/*
 * Copyright 1996-1997 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 */

package java.security.acl;

import java.security.Principal;

/**
 * Interface for managing owners of Access Control Lists (ACLs) or ACL
 * configurations. (Note that the Acl interface in the
 * <code> java.security.acl </code> package extends this Owner
 * interface.) The initial owner Principal should be specified as an
 * argument to the constructor of the class implementing this interface.
 *
 * @see java.security.acl.Acl
 *
 */
public interface Owner {

    /**
     * Adds an owner. Only owners can modify ACL contents. The caller
     * principal must be an owner of the ACL in order to invoke this method.
     * That is, only an owner can add another owner. The initial owner is
     * configured at ACL construction time.
     *
     * @param caller the principal invoking this method. It must be an owner
     * of the ACL.
     *
     * @param owner the owner that should be added to the list of owners.
     *
     * @return true if successful, false if owner is already an owner.
     * @exception NotOwnerException if the caller principal is not an owner
     * of the ACL.
     */
    public boolean addOwner(Principal caller, Principal owner)
      throws NotOwnerException;

    /**
     * Deletes an owner. If this is the last owner in the ACL, an exception is
     * raised.<p>
     *
     * The caller principal must be an owner of the ACL in order to invoke
     * this method.
     *
     * @param caller the principal invoking this method. It must be an owner
     * of the ACL.
     *
     * @param owner the owner to be removed from the list of owners.
     *
     * @return true if the owner is removed, false if the owner is not part
     * of the list of owners.
     *
     * @exception NotOwnerException if the caller principal is not an owner
     * of the ACL.
     *
     * @exception LastOwnerException if there is only one owner left, so that
     * deleteOwner would leave the ACL owner-less.
     */
    public boolean deleteOwner(Principal caller, Principal owner)
      throws NotOwnerException, LastOwnerException;

    /**
     * Returns true if the given principal is an owner of the ACL.
     *
     * @param owner the principal to be checked to determine whether or not
     * it is an owner.
     *
     * @return true if the passed principal is in the list of owners, false
     * if not.
     */
    public boolean isOwner(Principal owner);

}