Back to index...

	/*
	* Copyright (c) 1997, 2015, 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 java.security;

	import java.util.ArrayList;
	import java.util.List;

	import sun.security.util.Debug;
	import sun.security.util.FilePermCompat;
	import sun.security.util.SecurityConstants;


	/**
	* An AccessControlContext is used to make system resource access decisions
	* based on the context it encapsulates.
	*
	* <p>More specifically, it encapsulates a context and
	* has a single method, {@code checkPermission},
	* that is equivalent to the {@code checkPermission} method
	* in the AccessController class, with one difference: The AccessControlContext
	* {@code checkPermission} method makes access decisions based on the
	* context it encapsulates,
	* rather than that of the current execution thread.
	*
	* <p>Thus, the purpose of AccessControlContext is for those situations where
	* a security check that should be made within a given context
	* actually needs to be done from within a
	* <i>different</i> context (for example, from within a worker thread).
	*
	* <p> An AccessControlContext is created by calling the
	* {@code AccessController.getContext} method.
	* The {@code getContext} method takes a "snapshot"
	* of the current calling context, and places
	* it in an AccessControlContext object, which it returns. A sample call is
	* the following:
	*
	* <pre>
	* AccessControlContext acc = AccessController.getContext()
	* </pre>
	*
	* <p>
	* Code within a different context can subsequently call the
	* {@code checkPermission} method on the
	* previously-saved AccessControlContext object. A sample call is the
	* following:
	*
	* <pre>
	* acc.checkPermission(permission)
	* </pre>
	*
	* @see AccessController
	*
	* @author Roland Schemers
	* @since 1.2
	*/

	public final class AccessControlContext {

	private ProtectionDomain[] context;
	// isPrivileged and isAuthorized are referenced by the VM - do not remove
	// or change their names
	private boolean isPrivileged;
	private boolean isAuthorized = false;

	// Note: This field is directly used by the virtual machine
	// native codes. Don't touch it.
	private AccessControlContext privilegedContext;

	private DomainCombiner combiner = null;

	// limited privilege scope
	private Permission[] permissions;
	private AccessControlContext parent;
	private boolean isWrapped;

	// is constrained by limited privilege scope?
	private boolean isLimited;
	private ProtectionDomain[] limitedContext;

	private static boolean debugInit = false;
	private static Debug debug = null;

	static Debug getDebug()
	{
	if (debugInit)
	return debug;
	else {
	if (Policy.isSet()) {
	debug = Debug.getInstance("access");
	debugInit = true;
	}
	return debug;
	}
	}

	/**
	* Create an AccessControlContext with the given array of ProtectionDomains.
	* Context must not be null. Duplicate domains will be removed from the
	* context.
	*
	* @param context the ProtectionDomains associated with this context.
	* The non-duplicate domains are copied from the array. Subsequent
	* changes to the array will not affect this AccessControlContext.
	* @throws NullPointerException if {@code context} is {@code null}
	*/
	public AccessControlContext(ProtectionDomain[] context)
	{
	if (context.length == 0) {
	this.context = null;
	} else if (context.length == 1) {
	if (context[0] != null) {
	this.context = context.clone();
	} else {
	this.context = null;
	}
	} else {
	List<ProtectionDomain> v = new ArrayList<>(context.length);
	for (int i =0; i< context.length; i++) {
	if ((context[i] != null) && (!v.contains(context[i])))
	v.add(context[i]);
	}
	if (!v.isEmpty()) {
	this.context = new ProtectionDomain[v.size()];
	this.context = v.toArray(this.context);
	}
	}
	}

	/**
	* Create a new {@code AccessControlContext} with the given
	* {@code AccessControlContext} and {@code DomainCombiner}.
	* This constructor associates the provided
	* {@code DomainCombiner} with the provided
	* {@code AccessControlContext}.
	*
	* @param acc the {@code AccessControlContext} associated
	* with the provided {@code DomainCombiner}.
	*
	* @param combiner the {@code DomainCombiner} to be associated
	* with the provided {@code AccessControlContext}.
	*
	* @exception NullPointerException if the provided
	* {@code context} is {@code null}.
	*
	* @exception SecurityException if a security manager is installed and the
	* caller does not have the "createAccessControlContext"
	* {@link SecurityPermission}
	* @since 1.3
	*/
	public AccessControlContext(AccessControlContext acc,
	DomainCombiner combiner) {

