1 /*
2 * Copyright (c) 2001, 2017, 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 package jdk.internal.reflect;
27
28
29 import java.lang.reflect.*;
30 import java.util.HashMap;
31 import java.util.Map;
32 import java.util.Objects;
33 import jdk.internal.HotSpotIntrinsicCandidate;
34 import jdk.internal.loader.ClassLoaders;
35 import jdk.internal.misc.VM;
36
37 /** Common utility routines used by both java.lang and
38 java.lang.reflect */
39
40 public class Reflection {
41
42 /** Used to filter out fields and methods from certain classes from public
43 view, where they are sensitive or they may contain VM-internal objects.
44 These Maps are updated very rarely. Rather than synchronize on
45 each access, we use copy-on-write */
46 private static volatile Map<Class<?>,String[]> fieldFilterMap;
47 private static volatile Map<Class<?>,String[]> methodFilterMap;
48
49 static {
50 Map<Class<?>,String[]> map = new HashMap<Class<?>,String[]>();
51 map.put(Reflection.class,
52 new String[] {"fieldFilterMap", "methodFilterMap"});
53 map.put(System.class, new String[] {"security"});
54 map.put(Class.class, new String[] {"classLoader"});
55 fieldFilterMap = map;
56
57 methodFilterMap = new HashMap<>();
58 }
59
60 /** Returns the class of the caller of the method calling this method,
61 ignoring frames associated with java.lang.reflect.Method.invoke()
62 and its implementation. */
63 @CallerSensitive
64 @HotSpotIntrinsicCandidate
65 public static native Class<?> getCallerClass();
66
67 /** Retrieves the access flags written to the class file. For
68 inner classes these flags may differ from those returned by
69 Class.getModifiers(), which searches the InnerClasses
70 attribute to find the source-level access flags. This is used
71 instead of Class.getModifiers() for run-time access checks due
72 to compatibility reasons; see 4471811. Only the values of the
73 low 13 bits (i.e., a mask of 0x1FFF) are guaranteed to be
74 valid. */
75 @HotSpotIntrinsicCandidate
76 public static native int getClassAccessFlags(Class<?> c);
77
78
79 /**
80 * Ensures that access to a member is granted and throws
81 * IllegalAccessException if not.
82 *
83 * @param currentClass the class performing the access
84 * @param memberClass the declaring class of the member being accessed
85 * @param targetClass the class of target object if accessing instance
86 * field or method;
87 * or the declaring class if accessing constructor;
88 * or null if accessing static field or method
89 * @param modifiers the member's access modifiers
90 * @throws IllegalAccessException if access to member is denied
91 */
92 public static void ensureMemberAccess(Class<?> currentClass,
93 Class<?> memberClass,
94 Class<?> targetClass,
95 int modifiers)
96 throws IllegalAccessException
97 {
98 if (!verifyMemberAccess(currentClass, memberClass, targetClass, modifiers)) {
99 throw newIllegalAccessException(currentClass, memberClass, targetClass, modifiers);
100 }
101 }
102
103 /**
104 * Verify access to a member and return {@code true} if it is granted.
105 *
106 * @param currentClass the class performing the access
107 * @param memberClass the declaring class of the member being accessed
108 * @param targetClass the class of target object if accessing instance
109 * field or method;
110 * or the declaring class if accessing constructor;
111 * or null if accessing static field or method
112 * @param modifiers the member's access modifiers
113 * @return {@code true} if access to member is granted
114 */
115 public static boolean verifyMemberAccess(Class<?> currentClass,
116 Class<?> memberClass,
117 Class<?> targetClass,
118 int modifiers)
119 {
120 if (currentClass == memberClass) {
121 // Always succeeds
122 return true;
123 }
124
125 if (!verifyModuleAccess(currentClass.getModule(), memberClass)) {
126 return false;
127 }
128
129 boolean gotIsSameClassPackage = false;
130 boolean isSameClassPackage = false;
131
132 if (!Modifier.isPublic(getClassAccessFlags(memberClass))) {
133 isSameClassPackage = isSameClassPackage(currentClass, memberClass);
134 gotIsSameClassPackage = true;
135 if (!isSameClassPackage) {
136 return false;
137 }
138 }
139
140 // At this point we know that currentClass can access memberClass.
141
142 if (Modifier.isPublic(modifiers)) {
143 return true;
144 }
145
146 // Check for nestmate access if member is private
147 if (Modifier.isPrivate(modifiers)) {
148 // assert: isSubclassof(targetClass, memberClass)
149 // Note: targetClass may be outside the nest, but that is okay
150 // as long as memberClass is in the nest.
151 boolean nestmates = areNestMates(currentClass, memberClass);
152 if (nestmates) {
153 return true;
154 }
155 }
156
157 boolean successSoFar = false;
158
159 if (Modifier.isProtected(modifiers)) {
160 // See if currentClass is a subclass of memberClass
161 if (isSubclassOf(currentClass, memberClass)) {
162 successSoFar = true;
163 }
164 }
165
166 if (!successSoFar && !Modifier.isPrivate(modifiers)) {
167 if (!gotIsSameClassPackage) {
168 isSameClassPackage = isSameClassPackage(currentClass,
169 memberClass);
170 gotIsSameClassPackage = true;
171 }
172
173 if (isSameClassPackage) {
174 successSoFar = true;
175 }
176 }
177
178 if (!successSoFar) {
179 return false;
180 }
181
182 // Additional test for protected instance members
183 // and protected constructors: JLS 6.6.2
184 if (targetClass != null && Modifier.isProtected(modifiers) &&
185 targetClass != currentClass)
186 {
187 if (!gotIsSameClassPackage) {
188 isSameClassPackage = isSameClassPackage(currentClass, memberClass);
189 gotIsSameClassPackage = true;
190 }
191 if (!isSameClassPackage) {
192 if (!isSubclassOf(targetClass, currentClass)) {
193 return false;
194 }
195 }
196 }
197
198 return true;
199 }
200
201 /**
202 * Returns {@code true} if memberClass's module exports memberClass's
203 * package to currentModule.
