/*
* @(#)AccessibleObject.java 1.22 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.lang.reflect;
/**
* The AccessibleObject class is the base class for Field, Method and
* Constructor objects. It provides the ability to flag a reflected
* object as suppressing default Java language access control checks
* when it is used. The access checks--for public, default (package)
* access, protected, and private members--are performed when Fields,
* Methods or Constructors are used to set or get fields, to invoke
* methods, or to create and initialize new instances of classes,
* respectively.
*
* <p>Setting the <tt>accessible</tt> flag in a reflected object
* permits sophisticated applications with sufficient privilege, such
* as Java Object Serialization or other persistence mechanisms, to
* manipulate objects in a manner that would normally be prohibited.
*
* @see Field
* @see Method
* @see Constructor
* @see ReflectPermission
*
* @since 1.2
*/
public
class AccessibleObject {
/**
* The Permission object that is used to check whether a client
* has sufficient privilege to defeat Java language access
* control checks.
*/
static private java.security.Permission ACCESS_PERMISSION;
static private void initAccessPermission() {
ACCESS_PERMISSION = new ReflectPermission("suppressAccessChecks");
}
/**
* Convenience method to set the <tt>accessible</tt> flag for an
* array of objects with a single security check (for efficiency).
*
* <p>First, if there is a security manager, its
* <code>checkPermission</code> method is called with a
* <code>ReflectPermission("suppressAccessChecks")</code> permission.
*
* <p>A <code>SecurityException</code> is raised if <code>flag</code> is
* <code>true</code> but accessibility of any of the elements of the input
* <code>array</code> may not be changed (for example, if the element
* object is a {@link Constructor} object for the class {@link
* java.lang.Class}). In the event of such a SecurityException, the
* accessiblity of objects is set to <code>flag</code> for array elements
* upto (and excluding) the element for which the exception occurred; the
* accessiblity of elements beyond (and including) the element for which
* the exception occurred is unchanged.
*
* @param array the array of AccessibleObjects
* @param flag the new value for the <tt>accessible</tt> flag
* in each object
* @throws SecurityException if the request is denied.
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
*/
public static void setAccessible(AccessibleObject[] array, boolean flag)
throws SecurityException {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
if (ACCESS_PERMISSION == null) {
initAccessPermission();
}
sm.checkPermission(ACCESS_PERMISSION);
}
for (int i = 0; i < array.length; i++) {
setAccessible0(array[i], flag);
}
}
/**
* Set the <tt>accessible</tt> flag for this object to
* the indicated boolean value. A value of <tt>true</tt> indicates that
* the reflected object should suppress Java language access
* checking when it is used. A value of <tt>false</tt> indicates
* that the reflected object should enforce Java language access checks.
*
* <p>First, if there is a security manager, its
* <code>checkPermission</code> method is called with a
* <code>ReflectPermission("suppressAccessChecks")</code> permission.
*
* <p>A <code>SecurityException</code> is raised if <code>flag</code> is
* <code>true</code> but accessibility of this object may not be changed
* (for example, if this element object is a {@link Constructor} object for
* the class {@link java.lang.Class}).
*
* <p>A <code>SecurityException</code> is raised if this object is a {@link
* java.lang.reflect.Constructor} object for the class
* <code>java.lang.Class</code>, and <code>flag</code> is true.
*
* @param flag the new value for the <tt>accessible</tt> flag
* @throws SecurityException if the request is denied.
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
*/
public void setAccessible(boolean flag) throws SecurityException {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
if (ACCESS_PERMISSION == null) {
initAccessPermission();
}
sm.checkPermission(ACCESS_PERMISSION);
}
setAccessible0(this, flag);
}
/* Check that you aren't exposing java.lang.Class.<init>. */
private static void setAccessible0(AccessibleObject obj, boolean flag)
throws SecurityException
{
if (obj instanceof Constructor && flag == true) {
Constructor c = (Constructor)obj;
if (c.getDeclaringClass() == Class.class) {
throw new SecurityException("Can not make a java.lang.Class" +
" constructor accessible");
}
}
obj.override = flag;
}
/**
* Get the value of the <tt>accessible</tt> flag for this object.
*
* @return the value of the object's <tt>accessible</tt> flag
*/
public boolean isAccessible() {
return override;
}
/**
* Constructor: only used by the Java Virtual Machine.
*/
protected AccessibleObject() {}
// N.B. jvm depends on this field name, and initializes to <tt>false</tt>.
private boolean override;
}