jtulach@258: /*
jtulach@258:  * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved.
jtulach@258:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jtulach@258:  *
jtulach@258:  * This code is free software; you can redistribute it and/or modify it
jtulach@258:  * under the terms of the GNU General Public License version 2 only, as
jtulach@258:  * published by the Free Software Foundation.  Oracle designates this
jtulach@258:  * particular file as subject to the "Classpath" exception as provided
jtulach@258:  * by Oracle in the LICENSE file that accompanied this code.
jtulach@258:  *
jtulach@258:  * This code is distributed in the hope that it will be useful, but WITHOUT
jtulach@258:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jtulach@258:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jtulach@258:  * version 2 for more details (a copy is included in the LICENSE file that
jtulach@258:  * accompanied this code).
jtulach@258:  *
jtulach@258:  * You should have received a copy of the GNU General Public License version
jtulach@258:  * 2 along with this work; if not, write to the Free Software Foundation,
jtulach@258:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jtulach@258:  *
jtulach@258:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jtulach@258:  * or visit www.oracle.com if you need additional information or have any
jtulach@258:  * questions.
jtulach@258:  */
jtulach@258: 
jtulach@258: package java.lang.reflect;
jtulach@258: 
jtulach@258: import java.security.AccessController;
jtulach@258: import sun.reflect.Reflection;
jtulach@258: import sun.reflect.ReflectionFactory;
jtulach@258: import java.lang.annotation.Annotation;
jtulach@258: 
jtulach@258: /**
jtulach@258:  * The AccessibleObject class is the base class for Field, Method and
jtulach@258:  * Constructor objects.  It provides the ability to flag a reflected
jtulach@258:  * object as suppressing default Java language access control checks
jtulach@258:  * when it is used.  The access checks--for public, default (package)
jtulach@258:  * access, protected, and private members--are performed when Fields,
jtulach@258:  * Methods or Constructors are used to set or get fields, to invoke
jtulach@258:  * methods, or to create and initialize new instances of classes,
jtulach@258:  * respectively.
jtulach@258:  *
jtulach@258:  * <p>Setting the {@code accessible} flag in a reflected object
jtulach@258:  * permits sophisticated applications with sufficient privilege, such
jtulach@258:  * as Java Object Serialization or other persistence mechanisms, to
jtulach@258:  * manipulate objects in a manner that would normally be prohibited.
jtulach@258:  *
jtulach@258:  * <p>By default, a reflected object is <em>not</em> accessible.
jtulach@258:  *
jtulach@258:  * @see Field
jtulach@258:  * @see Method
jtulach@258:  * @see Constructor
jtulach@258:  * @see ReflectPermission
jtulach@258:  *
jtulach@258:  * @since 1.2
jtulach@258:  */
jtulach@258: public class AccessibleObject implements AnnotatedElement {
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * The Permission object that is used to check whether a client
jtulach@258:      * has sufficient privilege to defeat Java language access
jtulach@258:      * control checks.
jtulach@258:      */
jtulach@258:     static final private java.security.Permission ACCESS_PERMISSION =
jtulach@258:         new ReflectPermission("suppressAccessChecks");
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * Convenience method to set the {@code accessible} flag for an
jtulach@258:      * array of objects with a single security check (for efficiency).
jtulach@258:      *
jtulach@258:      * <p>First, if there is a security manager, its
jtulach@258:      * {@code checkPermission} method is called with a
jtulach@258:      * {@code ReflectPermission("suppressAccessChecks")} permission.
jtulach@258:      *
jtulach@258:      * <p>A {@code SecurityException} is raised if {@code flag} is
jtulach@258:      * {@code true} but accessibility of any of the elements of the input
jtulach@258:      * {@code array} may not be changed (for example, if the element
jtulach@258:      * object is a {@link Constructor} object for the class {@link
jtulach@258:      * java.lang.Class}).  In the event of such a SecurityException, the
jtulach@258:      * accessibility of objects is set to {@code flag} for array elements
jtulach@258:      * upto (and excluding) the element for which the exception occurred; the
jtulach@258:      * accessibility of elements beyond (and including) the element for which
jtulach@258:      * the exception occurred is unchanged.
jtulach@258:      *
jtulach@258:      * @param array the array of AccessibleObjects
jtulach@258:      * @param flag  the new value for the {@code accessible} flag
jtulach@258:      *              in each object
jtulach@258:      * @throws SecurityException if the request is denied.
