/*
 * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.security.action;

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

/**
 * A convenience class for retrieving the string value of a system
 * property as a privileged action.
 *
 * <p>An instance of this class can be used as the argument of
 * <code>AccessController.doPrivileged</code>.
 *
 * <p>The following code retrieves the value of the system
 * property named <code>"prop"</code> as a privileged action: <p>
 *
 * <pre>
 * String s = java.security.AccessController.doPrivileged
 *                      (new GetPropertyAction("prop"));
 * </pre>
 *
 * @author Roland Schemers
 * @see java.security.PrivilegedAction
 * @see java.security.AccessController
 * @since 1.2
 */

public class GetPropertyAction implements PrivilegedAction<String> {
    private String theProp;
    private String defaultVal;

    /**
     * Constructor that takes the name of the system property whose
     * string value needs to be determined.
     *
     * @param theProp the name of the system property.
     */
    public GetPropertyAction(String theProp) {
        this.theProp = theProp;
    }

    /**
     * Constructor that takes the name of the system property and the default
     * value of that property.
     *
     * @param theProp the name of the system property.
     * @param defaulVal the default value.
     */
    public GetPropertyAction(String theProp, String defaultVal) {
        this.theProp = theProp;
        this.defaultVal = defaultVal;
    }

    /**
     * Determines the string value of the system property whose
     * name was specified in the constructor.
     *
     * @return the string value of the system property,
     *         or the default value if there is no property with that key.
     */
    public String run() {
        String value = System.getProperty(theProp);
        return (value == null) ? defaultVal : value;
    }

    /**
     * Convenience method to get a property without going through doPrivileged
     * if no security manager is present. This is unsafe for inclusion in a
     * public API but allowable here since this class is by default restricted
     * by the package.access security property.
     *
     * Note that this method performs a privileged action using caller-provided
     * inputs. The caller of this method should take care to ensure that the
     * inputs are not tainted and the returned property is not made accessible
     * to untrusted code if it contains sensitive information.
     *
     * @param theProp the name of the system property.
     */
    public static String privilegedGetProperty(String theProp) {
        if (System.getSecurityManager() == null) {
            return System.getProperty(theProp);
        } else {
            return AccessController.doPrivileged(
                    new GetPropertyAction(theProp));
        }
    }

    /**
     * Convenience method to get a property without going through doPrivileged
     * if no security manager is present. This is unsafe for inclusion in a
     * public API but allowable here since this class is now encapsulated.
     *
     * Note that this method performs a privileged action using caller-provided
     * inputs. The caller of this method should take care to ensure that the
     * inputs are not tainted and the returned property is not made accessible
     * to untrusted code if it contains sensitive information.
     *
     * @param theProp the name of the system property.
     * @param defaultVal the default value.
     */
    public static String privilegedGetProperty(String theProp,
            String defaultVal) {
        if (System.getSecurityManager() == null) {
            return System.getProperty(theProp, defaultVal);
        } else {
            return AccessController.doPrivileged(
                    new GetPropertyAction(theProp, defaultVal));
        }
    }
}