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	/*
	* Copyright (c) 1999, 2016, 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 javax.crypto;

	import java.security.*;
	import java.util.Enumeration;
	import java.util.Hashtable;
	import java.util.Vector;
	import java.util.NoSuchElementException;
	import java.util.concurrent.ConcurrentHashMap;
	import java.io.Serializable;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.io.BufferedReader;
	import java.io.ObjectStreamField;
	import java.io.ObjectInputStream;
	import java.io.ObjectOutputStream;
	import java.io.IOException;

	/**
	* This class contains CryptoPermission objects, organized into
	* PermissionCollections according to algorithm names.
	*
	* <p>When the <code>add</code> method is called to add a
	* CryptoPermission, the CryptoPermission is stored in the
	* appropriate PermissionCollection. If no such
	* collection exists yet, the algorithm name associated with
	* the CryptoPermission object is
	* determined and the <code>newPermissionCollection</code> method
	* is called on the CryptoPermission or CryptoAllPermission class to
	* create the PermissionCollection and add it to the Permissions object.
	*
	* @see javax.crypto.CryptoPermission
	* @see java.security.PermissionCollection
	* @see java.security.Permissions
	*
	* @author Sharon Liu
	* @since 1.4
	*/
	final class CryptoPermissions extends PermissionCollection
	implements Serializable {

	private static final long serialVersionUID = 4946547168093391015L;

	/**
	* @serialField perms java.util.Hashtable
	*/
	private static final ObjectStreamField[] serialPersistentFields = {
	new ObjectStreamField("perms", Hashtable.class),
	};

	// Switched from Hashtable to ConcurrentHashMap to improve scalability.
	// To maintain serialization compatibility, this field is made transient
	// and custom readObject/writeObject methods are used.
	private transient ConcurrentHashMap<String,PermissionCollection> perms;

	/**
	* Creates a new CryptoPermissions object containing
	* no CryptoPermissionCollections.
	*/
	CryptoPermissions() {
	perms = new ConcurrentHashMap<>(7);
	}

	/**
	* Populates the crypto policy from the specified
	* InputStream into this CryptoPermissions object.
	*
	* @param in the InputStream to load from.
	*
	* @exception SecurityException if cannot load
	* successfully.
	*/
	void load(InputStream in)
	throws IOException, CryptoPolicyParser.ParsingException {
	CryptoPolicyParser parser = new CryptoPolicyParser();
	parser.read(new BufferedReader(new InputStreamReader(in, "UTF-8")));

	CryptoPermission[] parsingResult = parser.getPermissions();
	for (int i = 0; i < parsingResult.length; i++) {
	this.add(parsingResult[i]);
	}
	}

	/**
	* Returns true if this CryptoPermissions object doesn't
	* contain any CryptoPermission objects; otherwise, returns
	* false.
	*/
	boolean isEmpty() {
	return perms.isEmpty();
	}

	/**
	* Adds a permission object to the PermissionCollection for the
	* algorithm returned by
	* <code>(CryptoPermission)permission.getAlgorithm()</code>.
	*
	* This method creates
	* a new PermissionCollection object (and adds the permission to it)
	* if an appropriate collection does not yet exist. <p>
	*
	* @param permission the Permission object to add.
	*
	* @exception SecurityException if this CryptoPermissions object is
	* marked as readonly.
	*
	* @see isReadOnly
	*/
	@Override
	public void add(Permission permission) {

	if (isReadOnly()) {
	throw new SecurityException("Attempt to add a Permission " +
	"to a readonly CryptoPermissions " +
	"object");
	}

	if (!(permission instanceof CryptoPermission)) {
	return;
	}

	CryptoPermission cryptoPerm = (CryptoPermission)permission;
	PermissionCollection pc =
	getPermissionCollection(cryptoPerm);
	pc.add(cryptoPerm);
	String alg = cryptoPerm.getAlgorithm();
	perms.putIfAbsent(alg, pc);
	}

	/**
	* Checks if this object's PermissionCollection for permissons
	* of the specified permission's algorithm implies the specified
	* permission. Returns true if the checking succeeded.
	*
	* @param permission the Permission object to check.
	*
	* @return true if "permission" is implied by the permissions
	* in the PermissionCollection it belongs to, false if not.
	*
	*/
	@Override
	public boolean implies(Permission permission) {
	if (!(permission instanceof CryptoPermission)) {
	return false;
	}

	CryptoPermission cryptoPerm = (CryptoPermission)permission;

	PermissionCollection pc =
	getPermissionCollection(cryptoPerm.getAlgorithm());

	if (pc != null) {
	return pc.implies(cryptoPerm);
	} else {
	// none found
	return false;
	}
	}

