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 * 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

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package sun.security.acl;

import java.util.*;

import java.security.*;

import java.security.acl.*;

/**

 * This class implements a group of principals.

 * @author      Satish Dharmaraj

 */

public class GroupImpl implements Group {

    private Vector<Principal> groupMembers = new Vector<>(50, 100);

    private String group;

    /**

     * Constructs a Group object with no members.

     * @param groupName the name of the group

     */

    public GroupImpl(String groupName) {

        this.group = groupName;

    }

    /**

     * adds the specified member to the group.

     * @param user The principal to add to the group.

     * @return true if the member was added - false if the

     * member could not be added.

     */

    public boolean addMember(Principal user) {

        if (groupMembers.contains(user))

          return false;

        // do not allow groups to be added to itself.

        if (group.equals(user.toString()))

            throw new IllegalArgumentException();

        groupMembers.addElement(user);

        return true;

    }

    /**

     * removes the specified member from the group.

     * @param user The principal to remove from the group.

     * @param true if the principal was removed false if

     * the principal was not a member

     */

    public boolean removeMember(Principal user) {

        return groupMembers.removeElement(user);

    }

    /**

     * returns the enumeration of the members in the group.

     */

    public Enumeration<? extends Principal> members() {

        return groupMembers.elements();

    }

    /**

     * This function returns true if the group passed matches

     * the group represented in this interface.

     * @param another The group to compare this group to.

     */

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (obj instanceof Group == false) {

            return false;

        }

        Group another = (Group)obj;

        return group.equals(another.toString());

    }

    // equals(Group) for compatibility

    public boolean equals(Group another) {

        return equals((Object)another);

    }

    /**

     * Prints a stringified version of the group.

     */

    public String toString() {

        return group;

    }

    /**

     * return a hashcode for the principal.

     */

    public int hashCode() {

        return group.hashCode();

    }

    /**

     * returns true if the passed principal is a member of the group.

     * @param member The principal whose membership must be checked for.

     * @return true if the principal is a member of this group,

     * false otherwise

     */

    public boolean isMember(Principal member) {

        //

        // if the member is part of the group (common case), return true.

        // if not, recursively search depth first in the group looking for the

        // principal.

        //

        if (groupMembers.contains(member)) {

            return true;

        } else {

            Vector<Group> alreadySeen = new Vector<>(10);

            return isMemberRecurse(member, alreadySeen);

        }

    }

    /**

     * return the name of the principal.

     */

    public String getName() {

        return group;

    }

    //

    // This function is the recursive search of groups for this

    // implementation of the Group. The search proceeds building up

    // a vector of already seen groups. Only new groups are considered,

    // thereby avoiding loops.

    //

    boolean isMemberRecurse(Principal member, Vector<Group> alreadySeen) {

        Enumeration<? extends Principal> e = members();

        while (e.hasMoreElements()) {

            boolean mem = false;

            Principal p = (Principal) e.nextElement();

            // if the member is in this collection, return true

            if (p.equals(member)) {

                return true;

            } else if (p instanceof GroupImpl) {

                //

                // if not recurse if the group has not been checked already.

                // Can call method in this package only if the object is an

                // instance of this class. Otherwise call the method defined

                // in the interface. (This can lead to a loop if a mixture of

                // implementations form a loop, but we live with this improbable

                // case rather than clutter the interface by forcing the

                // implementation of this method.)

                //

                GroupImpl g = (GroupImpl) p;

                alreadySeen.addElement(this);

                if (!alreadySeen.contains(g))

                  mem =  g.isMemberRecurse(member, alreadySeen);

            } else if (p instanceof Group) {

                Group g = (Group) p;

                if (!alreadySeen.contains(g))

                  mem = g.isMember(member);

            }

            if (mem)

              return mem;

        }

        return false;

    }

}