	this(acc, combiner, false);
	}

	/**
	* package private to allow calls from ProtectionDomain without performing
	* the security check for {@linkplain SecurityConstants#CREATE_ACC_PERMISSION}
	* permission
	*/
	AccessControlContext(AccessControlContext acc,
	DomainCombiner combiner,
	boolean preauthorized) {
	if (!preauthorized) {
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(SecurityConstants.CREATE_ACC_PERMISSION);
	this.isAuthorized = true;
	}
	} else {
	this.isAuthorized = true;
	}

	this.context = acc.context;

	// we do not need to run the combine method on the
	// provided ACC. it was already "combined" when the
	// context was originally retrieved.
	//
	// at this point in time, we simply throw away the old
	// combiner and use the newly provided one.
	this.combiner = combiner;
	}

	/**
	* package private for AccessController
	*
	* This "argument wrapper" context will be passed as the actual context
	* parameter on an internal doPrivileged() call used in the implementation.
	*/
	AccessControlContext(ProtectionDomain caller, DomainCombiner combiner,
	AccessControlContext parent, AccessControlContext context,
	Permission[] perms)
	{
	/*
	* Combine the domains from the doPrivileged() context into our
	* wrapper context, if necessary.
	*/
	ProtectionDomain[] callerPDs = null;
	if (caller != null) {
	callerPDs = new ProtectionDomain[] { caller };
	}
	if (context != null) {
	if (combiner != null) {
	this.context = combiner.combine(callerPDs, context.context);
	} else {
	this.context = combine(callerPDs, context.context);
	}
	} else {
	/*
	* Call combiner even if there is seemingly nothing to combine.
	*/
	if (combiner != null) {
	this.context = combiner.combine(callerPDs, null);
	} else {
	this.context = combine(callerPDs, null);
	}
	}
	this.combiner = combiner;

	Permission[] tmp = null;
	if (perms != null) {
	tmp = new Permission[perms.length];
	for (int i=0; i < perms.length; i++) {
	if (perms[i] == null) {
	throw new NullPointerException("permission can't be null");
	}

	/*
	* An AllPermission argument is equivalent to calling
	* doPrivileged() without any limit permissions.
	*/
	if (perms[i].getClass() == AllPermission.class) {
	parent = null;
	}
	// Add altPath into permission for compatibility.
	tmp[i] = FilePermCompat.newPermPlusAltPath(perms[i]);
	}
	}

	/*
	* For a doPrivileged() with limited privilege scope, initialize
	* the relevant fields.
	*
	* The limitedContext field contains the union of all domains which
	* are enclosed by this limited privilege scope. In other words,
	* it contains all of the domains which could potentially be checked
	* if none of the limiting permissions implied a requested permission.
	*/
	if (parent != null) {
	this.limitedContext = combine(parent.context, parent.limitedContext);
	this.isLimited = true;
	this.isWrapped = true;
	this.permissions = tmp;
	this.parent = parent;
	this.privilegedContext = context; // used in checkPermission2()
	}
	this.isAuthorized = true;
	}


	/**
	* package private constructor for AccessController.getContext()
	*/

	AccessControlContext(ProtectionDomain[] context,
	boolean isPrivileged)
	{
	this.context = context;
	this.isPrivileged = isPrivileged;
	this.isAuthorized = true;
	}

	/**
	* Constructor for JavaSecurityAccess.doIntersectionPrivilege()
	*/
	AccessControlContext(ProtectionDomain[] context,
	AccessControlContext privilegedContext)
	{
	this.context = context;
	this.privilegedContext = privilegedContext;
	this.isPrivileged = true;
	}

	/**
	* Returns this context's context.
	*/
	ProtectionDomain[] getContext() {
	return context;
	}

	/**
	* Returns true if this context is privileged.
	*/
	boolean isPrivileged()
	{
	return isPrivileged;
	}

	/**
	* get the assigned combiner from the privileged or inherited context
	*/
	DomainCombiner getAssignedCombiner() {
	AccessControlContext acc;
	if (isPrivileged) {
	acc = privilegedContext;
	} else {
	acc = AccessController.getInheritedAccessControlContext();
	}
	if (acc != null) {
	return acc.combiner;
	}
	return null;
	}

