server/apps/contacts/ajax/deletebook.php

<?php
/**
 * ownCloud - Addressbook
 *
 * @author Jakob Sack
 * @copyright 2011 Jakob Sack mail@jakobsack.de
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or any later version.
 *
 * This library 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 along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

// Init owncloud
require_once('../../../lib/base.php');

$id = $_POST['id'];

OC_Log::write('contacts','deletebook.php: '.$id,OC_Log::DEBUG);	

$l10n = new OC_L10N('contacts');

// Check if we are a user
OC_JSON::checkLoggedIn();
OC_JSON::checkAppEnabled('contacts');

$addressbook = OC_Contacts_Addressbook::find( $id );
if( $addressbook === false || $addressbook['userid'] != OC_USER::getUser()){
	OC_JSON::error(array('data' => array( 'message' => $l10n->t('This is not your contact.'))));
	exit();
}

OC_Contacts_Addressbook::delete($id);
OC_JSON::success(array('data' => array( 'id' => $id )));