jtulach@258:      * @see SecurityManager#checkPermission
jtulach@258:      * @see java.lang.RuntimePermission
jtulach@258:      */
jtulach@258:     public static void setAccessible(AccessibleObject[] array, boolean flag)
jtulach@258:         throws SecurityException {
jtulach@258:         SecurityManager sm = System.getSecurityManager();
jtulach@258:         if (sm != null) sm.checkPermission(ACCESS_PERMISSION);
jtulach@258:         for (int i = 0; i < array.length; i++) {
jtulach@258:             setAccessible0(array[i], flag);
jtulach@258:         }
jtulach@258:     }
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * Set the {@code accessible} flag for this object to
jtulach@258:      * the indicated boolean value.  A value of {@code true} indicates that
jtulach@258:      * the reflected object should suppress Java language access
jtulach@258:      * checking when it is used.  A value of {@code false} indicates
jtulach@258:      * that the reflected object should enforce Java language access checks.
jtulach@258:      *
jtulach@258:      * <p>First, if there is a security manager, its
jtulach@258:      * {@code checkPermission} method is called with a
jtulach@258:      * {@code ReflectPermission("suppressAccessChecks")} permission.
jtulach@258:      *
jtulach@258:      * <p>A {@code SecurityException} is raised if {@code flag} is
jtulach@258:      * {@code true} but accessibility of this object may not be changed
jtulach@258:      * (for example, if this element object is a {@link Constructor} object for
jtulach@258:      * the class {@link java.lang.Class}).
jtulach@258:      *
jtulach@258:      * <p>A {@code SecurityException} is raised if this object is a {@link
jtulach@258:      * java.lang.reflect.Constructor} object for the class
jtulach@258:      * {@code java.lang.Class}, and {@code flag} is true.
jtulach@258:      *
jtulach@258:      * @param flag the new value for the {@code accessible} flag
jtulach@258:      * @throws SecurityException if the request is denied.
jtulach@258:      * @see SecurityManager#checkPermission
jtulach@258:      * @see java.lang.RuntimePermission
jtulach@258:      */
jtulach@258:     public void setAccessible(boolean flag) throws SecurityException {
jtulach@258:         SecurityManager sm = System.getSecurityManager();
jtulach@258:         if (sm != null) sm.checkPermission(ACCESS_PERMISSION);
jtulach@258:         setAccessible0(this, flag);
jtulach@258:     }
jtulach@258: 
jtulach@258:     /* Check that you aren't exposing java.lang.Class.<init>. */
jtulach@258:     private static void setAccessible0(AccessibleObject obj, boolean flag)
jtulach@258:         throws SecurityException
jtulach@258:     {
jtulach@258:         if (obj instanceof Constructor && flag == true) {
jtulach@258:             Constructor<?> c = (Constructor<?>)obj;
jtulach@258:             if (c.getDeclaringClass() == Class.class) {
jtulach@258:                 throw new SecurityException("Can not make a java.lang.Class" +
jtulach@258:                                             " constructor accessible");
jtulach@258:             }
jtulach@258:         }
jtulach@258:         obj.override = flag;
jtulach@258:     }
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * Get the value of the {@code accessible} flag for this object.
jtulach@258:      *
jtulach@258:      * @return the value of the object's {@code accessible} flag
jtulach@258:      */
jtulach@258:     public boolean isAccessible() {
jtulach@258:         return override;
jtulach@258:     }
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * Constructor: only used by the Java Virtual Machine.
jtulach@258:      */
jtulach@258:     protected AccessibleObject() {}
jtulach@258: 
jtulach@258:     // Indicates whether language-level access checks are overridden
jtulach@258:     // by this object. Initializes to "false". This field is used by
jtulach@258:     // Field, Method, and Constructor.
jtulach@258:     //
jtulach@258:     // NOTE: for security purposes, this field must not be visible
jtulach@258:     // outside this package.
jtulach@258:     boolean override;
jtulach@258: 
jtulach@258:     // Reflection factory used by subclasses for creating field,
jtulach@258:     // method, and constructor accessors. Note that this is called
jtulach@258:     // very early in the bootstrapping process.
