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	/*
	* Copyright (c) 1999, 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 com.sun.jndi.ldap;

	import com.sun.jndi.toolkit.ctx.Continuation;
	import java.util.NoSuchElementException;
	import java.util.Vector;

	import javax.naming.*;
	import javax.naming.directory.Attributes;
	import javax.naming.ldap.Control;

	/**
	* Basic enumeration for NameClassPair, Binding, and SearchResults.
	*/

	abstract class AbstractLdapNamingEnumeration<T extends NameClassPair>
	implements NamingEnumeration<T>, ReferralEnumeration<T> {

	protected Name listArg;

	private boolean cleaned = false;
	private LdapResult res;
	private LdapClient enumClnt;
	private Continuation cont; // used to fill in exceptions
	private Vector<LdapEntry> entries = null;
	private int limit = 0;
	private int posn = 0;
	protected LdapCtx homeCtx;
	private LdapReferralException refEx = null;
	private NamingException errEx = null;

	/*
	* Record the next set of entries and/or referrals.
	*/
	AbstractLdapNamingEnumeration(LdapCtx homeCtx, LdapResult answer, Name listArg,
	Continuation cont) throws NamingException {

	// These checks are to accommodate referrals and limit exceptions
	// which will generate an enumeration and defer the exception
	// to be thrown at the end of the enumeration.
	// All other exceptions are thrown immediately.
	// Exceptions shouldn't be thrown here anyhow because
	// process_return_code() is called before the constructor
	// is called, so these are just safety checks.

	if ((answer.status != LdapClient.LDAP_SUCCESS) &&
	(answer.status != LdapClient.LDAP_SIZE_LIMIT_EXCEEDED) &&
	(answer.status != LdapClient.LDAP_TIME_LIMIT_EXCEEDED) &&
	(answer.status != LdapClient.LDAP_ADMIN_LIMIT_EXCEEDED) &&
	(answer.status != LdapClient.LDAP_REFERRAL) &&
	(answer.status != LdapClient.LDAP_PARTIAL_RESULTS)) {

	// %%% need to deal with referral
	NamingException e = new NamingException(
	LdapClient.getErrorMessage(
	answer.status, answer.errorMessage));

	throw cont.fillInException(e);
	}

	// otherwise continue

	res = answer;
	entries = answer.entries;
	limit = (entries == null) ? 0 : entries.size(); // handle empty set
	this.listArg = listArg;
	this.cont = cont;

	if (answer.refEx != null) {
	refEx = answer.refEx;
	}

	// Ensures that context won't get closed from underneath us
	this.homeCtx = homeCtx;
	homeCtx.incEnumCount();
	enumClnt = homeCtx.clnt; // remember
	}

	@Override
	public final T nextElement() {
	try {
	return next();
	} catch (NamingException e) {
	// can't throw exception
	cleanup();
	return null;
	}
	}

	@Override
	public final boolean hasMoreElements() {
	try {
	return hasMore();
	} catch (NamingException e) {
	// can't throw exception
	cleanup();
	return false;
	}
	}

	/*
	* Retrieve the next set of entries and/or referrals.
	*/
	private void getNextBatch() throws NamingException {

	res = homeCtx.getSearchReply(enumClnt, res);
	if (res == null) {
	limit = posn = 0;
	return;
	}

	entries = res.entries;
	limit = (entries == null) ? 0 : entries.size(); // handle empty set
	posn = 0; // reset

	// mimimize the number of calls to processReturnCode()
	// (expensive when batchSize is small and there are many results)
	if ((res.status != LdapClient.LDAP_SUCCESS) \|\|
	((res.status == LdapClient.LDAP_SUCCESS) &&
	(res.referrals != null))) {

	try {
	// convert referrals into a chain of LdapReferralException
	homeCtx.processReturnCode(res, listArg);

	} catch (LimitExceededException \| PartialResultException e) {
	setNamingException(e);

	}
	}

	// merge any newly received referrals with any current referrals
	if (res.refEx != null) {
	if (refEx == null) {
	refEx = res.refEx;
	} else {
	refEx = refEx.appendUnprocessedReferrals(res.refEx);
	}
	res.refEx = null; // reset
	}

	if (res.resControls != null) {
	homeCtx.respCtls = res.resControls;
	}
	}

	private boolean more = true; // assume we have something to start with
	private boolean hasMoreCalled = false;

	/*
	* Test if unprocessed entries or referrals exist.
	*/
	@Override
	public final boolean hasMore() throws NamingException {

	if (hasMoreCalled) {
	return more;
	}

	hasMoreCalled = true;

	if (!more) {
	return false;
	} else {
	return (more = hasMoreImpl());
	}
	}

	/*
	* Retrieve the next entry.
	*/
	@Override
	public final T next() throws NamingException {

	if (!hasMoreCalled) {
	hasMore();
	}
	hasMoreCalled = false;
	return nextImpl();
	}

