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 boolean successSoFar = false;
147
148 if (Modifier.isProtected(modifiers)) {
149 // See if currentClass is a subclass of memberClass
150 if (isSubclassOf(currentClass, memberClass)) {
151 successSoFar = true;
152 }
153 }
154
155 if (!successSoFar && !Modifier.isPrivate(modifiers)) {
156 if (!gotIsSameClassPackage) {
157 isSameClassPackage = isSameClassPackage(currentClass,
158 memberClass);
159 gotIsSameClassPackage = true;
160 }
161
162 if (isSameClassPackage) {
163 successSoFar = true;
164 }
165 }
166
167 if (!successSoFar) {
168 return false;
169 }
170
171 // Additional test for protected instance members
172 // and protected constructors: JLS 6.6.2
173 if (targetClass != null && Modifier.isProtected(modifiers) &&
174 targetClass != currentClass)
175 {
176 if (!gotIsSameClassPackage) {
177 isSameClassPackage = isSameClassPackage(currentClass, memberClass);
178 gotIsSameClassPackage = true;
179 }
180 if (!isSameClassPackage) {
181 if (!isSubclassOf(targetClass, currentClass)) {
182 return false;
183 }
184 }
185 }
186
187 return true;
188 }
189
190 /**
191 * Returns {@code true} if memberClass's module exports memberClass's
192 * package to currentModule.
193 */
194 public static boolean verifyModuleAccess(Module currentModule, Class<?> memberClass) {
195 Module memberModule = memberClass.getModule();
196 if (currentModule == memberModule) {
197 // same module (named or unnamed) or both null if called
198 // before module system is initialized, which means we are
199 // dealing with java.base only.
200 return true;
201 } else {
202 String pkg = memberClass.getPackageName();
203 return memberModule.isExported(pkg, currentModule);
204 }
205 }
206
207 /**
208 * Returns true if two classes in the same package.
209 */
210 private static boolean isSameClassPackage(Class<?> c1, Class<?> c2) {
211 if (c1.getClassLoader() != c2.getClassLoader())
212 return false;
213 return Objects.equals(c1.getPackageName(), c2.getPackageName());
214 }
215
216 static boolean isSubclassOf(Class<?> queryClass,
217 Class<?> ofClass)
218 {
219 while (queryClass != null) {
220 if (queryClass == ofClass) {
221 return true;
222 }
223 queryClass = queryClass.getSuperclass();
224 }
225 return false;
226 }
227
228 // fieldNames must contain only interned Strings
229 public static synchronized void registerFieldsToFilter(Class<?> containingClass,
230 String ... fieldNames) {
231 fieldFilterMap =
232 registerFilter(fieldFilterMap, containingClass, fieldNames);
233 }
234
235 // methodNames must contain only interned Strings
236 public static synchronized void registerMethodsToFilter(Class<?> containingClass,
237 String ... methodNames) {
238 methodFilterMap =
239 registerFilter(methodFilterMap, containingClass, methodNames);
240 }
241
242 private static Map<Class<?>,String[]> registerFilter(Map<Class<?>,String[]> map,
243 Class<?> containingClass, String ... names) {
244 if (map.get(containingClass) != null) {
245 throw new IllegalArgumentException
246 ("Filter already registered: " + containingClass);
247 }
248 map = new HashMap<Class<?>,String[]>(map);
249 map.put(containingClass, names);
250 return map;
251 }
252
253 public static Field[] filterFields(Class<?> containingClass,
254 Field[] fields) {
255 if (fieldFilterMap == null) {
256 // Bootstrapping
257 return fields;
258 }
259 return (Field[])filter(fields, fieldFilterMap.get(containingClass));
260 }
261
262 public static Method[] filterMethods(Class<?> containingClass, Method[] methods) {
263 if (methodFilterMap == null) {
264 // Bootstrapping
265 return methods;
266 }
267 return (Method[])filter(methods, methodFilterMap.get(containingClass));
268 }
269
270 private static Member[] filter(Member[] members, String[] filteredNames) {
271 if ((filteredNames == null) || (members.length == 0)) {
272 return members;
273 }
274 int numNewMembers = 0;
275 for (Member member : members) {
276 boolean shouldSkip = false;
277 for (String filteredName : filteredNames) {
278 if (member.getName() == filteredName) {
279 shouldSkip = true;
280 break;
281 }
282 }
283 if (!shouldSkip) {
284 ++numNewMembers;
285 }
286 }
287 Member[] newMembers =
288 (Member[])Array.newInstance(members[0].getClass(), numNewMembers);
289 int destIdx = 0;
290 for (Member member : members) {
291 boolean shouldSkip = false;
292 for (String filteredName : filteredNames) {
293 if (member.getName() == filteredName) {
294 shouldSkip = true;
295 break;
296 }
297 }
298 if (!shouldSkip) {
299 newMembers[destIdx++] = member;
300 }
301 }
302 return newMembers;
303 }
304
305 /**
306 * Tests if the given method is caller-sensitive and the declaring class
307 * is defined by either the bootstrap class loader or platform class loader.
308 */
309 public static boolean isCallerSensitive(Method m) {
310 final ClassLoader loader = m.getDeclaringClass().getClassLoader();
311 if (VM.isSystemDomainLoader(loader)) {
312 return m.isAnnotationPresent(CallerSensitive.class);
313 }
314 return false;
315 }
316
317 /**
318 * Returns an IllegalAccessException with an exception message based on
319 * the access that is denied.
320 */
321 public static IllegalAccessException newIllegalAccessException(Class<?> currentClass,
322 Class<?> memberClass,
323 Class<?> targetClass,
324 int modifiers)
325 throws IllegalAccessException
326 {
327 String currentSuffix = "";
328 String memberSuffix = "";
329 Module m1 = currentClass.getModule();
330 if (m1.isNamed())
331 currentSuffix = " (in " + m1 + ")";
332 Module m2 = memberClass.getModule();
333 if (m2.isNamed())
334 memberSuffix = " (in " + m2 + ")";
335
336 String memberPackageName = memberClass.getPackageName();
337
338 String msg = currentClass + currentSuffix + " cannot access ";
339 if (m2.isExported(memberPackageName, m1)) {
340
341 // module access okay so include the modifiers in the message
342 msg += "a member of " + memberClass + memberSuffix +
343 " with modifiers \"" + Modifier.toString(modifiers) + "\"";
344
345 } else {
346 // module access failed
347 msg += memberClass + memberSuffix+ " because "
348 + m2 + " does not export " + memberPackageName;
349 if (m2.isNamed()) msg += " to " + m1;
350 }
351
352 return new IllegalAccessException(msg);
353 }
354 }