/*
 * Copyright 2000 Sun Microsystems, Inc.  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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.rmi.rmid;

import java.security.*;
import java.io.*;
import java.util.*;

/**
 * The ExecPermission class represents permission for rmid to execute
 * a specific command to launch an activation group.  An ExecPermission
 * consists of a pathname of a command to launch an activation group.
 * <P>
 * Pathname is the pathname of the file or directory to grant rmid
 * execute permission.  A pathname that ends in "/*" (where "/" is
 * the file separator character, <code>File.separatorChar</code>) indicates
 * all the files and directories contained in that directory. A pathname
 * that ends with "/-" indicates (recursively) all files
 * and subdirectories contained in that directory. A pathname consisting of
 * the special token "&lt;&lt;ALL FILES&gt;&gt;" matches <bold>any</bold> file.
 * <P>
 * Note: A pathname consisting of a single "*" indicates all the files
 * in the current directory, while a pathname consisting of a single "-"
 * indicates all the files in the current directory and
 * (recursively) all files and subdirectories contained in the current
 * directory.
 * <P>
 *
 *
 * @author Ann Wollrath
 *
 * @serial exclude
 */
public final class ExecPermission extends Permission
{
    /**
     * UID for serialization
     */
    private static final long serialVersionUID = -6208470287358147919L;

    private transient FilePermission fp;

    /**
     * Creates a new ExecPermission object with the specified path.
     * <i>path</i> is the pathname of a file or directory.
     *
     * <p>A pathname that ends in "/*" (where "/" is
     * the file separator character, <code>File.separatorChar</code>) indicates
     * a directory and all the files contained in that directory. A pathname
     * that ends with "/-" indicates a directory and (recursively) all files
     * and subdirectories contained in that directory. The special pathname
     * "&lt;&lt;ALL FILES&gt;&gt;" matches all files.
     *
     * <p>A pathname consisting of a single "*" indicates all the files
     * in the current directory, while a pathname consisting of a single "-"
     * indicates all the files in the current directory and
     * (recursively) all files and subdirectories contained in the current
     * directory.
     *
     * @param path the pathname of the file/directory.
     */
    public ExecPermission(String path) {
        super(path);
        init(path);
    }

    /**
     * Creates a new ExecPermission object with the specified path.
     * <i>path</i> is the pathname of a file or directory.
     *
     * <p>A pathname that ends in "/*" (where "/" is
     * the file separator character, <code>File.separatorChar</code>) indicates
     * a directory and all the files contained in that directory. A pathname
     * that ends with "/-" indicates a directory and (recursively) all files
     * and subdirectories contained in that directory. The special pathname
     * "&lt;&lt;ALL FILES&gt;&gt;" matches all files.
     *
     * <p>A pathname consisting of a single "*" indicates all the files
     * in the current directory, while a pathname consisting of a single "-"
     * indicates all the files in the current directory and
     * (recursively) all files and subdirectories contained in the current
     * directory.
     *
     * @param path the pathname of the file/directory.
     * @param actions the action string (unused)
     */
    public ExecPermission(String path, String actions) {
        this(path);
    }

    /**
     * Checks if this ExecPermission object "implies" the specified permission.
     * <P>
     * More specifically, this method returns true if:<p>
     * <ul>
     * <li> <i>p</i> is an instanceof ExecPermission,<p> and
     * <li> <i>p</i>'s pathname is implied by this object's
     *      pathname. For example, "/tmp/*" implies "/tmp/foo", since
     *      "/tmp/*" encompasses the "/tmp" directory and all files in that
     *      directory, including the one named "foo".
     * </ul>
     * @param p the permission to check against.
     *
     * @return true if the specified permission is implied by this object,
     * false if not.
     */
    public boolean implies(Permission p) {
        if (!(p instanceof ExecPermission))
            return false;

