org.codehaus.gmaven.plugin.util.SystemNoExitGuard Maven / Gradle / Ivy

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/*
 * Copyright (c) 2007-2013, the original author or authors.
 *
 * This program is licensed to you under the Apache License Version 2.0,
 * and you may not use this file except in compliance with the Apache License Version 2.0.
 * You may obtain a copy of the Apache License Version 2.0 at http://www.apache.org/licenses/LICENSE-2.0.
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the Apache License Version 2.0 is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Apache License Version 2.0 for the specific language governing permissions and limitations there under.
 */
package org.codehaus.gmaven.plugin.util;

import java.io.InputStream;
import java.io.PrintStream;

/**
 * Helper to guard {@link Task} execution against use of {@link System#exit(int)} (and related)
 * and to restore system streams once the task has finished.
 *
 * @since 2.0
 */
public class SystemNoExitGuard
{
  /**
   * Runnable-like interface which allows Exceptions.
   */
  public static interface Task
  {
    void run() throws Exception;
  }

  public void run(final Task task) throws Exception {
    // capture system streams
    final InputStream systemIn = System.in;
    final PrintStream systemOut = System.out;
    final PrintStream systemErr = System.err;

    // replace security manager
    final SecurityManager sm = System.getSecurityManager();
    System.setSecurityManager(new NoExitSecurityManager(sm));

    try {
      task.run();
    }
    finally {
      // restore security manager and system streams
      System.setSecurityManager(sm);
      System.setIn(systemIn);
      System.setOut(systemOut);
      System.setErr(systemErr);
    }
  }
}