	/**
	* Get the {@code DomainCombiner} associated with this
	* {@code AccessControlContext}.
	*
	* @return the {@code DomainCombiner} associated with this
	* {@code AccessControlContext}, or {@code null}
	* if there is none.
	*
	* @exception SecurityException if a security manager is installed and
	* the caller does not have the "getDomainCombiner"
	* {@link SecurityPermission}
	* @since 1.3
	*/
	public DomainCombiner getDomainCombiner() {

	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(SecurityConstants.GET_COMBINER_PERMISSION);
	}
	return getCombiner();
	}

	/**
	* package private for AccessController
	*/
	DomainCombiner getCombiner() {
	return combiner;
	}

	boolean isAuthorized() {
	return isAuthorized;
	}

	/**
	* Determines whether the access request indicated by the
	* specified permission should be allowed or denied, based on
	* the security policy currently in effect, and the context in
	* this object. The request is allowed only if every ProtectionDomain
	* in the context implies the permission. Otherwise the request is
	* denied.
	*
	* <p>
	* This method quietly returns if the access request
	* is permitted, or throws a suitable AccessControlException otherwise.
	*
	* @param perm the requested permission.
	*
	* @exception AccessControlException if the specified permission
	* is not permitted, based on the current security policy and the
	* context encapsulated by this object.
	* @exception NullPointerException if the permission to check for is null.
	*/
	public void checkPermission(Permission perm)
	throws AccessControlException
	{
	boolean dumpDebug = false;

	if (perm == null) {
	throw new NullPointerException("permission can't be null");
	}
	if (getDebug() != null) {
	// If "codebase" is not specified, we dump the info by default.
	dumpDebug = !Debug.isOn("codebase=");
	if (!dumpDebug) {
	// If "codebase" is specified, only dump if the specified code
	// value is in the stack.
	for (int i = 0; context != null && i < context.length; i++) {
	if (context[i].getCodeSource() != null &&
	context[i].getCodeSource().getLocation() != null &&
	Debug.isOn("codebase=" + context[i].getCodeSource().getLocation().toString())) {
	dumpDebug = true;
	break;
	}
	}
	}

	dumpDebug &= !Debug.isOn("permission=") \|\|
	Debug.isOn("permission=" + perm.getClass().getCanonicalName());

	if (dumpDebug && Debug.isOn("stack")) {
	Thread.dumpStack();
	}

	if (dumpDebug && Debug.isOn("domain")) {
	if (context == null) {
	debug.println("domain (context is null)");
	} else {
	for (int i=0; i< context.length; i++) {
	debug.println("domain "+i+" "+context[i]);
	}
	}
	}
	}

	/*
	* iterate through the ProtectionDomains in the context.
	* Stop at the first one that doesn't allow the
	* requested permission (throwing an exception).
	*
	*/

	/* if ctxt is null, all we had on the stack were system domains,
	or the first domain was a Privileged system domain. This
	is to make the common case for system code very fast */

	if (context == null) {
	checkPermission2(perm);
	return;
	}

	for (int i=0; i< context.length; i++) {
	if (context[i] != null && !context[i].impliesWithAltFilePerm(perm)) {
	if (dumpDebug) {
	debug.println("access denied " + perm);
	}

	if (Debug.isOn("failure") && debug != null) {
	// Want to make sure this is always displayed for failure,
	// but do not want to display again if already displayed
	// above.
	if (!dumpDebug) {
	debug.println("access denied " + perm);
	}
	Thread.dumpStack();
	final ProtectionDomain pd = context[i];
	final Debug db = debug;
	AccessController.doPrivileged (new PrivilegedAction<>() {
	public Void run() {
	db.println("domain that failed "+pd);
	return null;
	}
	});
	}
	throw new AccessControlException("access denied "+perm, perm);
	}
	}

	// allow if all of them allowed access
	if (dumpDebug) {
	debug.println("access allowed "+perm);
	}

	checkPermission2(perm);
	}

	/*
	* Check the domains associated with the limited privilege scope.
	*/
	private void checkPermission2(Permission perm) {
	if (!isLimited) {
	return;
	}

