/*
 * 
 * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * The contents of this file are subject to the Sun Community Source
 * License v3.0/Jini Technology Specific Attachment v 1.0 (the
 * "License"). You may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 * http://wwws.sun.com/software/jini/licensing/SCSL3_JiniTSA1.html.
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * The Reference Code is Jini Technology Core Platform code, v2.0. The
 * Developer of the Reference Code is Sun Microsystems, Inc.
 * 
 * Contributor(s): Sun Microsystems, Inc.
 * 
 * The contents of this file comply with the Jini Technology Core
 * Platform Compatibility Kit, v2.0A.
 * 
 * Tester(s): Sun Microsystems, Inc.
 * 
 * Test Platform(s):
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Solaris(TM)SPARC/x86
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Linux (Intel x86)
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Windows (Intel Platform)
 * 
 */

package com.sun.jini.phoenix;

import java.security.Permission;
import java.io.FilePermission;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;

/**
 * Represents permission to execute a command to create an activation group.
 * An instance of this class contains a name (also referred to as a "target
 * name") but no actions list; you either have the named permission or you
 * don't. The target name is any name accepted by {@link FilePermission},
 * with the same matching semantics.
 *
 * @author Sun Microsystems, Inc.
 * 
 * @since 2.0
 */
public final class ExecPermission extends Permission {
    private static final long serialVersionUID = -6208470287358147919L;
    
    /*
     * FilePermission containing the name.
     */
    private transient Permission fp;
    
    /**
     * Constructs an instance with the specified name.
     *
     * @param name the target name
     * @throws NullPointerException if the name is <code>null</code>
     */
    public ExecPermission(String name) {
	super(name);
	fp = new FilePermission(name, "execute");
    }

    /**
     * Returns <code>true</code> if the specified permission is an instance
     * of <code>ExecPermission</code> and a <code>FilePermission</code>
     * constructed with the name of this permission implies a
     * <code>FilePermission</code> constructed with the name of the specified
     * permission; returns <code>false</code> otherwise.
     *
     * @param p the permission to check
     * @return <code>true</code> if the specified permission is an instance
     * of <code>ExecPermission</code> and a <code>FilePermission</code>
     * constructed with the name of this permission implies a
     * <code>FilePermission</code> constructed with the name of the specified
     * permission; returns <code>false</code> otherwise.
     */
    public boolean implies(Permission p) {
	return (p instanceof ExecPermission &&
		fp.implies(((ExecPermission) p).fp));
    }

    /**
     * Two instances of this class are equal if <code>FilePermission</code>
     * instances created with their names are equal.
     */
    public boolean equals(Object obj) {
	return (obj instanceof ExecPermission &&
		fp.equals(((ExecPermission) obj).fp));
    }

    /**
     * Returns a hash code value for this object.
     */
    public int hashCode() {
	return fp.hashCode();
    }

    /**
     * Returns the empty string.
     */
    public String getActions() {
	return "";
    }

    /**
     * Recreates any transient state.
     *
     * @throws InvalidObjectException if the target name is <code>null</code>
     */
    private synchronized void readObject(ObjectInputStream s)
         throws IOException, ClassNotFoundException
    {
	s.defaultReadObject();
	if (getName() == null) {
	    throw new InvalidObjectException("name cannot be null");
	}
	fp = new FilePermission(getName(), "execute");
    }
}
