Apple Developer Connection Student Program/ADC Tools Sampler CD Disk 3 1999.iso/Metrowerks CodeWarrior/Java Support/Java_Source/Java2/src/java/security/BasicPermission.java

Java Source | 1999-05-28 | 10.2 KB | 378 lines | [TEXT/CWIE]

/*
 * @(#)BasicPermission.java    1.16 98/09/15
 *
 * Copyright 1997, 1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */

package java.security;

import java.security.*;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.StringTokenizer;
import java.io.IOException;

/**
 * The BasicPermission class extends the Permission class, and
 * can be used as the base class for permissions that want to
 * follow the same naming convention as BasicPermission.
 * <P>
 * The name for a BasicPermission is the name of the given permission
 * (for example, "exit",
 * "setFactory", "print.queueJob", etc). The naming
 * convention follows the  hierarchical property naming convention.
 * An asterisk
 * may appear at the end of the name, following a ".", or by itself, to
 * signify a wildcard match. For example: "java.*" or "*" is valid,
 * "*java" or "a*b" is not valid.
 * <P>
 * The action string (inherited from Permission) is unused.
 * Thus, BasicPermission is commonly used as the base class for
 * "named" permissions
 * (ones that contain a name but no actions list; you either have the
 * named permission or you don't.)
 * Subclasses may implement actions on top of BasicPermission,
 * if desired.
 * <p>
 * <P>
 * @see java.security.Permission
 * @see java.security.Permissions
 * @see java.security.PermissionCollection
 * @see java.lang.RuntimePermission
 * @see java.security.SecurityPermission
 * @see java.util.PropertyPermission
 * @see java.awt.AWTPermission
 * @see java.net.NetPermission
 * @see java.lang.SecurityManager
 *
 * @version 1.16 99/03/26
 *
 * @author Marianne Mueller
 * @author Roland Schemers
 */

public abstract class BasicPermission extends Permission
implements java.io.Serializable
{

    // does this permission have a wildcard at the end?
    private transient boolean wildcard;

    // the name without the wildcard on the end
    private transient String path;

    /**
     * initialize a BasicPermission object. Common to all constructors.
     *
     */

    private void init(String name)
    {

    if (name == null)
        throw new IllegalArgumentException("name can't be null");

    if (name.endsWith(".*") || name.equals("*")) {
        wildcard = true;
        if (name.length() == 1) {
        path = "";
        } else {
        path = name.substring(0, name.length()-1);
        }
    } else {
        path = name;
    }
    }

    /**
     * Creates a new BasicPermission with the specified name.
     * Name is the symbolic name of the permission, such as
     * "setFactory",
     * "print.queueJob", or "topLevelWindow", etc. An asterisk
     * may appear at the end of the name, following a ".", or by itself, to
     * signify a wildcard match.
     *
     * @param name the name of the BasicPermission.
     */

    public BasicPermission(String name)
    {
    super(name);
    init(name);
    }


    /**
     * Creates a new BasicPermission object with the specified name.
     * The name is the symbolic name of the BasicPermission, and the
     * actions String is currently unused. This
     * constructor exists for use by the <code>Policy</code> object
     * to instantiate new Permission objects.
     *
     * @param name the name of the BasicPermission.
     * @param actions ignored.
     */
    public BasicPermission(String name, String actions)
    {
    super(name);
    init(name);
    }

    /**
     * Checks if the specified permission is "implied" by
     * this object.
     * <P>
     * More specifically, this method returns true if:<p>
     * <ul>
     * <li> <i>p</i>'s class is the same as this object's class, and<p>
     * <li> <i>p</i>'s name equals or (in the case of wildcards)
     *      is implied by this object's
     *      name. For example, "a.b.*" implies "a.b.c".
     * </ul>
     *
     * @param p the permission to check against.
     *
     * @return true if the passed permission is equal to or
     * implied by this permission, false otherwise.
     */
    public boolean implies(Permission p) {
    if ((p == null) || (p.getClass() != getClass()))
        return false;