204 */
205 public static boolean verifyModuleAccess(Module currentModule, Class<?> memberClass) {
206 Module memberModule = memberClass.getModule();
207 if (currentModule == memberModule) {
208 // same module (named or unnamed) or both null if called
209 // before module system is initialized, which means we are
210 // dealing with java.base only.
211 return true;
212 } else {
213 String pkg = memberClass.getPackageName();
214 return memberModule.isExported(pkg, currentModule);
215 }
216 }
217
218 /**
219 * Returns true if two classes in the same package.
220 */
221 private static boolean isSameClassPackage(Class<?> c1, Class<?> c2) {
222 if (c1.getClassLoader() != c2.getClassLoader())
223 return false;
224 return Objects.equals(c1.getPackageName(), c2.getPackageName());
225 }
226
227 static boolean isSubclassOf(Class<?> queryClass,
228 Class<?> ofClass)
229 {
230 while (queryClass != null) {
231 if (queryClass == ofClass) {
232 return true;
233 }
234 queryClass = queryClass.getSuperclass();
235 }
236 return false;
237 }
238
239 // fieldNames must contain only interned Strings
240 public static synchronized void registerFieldsToFilter(Class<?> containingClass,
241 String ... fieldNames) {
242 fieldFilterMap =
243 registerFilter(fieldFilterMap, containingClass, fieldNames);
244 }
245
246 // methodNames must contain only interned Strings
247 public static synchronized void registerMethodsToFilter(Class<?> containingClass,
248 String ... methodNames) {
249 methodFilterMap =
250 registerFilter(methodFilterMap, containingClass, methodNames);
251 }
252
253 private static Map<Class<?>,String[]> registerFilter(Map<Class<?>,String[]> map,
254 Class<?> containingClass, String ... names) {
255 if (map.get(containingClass) != null) {
256 throw new IllegalArgumentException
257 ("Filter already registered: " + containingClass);
258 }
259 map = new HashMap<Class<?>,String[]>(map);
260 map.put(containingClass, names);
261 return map;
262 }
263
264 public static Field[] filterFields(Class<?> containingClass,
265 Field[] fields) {
266 if (fieldFilterMap == null) {
267 // Bootstrapping
268 return fields;
269 }
270 return (Field[])filter(fields, fieldFilterMap.get(containingClass));
271 }
272
273 public static Method[] filterMethods(Class<?> containingClass, Method[] methods) {
274 if (methodFilterMap == null) {
275 // Bootstrapping
276 return methods;
277 }
278 return (Method[])filter(methods, methodFilterMap.get(containingClass));
279 }
280
281 private static Member[] filter(Member[] members, String[] filteredNames) {
282 if ((filteredNames == null) || (members.length == 0)) {
283 return members;
284 }
285 int numNewMembers = 0;
286 for (Member member : members) {
287 boolean shouldSkip = false;
288 for (String filteredName : filteredNames) {
289 if (member.getName() == filteredName) {
290 shouldSkip = true;
291 break;
292 }
293 }
294 if (!shouldSkip) {
295 ++numNewMembers;
296 }
297 }
298 Member[] newMembers =
299 (Member[])Array.newInstance(members[0].getClass(), numNewMembers);
300 int destIdx = 0;
301 for (Member member : members) {
302 boolean shouldSkip = false;
303 for (String filteredName : filteredNames) {
304 if (member.getName() == filteredName) {
305 shouldSkip = true;
306 break;
307 }
308 }
309 if (!shouldSkip) {
310 newMembers[destIdx++] = member;
311 }
312 }
313 return newMembers;
314 }
315
316 /**
317 * Tests if the given method is caller-sensitive and the declaring class
318 * is defined by either the bootstrap class loader or platform class loader.
319 */
320 public static boolean isCallerSensitive(Method m) {
321 final ClassLoader loader = m.getDeclaringClass().getClassLoader();
322 if (VM.isSystemDomainLoader(loader)) {
323 return m.isAnnotationPresent(CallerSensitive.class);
324 }
325 return false;
326 }
327
328 /**
329 * Returns an IllegalAccessException with an exception message based on
330 * the access that is denied.
331 */
332 public static IllegalAccessException newIllegalAccessException(Class<?> currentClass,
333 Class<?> memberClass,
334 Class<?> targetClass,
335 int modifiers)
336 throws IllegalAccessException
337 {
338 String currentSuffix = "";
339 String memberSuffix = "";
340 Module m1 = currentClass.getModule();
341 if (m1.isNamed())
342 currentSuffix = " (in " + m1 + ")";
343 Module m2 = memberClass.getModule();
344 if (m2.isNamed())
345 memberSuffix = " (in " + m2 + ")";
346
347 String memberPackageName = memberClass.getPackageName();
348
349 String msg = currentClass + currentSuffix + " cannot access ";
350 if (m2.isExported(memberPackageName, m1)) {
351
352 // module access okay so include the modifiers in the message
353 msg += "a member of " + memberClass + memberSuffix +
354 " with modifiers \"" + Modifier.toString(modifiers) + "\"";
355
356 } else {
357 // module access failed
358 msg += memberClass + memberSuffix+ " because "
359 + m2 + " does not export " + memberPackageName;
360 if (m2.isNamed()) msg += " to " + m1;
361 }
362
363 return new IllegalAccessException(msg);
364 }
365
366 public static native boolean areNestMates(Class<?> currentClass,
367 Class<?> memberClass);
368 }