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.inline.hpp"
29 #include "prims/jvmtiGetLoadedClasses.hpp"
30 #include "runtime/thread.hpp"
31 #include "utilities/stack.inline.hpp"
32
33
34 // The closure for GetLoadedClasses
35 class LoadedClassesClosure : public KlassClosure {
36 private:
37 Stack<jclass, mtInternal> _classStack;
38 JvmtiEnv* _env;
39 Thread* _cur_thread;
40
41 public:
42 LoadedClassesClosure(Thread* thread, JvmtiEnv* env) : _cur_thread(thread), _env(env) {
43 assert(_cur_thread == Thread::current(), "must be current thread");
44 }
45
46 void do_klass(Klass* k) {
47 // Collect all jclasses
48 _classStack.push((jclass) _env->jni_reference(Handle(_cur_thread, k->java_mirror())));
49 Klass::ensure_klass_alive(k->java_mirror());
50 }
51
52 int extract(jclass* result_list) {
53 // The size of the Stack will be 0 after extract, so get it here
54 int count = (int)_classStack.size();
55 int i = count;
56
57 // Pop all jclasses, fill backwards
58 while (!_classStack.is_empty()) {
59 result_list[--i] = _classStack.pop();
60 }
61
62 // Return the number of elements written
63 return count;
64 }
65
66 // Return current size of the Stack
67 int get_count() {
68 return (int)_classStack.size();
69 }
70 };
71
72 // The closure for GetClassLoaderClasses
73 class JvmtiGetLoadedClassesClosure : public StackObj {
74 // Since the ClassLoaderDataGraph::dictionary_all_entries_do callback
75 // doesn't pass a closureData pointer,
76 // we use a thread-local slot to hold a pointer to
77 // a stack allocated instance of this structure.
78 private:
79 jobject _initiatingLoader;
80 int _count;
81 Handle* _list;
82 int _index;
83
84 private:
85 // Getting and setting the thread local pointer
86 static JvmtiGetLoadedClassesClosure* get_this() {
87 JvmtiGetLoadedClassesClosure* result = NULL;
88 JavaThread* thread = JavaThread::current();
89 result = thread->get_jvmti_get_loaded_classes_closure();
90 return result;
91 }
92 static void set_this(JvmtiGetLoadedClassesClosure* that) {
93 JavaThread* thread = JavaThread::current();
94 thread->set_jvmti_get_loaded_classes_closure(that);
95 }
96
97 public:
98 // Constructor/Destructor
99 JvmtiGetLoadedClassesClosure() {
100 JvmtiGetLoadedClassesClosure* that = get_this();
101 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
102 _initiatingLoader = NULL;
103 _count = 0;
104 _list = NULL;
105 _index = 0;
106 set_this(this);
107 }
108
109 JvmtiGetLoadedClassesClosure(jobject initiatingLoader) {
110 JvmtiGetLoadedClassesClosure* that = get_this();
111 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
112 _initiatingLoader = initiatingLoader;
113 _count = 0;
114 _list = NULL;
115 _index = 0;
116 set_this(this);
117 }
118
119 ~JvmtiGetLoadedClassesClosure() {
120 JvmtiGetLoadedClassesClosure* that = get_this();
121 assert(that != NULL, "JvmtiGetLoadedClassesClosure not found");
122 set_this(NULL);
123 _initiatingLoader = NULL;
124 _count = 0;
125 if (_list != NULL) {
126 FreeHeap(_list);
127 _list = NULL;
128 }
129 _index = 0;
130 }
131
132 // Accessors.
133 jobject get_initiatingLoader() {
134 return _initiatingLoader;
135 }
136
137 int get_count() {
138 return _count;
139 }
140
141 void set_count(int value) {
142 _count = value;
143 }
144
145 Handle* get_list() {
146 return _list;
147 }
148
149 void set_list(Handle* value) {
150 _list = value;
151 }
152
153 int get_index() {
154 return _index;
155 }
156
157 void set_index(int value) {
158 _index = value;
159 }
160
161 Handle get_element(int index) {
162 if ((_list != NULL) && (index < _count)) {
163 return _list[index];
164 } else {
165 assert(false, "empty get_element");
166 return Handle();
167 }
168 }
169
170 void set_element(int index, Handle value) {
171 if ((_list != NULL) && (index < _count)) {
172 _list[index] = value;
173 } else {
174 assert(false, "bad set_element");
175 }
176 }
177
178 // Other predicates
179 bool available() {
180 return (_list != NULL);
181 }
182
183 #ifdef ASSERT
184 // For debugging.
