SecureSet(Subject subject,
    int which) 
{
            this.subject = subject;
            this.which = which;
            this.elements = new LinkedList< E >();
}

 SecureSet(Subject subject,
    int which,
    Set<? extends E> set) 
{
            this.subject = subject;
            this.which = which;
            this.elements = new LinkedList< E >(set);
}

 public boolean add(E o) 
{
            if (subject.isReadOnly()) {
                throw new IllegalStateException
                        (ResourcesMgr.getString("Subject.is.read.only"));
            }
            java.lang.SecurityManager sm = System.getSecurityManager();
            if (sm != null) {
                switch (which) {
                case Subject.PRINCIPAL_SET:
                    sm.checkPermission(AuthPermissionHolder.MODIFY_PRINCIPALS_PERMISSION);
                    break;
                case Subject.PUB_CREDENTIAL_SET:
                    sm.checkPermission(AuthPermissionHolder.MODIFY_PUBLIC_CREDENTIALS_PERMISSION);
                    break;
                default:
                    sm.checkPermission(AuthPermissionHolder.MODIFY_PRIVATE_CREDENTIALS_PERMISSION);
                    break;
                }
            }
            switch (which) {
            case Subject.PRINCIPAL_SET:
                if (!(o instanceof Principal)) {
                    throw new SecurityException(ResourcesMgr.getString
                        ("attempting.to.add.an.object.which.is.not.an.instance.of.java.security.Principal.to.a.Subject.s.Principal.Set"));
                }
                break;
            default:
                // ok to add Objects of any kind to credential sets
                break;
            }
            // check for duplicates
            if (!elements.contains(o))
                return elements.add(o);
            else
                return false;
}

 public  void clear() 
{
            final Iterator< E > e = iterator();
            while (e.hasNext()) {
                E next;
                if (which != Subject.PRIV_CREDENTIAL_SET) {
                    next = e.next();
                } else {
                    next = java.security.AccessController.doPrivileged
                        (new java.security.PrivilegedAction< E >() {
                        public E run() {
                            return e.next();
                        }
                    });
                }
                e.remove();
            }
}

 public boolean contains(Object o) 
{
            final Iterator< E > e = iterator();
            while (e.hasNext()) {
                E next;
                if (which != Subject.PRIV_CREDENTIAL_SET) {
                    next = e.next();
                } else {
                    // For private credentials:
                    // If the caller does not have read permission for
                    // for o.getClass(), we throw a SecurityException.
                    // Otherwise we check the private cred set to see whether
                    // it contains the Object
                    SecurityManager sm = System.getSecurityManager();
                    if (sm != null) {
                        sm.checkPermission(new PrivateCredentialPermission
                                                (o.getClass().getName(),
                                                subject.getPrincipals()));
                    }
                    next = java.security.AccessController.doPrivileged
                        (new java.security.PrivilegedAction< E >() {
                        public E run() {
                            return e.next();
                        }
                    });
                }
                if (next == null) {
                    if (o == null) {
                        return true;
                    }
                } else if (next.equals(o)) {
                    return true;
                }
            }
            return false;
}

 public Iterator<E> iterator() 
{
            final LinkedList< E > list = elements;
            return new Iterator< E >() {
                ListIterator< E > i = list.listIterator(0);
                public boolean hasNext() {return i.hasNext();}
                public E next() {
                    if (which != Subject.PRIV_CREDENTIAL_SET) {
                        return i.next();
                    }
                    SecurityManager sm = System.getSecurityManager();
                    if (sm != null) {
                        try {
                            sm.checkPermission(new PrivateCredentialPermission
                                (list.get(i.nextIndex()).getClass().getName(),
                                subject.getPrincipals()));
                        } catch (SecurityException se) {
                            i.next();
                            throw (se);
                        }
                    }
                    return i.next();
                }
                public void remove() {
                    if (subject.isReadOnly()) {
                        throw new IllegalStateException(ResourcesMgr.getString
                                ("Subject.is.read.only"));
                    }
                    java.lang.SecurityManager sm = System.getSecurityManager();
                    if (sm != null) {
                        switch (which) {
                        case Subject.PRINCIPAL_SET:
                            sm.checkPermission(AuthPermissionHolder.MODIFY_PRINCIPALS_PERMISSION);
                            break;
                        case Subject.PUB_CREDENTIAL_SET:
                            sm.checkPermission(AuthPermissionHolder.MODIFY_PUBLIC_CREDENTIALS_PERMISSION);
                            break;
                        default:
                            sm.checkPermission(AuthPermissionHolder.MODIFY_PRIVATE_CREDENTIALS_PERMISSION);
                            break;
                        }
                    }
                    i.remove();
                }
            };
}

 public boolean remove(Object o) 
{
            final Iterator< E > e = iterator();
            while (e.hasNext()) {
                E next;
                if (which != Subject.PRIV_CREDENTIAL_SET) {
                    next = e.next();
                } else {
                    next = java.security.AccessController.doPrivileged
                        (new java.security.PrivilegedAction< E >() {
                        public E run() {
                            return e.next();
                        }
                    });
                }
                if (next == null) {
                    if (o == null) {
                        e.remove();
                        return true;
                    }
                } else if (next.equals(o)) {
                    e.remove();
                    return true;
                }
            }
            return false;
}

 public boolean removeAll(Collection<?> c) 
{
            boolean modified = false;
            final Iterator< E > e = iterator();
            while (e.hasNext()) {
                E next;
                if (which != Subject.PRIV_CREDENTIAL_SET) {
                    next = e.next();
                } else {
                    next = java.security.AccessController.doPrivileged
                        (new java.security.PrivilegedAction< E >() {
                        public E run() {
                            return e.next();
                        }
                    });
                }
                Iterator< ? > ce = c.iterator();
                while (ce.hasNext()) {
                    Object o = ce.next();
                    if (next == null) {
                        if (o == null) {
                            e.remove();
                            modified = true;
                            break;
                        }
                    } else if (next.equals(o)) {
                        e.remove();
                        modified = true;
                        break;
                    }
                }
            }
            return modified;
}

 public boolean retainAll(Collection<?> c) 
{
            boolean modified = false;
            boolean retain = false;
            final Iterator< E > e = iterator();
            while (e.hasNext()) {
                retain = false;
                E next;
                if (which != Subject.PRIV_CREDENTIAL_SET) {
                    next = e.next();
                } else {
                    next = java.security.AccessController.doPrivileged
                        (new java.security.PrivilegedAction< E >() {
                        public E run() {
                            return e.next();
                        }
                    });
                }
                Iterator< ? > ce = c.iterator();
                while (ce.hasNext()) {
                    Object o = ce.next();
                    if (next == null) {
                        if (o == null) {
                            retain = true;
                            break;
                        }
                    } else if (next.equals(o)) {
                        retain = true;
                        break;
                    }
                }
                if (!retain) {
                    e.remove();
                    retain = false;
                    modified = true;
                }
            }
            return modified;
}

 public int size() 
{
            return elements.size();
}