	/*
	* Check the doPrivileged() context parameter, if present.
	*/
	if (privilegedContext != null) {
	privilegedContext.checkPermission2(perm);
	}

	/*
	* Ignore the limited permissions and parent fields of a wrapper
	* context since they were already carried down into the unwrapped
	* context.
	*/
	if (isWrapped) {
	return;
	}

	/*
	* Try to match any limited privilege scope.
	*/
	if (permissions != null) {
	Class<?> permClass = perm.getClass();
	for (int i=0; i < permissions.length; i++) {
	Permission limit = permissions[i];
	if (limit.getClass().equals(permClass) && limit.implies(perm)) {
	return;
	}
	}
	}

	/*
	* Check the limited privilege scope up the call stack or the inherited
	* parent thread call stack of this ACC.
	*/
	if (parent != null) {
	/*
	* As an optimization, if the parent context is the inherited call
	* stack context from a parent thread then checking the protection
	* domains of the parent context is redundant since they have
	* already been merged into the child thread's context by
	* optimize(). When parent is set to an inherited context this
	* context was not directly created by a limited scope
	* doPrivileged() and it does not have its own limited permissions.
	*/
	if (permissions == null) {
	parent.checkPermission2(perm);
	} else {
	parent.checkPermission(perm);
	}
	}
	}

	/**
	* Take the stack-based context (this) and combine it with the
	* privileged or inherited context, if need be. Any limited
	* privilege scope is flagged regardless of whether the assigned
	* context comes from an immediately enclosing limited doPrivileged().
	* The limited privilege scope can indirectly flow from the inherited
	* parent thread or an assigned context previously captured by getContext().
	*/
	AccessControlContext optimize() {
	// the assigned (privileged or inherited) context
	AccessControlContext acc;
	DomainCombiner combiner = null;
	AccessControlContext parent = null;
	Permission[] permissions = null;

	if (isPrivileged) {
	acc = privilegedContext;
	if (acc != null) {
	/*
	* If the context is from a limited scope doPrivileged() then
	* copy the permissions and parent fields out of the wrapper
	* context that was created to hold them.
	*/
	if (acc.isWrapped) {
	permissions = acc.permissions;
	parent = acc.parent;
	}
	}
	} else {
	acc = AccessController.getInheritedAccessControlContext();
	if (acc != null) {
	/*
	* If the inherited context is constrained by a limited scope
	* doPrivileged() then set it as our parent so we will process
	* the non-domain-related state.
	*/
	if (acc.isLimited) {
	parent = acc;
	}
	}
	}

	// this.context could be null if only system code is on the stack;
	// in that case, ignore the stack context
	boolean skipStack = (context == null);

	// acc.context could be null if only system code was involved;
	// in that case, ignore the assigned context
	boolean skipAssigned = (acc == null \|\| acc.context == null);
	ProtectionDomain[] assigned = (skipAssigned) ? null : acc.context;
	ProtectionDomain[] pd;

	// if there is no enclosing limited privilege scope on the stack or
	// inherited from a parent thread
	boolean skipLimited = ((acc == null \|\| !acc.isWrapped) && parent == null);

	if (acc != null && acc.combiner != null) {
	// let the assigned acc's combiner do its thing
	if (getDebug() != null) {
	debug.println("AccessControlContext invoking the Combiner");
	}

	// No need to clone current and assigned.context
	// combine() will not update them
	combiner = acc.combiner;
	pd = combiner.combine(context, assigned);
	} else {
	if (skipStack) {
	if (skipAssigned) {
	calculateFields(acc, parent, permissions);
	return this;
	} else if (skipLimited) {
	return acc;
	}
	} else if (assigned != null) {
	if (skipLimited) {
	// optimization: if there is a single stack domain and
	// that domain is already in the assigned context; no
	// need to combine
	if (context.length == 1 && context[0] == assigned[0]) {
	return acc;
	}
	}
	}

	pd = combine(context, assigned);
	if (skipLimited && !skipAssigned && pd == assigned) {
	return acc;
	} else if (skipAssigned && pd == context) {
	calculateFields(acc, parent, permissions);
	return this;
	}
	}

