1 /*
2 * Copyright (c) 2003, 2018, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "gc/shared/collectedHeap.hpp"
28 #include "memory/universe.hpp"
29 #include "prims/jvmtiGetLoadedClasses.hpp"
30 #include "runtime/jniHandles.inline.hpp"
31 #include "runtime/thread.hpp"
32 #include "utilities/stack.inline.hpp"
33 #if INCLUDE_ALL_GCS
34 #include "gc/g1/g1BarrierSet.hpp"
35 #endif
36
37
38 // The closure for GetLoadedClasses
39 class LoadedClassesClosure : public KlassClosure {
40 private:
41 Stack<jclass, mtInternal> _classStack;
42 JvmtiEnv* _env;
43 Thread* _cur_thread;
44
45 public:
46 LoadedClassesClosure(Thread* thread, JvmtiEnv* env) : _cur_thread(thread), _env(env) {
47 assert(_cur_thread == Thread::current(), "must be current thread");
48 }
49
50 void do_klass(Klass* k) {
51 // Collect all jclasses
52 _classStack.push((jclass) _env->jni_reference(Handle(_cur_thread, k->java_mirror())));
53 }
54
55 int extract(jclass* result_list) {
56 // The size of the Stack will be 0 after extract, so get it here
57 int count = (int)_classStack.size();
58 int i = count;
59
60 // Pop all jclasses, fill backwards
61 while (!_classStack.is_empty()) {
62 result_list[--i] = _classStack.pop();
63 }
64
65 // Return the number of elements written
66 return count;
67 }
68
69 // Return current size of the Stack
70 int get_count() {
71 return (int)_classStack.size();
72 }
73 };
74
75 // The closure for GetClassLoaderClasses
76 class JvmtiGetLoadedClassesClosure : public StackObj {
77 // Since the ClassLoaderDataGraph::dictionary_all_entries_do callback
78 // doesn't pass a closureData pointer,
79 // we use a thread-local slot to hold a pointer to
80 // a stack allocated instance of this structure.
81 private:
82 jobject _initiatingLoader;
83 int _count;
84 Handle* _list;
85 int _index;
86
87 private:
88 // Getting and setting the thread local pointer
89 static JvmtiGetLoadedClassesClosure* get_this() {
90 JvmtiGetLoadedClassesClosure* result = NULL;
91 JavaThread* thread = JavaThread::current();
92 result = thread->get_jvmti_get_loaded_classes_closure();
93 return result;
94 }
95 static void set_this(JvmtiGetLoadedClassesClosure* that) {
96 JavaThread* thread = JavaThread::current();
97 thread->set_jvmti_get_loaded_classes_closure(that);
98 }
99
100 public:
101 // Constructor/Destructor
102 JvmtiGetLoadedClassesClosure() {
103 JvmtiGetLoadedClassesClosure* that = get_this();
104 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
105 _initiatingLoader = NULL;
106 _count = 0;
107 _list = NULL;
108 _index = 0;
109 set_this(this);
110 }
111
112 JvmtiGetLoadedClassesClosure(jobject initiatingLoader) {
113 JvmtiGetLoadedClassesClosure* that = get_this();
114 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
115 _initiatingLoader = initiatingLoader;
116 _count = 0;
117 _list = NULL;
118 _index = 0;
119 set_this(this);
120 }
121
122 ~JvmtiGetLoadedClassesClosure() {
123 JvmtiGetLoadedClassesClosure* that = get_this();
124 assert(that != NULL, "JvmtiGetLoadedClassesClosure not found");
125 set_this(NULL);
126 _initiatingLoader = NULL;
127 _count = 0;
128 if (_list != NULL) {
129 FreeHeap(_list);
130 _list = NULL;
131 }
132 _index = 0;
133 }
134
135 // Accessors.
136 jobject get_initiatingLoader() {
137 return _initiatingLoader;
138 }
139
140 int get_count() {
141 return _count;
142 }
143
144 void set_count(int value) {
145 _count = value;
146 }
147
148 Handle* get_list() {
149 return _list;
150 }
151
152 void set_list(Handle* value) {
153 _list = value;
154 }
155
156 int get_index() {
157 return _index;
158 }
159
160 void set_index(int value) {
161 _index = value;
162 }
163
164 Handle get_element(int index) {
165 if ((_list != NULL) && (index < _count)) {
166 return _list[index];
167 } else {
168 assert(false, "empty get_element");
169 return Handle();
170 }
171 }
172
173 void set_element(int index, Handle value) {
174 if ((_list != NULL) && (index < _count)) {
175 _list[index] = value;
176 } else {
177 assert(false, "bad set_element");
178 }
179 }
180
181 // Other predicates
182 bool available() {
183 return (_list != NULL);
184 }
185
186 #ifdef ASSERT
187 // For debugging.
