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JDKSpecific.java
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JDKSpecific.java
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/*
* JBoss, Home of Professional Open Source
*
* Copyright 2018 Red Hat, Inc. and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.wildfly.security.manager;
import static java.security.AccessController.doPrivileged;
import java.lang.StackWalker.Option;
import java.security.PrivilegedAction;
import java.util.List;
import java.util.stream.Collectors;
/**
* JDK-specific classes which are replaced for different JDK major versions. This class is for JDK 9.
* @author <a href="mailto:jucook@redhat.com">Justin Cook</a>
*/
final class JDKSpecific {
/*
* Using StackWalker the OFFSET is the minimum number of StackFrames, the first will always be
* JDKSpecific,getCallerClass(int), the second will always be the caller of this class.
*/
private static final int OFFSET = 2;
public static Class<?> getCallerClass(int n){
// Although we know WildFlySecurityManager is making the call it may not be the actual SecurityManager
// so we need to use doPrivileged instead of a doUnchecked unless we can be sure checking has been switched off.
final StackWalker stackWalker = WildFlySecurityManager.isChecking() ?
doPrivileged((PrivilegedAction<StackWalker>)JDKSpecific::getStackWalker) : getStackWalker();
List<StackWalker.StackFrame> frames = stackWalker.walk(s ->
s.limit(n + OFFSET).collect(Collectors.toList())
);
return frames.get(frames.size() - 1).getDeclaringClass();
}
private static StackWalker getStackWalker() {
return StackWalker.getInstance(Option.RETAIN_CLASS_REFERENCE);
}
public static boolean usingStackWalker() {
return true;
}
}