    BasicPermission that = (BasicPermission) p;

    if (this.wildcard) {
        if (that.wildcard)
        // one wildcard can imply another
        return that.path.startsWith(path);
        else
        // make sure ap.path is longer so a.b.* doesn't imply a.b
        return (that.path.length() > this.path.length()) &&
            that.path.startsWith(this.path);
    } else {
        if (that.wildcard) {
        // a non-wildcard can't imply a wildcard
        return false;
        }
        else {
        return this.path.equals(that.path);
        }
    }
    }

    /**
     * Checks two BasicPermission 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 a BasicPermission, and has the same name
     *  as this BasicPermission object, false otherwise.
     */
    public boolean equals(Object obj) {
    if (obj == this)
        return true;

    if ((obj == null) || (obj.getClass() != getClass()))
        return false;

    BasicPermission bp = (BasicPermission) obj;

    return getName().equals(bp.getName());
    }


    /**
     * Returns the hash code value for this object.
     * The hash code used is the hash code of the name, that is,
     * <code>getName().hashCode()</code>, where <code>getName</code> is
     * from the Permission superclass.
     *
     * @return a hash code value for this object.
     */

    public int hashCode() {
    return this.getName().hashCode();
    }

    /**
     * Returns the canonical string representation of the actions,
     * which currently is the empty string "", since there are no actions for
     * a BasicPermission.
     *
     * @return the empty string "".
     */
    public String getActions()
    {
    return "";
    }

    /**
     * Returns a new PermissionCollection object for storing BasicPermission
     * objects.
     * <p>
     * A BasicPermissionCollection stores a collection of
     * BasicPermission permissions.
     *
     * <p>BasicPermission 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 BasicPermissions.
     */

    public PermissionCollection newPermissionCollection() {
    return new BasicPermissionCollection();
    }

    /**
     * readObject is called to restore the state of the BasicPermission 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());
    }
}

/**
 * A BasicPermissionCollection stores a collection
 * of BasicPermission permissions. BasicPermission 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.
 *
 * A BasicPermissionCollection handles comparing a permission like "a.b.c.d.e"
 * with a Permission such as "a.b.*", or "*".
 *
 * @see java.security.Permission
 * @see java.security.Permissions
 * @see java.security.PermissionsImpl
 *
 * @version 1.16 99/03/26
 *
 * @author Roland Schemers
 */

final class BasicPermissionCollection
extends PermissionCollection
implements java.io.Serializable
{

    private Hashtable permissions;
    private boolean all_allowed; // true if "*" is in the collection

    /**
     * Create an empty BasicPermissions object.
     *
     */

    public BasicPermissionCollection() {
    permissions = new Hashtable(11);
    all_allowed = false;
    }

    /**
     * Adds a permission to the BasicPermissions. The key for the hash is
     * permission.path.
     *
     * @param permission the Permission object to add.
     */

    public void add(Permission permission)
    {
    if (! (permission instanceof BasicPermission))
        throw new IllegalArgumentException("invalid permission: "+
                           permission);
    BasicPermission bp = (BasicPermission) permission;

    permissions.put(bp.getName(), permission);
        if (!all_allowed) {
        if (bp.getName().equals("*"))
        all_allowed = true;
    }
    }

    /**
     * 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 BasicPermission))
           return false;

    BasicPermission bp = (BasicPermission) permission;

    // short circuit if the "*" Permission was added
    if (all_allowed)
        return true;

    // strategy:
    // Check for full match first. Then work our way up the
    // path looking for matches on a.b..*

    String path = bp.getName();
    //System.out.println("check "+path);

    Permission x = (Permission) permissions.get(path);

    if (x != null) {
        // we have a direct hit!
        return x.implies(permission);
    }

    // work our way up the tree...
    int last, offset;

    offset = path.length()-1;

    while ((last = path.lastIndexOf(".", offset)) != -1) {

        path = path.substring(0, last+1) + "*";
        //System.out.println("check "+path);
        x = (Permission) permissions.get(path);

        if (x != null) {
        return x.implies(permission);
        }
        offset = last -1;
    }

    // we don't have to check for "*" as it was already checked
    // at the top (all_allowed), so we just return false
    return false;
    }

    /**
     * Returns an enumeration of all the BasicPermission objects in the
     * container.
     *
     * @return an enumeration of all the BasicPermission objects.
     */

    public Enumeration elements()
    {
    return permissions.elements();
    }
}