org.codice.ddf.configuration.migration.AccessUtils.java Source code

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Here is the source code for org.codice.ddf.configuration.migration.AccessUtils.java

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/**
 * Copyright (c) Codice Foundation
 *
 * <p>This is free software: you can redistribute it and/or modify it under the terms of the GNU
 * Lesser General Public License as published by the Free Software Foundation, either version 3 of
 * the License, or any later version.
 *
 * <p>This program 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 Lesser General Public License for more details. A copy of the GNU Lesser General Public
 * License is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 */
package org.codice.ddf.configuration.migration;

import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import org.apache.commons.lang.Validate;
import org.codice.ddf.util.function.ThrowingRunnable;
import org.codice.ddf.util.function.ThrowingSupplier;

/** Utility classes to help with the access controller. */
public class AccessUtils {

    private static final String INVALID_NULL_ACTION = "invalid null action";

    /** Prevents instantiation. */
    private AccessUtils() {
    }

    /**
     * Performs the specified action with privileges enabled. The action is performed with <i>all</i>
     * of the permissions possessed by this class' (or by the migration framework's) protection
     * domain.
     *
     * <p>If the action's {@link ThrowingSupplier#get} method throws an <i>unchecked</i> exception, it
     * will propagate through this method.
     *
     * <p><i>Note:</i> Any DomainCombiner associated with the current AccessControlContext will be
     * ignored while the action is performed.
     *
     * @param <T> the type of the value returned by the action
     * @param <E> the type of exceptions thrown by the action
     * @param action the action to be performed
     * @return the value returned by the action's {@code run} method
     * @throws E if the specified action's threw the exception
     * @throws IllegalArgumentException if <code>action</code> is <code>null</code>
     */
    public static <T, E extends Exception> T doPrivileged(ThrowingSupplier<T, E> action) throws E {
        Validate.notNull(action, AccessUtils.INVALID_NULL_ACTION);
        try {
            return AccessController.doPrivileged(new PrivilegedExceptionAction<T>() {
                @Override
                public T run() throws Exception {
                    return action.get();
                }
            });
        } catch (PrivilegedActionException pe) {
            final Exception e = pe.getException();

            if (e instanceof RuntimeException) { // should never happen but just to be safe!
                throw (RuntimeException) e;
            } else { // by design, the action is declared to only throw E
                throw (E) e;
            }
        }
    }

    /**
     * Performs the specified action with privileges enabled if the specified condition is <code>true
     * </code>. The action is performed with <i>all</i> of the permissions possessed by this class'
     * (or by the migration framework's) protection domain. Otherwise performs the specified action
     * using the caller's permissions.
     *
     * <p>If the action's {@link ThrowingSupplier#get} method throws an <i>unchecked</i> exception, it
     * will propagate through this method.
     *
     * <p><i>Note:</i> Any DomainCombiner associated with the current AccessControlContext will be
     * ignored while the action is performed.
     *
     * @param <T> the type of the value returned by the action
     * @param <E> the type of exceptions thrown by the action
     * @param condition <code>true</code> to perform the action with the permissions possessed by this
     *     class; <code>false</code> to use the caller's permissions
     * @param action the action to be performed
     * @return the value returned by the action's {@code run} method
     * @throws E if the specified action's threw the exception
     * @throws IllegalArgumentException if <code>action</code> is <code>null</code>
     */
    public static <T, E extends Exception> T doConditionallyPrivileged(boolean condition,
            ThrowingSupplier<T, E> action) throws E {
        if (condition) {
            return AccessUtils.doPrivileged(action);
        }
        Validate.notNull(action, AccessUtils.INVALID_NULL_ACTION);
        return action.get();
    }

    /**
     * Performs the specified action with privileges enabled. The action is performed with <i>all</i>
     * of the permissions possessed by this class' (or by the migration framework's) protection
     * domain.
     *
     * <p>If the action's {@link ThrowingSupplier#get} method throws an <i>unchecked</i> exception, it
     * will propagate through this method.
     *
     * <p><i>Note:</i> Any DomainCombiner associated with the current AccessControlContext will be
     * ignored while the action is performed.
     *
     * @param <E> the type of exceptions thrown by the action
     * @param action the action to be performed
     * @throws E if the specified action's threw the exception
     * @throws IllegalArgumentException if <code>action</code> is <code>null</code>
     */
    public static <E extends Exception> void doPrivileged(ThrowingRunnable<E> action) throws E {
        Validate.notNull(action, AccessUtils.INVALID_NULL_ACTION);
        try {
            AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
                @Override
                public Void run() throws Exception {
                    action.run();
                    return null;
                }
            });
        } catch (PrivilegedActionException pe) {
            final Exception e = pe.getException();

            if (e instanceof RuntimeException) { // should never happen but just to be safe!
                throw (RuntimeException) e;
            } else { // by design, the action is declared to only throw E
                throw (E) e;
            }
        }
    }

    /**
     * Performs the specified action with privileges enabled if the specified condition is <code>true
     * </code>. The action is performed with <i>all</i> of the permissions possessed by this class'
     * (or by the migration framework's) protection domain. Otherwise performs the specified action
     * using the caller's permissions.
     *
     * <p>If the action's {@link ThrowingSupplier#get} method throws an <i>unchecked</i> exception, it
     * will propagate through this method.
     *
     * <p><i>Note:</i> Any DomainCombiner associated with the current AccessControlContext will be
     * ignored while the action is performed.
     *
     * @param <E> the type of exceptions thrown by the action
     * @param condition <code>true</code> to perform the action with the permissions possessed by this
     *     class; <code>false</code> to use the caller's permissions
     * @param action the action to be performed
     * @throws E if the specified action's threw the exception
     * @throws IllegalArgumentException if <code>action</code> is <code>null</code>
     */
    public static <E extends Exception> void doConditionallyPrivileged(boolean condition,
            ThrowingRunnable<E> action) throws E {
        if (condition) {
            AccessUtils.doPrivileged(action);
        } else {
            Validate.notNull(action, AccessUtils.INVALID_NULL_ACTION);
            action.run();
        }
    }
}