source: trunk/gcc/libjava/java/security/UnresolvedPermission.java

/* UnresolvedPermission.java -- Placeholder for unresolved permissions
   Copyright (C) 1998, 2001, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath 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 for more details.

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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package java.security;

import java.io.Serializable;
// All uses of Certificate in this file refer to the one in the listed
// package, not this one.
import java.security.cert.Certificate;
import java.util.Arrays;
import java.util.Hashtable;
import java.util.Vector;
import java.util.Enumeration;
import java.util.NoSuchElementException;

/**
 * This class is used to hold instances of all permissions that cannot
 * be resolved to available permission classes when the security
 * <code>Policy</code> object is instantiated.  This may happen when the
 * necessary security class has not yet been downloaded from the network.
 *
 * <p>Instances of this class are re-resolved when
 * <code>AccessController</code> check is done.  At that time, a scan is
 * made of all existing <code>UnresolvedPermission</code> objects and they
 * are converted to objects of the appropriate permission type if the class
 * for that type is then available.
 *
 * @author Aaron M. Renn (arenn@urbanophile.com)
 * @see Permission
 * @see Permissions
 * @see PermissionCollection
 * @see Policy
 * @since 1.1
 * @status updated to 1.4
 */
public final class UnresolvedPermission extends Permission
{
  /**
   * Compatible with JDK 1.1+.
   */
  private static final long serialVersionUID = -4821973115467008846L;

  /**
   * The list of actions associated with this permission object.
   *
   * @serial the permission actions
   */
  private final String actions;

  /**
   * The list of <code>Certificates</code> associated with this object.
   */
  private final transient Certificate[] certs;

  /**
   * The name of the class this object should be resolved to.
   *
   * @serial the fully-qualified classname of the resolved type
   */
  // Package visible for use by UnresolvedPermissionCollection.
  final String type;

  /**
   * The name of the permission.
   *
   * @serial the permission name
   */
  private final String name;

  /**
   * Create a new instance with all the information necessary to resolve it
   * to an instance of the proper class at a future time.
   *
   * @param type the fully-qualified name of the class of this permission
   * @param name the name of this permission
   * @param actions the action list for this permission
   * @param certs the list of certificates that sign this permission
   */
  public UnresolvedPermission(String type, String name, String actions,
                              Certificate[] certs)
  {
    super(name);
    this.name = name;
    this.type = type;
    this.actions = actions;
    this.certs = certs;
  }

  /**
   * This method returns <code>false</code> always to indicate that this
   * permission does not imply the specified permission.  An
   * <code>UnresolvedPermission</code> never grants any permissions.
   *
   * @param perm the <code>Permission</code> object to test
   * @return false; until a permission is resolved, it implies nothing
   */
  public boolean implies(Permission perm)
  {
    return false;
  }

  /**
   * This method tests this permission for equality against the specified
   * <code>Object</code>. This will be true if and only if the following
   * conditions are met:<ul>
   * <li>The specified <code>Object</code> is an UnresolvedPermission</li>
   * <li>The specified permission has the same type (i.e., desired class name)
   *     as this permission.</li>
   * <li>The specified permission has the same name as this one.</li>
   * <li>The specified permissoin has the same action list as this one.</li>
   * <li>The specified permission has the same certificate list as this
   *     one.</li>
   * </ul>
   *
   * @param obj the <code>Object</code> to test for equality
   * @return true if the specified object is equal to this one
   */
  public boolean equals(Object obj)
  {
    if (! (obj instanceof UnresolvedPermission))
      return (false);
    UnresolvedPermission up = (UnresolvedPermission) obj;
    return up.name.equals(name) && up.actions.equals(actions)
      && up.type.equals(type) && Arrays.equals(up.certs, certs);
  }

  /**
   * Returns a hash code value for this object. Following the lead of
   * Permission, this returns the hashcode of the permission name.
   *
   * @return A hash value
   */
  public int hashCode()
  {
    return name.hashCode();
  }

  /**
   * This method returns the list of actions associated with this
   * permission.
   *
   * @return the action list
   */
  public String getActions()
  {
    return actions;
  }

  /**
   * This method returns a <code>String</code> representation of this
   * class.  The format is: '(unresolved "ClassName "name" "actions")'
   *
   * @return  <code>String</code> representation of this object
   */
  public String toString()
  {
    return "(unresolved " + type + ' ' + name + ' ' + actions + ')';
  }

  /**
   * This class returns a <code>PermissionCollection</code> object that can
   * be used to store instances of <code>UnresolvedPermission</code>.
   *
   * @return a new <code>PermissionCollection</code>
   */
  public PermissionCollection newPermissionCollection()
  {
    return new UnresolvedPermissionCollection();
  }
} // class UnresolvedPermission

/**
 * Implements the permission collection for unresolved permissions, and
 * obeys serialization of JDK.
 *
 * @author Eric Blake <ebb9@email.byu.edu>
 */
class UnresolvedPermissionCollection extends PermissionCollection
{
  /**
   * Compatible with JDK 1.1+.
   */
  private static final long serialVersionUID = -7176153071733132400L;

  /**
   * Hashtable where we store permissions.
   *
   * @serial map of typename to a Vector of permissions (you'd think Sun
   *         would document this better!)
   */
  private final Hashtable permissions = new Hashtable();

  /**
   * Add a permission.
   *
   * @param perm the permission to add
   * @throws IllegalArgumentException if perm is not an UnresolvedPermission
   * @throws SecurityException if the collection is read-only
   */
  public void add(Permission perm)
  {
    if (isReadOnly())
      throw new SecurityException();
    if (! (perm instanceof UnresolvedPermission))
      throw new IllegalArgumentException();
    UnresolvedPermission up = (UnresolvedPermission) perm;
    Vector v = (Vector) permissions.get(up.type);
    if (v == null)
      {
        v = new Vector();
        permissions.put(up.type, v);
      }
    v.add(up);
  }

  /**
   * Returns true if perm is implied by the collection.
   *
   * @param perm the permission to check
   * @return false; unresolved permissions imply nothing
   */
  public boolean implies(Permission perm)
  {
    return false;
  }

  /**
   * Return the elements.
   *
   * @return the elements
   */
  public Enumeration elements()
  {
    return new Enumeration()
    {
      Enumeration main_enum = permissions.elements();
      Enumeration sub_enum;

      public boolean hasMoreElements()
      {
        if (sub_enum == null)
          {
            if (main_enum == null)
              return false;
            if (! main_enum.hasMoreElements())
              {
                main_enum = null;
                return false;
              }
            Vector v = (Vector) main_enum.nextElement();
            sub_enum = v.elements();
          }
        if (! sub_enum.hasMoreElements())
          {
            sub_enum = null;
            return hasMoreElements();
          }
        return true;
      }

      public Object nextElement()
      {
        if (! hasMoreElements())
          throw new NoSuchElementException();
        return sub_enum.nextElement();
      }
    };
  }
} // class UnresolvedPermissionCollection