	/*
	* Test if unprocessed entries or referrals exist.
	*/
	private boolean hasMoreImpl() throws NamingException {
	// when page size is supported, this
	// might generate an exception while attempting
	// to fetch the next batch to determine
	// whether there are any more elements

	// test if the current set of entries has been processed
	if (posn == limit) {
	getNextBatch();
	}

	// test if any unprocessed entries exist
	if (posn < limit) {
	return true;
	} else {

	try {
	// try to process another referral
	return hasMoreReferrals();

	} catch (LdapReferralException \|
	LimitExceededException \|
	PartialResultException e) {
	cleanup();
	throw e;

	} catch (NamingException e) {
	cleanup();
	PartialResultException pre = new PartialResultException();
	pre.setRootCause(e);
	throw pre;
	}
	}
	}

	/*
	* Retrieve the next entry.
	*/
	private T nextImpl() throws NamingException {
	try {
	return nextAux();
	} catch (NamingException e) {
	cleanup();
	throw cont.fillInException(e);
	}
	}

	private T nextAux() throws NamingException {
	if (posn == limit) {
	getNextBatch(); // updates posn and limit
	}

	if (posn >= limit) {
	cleanup();
	throw new NoSuchElementException("invalid enumeration handle");
	}

	LdapEntry result = entries.elementAt(posn++);

	// gets and outputs DN from the entry
	return createItem(result.DN, result.attributes, result.respCtls);
	}

	protected final String getAtom(String dn) {
	// need to strip off all but lowest component of dn
	// so that is relative to current context (currentDN)
	try {
	Name parsed = new LdapName(dn);
	return parsed.get(parsed.size() - 1);
	} catch (NamingException e) {
	return dn;
	}
	}

	protected abstract T createItem(String dn, Attributes attrs,
	Vector<Control> respCtls) throws NamingException;

	/*
	* Append the supplied (chain of) referrals onto the
	* end of the current (chain of) referrals.
	*/
	@Override
	public void appendUnprocessedReferrals(LdapReferralException ex) {
	if (refEx != null) {
	refEx = refEx.appendUnprocessedReferrals(ex);
	} else {
	refEx = ex.appendUnprocessedReferrals(refEx);
	}
	}

	final void setNamingException(NamingException e) {
	errEx = e;
	}

	protected abstract AbstractLdapNamingEnumeration<? extends NameClassPair> getReferredResults(
	LdapReferralContext refCtx) throws NamingException;

	/*
	* Iterate through the URLs of a referral. If successful then perform
	* a search operation and merge the received results with the current
	* results.
	*/
	protected final boolean hasMoreReferrals() throws NamingException {

	if ((refEx != null) &&
	(refEx.hasMoreReferrals() \|\|
	refEx.hasMoreReferralExceptions())) {

	if (homeCtx.handleReferrals == LdapClient.LDAP_REF_THROW) {
	throw (NamingException)(refEx.fillInStackTrace());
	}

	// process the referrals sequentially
	while (true) {

	LdapReferralContext refCtx =
	(LdapReferralContext)refEx.getReferralContext(
	homeCtx.envprops, homeCtx.reqCtls);

	try {

	update(getReferredResults(refCtx));
	break;

	} catch (LdapReferralException re) {

	// record a previous exception
	if (errEx == null) {
	errEx = re.getNamingException();
	}
	refEx = re;
	continue;

	} finally {
	// Make sure we close referral context
	refCtx.close();
	}
	}
	return hasMoreImpl();

	} else {
	cleanup();

	if (errEx != null) {
	throw errEx;
	}
	return (false);
	}
	}

	/*
	* Merge the entries and/or referrals from the supplied enumeration
	* with those of the current enumeration.
	*/
	protected void update(AbstractLdapNamingEnumeration<? extends NameClassPair> ne) {
	// Cleanup previous context first
	homeCtx.decEnumCount();

	// New enum will have already incremented enum count and recorded clnt
	homeCtx = ne.homeCtx;
	enumClnt = ne.enumClnt;

	// Do this to prevent referral enumeration (ne) from decrementing
	// enum count because we'll be doing that here from this
	// enumeration.
	ne.homeCtx = null;

	// Record rest of information from new enum
	posn = ne.posn;
	limit = ne.limit;
	res = ne.res;
	entries = ne.entries;
	refEx = ne.refEx;
	listArg = ne.listArg;
	}

	protected final void finalize() {
	cleanup();
	}

	protected final void cleanup() {
	if (cleaned) return; // been there; done that

	if(enumClnt != null) {
	enumClnt.clearSearchReply(res, homeCtx.reqCtls);
	}

	enumClnt = null;
	cleaned = true;
	if (homeCtx != null) {
	homeCtx.decEnumCount();
	homeCtx = null;
	}
	}

	@Override
	public final void close() {
	cleanup();
	}
	}

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