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/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.javascript;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;

/**
 * @author Attila Szegedi
 */
public class SecurityUtilities
{
    /**
     * Retrieves a system property within a privileged block. Use it only when
     * the property is used from within Rhino code and is not passed out of it.
     * @param name the name of the system property
     * @return the value of the system property
     */
    public static String getSystemProperty(final String name)
    {
        return AccessController.doPrivileged(
            new PrivilegedAction()
            {
                public String run()
                {
                    return System.getProperty(name);
                }
            });
    }

    public static ProtectionDomain getProtectionDomain(final Class clazz)
    {
        return AccessController.doPrivileged(
                new PrivilegedAction()
                {
                    public ProtectionDomain run()
                    {
                        return clazz.getProtectionDomain();
                    }
                });
    }

    /**
     * Look up the top-most element in the current stack representing a
     * script and return its protection domain. This relies on the system-wide
     * SecurityManager being an instance of {@link RhinoSecurityManager},
     * otherwise it returns null.
     * @return The protection of the top-most script in the current stack, or null
     */
    public static ProtectionDomain getScriptProtectionDomain() {
        final SecurityManager securityManager = System.getSecurityManager();
        if (securityManager instanceof RhinoSecurityManager) {
            return AccessController.doPrivileged(
                new PrivilegedAction() {
                    public ProtectionDomain run() {
                        Class c = ((RhinoSecurityManager) securityManager)
                                    .getCurrentScriptClass();
                        return c == null ? null : c.getProtectionDomain();
                    }
                }
            );
        }
        return null;
    }
}