,7 @@
 namespace OCA\DAV\CardDAV;
 
 use OCA\DAV\CardDAV\Sharing\IShareableAddressBook;
+use Sabre\DAV\Exception\NotFound;
 
 class AddressBook extends \Sabre\CardDAV\AddressBook implements IShareableAddressBook {
 
@@ -77,4 +78,13 @@ class AddressBook extends \Sabre\CardDAV\AddressBook implements IShareableAddres
 
 		return $acl;
 	}
+
+	function getChild($name) {
+		$obj = $this->carddavBackend->getCard($this->addressBookInfo['id'], $name);
+		if (!$obj) {
+			throw new NotFound('Card not found');
+		}
+		return new Card($this->carddavBackend, $this->addressBookInfo, $obj);
+	}
+
 }

apps/dav/lib/carddav/card.php

@@ -0,0 +1,39 @@
+<?php
+/**
+ * @author Thomas Müller <thomas.mueller@tmit.eu>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\DAV\CardDAV;
+
+class Card extends \Sabre\CardDAV\Card {
+
+	function getACL() {
+		$acl = parent::getACL();
+		if ($this->getOwner() === 'principals/system/system') {
+			$acl[] = [
+				'privilege' => '{DAV:}read',
+				'principal' => '{DAV:}authenticated',
+				'protected' => true,
+			];
+		}
+
+		return $acl;
+	}
+
+}