188 void check(int limit) {
189 for (int i = 0; i < limit; i += 1) {
190 assert(Universe::heap()->is_in(get_element(i)()), "check fails");
191 }
192 }
193 #endif
194
195 // Public methods that get called within the scope of the closure
196 void allocate() {
197 _list = NEW_C_HEAP_ARRAY(Handle, _count, mtInternal);
198 assert(_list != NULL, "Out of memory");
199 if (_list == NULL) {
200 _count = 0;
201 }
202 }
203
204 void extract(JvmtiEnv *env, jclass* result) {
205 for (int index = 0; index < _count; index += 1) {
206 result[index] = (jclass) env->jni_reference(get_element(index));
207 }
208 }
209
210 static void increment_with_loader(InstanceKlass* k, ClassLoaderData* loader_data) {
211 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
212 oop class_loader = loader_data->class_loader();
213 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
214 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
215 that->set_count(that->get_count() + 1);
216 }
217 }
218 }
219
220 static void add_with_loader(InstanceKlass* k, ClassLoaderData* loader_data) {
221 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
222 if (that->available()) {
223 oop class_loader = loader_data->class_loader();
224 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
225 Thread *thread = Thread::current();
226 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
227 Handle mirror(thread, l->java_mirror());
228 that->set_element(that->get_index(), mirror);
229 that->set_index(that->get_index() + 1);
230 }
231 }
232 }
233 }
234
235 // increment the count for the given basic type array class (and any
236 // multi-dimensional arrays). For example, for [B we check for
237 // [[B, [[[B, .. and the count is incremented for each one that exists.
238 static void increment_for_basic_type_arrays(Klass* k) {
239 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
240 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
241 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
242 that->set_count(that->get_count() + 1);
243 }
244 }
245
246 // add the basic type array class and its multi-dimensional array classes to the list
247 static void add_for_basic_type_arrays(Klass* k) {
248 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
249 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
250 assert(that->available(), "no list");
251 Thread *thread = Thread::current();
252 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
253 Handle mirror(thread, l->java_mirror());
254 that->set_element(that->get_index(), mirror);
255 that->set_index(that->get_index() + 1);
256 }
257 }
258 };
259
260
261 jvmtiError
262 JvmtiGetLoadedClasses::getLoadedClasses(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
263
264 LoadedClassesClosure closure(Thread::current(), env);
265 {
266 // To get a consistent list of classes we need MultiArray_lock to ensure
267 // array classes aren't created.
268 MutexLocker ma(MultiArray_lock);
269
270 // Iterate through all classes in ClassLoaderDataGraph
271 // and collect them using the LoadedClassesClosure
272 ClassLoaderDataGraph::loaded_classes_do(&closure);
273 }
274
275 // Return results by extracting the collected contents into a list
276 // allocated via JvmtiEnv
277 jclass* result_list;
278 jvmtiError error = env->Allocate(closure.get_count() * sizeof(jclass),
279 (unsigned char**)&result_list);
280
281 if (error == JVMTI_ERROR_NONE) {
282 int count = closure.extract(result_list);
283 *classCountPtr = count;
284 *classesPtr = result_list;
285 }
286 return error;
287 }
288
289 jvmtiError
290 JvmtiGetLoadedClasses::getClassLoaderClasses(JvmtiEnv *env, jobject initiatingLoader,
291 jint* classCountPtr, jclass** classesPtr) {
292 // Since ClassLoaderDataGraph::dictionary_all_entries_do only takes a function pointer
293 // and doesn't call back with a closure data pointer,
294 // we can only pass static methods.
295 JvmtiGetLoadedClassesClosure closure(initiatingLoader);
296 {
297 // To get a consistent list of classes we need MultiArray_lock to ensure
298 // array classes aren't created, and SystemDictionary_lock to ensure that
299 // classes aren't added to the class loader data dictionaries.
300 MutexLocker ma(MultiArray_lock);
301 MutexLocker sd(SystemDictionary_lock);
302 // First, count the classes in the class loader data dictionaries which have this loader recorded
303 // as an initiating loader. For basic type arrays this information is not recorded
304 // so GetClassLoaderClasses will return all of the basic type arrays. This is okay
305 // because the defining loader for basic type arrays is always the boot class loader
306 // and these classes are "visible" to all loaders.
307 ClassLoaderDataGraph::dictionary_all_entries_do(&JvmtiGetLoadedClassesClosure::increment_with_loader);
308 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::increment_for_basic_type_arrays);
309 // Next, fill in the classes
310 closure.allocate();
311 ClassLoaderDataGraph::dictionary_all_entries_do(&JvmtiGetLoadedClassesClosure::add_with_loader);
312 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::add_for_basic_type_arrays);
313 // Drop the SystemDictionary_lock, so the results could be wrong from here,
314 // but we still have a snapshot.
315 }
316 // Post results
317 jclass* result_list;
318 jvmtiError err = env->Allocate(closure.get_count() * sizeof(jclass),
319 (unsigned char**)&result_list);
320 if (err != JVMTI_ERROR_NONE) {
321 return err;
322 }
323 closure.extract(env, result_list);
324 *classCountPtr = closure.get_count();
325 *classesPtr = result_list;
326 return JVMTI_ERROR_NONE;
327 }