1 /*
2 * Copyright (c) 2003, 2024, 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/classLoaderDataGraph.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "gc/shared/collectedHeap.hpp"
30 #include "memory/universe.hpp"
31 #include "oops/klass.inline.hpp"
32 #include "prims/jvmtiGetLoadedClasses.hpp"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/javaThread.hpp"
35 #include "runtime/jniHandles.inline.hpp"
36 #include "utilities/stack.inline.hpp"
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 bool _dictionary_walk;
45
46 int extract(jclass* result_list) {
47 // The size of the Stack will be 0 after extract, so get it here
48 int count = (int)_classStack.size();
49 int i = count;
50
51 // Pop all jclasses, fill backwards
52 while (!_classStack.is_empty()) {
53 result_list[--i] = _classStack.pop();
54 }
55
56 // Return the number of elements written
57 return count;
58 }
59
60 // Return current size of the Stack
61 int get_count() {
62 return (int)_classStack.size();
63 }
64
65 public:
66 LoadedClassesClosure(JvmtiEnv* env, bool dictionary_walk) :
67 _env(env),
68 _cur_thread(Thread::current()),
69 _dictionary_walk(dictionary_walk) {
70 }
71
72 void do_klass(Klass* k) {
73 // Collect all jclasses
74 _classStack.push((jclass) _env->jni_reference(Handle(_cur_thread, k->java_mirror())));
75 if (_dictionary_walk) {
76 // Collect array classes this way when walking the dictionary (because array classes are
77 // not in the dictionary).
78 for (Klass* l = k->array_klass_or_null(); l != nullptr; l = l->array_klass_or_null()) {
79 _classStack.push((jclass) _env->jni_reference(Handle(_cur_thread, l->java_mirror())));
80 }
81 }
82 }
83
84 jvmtiError get_result(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
85 // Return results by extracting the collected contents into a list
86 // allocated via JvmtiEnv
87 jclass* result_list;
88 jvmtiError error = env->Allocate(get_count() * sizeof(jclass),
89 (unsigned char**)&result_list);
90
91 if (error == JVMTI_ERROR_NONE) {
92 int count = extract(result_list);
93 *classCountPtr = count;
94 *classesPtr = result_list;
95 }
96 return error;
97 }
98 };
99
100 jvmtiError
101 JvmtiGetLoadedClasses::getLoadedClasses(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
102
103 LoadedClassesClosure closure(env, false);
104 {
105 // Iterate through all classes in ClassLoaderDataGraph
106 // and collect them using the LoadedClassesClosure
107 MutexLocker mcld(ClassLoaderDataGraph_lock);
108 ClassLoaderDataGraph::loaded_classes_do_keepalive(&closure);
109 }
110
111 return closure.get_result(env, classCountPtr, classesPtr);
112 }
113
114 jvmtiError
115 JvmtiGetLoadedClasses::getClassLoaderClasses(JvmtiEnv *env, jobject initiatingLoader,
116 jint* classCountPtr, jclass** classesPtr) {
117
118 LoadedClassesClosure closure(env, true);
119 {
120 // To get a consistent list of classes we need MultiArray_lock to ensure
121 // array classes aren't created by another thread during this walk. This walks through the
122 // InstanceKlass::_array_klasses links.
123 RecursiveLocker ma(MultiArray_lock, Thread::current());
124 MutexLocker sd(SystemDictionary_lock);
125 oop loader = JNIHandles::resolve(initiatingLoader);
126 // All classes loaded from this loader as initiating loader are
127 // requested, so only need to walk this loader's ClassLoaderData
128 // dictionary, or the null ClassLoaderData dictionary for bootstrap loader.
129 if (loader != nullptr) {
130 ClassLoaderData* data = java_lang_ClassLoader::loader_data_acquire(loader);
131 // ClassLoader may not be used yet for loading.
132 if (data != nullptr && data->dictionary() != nullptr) {
133 data->dictionary()->all_entries_do(&closure);
134 }
135 } else {
136 ClassLoaderData::the_null_class_loader_data()->dictionary()->all_entries_do(&closure);
137 }
138 // Get basic arrays for all loaders.
139 Universe::basic_type_classes_do(&closure);
140 }
141
142 return closure.get_result(env, classCountPtr, classesPtr);
143 }