1 /*
   2  * Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 
  27 package sun.reflect.misc;
  28 
  29 import java.lang.reflect.Modifier;
  30 import sun.reflect.Reflection;
  31 
  32 public final class ReflectUtil {
  33 
  34     private ReflectUtil() {
  35     }
  36 
  37     public static Class<?> forName(String name)
  38         throws ClassNotFoundException {
  39         checkPackageAccess(name);
  40         return Class.forName(name);
  41     }
  42 
  43     public static Object newInstance(Class<?> cls)
  44         throws InstantiationException, IllegalAccessException {
  45         checkPackageAccess(cls);
  46         return cls.newInstance();
  47     }
  48 
  49     /*
  50      * Reflection.ensureMemberAccess is overly-restrictive
  51      * due to a bug. We awkwardly work around it for now.
  52      */
  53     public static void ensureMemberAccess(Class<?> currentClass,
  54                                           Class<?> memberClass,
  55                                           Object target,
  56                                           int modifiers)
  57         throws IllegalAccessException
  58     {
  59         if (target == null && Modifier.isProtected(modifiers)) {
  60             int mods = modifiers;
  61             mods = mods & (~Modifier.PROTECTED);
  62             mods = mods | Modifier.PUBLIC;
  63 
  64             /*
  65              * See if we fail because of class modifiers
  66              */
  67             Reflection.ensureMemberAccess(currentClass,
  68                                           memberClass,
  69                                           target,
  70                                           mods);
  71             try {
  72                 /*
  73                  * We're still here so class access was ok.
  74                  * Now try with default field access.
  75                  */
  76                 mods = mods & (~Modifier.PUBLIC);
  77                 Reflection.ensureMemberAccess(currentClass,
  78                                               memberClass,
  79                                               target,
  80                                               mods);
  81                 /*
  82                  * We're still here so access is ok without
  83                  * checking for protected.
  84                  */
  85                 return;
  86             } catch (IllegalAccessException e) {
  87                 /*
  88                  * Access failed but we're 'protected' so
  89                  * if the test below succeeds then we're ok.
  90                  */
  91                 if (isSubclassOf(currentClass, memberClass)) {
  92                     return;
  93                 } else {
  94                     throw e;
  95                 }
  96             }
  97         } else {
  98             Reflection.ensureMemberAccess(currentClass,
  99                                           memberClass,
 100                                           target,
 101                                           modifiers);
 102         }
 103     }
 104 
 105     private static boolean isSubclassOf(Class<?> queryClass,
 106                                         Class<?> ofClass)
 107     {
 108         while (queryClass != null) {
 109             if (queryClass == ofClass) {
 110                 return true;
 111             }
 112             queryClass = queryClass.getSuperclass();
 113         }
 114         return false;
 115     }
 116 
 117 
 118     public static void checkPackageAccess(Class<?> clazz) {
 119         checkPackageAccess(clazz.getName());
 120     }
 121 
 122     public static void checkPackageAccess(String name) {
 123         SecurityManager s = System.getSecurityManager();
 124         if (s != null) {
 125             String cname = name.replace('/', '.');
 126             if (cname.startsWith("[")) {
 127                 int b = cname.lastIndexOf('[') + 2;
 128                 if (b > 1 && b < cname.length()) {
 129                     cname = cname.substring(b);
 130                 }
 131             }
 132             int i = cname.lastIndexOf('.');
 133             if (i != -1) {
 134                 s.checkPackageAccess(cname.substring(0, i));
 135             }
 136         }
 137     }
 138 
 139     public static boolean isPackageAccessible(Class<?> clazz) {
 140         try {
 141             checkPackageAccess(clazz);
 142         } catch (SecurityException e) {
 143             return false;
 144         }
 145         return true;
 146     }
 147 }