core-common/src/main/java8/org/glassfish/jersey/internal/jsr166/UnsafeAccessor.java

/*
 * Copyright (c) 2017, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.jersey.internal.jsr166;

import sun.misc.Unsafe;

import java.lang.reflect.Field;
import java.security.PrivilegedExceptionAction;

/**
 * Helper for classes in the jsr166 package to access the {@code sun.misc.Unsafe} instance.
 *
 * @author Adam Lindenthal
 */
class UnsafeAccessor {
    static sun.misc.Unsafe getUnsafe() {
        try {
            return sun.misc.Unsafe.getUnsafe();
        } catch (SecurityException tryReflectionInstead) {
        }
        try {
            return java.security.AccessController.doPrivileged((PrivilegedExceptionAction<Unsafe>) () -> {
                Class<Unsafe> k = Unsafe.class;
                for (Field f : k.getDeclaredFields()) {
                    f.setAccessible(true);
                    Object x = f.get(null);
                    if (k.isInstance(x)) {
                        return k.cast(x);
                    }
                }
                throw new NoSuchFieldError("the Unsafe");
            });
        } catch (java.security.PrivilegedActionException e) {
            throw new RuntimeException("Could not initialize intrinsics", e.getCause());
        }


    }
}