        ExecPermission that = (ExecPermission) p;

        return fp.implies(that.fp);
    }

    /**
     * Checks two ExecPermission objects for equality.
     * Checks that <i>obj</i>'s class is the same as this object's class
     * and has the same name as this object.
     * <P>
     * @param obj the object we are testing for equality with this object.
     * @return true if <i>obj</i> is an ExecPermission, and has the same
     * pathname as this ExecPermission object, false otherwise.
     */
    public boolean equals(Object obj) {
        if (obj == this)
            return true;

        if (! (obj instanceof ExecPermission))
            return false;

        ExecPermission that = (ExecPermission) obj;

        return fp.equals(that.fp);
    }

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

    /**
     * Returns the canonical string representation of the actions.
     *
     * @return the canonical string representation of the actions.
     */
    public String getActions() {
        return "";
    }

    /**
     * Returns a new PermissionCollection object for storing
     * ExecPermission objects.
     * <p>
     * A ExecPermissionCollection stores a collection of
     * ExecPermission permissions.
     *
     * <p>ExecPermission objects must be stored in a manner that allows
     * them to be inserted in any order, but that also enables the
     * PermissionCollection <code>implies</code> method
     * to be implemented in an efficient (and consistent) manner.
     *
     * @return a new PermissionCollection object suitable for
     * storing ExecPermissions.
     */
    public PermissionCollection newPermissionCollection() {
        return new ExecPermissionCollection();
    }

    /**
     * readObject is called to restore the state of the ExecPermission
     * from a stream.
     */
    private synchronized void readObject(java.io.ObjectInputStream s)
         throws IOException, ClassNotFoundException
    {
        s.defaultReadObject();
        // init is called to initialize the rest of the values.
        init(getName());
    }

    /**
     * Initialize a ExecPermission object. Common to all constructors.
     * Also called during de-serialization.
     */
    private void init(String path) {
        this.fp = new FilePermission(path, "execute");
    }

    /**
     * A ExecPermissionCollection stores a collection
     * of ExecPermission permissions. ExecPermission objects
     * must be stored in a manner that allows them to be inserted in any
     * order, but enable the implies function to evaluate the implies
     * method in an efficient (and consistent) manner.
     *
     * @serial include
     */
    private static class ExecPermissionCollection
        extends PermissionCollection
        implements java.io.Serializable
    {
        private Vector permissions;

        private static final long serialVersionUID = -3352558508888368273L;

        /**
         * Create an empty ExecPermissionCollection.
         */
        public ExecPermissionCollection() {
            permissions = new Vector();
        }

        /**
         * Adds a permission to the collection.
         *
         * @param permission the Permission object to add.
         *
         * @exception IllegalArgumentException - if the permission is not a
         *                                       ExecPermission
         *
         * @exception SecurityException - if this ExecPermissionCollection
         *                                object has been marked readonly
         */
        public void add(Permission permission)
        {
            if (! (permission instanceof ExecPermission))
                throw new IllegalArgumentException("invalid permission: "+
                                                   permission);
            if (isReadOnly())
                throw new SecurityException("attempt to add a Permission to a readonly PermissionCollection");

            permissions.addElement(permission);
        }

        /**
         * Check and see if this set of permissions implies the permissions
         * expressed in "permission".
         *
         * @param p the Permission object to compare
         *
         * @return true if "permission" is a proper subset of a permission in
         * the set, false if not.
         */
        public boolean implies(Permission permission)
        {
            if (! (permission instanceof ExecPermission))
                return false;

            Enumeration e = permissions.elements();

            while (e.hasMoreElements()) {
                ExecPermission x = (ExecPermission) e.nextElement();
                if (x.implies(permission)) {
                    return true;
                }
            }
            return false;
        }

        /**
         * Returns an enumeration of all the ExecPermission objects in the
         * container.
         *
         * @return an enumeration of all the ExecPermission objects.
         */
        public Enumeration elements()
        {
            return permissions.elements();
        }
    }
}