185 void check(int limit) {
186 for (int i = 0; i < limit; i += 1) {
187 assert(Universe::heap()->is_in(get_element(i)()), "check fails");
188 }
189 }
190 #endif
191
192 // Public methods that get called within the scope of the closure
193 void allocate() {
194 _list = NEW_C_HEAP_ARRAY(Handle, _count, mtInternal);
195 assert(_list != NULL, "Out of memory");
196 if (_list == NULL) {
197 _count = 0;
198 }
199 }
200
201 void extract(JvmtiEnv *env, jclass* result) {
202 for (int index = 0; index < _count; index += 1) {
203 result[index] = (jclass) env->jni_reference(get_element(index));
204 }
205 }
206
207 static void increment_with_loader(InstanceKlass* k, ClassLoaderData* loader_data) {
208 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
209 oop class_loader = loader_data->class_loader();
210 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
211 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
212 that->set_count(that->get_count() + 1);
213 }
214 }
215 }
216
217 static void add_with_loader(InstanceKlass* k, ClassLoaderData* loader_data) {
218 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
219 if (that->available()) {
220 oop class_loader = loader_data->class_loader();
221 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
222 Thread *thread = Thread::current();
223 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
224 Handle mirror(thread, l->java_mirror());
225 that->set_element(that->get_index(), mirror);
226 that->set_index(that->get_index() + 1);
227 }
228 }
229 }
230 }
231
232 // increment the count for the given basic type array class (and any
233 // multi-dimensional arrays). For example, for [B we check for
234 // [[B, [[[B, .. and the count is incremented for each one that exists.
235 static void increment_for_basic_type_arrays(Klass* k) {
236 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
237 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
238 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
239 that->set_count(that->get_count() + 1);
240 }
241 }
242
243 // add the basic type array class and its multi-dimensional array classes to the list
244 static void add_for_basic_type_arrays(Klass* k) {
245 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
246 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
247 assert(that->available(), "no list");
248 Thread *thread = Thread::current();
249 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
250 Handle mirror(thread, l->java_mirror());
251 that->set_element(that->get_index(), mirror);
252 that->set_index(that->get_index() + 1);
253 }
254 }
255 };
256
257
258 jvmtiError
259 JvmtiGetLoadedClasses::getLoadedClasses(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
260
261 LoadedClassesClosure closure(Thread::current(), env);
262 {
263 // To get a consistent list of classes we need MultiArray_lock to ensure
264 // array classes aren't created.
265 MutexLocker ma(MultiArray_lock);
266
267 // Iterate through all classes in ClassLoaderDataGraph
268 // and collect them using the LoadedClassesClosure
269 ClassLoaderDataGraph::loaded_classes_do(&closure);
270 }
271
272 // Return results by extracting the collected contents into a list
273 // allocated via JvmtiEnv
274 jclass* result_list;
275 jvmtiError error = env->Allocate(closure.get_count() * sizeof(jclass),
276 (unsigned char**)&result_list);
277
278 if (error == JVMTI_ERROR_NONE) {
279 int count = closure.extract(result_list);
280 *classCountPtr = count;
281 *classesPtr = result_list;
282 }
283 return error;
284 }
285
286 jvmtiError
287 JvmtiGetLoadedClasses::getClassLoaderClasses(JvmtiEnv *env, jobject initiatingLoader,
288 jint* classCountPtr, jclass** classesPtr) {
289 // Since ClassLoaderDataGraph::dictionary_all_entries_do only takes a function pointer
290 // and doesn't call back with a closure data pointer,
291 // we can only pass static methods.
292 JvmtiGetLoadedClassesClosure closure(initiatingLoader);
293 {
294 // To get a consistent list of classes we need MultiArray_lock to ensure
295 // array classes aren't created, and SystemDictionary_lock to ensure that
296 // classes aren't added to the class loader data dictionaries.
297 MutexLocker ma(MultiArray_lock);
298 MutexLocker sd(SystemDictionary_lock);
299 // First, count the classes in the class loader data dictionaries which have this loader recorded
300 // as an initiating loader. For basic type arrays this information is not recorded
301 // so GetClassLoaderClasses will return all of the basic type arrays. This is okay
302 // because the defining loader for basic type arrays is always the boot class loader
303 // and these classes are "visible" to all loaders.
304 ClassLoaderDataGraph::dictionary_all_entries_do(&JvmtiGetLoadedClassesClosure::increment_with_loader);
305 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::increment_for_basic_type_arrays);
306 // Next, fill in the classes
307 closure.allocate();
308 ClassLoaderDataGraph::dictionary_all_entries_do(&JvmtiGetLoadedClassesClosure::add_with_loader);
309 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::add_for_basic_type_arrays);
310 // Drop the SystemDictionary_lock, so the results could be wrong from here,
311 // but we still have a snapshot.
312 }
313 // Post results
314 jclass* result_list;
315 jvmtiError err = env->Allocate(closure.get_count() * sizeof(jclass),
316 (unsigned char**)&result_list);
317 if (err != JVMTI_ERROR_NONE) {
318 return err;
319 }
320 closure.extract(env, result_list);
321 *classCountPtr = closure.get_count();
322 *classesPtr = result_list;
323 return JVMTI_ERROR_NONE;
324 }