	// Reuse existing ACC
	this.context = pd;
	this.combiner = combiner;
	this.isPrivileged = false;

	calculateFields(acc, parent, permissions);
	return this;
	}


	/*
	* Combine the current (stack) and assigned domains.
	*/
	private static ProtectionDomain[] combine(ProtectionDomain[] current,
	ProtectionDomain[] assigned) {

	// current could be null if only system code is on the stack;
	// in that case, ignore the stack context
	boolean skipStack = (current == null);

	// assigned could be null if only system code was involved;
	// in that case, ignore the assigned context
	boolean skipAssigned = (assigned == null);

	int slen = (skipStack) ? 0 : current.length;

	// optimization: if there is no assigned context and the stack length
	// is less then or equal to two; there is no reason to compress the
	// stack context, it already is
	if (skipAssigned && slen <= 2) {
	return current;
	}

	int n = (skipAssigned) ? 0 : assigned.length;

	// now we combine both of them, and create a new context
	ProtectionDomain[] pd = new ProtectionDomain[slen + n];

	// first copy in the assigned context domains, no need to compress
	if (!skipAssigned) {
	System.arraycopy(assigned, 0, pd, 0, n);
	}

	// now add the stack context domains, discarding nulls and duplicates
	outer:
	for (int i = 0; i < slen; i++) {
	ProtectionDomain sd = current[i];
	if (sd != null) {
	for (int j = 0; j < n; j++) {
	if (sd == pd[j]) {
	continue outer;
	}
	}
	pd[n++] = sd;
	}
	}

	// if length isn't equal, we need to shorten the array
	if (n != pd.length) {
	// optimization: if we didn't really combine anything
	if (!skipAssigned && n == assigned.length) {
	return assigned;
	} else if (skipAssigned && n == slen) {
	return current;
	}
	ProtectionDomain[] tmp = new ProtectionDomain[n];
	System.arraycopy(pd, 0, tmp, 0, n);
	pd = tmp;
	}

	return pd;
	}


	/*
	* Calculate the additional domains that could potentially be reached via
	* limited privilege scope. Mark the context as being subject to limited
	* privilege scope unless the reachable domains (if any) are already
	* contained in this domain context (in which case any limited
	* privilege scope checking would be redundant).
	*/
	private void calculateFields(AccessControlContext assigned,
	AccessControlContext parent, Permission[] permissions)
	{
	ProtectionDomain[] parentLimit = null;
	ProtectionDomain[] assignedLimit = null;
	ProtectionDomain[] newLimit;

	parentLimit = (parent != null)? parent.limitedContext: null;
	assignedLimit = (assigned != null)? assigned.limitedContext: null;
	newLimit = combine(parentLimit, assignedLimit);
	if (newLimit != null) {
	if (context == null \|\| !containsAllPDs(newLimit, context)) {
	this.limitedContext = newLimit;
	this.permissions = permissions;
	this.parent = parent;
	this.isLimited = true;
	}
	}
	}


	/**
	* Checks two AccessControlContext objects for equality.
	* Checks that {@code obj} is
	* an AccessControlContext and has the same set of ProtectionDomains
	* as this context.
	*
	* @param obj the object we are testing for equality with this object.
	* @return true if {@code obj} is an AccessControlContext, and has the
	* same set of ProtectionDomains as this context, false otherwise.
	*/
	public boolean equals(Object obj) {
	if (obj == this)
	return true;

	if (! (obj instanceof AccessControlContext))
	return false;

	AccessControlContext that = (AccessControlContext) obj;

	if (!equalContext(that))
	return false;

	if (!equalLimitedContext(that))
	return false;

	return true;
	}

	/*
	* Compare for equality based on state that is free of limited
	* privilege complications.
	*/
	private boolean equalContext(AccessControlContext that) {
	if (!equalPDs(this.context, that.context))
	return false;

	if (this.combiner == null && that.combiner != null)
	return false;

	if (this.combiner != null && !this.combiner.equals(that.combiner))
	return false;

	return true;
	}

	private boolean equalPDs(ProtectionDomain[] a, ProtectionDomain[] b) {
	if (a == null) {
	return (b == null);
	}

	if (b == null)
	return false;

	if (!(containsAllPDs(a, b) && containsAllPDs(b, a)))
	return false;

	return true;
	}

	/*
	* Compare for equality based on state that is captured during a
	* call to AccessController.getContext() when a limited privilege
	* scope is in effect.
	*/
	private boolean equalLimitedContext(AccessControlContext that) {
	if (that == null)
	return false;