jtulach@258:     static final ReflectionFactory reflectionFactory =
jtulach@258:         AccessController.doPrivileged(
jtulach@258:             new sun.reflect.ReflectionFactory.GetReflectionFactoryAction());
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * @throws NullPointerException {@inheritDoc}
jtulach@258:      * @since 1.5
jtulach@258:      */
jtulach@258:     public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
jtulach@258:         throw new AssertionError("All subclasses should override this method");
jtulach@258:     }
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * @throws NullPointerException {@inheritDoc}
jtulach@258:      * @since 1.5
jtulach@258:      */
jtulach@258:     public boolean isAnnotationPresent(
jtulach@258:         Class<? extends Annotation> annotationClass) {
jtulach@258:         return getAnnotation(annotationClass) != null;
jtulach@258:     }
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * @since 1.5
jtulach@258:      */
jtulach@258:     public Annotation[] getAnnotations() {
jtulach@258:         return getDeclaredAnnotations();
jtulach@258:     }
jtulach@258: 
jtulach@258:     /**
jtulach@258:      * @since 1.5
jtulach@258:      */
jtulach@258:     public Annotation[] getDeclaredAnnotations()  {
jtulach@258:         throw new AssertionError("All subclasses should override this method");
jtulach@258:     }
jtulach@258: 
jtulach@258: 
jtulach@258:     // Shared access checking logic.
jtulach@258: 
jtulach@258:     // For non-public members or members in package-private classes,
jtulach@258:     // it is necessary to perform somewhat expensive security checks.
jtulach@258:     // If the security check succeeds for a given class, it will
jtulach@258:     // always succeed (it is not affected by the granting or revoking
jtulach@258:     // of permissions); we speed up the check in the common case by
jtulach@258:     // remembering the last Class for which the check succeeded.
jtulach@258:     //
jtulach@258:     // The simple security check for Constructor is to see if
jtulach@258:     // the caller has already been seen, verified, and cached.
jtulach@258:     // (See also Class.newInstance(), which uses a similar method.)
jtulach@258:     //
jtulach@258:     // A more complicated security check cache is needed for Method and Field
jtulach@258:     // The cache can be either null (empty cache), a 2-array of {caller,target},
jtulach@258:     // or a caller (with target implicitly equal to this.clazz).
jtulach@258:     // In the 2-array case, the target is always different from the clazz.
jtulach@258:     volatile Object securityCheckCache;
jtulach@258: 
jtulach@258:     void checkAccess(Class<?> caller, Class<?> clazz, Object obj, int modifiers)
jtulach@258:         throws IllegalAccessException
jtulach@258:     {
jtulach@258:         if (caller == clazz) {  // quick check
jtulach@258:             return;             // ACCESS IS OK
jtulach@258:         }
jtulach@258:         Object cache = securityCheckCache;  // read volatile
jtulach@258:         Class<?> targetClass = clazz;
jtulach@258:         if (obj != null
jtulach@258:             && Modifier.isProtected(modifiers)
jtulach@258:             && ((targetClass = obj.getClass()) != clazz)) {
jtulach@258:             // Must match a 2-list of { caller, targetClass }.
jtulach@258:             if (cache instanceof Class[]) {
jtulach@258:                 Class<?>[] cache2 = (Class<?>[]) cache;
jtulach@258:                 if (cache2[1] == targetClass &&
jtulach@258:                     cache2[0] == caller) {
jtulach@258:                     return;     // ACCESS IS OK
jtulach@258:                 }
jtulach@258:                 // (Test cache[1] first since range check for [1]
jtulach@258:                 // subsumes range check for [0].)
jtulach@258:             }
jtulach@258:         } else if (cache == caller) {
jtulach@258:             // Non-protected case (or obj.class == this.clazz).
jtulach@258:             return;             // ACCESS IS OK
jtulach@258:         }
jtulach@258: 
jtulach@258:         // If no return, fall through to the slow path.
jtulach@258:         slowCheckMemberAccess(caller, clazz, obj, modifiers, targetClass);
jtulach@258:     }
jtulach@258: 
jtulach@258:     // Keep all this slow stuff out of line:
jtulach@258:     void slowCheckMemberAccess(Class<?> caller, Class<?> clazz, Object obj, int modifiers,
jtulach@258:                                Class<?> targetClass)
jtulach@258:         throws IllegalAccessException
jtulach@258:     {
jtulach@258:         Reflection.ensureMemberAccess(caller, clazz, obj, modifiers);
jtulach@258: 
jtulach@258:         // Success: Update the cache.
jtulach@258:         Object cache = ((targetClass == clazz)
jtulach@258:                         ? caller
jtulach@258:                         : new Class<?>[] { caller, targetClass });
jtulach@258: 
jtulach@258:         // Note:  The two cache elements are not volatile,
jtulach@258:         // but they are effectively final.  The Java memory model
jtulach@258:         // guarantees that the initializing stores for the cache
jtulach@258:         // elements will occur before the volatile write.
jtulach@258:         securityCheckCache = cache;         // write volatile
jtulach@258:     }
jtulach@258: }