	/**
	* Returns an enumeration of all the Permission objects in all the
	* PermissionCollections in this CryptoPermissions object.
	*
	* @return an enumeration of all the Permissions.
	*/
	@Override
	public Enumeration<Permission> elements() {
	// go through each Permissions in the hash table
	// and call their elements() function.
	return new PermissionsEnumerator(perms.elements());
	}

	/**
	* Returns a CryptoPermissions object which
	* represents the minimum of the specified
	* CryptoPermissions object and this
	* CryptoPermissions object.
	*
	* @param other the CryptoPermission
	* object to compare with this object.
	*/
	CryptoPermissions getMinimum(CryptoPermissions other) {
	if (other == null) {
	return null;
	}

	if (this.perms.containsKey(CryptoAllPermission.ALG_NAME)) {
	return other;
	}

	if (other.perms.containsKey(CryptoAllPermission.ALG_NAME)) {
	return this;
	}

	CryptoPermissions ret = new CryptoPermissions();


	PermissionCollection thatWildcard =
	other.perms.get(CryptoPermission.ALG_NAME_WILDCARD);
	int maxKeySize = 0;
	if (thatWildcard != null) {
	maxKeySize = ((CryptoPermission)
	thatWildcard.elements().nextElement()).getMaxKeySize();
	}
	// For each algorithm in this CryptoPermissions,
	// find out if there is anything we should add into
	// ret.
	Enumeration<String> thisKeys = this.perms.keys();
	while (thisKeys.hasMoreElements()) {
	String alg = thisKeys.nextElement();

	PermissionCollection thisPc = this.perms.get(alg);
	PermissionCollection thatPc = other.perms.get(alg);

	CryptoPermission[] partialResult;

	if (thatPc == null) {
	if (thatWildcard == null) {
	// The other CryptoPermissions
	// doesn't allow this given
	// algorithm at all. Just skip this
	// algorithm.
	continue;
	}
	partialResult = getMinimum(maxKeySize, thisPc);
	} else {
	partialResult = getMinimum(thisPc, thatPc);
	}

	for (int i = 0; i < partialResult.length; i++) {
	ret.add(partialResult[i]);
	}
	}

	PermissionCollection thisWildcard =
	this.perms.get(CryptoPermission.ALG_NAME_WILDCARD);

	// If this CryptoPermissions doesn't
	// have a wildcard, we are done.
	if (thisWildcard == null) {
	return ret;
	}

	// Deal with the algorithms only appear
	// in the other CryptoPermissions.
	maxKeySize =
	((CryptoPermission)
	thisWildcard.elements().nextElement()).getMaxKeySize();
	Enumeration<String> thatKeys = other.perms.keys();
	while (thatKeys.hasMoreElements()) {
	String alg = thatKeys.nextElement();

	if (this.perms.containsKey(alg)) {
	continue;
	}

	PermissionCollection thatPc = other.perms.get(alg);

	CryptoPermission[] partialResult;

	partialResult = getMinimum(maxKeySize, thatPc);

	for (int i = 0; i < partialResult.length; i++) {
	ret.add(partialResult[i]);
	}
	}
	return ret;
	}

	/**
	* Get the minimum of the two given PermissionCollection
	* <code>thisPc</code> and <code>thatPc</code>.
	*
	* @param thisPc the first given PermissionColloection
	* object.
	*
	* @param thatPc the second given PermissionCollection
	* object.
	*/
	private CryptoPermission[] getMinimum(PermissionCollection thisPc,
	PermissionCollection thatPc) {
	Vector<CryptoPermission> permVector = new Vector<>(2);

	Enumeration<Permission> thisPcPermissions = thisPc.elements();

	// For each CryptoPermission in
	// thisPc object, do the following:
	// 1) if this CryptoPermission is implied
	// by thatPc, this CryptoPermission
	// should be returned, and we can
	// move on to check the next
	// CryptoPermission in thisPc.
	// 2) otherwise, we should return
	// all CryptoPermissions in thatPc
	// which
	// are implied by this CryptoPermission.
	// Then we can move on to the
	// next CryptoPermission in thisPc.
	while (thisPcPermissions.hasMoreElements()) {
	CryptoPermission thisCp =
	(CryptoPermission)thisPcPermissions.nextElement();

	Enumeration<Permission> thatPcPermissions = thatPc.elements();
	while (thatPcPermissions.hasMoreElements()) {
	CryptoPermission thatCp =
	(CryptoPermission)thatPcPermissions.nextElement();

	if (thatCp.implies(thisCp)) {
	permVector.addElement(thisCp);
	break;
	}
	if (thisCp.implies(thatCp)) {
	permVector.addElement(thatCp);
	}
	}
	}

	CryptoPermission[] ret = new CryptoPermission[permVector.size()];
	permVector.copyInto(ret);
	return ret;
	}