	/*
	* If neither instance has limited privilege scope then we're done.
	*/
	if (!this.isLimited && !that.isLimited)
	return true;

	/*
	* If only one instance has limited privilege scope then we're done.
	*/
	if (!(this.isLimited && that.isLimited))
	return false;

	/*
	* Wrapped instances should never escape outside the implementation
	* this class and AccessController so this will probably never happen
	* but it only makes any sense to compare if they both have the same
	* isWrapped state.
	*/
	if ((this.isWrapped && !that.isWrapped) \|\|
	(!this.isWrapped && that.isWrapped)) {
	return false;
	}

	if (this.permissions == null && that.permissions != null)
	return false;

	if (this.permissions != null && that.permissions == null)
	return false;

	if (!(this.containsAllLimits(that) && that.containsAllLimits(this)))
	return false;

	/*
	* Skip through any wrapped contexts.
	*/
	AccessControlContext thisNextPC = getNextPC(this);
	AccessControlContext thatNextPC = getNextPC(that);

	/*
	* The protection domains and combiner of a privilegedContext are
	* not relevant because they have already been included in the context
	* of this instance by optimize() so we only care about any limited
	* privilege state they may have.
	*/
	if (thisNextPC == null && thatNextPC != null && thatNextPC.isLimited)
	return false;

	if (thisNextPC != null && !thisNextPC.equalLimitedContext(thatNextPC))
	return false;

	if (this.parent == null && that.parent != null)
	return false;

	if (this.parent != null && !this.parent.equals(that.parent))
	return false;

	return true;
	}

	/*
	* Follow the privilegedContext link making our best effort to skip
	* through any wrapper contexts.
	*/
	private static AccessControlContext getNextPC(AccessControlContext acc) {
	while (acc != null && acc.privilegedContext != null) {
	acc = acc.privilegedContext;
	if (!acc.isWrapped)
	return acc;
	}
	return null;
	}

	private static boolean containsAllPDs(ProtectionDomain[] thisContext,
	ProtectionDomain[] thatContext) {
	boolean match = false;

	//
	// ProtectionDomains within an ACC currently cannot be null
	// and this is enforced by the constructor and the various
	// optimize methods. However, historically this logic made attempts
	// to support the notion of a null PD and therefore this logic continues
	// to support that notion.
	ProtectionDomain thisPd;
	for (int i = 0; i < thisContext.length; i++) {
	match = false;
	if ((thisPd = thisContext[i]) == null) {
	for (int j = 0; (j < thatContext.length) && !match; j++) {
	match = (thatContext[j] == null);
	}
	} else {
	Class<?> thisPdClass = thisPd.getClass();
	ProtectionDomain thatPd;
	for (int j = 0; (j < thatContext.length) && !match; j++) {
	thatPd = thatContext[j];

	// Class check required to avoid PD exposure (4285406)
	match = (thatPd != null &&
	thisPdClass == thatPd.getClass() && thisPd.equals(thatPd));
	}
	}
	if (!match) return false;
	}
	return match;
	}

	private boolean containsAllLimits(AccessControlContext that) {
	boolean match = false;
	Permission thisPerm;

	if (this.permissions == null && that.permissions == null)
	return true;

	for (int i = 0; i < this.permissions.length; i++) {
	Permission limit = this.permissions[i];
	Class <?> limitClass = limit.getClass();
	match = false;
	for (int j = 0; (j < that.permissions.length) && !match; j++) {
	Permission perm = that.permissions[j];
	match = (limitClass.equals(perm.getClass()) &&
	limit.equals(perm));
	}
	if (!match) return false;
	}
	return match;
	}


	/**
	* Returns the hash code value for this context. The hash code
	* is computed by exclusive or-ing the hash code of all the protection
	* domains in the context together.
	*
	* @return a hash code value for this context.
	*/

	public int hashCode() {
	int hashCode = 0;

	if (context == null)
	return hashCode;

	for (int i =0; i < context.length; i++) {
	if (context[i] != null)
	hashCode ^= context[i].hashCode();
	}

	return hashCode;
	}
	}

Back to index...