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	/*
	* Copyright (c) 1999, 2018, 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.security.auth;

	import java.security.AccessController;
	import java.security.Principal;
	import java.security.PrivilegedAction;
	import java.security.ProtectionDomain;
	import java.util.Set;
	import java.util.WeakHashMap;
	import java.lang.ref.WeakReference;

	/**
	* A {@code SubjectDomainCombiner} updates ProtectionDomains
	* with Principals from the {@code Subject} associated with this
	* {@code SubjectDomainCombiner}.
	*
	* @since 1.4
	*/
	public class SubjectDomainCombiner implements java.security.DomainCombiner {

	private Subject subject;
	private WeakKeyValueMap<ProtectionDomain, ProtectionDomain> cachedPDs =
	new WeakKeyValueMap<>();
	private Set<Principal> principalSet;
	private Principal[] principals;

	private static final sun.security.util.Debug debug =
	sun.security.util.Debug.getInstance("combiner",
	"\t[SubjectDomainCombiner]");

	/**
	* Associate the provided {@code Subject} with this
	* {@code SubjectDomainCombiner}.
	*
	* @param subject the {@code Subject} to be associated with
	* with this {@code SubjectDomainCombiner}.
	*/
	public SubjectDomainCombiner(Subject subject) {
	this.subject = subject;

	if (subject.isReadOnly()) {
	principalSet = subject.getPrincipals();
	principals = principalSet.toArray
	(new Principal[principalSet.size()]);
	}
	}

	/**
	* Get the {@code Subject} associated with this
	* {@code SubjectDomainCombiner}.
	*
	* @return the {@code Subject} associated with this
	* {@code SubjectDomainCombiner}, or {@code null}
	* if no {@code Subject} is associated with this
	* {@code SubjectDomainCombiner}.
	*
	* @exception SecurityException if the caller does not have permission
	* to get the {@code Subject} associated with this
	* {@code SubjectDomainCombiner}.
	*/
	public Subject getSubject() {
	java.lang.SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(new AuthPermission
	("getSubjectFromDomainCombiner"));
	}
	return subject;
	}

	/**
	* Update the relevant ProtectionDomains with the Principals
	* from the {@code Subject} associated with this
	* {@code SubjectDomainCombiner}.
	*
	* <p> A new {@code ProtectionDomain} instance is created
	* for each non-static {@code ProtectionDomain} (
	* (staticPermissionsOnly() == false)
	* in the {@code currentDomains} array. Each new {@code ProtectionDomain}
	* instance is created using the {@code CodeSource},
	* {@code Permission}s and {@code ClassLoader}
	* from the corresponding {@code ProtectionDomain} in
	* {@code currentDomains}, as well as with the Principals from
	* the {@code Subject} associated with this
	* {@code SubjectDomainCombiner}. Static ProtectionDomains are
	* combined as-is and no new instance is created.
	*
	* <p> All of the ProtectionDomains (static and newly instantiated) are
	* combined into a new array. The ProtectionDomains from the
	* {@code assignedDomains} array are appended to this new array,
	* and the result is returned.
	*
	* <p> Note that optimizations such as the removal of duplicate
	* ProtectionDomains may have occurred.
	* In addition, caching of ProtectionDomains may be permitted.
	*
	* @param currentDomains the ProtectionDomains associated with the
	* current execution Thread, up to the most recent
	* privileged {@code ProtectionDomain}.
	* The ProtectionDomains are listed in order of execution,
	* with the most recently executing {@code ProtectionDomain}
	* residing at the beginning of the array. This parameter may
	* be {@code null} if the current execution Thread
	* has no associated ProtectionDomains.
	*
	* @param assignedDomains the ProtectionDomains inherited from the
	* parent Thread, or the ProtectionDomains from the
	* privileged {@code context}, if a call to
	* {@code AccessController.doPrivileged(..., context)}
	* had occurred This parameter may be {@code null}
	* if there were no ProtectionDomains inherited from the
	* parent Thread, or from the privileged {@code context}.
	*
	* @return a new array consisting of the updated ProtectionDomains,
	* or {@code null}.
	*/
	public ProtectionDomain[] combine(ProtectionDomain[] currentDomains,
	ProtectionDomain[] assignedDomains) {
	if (debug != null) {
	if (subject == null) {
	debug.println("null subject");
	} else {
	final Subject s = subject;
	AccessController.doPrivileged
	(new java.security.PrivilegedAction<Void>() {
	public Void run() {
	debug.println(s.toString());
	return null;
	}
	});
	}
	printInputDomains(currentDomains, assignedDomains);
	}

	if (currentDomains == null \|\| currentDomains.length == 0) {
	// No need to optimize assignedDomains because it should
	// have been previously optimized (when it was set).

	// Note that we are returning a direct reference
	// to the input array - since ACC does not clone
	// the arrays when it calls combiner.combine,
	// multiple ACC instances may share the same
	// array instance in this case

	return assignedDomains;
	}

	// optimize currentDomains
	//
	// No need to optimize assignedDomains because it should
	// have been previously optimized (when it was set).

	currentDomains = optimize(currentDomains);
	if (debug != null) {
	debug.println("after optimize");
	printInputDomains(currentDomains, assignedDomains);
	}

	if (currentDomains == null && assignedDomains == null) {
	return null;
	}

	int cLen = (currentDomains == null ? 0 : currentDomains.length);
	int aLen = (assignedDomains == null ? 0 : assignedDomains.length);

	// the ProtectionDomains for the new AccessControlContext
	// that we will return
	ProtectionDomain[] newDomains = new ProtectionDomain[cLen + aLen];

	boolean allNew = true;
	synchronized(cachedPDs) {
	if (!subject.isReadOnly() &&
	!subject.getPrincipals().equals(principalSet)) {