	/**
	* Returns all the CryptoPermission objects in the given
	* PermissionCollection object
	* whose maximum keysize no greater than <code>maxKeySize</code>.
	* For all CryptoPermission objects with a maximum keysize greater
	* than <code>maxKeySize</code>, this method constructs a
	* corresponding CryptoPermission object whose maximum keysize is
	* set to <code>maxKeySize</code>, and includes that in the result.
	*
	* @param maxKeySize the given maximum key size.
	*
	* @param pc the given PermissionCollection object.
	*/
	private CryptoPermission[] getMinimum(int maxKeySize,
	PermissionCollection pc) {
	Vector<CryptoPermission> permVector = new Vector<>(1);

	Enumeration<Permission> enum_ = pc.elements();

	while (enum_.hasMoreElements()) {
	CryptoPermission cp =
	(CryptoPermission)enum_.nextElement();
	if (cp.getMaxKeySize() <= maxKeySize) {
	permVector.addElement(cp);
	} else {
	if (cp.getCheckParam()) {
	permVector.addElement(
	new CryptoPermission(cp.getAlgorithm(),
	maxKeySize,
	cp.getAlgorithmParameterSpec(),
	cp.getExemptionMechanism()));
	} else {
	permVector.addElement(
	new CryptoPermission(cp.getAlgorithm(),
	maxKeySize,
	cp.getExemptionMechanism()));
	}
	}
	}

	CryptoPermission[] ret = new CryptoPermission[permVector.size()];
	permVector.copyInto(ret);
	return ret;
	}

	/**
	* Returns the PermissionCollection for the
	* specified algorithm. Returns null if there
	* isn't such a PermissionCollection.
	*
	* @param alg the algorithm name.
	*/
	PermissionCollection getPermissionCollection(String alg) {
	// If this CryptoPermissions includes CryptoAllPermission,
	// we should return CryptoAllPermission.
	PermissionCollection pc = perms.get(CryptoAllPermission.ALG_NAME);
	if (pc == null) {
	pc = perms.get(alg);

	// If there isn't a PermissionCollection for
	// the given algorithm,we should return the
	// PermissionCollection for the wildcard
	// if there is one.
	if (pc == null) {
	pc = perms.get(CryptoPermission.ALG_NAME_WILDCARD);
	}
	}
	return pc;
	}

	/**
	* Returns the PermissionCollection for the algorithm
	* associated with the specified CryptoPermission
	* object. Creates such a PermissionCollection
	* if such a PermissionCollection does not
	* exist yet.
	*
	* @param cryptoPerm the CryptoPermission object.
	*/
	private PermissionCollection getPermissionCollection(
	CryptoPermission cryptoPerm) {

	String alg = cryptoPerm.getAlgorithm();

	PermissionCollection pc = perms.get(alg);

	if (pc == null) {
	pc = cryptoPerm.newPermissionCollection();
	}
	return pc;
	}

	private void readObject(ObjectInputStream s)
	throws IOException, ClassNotFoundException {
	ObjectInputStream.GetField fields = s.readFields();
	@SuppressWarnings("unchecked")
	Hashtable<String,PermissionCollection> permTable =
	(Hashtable<String,PermissionCollection>)
	(fields.get("perms", null));
	if (permTable != null) {
	perms = new ConcurrentHashMap<>(permTable);
	} else {
	perms = new ConcurrentHashMap<>();
	}
	}

	private void writeObject(ObjectOutputStream s) throws IOException {
	Hashtable<String,PermissionCollection> permTable =
	new Hashtable<>(perms);
	ObjectOutputStream.PutField fields = s.putFields();
	fields.put("perms", permTable);
	s.writeFields();
	}
	}

	final class PermissionsEnumerator implements Enumeration<Permission> {

	// all the perms
	private final Enumeration<PermissionCollection> perms;
	// the current set
	private Enumeration<Permission> permset;

	PermissionsEnumerator(Enumeration<PermissionCollection> e) {
	perms = e;
	permset = getNextEnumWithMore();
	}

	@Override
	public synchronized boolean hasMoreElements() {
	// if we enter with permissionimpl null, we know
	// there are no more left.

	if (permset == null) {
	return false;
	}

	// try to see if there are any left in the current one

	if (permset.hasMoreElements()) {
	return true;
	}

	// get the next one that has something in it...
	permset = getNextEnumWithMore();

	// if it is null, we are done!
	return (permset != null);
	}

	@Override
	public synchronized Permission nextElement() {
	// hasMoreElements will update permset to the next permset
	// with something in it...

	if (hasMoreElements()) {
	return permset.nextElement();
	} else {
	throw new NoSuchElementException("PermissionsEnumerator");
	}
	}

	private Enumeration<Permission> getNextEnumWithMore() {
	while (perms.hasMoreElements()) {
	PermissionCollection pc = perms.nextElement();
	Enumeration<Permission> next = pc.elements();
	if (next.hasMoreElements()) {
	return next;
	}
	}
	return null;
	}
	}

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