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	/*
	* Copyright (c) 1996, 2011, Oracle and/or its affiliates. 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. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package sun.security.acl;

	import java.util.*;
	import java.security.Principal;
	import java.security.acl.*;

	/**
	* This is a class that describes one entry that associates users
	* or groups with permissions in the ACL.
	* The entry may be used as a way of granting or denying permissions.
	* @author Satish Dharmaraj
	*/
	public class AclEntryImpl implements AclEntry {
	private Principal user = null;
	private Vector<Permission> permissionSet = new Vector<>(10, 10);
	private boolean negative = false;

	/**
	* Construct an ACL entry that associates a user with permissions
	* in the ACL.
	* @param user The user that is associated with this entry.
	*/
	public AclEntryImpl(Principal user) {
	this.user = user;
	}

	/**
	* Construct a null ACL entry
	*/
	public AclEntryImpl() {
	}

	/**
	* Sets the principal in the entity. If a group or a
	* principal had already been set, a false value is
	* returned, otherwise a true value is returned.
	* @param user The user that is associated with this entry.
	* @return true if the principal is set, false if there is
	* one already.
	*/
	public boolean setPrincipal(Principal user) {
	if (this.user != null)
	return false;
	this.user = user;
	return true;
	}

	/**
	* This method sets the ACL to have negative permissions.
	* That is the user or group is denied the permission set
	* specified in the entry.
	*/
	public void setNegativePermissions() {
	negative = true;
	}

	/**
	* Returns true if this is a negative ACL.
	*/
	public boolean isNegative() {
	return negative;
	}

	/**
	* A principal or a group can be associated with multiple
	* permissions. This method adds a permission to the ACL entry.
	* @param permission The permission to be associated with
	* the principal or the group in the entry.
	* @return true if the permission was added, false if the
	* permission was already part of the permission set.
	*/
	public boolean addPermission(Permission permission) {

	if (permissionSet.contains(permission))
	return false;

	permissionSet.addElement(permission);

	return true;
	}

	/**
	* The method disassociates the permission from the Principal
	* or the Group in this ACL entry.
	* @param permission The permission to be disassociated with
	* the principal or the group in the entry.
	* @return true if the permission is removed, false if the
	* permission is not part of the permission set.
	*/
	public boolean removePermission(Permission permission) {
	return permissionSet.removeElement(permission);
	}

	/**
	* Checks if the passed permission is part of the allowed
	* permission set in this entry.
	* @param permission The permission that has to be part of
	* the permission set in the entry.
	* @return true if the permission passed is part of the
	* permission set in the entry, false otherwise.
	*/
	public boolean checkPermission(Permission permission) {
	return permissionSet.contains(permission);
	}

	/**
	* return an enumeration of the permissions in this ACL entry.
	*/
	public Enumeration<Permission> permissions() {
	return permissionSet.elements();
	}

	/**
	* Return a string representation of the contents of the ACL entry.
	*/
	public String toString() {
	StringBuffer s = new StringBuffer();
	if (negative)
	s.append("-");
	else
	s.append("+");
	if (user instanceof Group)
	s.append("Group.");
	else
	s.append("User.");
	s.append(user + "=");
	Enumeration<Permission> e = permissions();
	while(e.hasMoreElements()) {
	Permission p = e.nextElement();
	s.append(p);
	if (e.hasMoreElements())
	s.append(",");
	}
	return new String(s);
	}

	/**
	* Clones an AclEntry.
	*/
	@SuppressWarnings("unchecked") // Safe casts assuming clone() works correctly
	public synchronized Object clone() {
	AclEntryImpl cloned;
	cloned = new AclEntryImpl(user);
	cloned.permissionSet = (Vector<Permission>) permissionSet.clone();
	cloned.negative = negative;
	return cloned;
	}

	/**
	* Return the Principal associated in this ACL entry.
	* The method returns null if the entry uses a group
	* instead of a principal.
	*/
	public Principal getPrincipal() {
	return user;
	}
	}

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