	// if the Subject was mutated, clear the PD cache
	Set<Principal> newSet = subject.getPrincipals();
	synchronized(newSet) {
	principalSet = new java.util.HashSet<Principal>(newSet);
	}
	principals = principalSet.toArray
	(new Principal[principalSet.size()]);
	cachedPDs.clear();

	if (debug != null) {
	debug.println("Subject mutated - clearing cache");
	}
	}

	ProtectionDomain subjectPd;
	for (int i = 0; i < cLen; i++) {
	ProtectionDomain pd = currentDomains[i];

	subjectPd = cachedPDs.getValue(pd);

	if (subjectPd == null) {
	if (pd.staticPermissionsOnly()) {
	// keep static ProtectionDomain objects static
	subjectPd = pd;
	} else {
	subjectPd = new ProtectionDomain(pd.getCodeSource(),
	pd.getPermissions(),
	pd.getClassLoader(),
	principals);
	}
	cachedPDs.putValue(pd, subjectPd);
	} else {
	allNew = false;
	}
	newDomains[i] = subjectPd;
	}
	}

	if (debug != null) {
	debug.println("updated current: ");
	for (int i = 0; i < cLen; i++) {
	debug.println("\tupdated[" + i + "] = " +
	printDomain(newDomains[i]));
	}
	}

	// now add on the assigned domains
	if (aLen > 0) {
	System.arraycopy(assignedDomains, 0, newDomains, cLen, aLen);

	// optimize the result (cached PDs might exist in assignedDomains)
	if (!allNew) {
	newDomains = optimize(newDomains);
	}
	}

	// if aLen == 0 \|\| allNew, no need to further optimize newDomains

	if (debug != null) {
	if (newDomains == null \|\| newDomains.length == 0) {
	debug.println("returning null");
	} else {
	debug.println("combinedDomains: ");
	for (int i = 0; i < newDomains.length; i++) {
	debug.println("newDomain " + i + ": " +
	printDomain(newDomains[i]));
	}
	}
	}

	// return the new ProtectionDomains
	if (newDomains == null \|\| newDomains.length == 0) {
	return null;
	} else {
	return newDomains;
	}
	}

	private static ProtectionDomain[] optimize(ProtectionDomain[] domains) {
	if (domains == null \|\| domains.length == 0)
	return null;

	ProtectionDomain[] optimized = new ProtectionDomain[domains.length];
	ProtectionDomain pd;
	int num = 0;
	for (int i = 0; i < domains.length; i++) {

	// skip domains with AllPermission
	// XXX
	//
	// if (domains[i].implies(ALL_PERMISSION))
	// continue;

	// skip System Domains
	if ((pd = domains[i]) != null) {

	// remove duplicates
	boolean found = false;
	for (int j = 0; j < num && !found; j++) {
	found = (optimized[j] == pd);
	}
	if (!found) {
	optimized[num++] = pd;
	}
	}
	}

	// resize the array if necessary
	if (num > 0 && num < domains.length) {
	ProtectionDomain[] downSize = new ProtectionDomain[num];
	System.arraycopy(optimized, 0, downSize, 0, downSize.length);
	optimized = downSize;
	}

	return ((num == 0 \|\| optimized.length == 0) ? null : optimized);
	}

	private static void printInputDomains(ProtectionDomain[] currentDomains,
	ProtectionDomain[] assignedDomains) {
	if (currentDomains == null \|\| currentDomains.length == 0) {
	debug.println("currentDomains null or 0 length");
	} else {
	for (int i = 0; currentDomains != null &&
	i < currentDomains.length; i++) {
	if (currentDomains[i] == null) {
	debug.println("currentDomain " + i + ": SystemDomain");
	} else {
	debug.println("currentDomain " + i + ": " +
	printDomain(currentDomains[i]));
	}
	}
	}

	if (assignedDomains == null \|\| assignedDomains.length == 0) {
	debug.println("assignedDomains null or 0 length");
	} else {
	debug.println("assignedDomains = ");
	for (int i = 0; assignedDomains != null &&
	i < assignedDomains.length; i++) {
	if (assignedDomains[i] == null) {
	debug.println("assignedDomain " + i + ": SystemDomain");
	} else {
	debug.println("assignedDomain " + i + ": " +
	printDomain(assignedDomains[i]));
	}
	}
	}
	}

	private static String printDomain(final ProtectionDomain pd) {
	if (pd == null) {
	return "null";
	}
	return AccessController.doPrivileged(new PrivilegedAction<String>() {
	public String run() {
	return pd.toString();
	}
	});
	}

	/**
	* A HashMap that has weak keys and values.
	*
	* Key objects in this map are the "current" ProtectionDomain instances
	* received via the combine method. Each "current" PD is mapped to a
	* new PD instance that holds both the contents of the "current" PD,
	* as well as the principals from the Subject associated with this combiner.
	*
	* The newly created "principal-based" PD values must be stored as
	* WeakReferences since they contain strong references to the
	* corresponding key object (the "current" non-principal-based PD),
	* which will prevent the key from being GC'd. Specifically,
	* a "principal-based" PD contains strong references to the CodeSource,
	* signer certs, PermissionCollection and ClassLoader objects
	* in the "current PD".
	*/
	private static class WeakKeyValueMap<K,V> extends
	WeakHashMap<K,WeakReference<V>> {

	public V getValue(K key) {
	WeakReference<V> wr = super.get(key);
	if (wr != null) {
	return wr.get();
	}
	return null;
	}

	public V putValue(K key, V value) {
	WeakReference<V> wr = super.put(key, new WeakReference<V>(value));
	if (wr != null) {
	return wr.get();
	}
	return null;
	}
	}
	}

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