/******************************************************************************
 * Copyright (c) 2013 Timo Kinnunen.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which is available at http://www.eclipse.org/legal/epl-v10.html
 *****************************************************************************/
package utils.security;

import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.security.AccessControlException;

public class SecurityManagerUtil {
  
  public static void preventSystemExit() {
    
    try {
      Path path = Files.createTempFile("all", ".policy");
      Charset ascii = Charset.forName("ASCII");
      byte[] bytes = ("grant {\n"
          + "  permission java.security.AllPermission;\n" + "};")
          .getBytes(ascii);
      Files.write(path, bytes);
      System.setProperty("java.security.policy", path.toString());
      SecurityManager manager = new SecurityManager() {
        
        @Override
        public void checkExit(int status) {
          
          super.checkExit(status);
          throw new AccessControlException("Calling System.exit() not allowed");
        }
      };
      System.setSecurityManager(manager);
      try {
        manager.checkExit(0);
      } catch(Exception expected) {
        return;
      } finally {
        Files.deleteIfExists(path);
      }
    } catch(IOException e) {
      throw new AssertionError("Cannot prevent System.exit()", e);
    }
    throw new AssertionError("Cannot prevent System.exit()");
  }
}