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/classLoaderDataGraph.hpp"
  27 #include "classfile/dictionary.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "gc/shared/collectedHeap.hpp"
  30 #include "memory/universe.hpp"
  31 #include "prims/jvmtiGetLoadedClasses.hpp"
  32 #include "runtime/handles.inline.hpp"
  33 #include "runtime/jniHandles.inline.hpp"
  34 #include "runtime/thread.hpp"
  35 #include "utilities/stack.inline.hpp"
  36 
  37 // The closure for GetLoadedClasses
  38 class LoadedClassesClosure : public KlassClosure {
  39 private:
  40   Stack<jclass, mtInternal> _classStack;
  41   JvmtiEnv* _env;
  42   Thread*   _cur_thread;
  43   bool      _dictionary_walk;
  44 
  45   int extract(jclass* result_list) {
  46     // The size of the Stack will be 0 after extract, so get it here
  47     int count = (int)_classStack.size();
  48     int i = count;
  49 
  50     // Pop all jclasses, fill backwards
  51     while (!_classStack.is_empty()) {
  52       result_list[--i] = _classStack.pop();
  53     }
  54 
  55     // Return the number of elements written
  56     return count;
  57   }
  58 
  59   // Return current size of the Stack
  60   int get_count() {
  61     return (int)_classStack.size();
  62   }
  63 
  64 public:
  65   LoadedClassesClosure(JvmtiEnv* env, bool dictionary_walk) :
  66       _env(env),
  67       _cur_thread(Thread::current()),
  68       _dictionary_walk(dictionary_walk) {
  69   }
  70 
  71   void do_klass(Klass* k) {
  72     // Collect all jclasses
  73     _classStack.push((jclass) _env->jni_reference(Handle(_cur_thread, k->java_mirror())));
  74     if (_dictionary_walk) {
  75       // Collect array classes this way when walking the dictionary (because array classes are
  76       // not in the dictionary).
  77       for (Klass* l = k->array_klass_or_null(); l != NULL; l = l->array_klass_or_null()) {
  78         _classStack.push((jclass) _env->jni_reference(Handle(_cur_thread, l->java_mirror())));
  79       }

  80     }
  81   }
  82 
  83   jvmtiError get_result(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
  84     // Return results by extracting the collected contents into a list
  85     // allocated via JvmtiEnv
  86     jclass* result_list;
  87     jvmtiError error = env->Allocate(get_count() * sizeof(jclass),
  88                                (unsigned char**)&result_list);
  89 
  90     if (error == JVMTI_ERROR_NONE) {
  91       int count = extract(result_list);
  92       *classCountPtr = count;
  93       *classesPtr = result_list;
  94     }
  95     return error;
  96   }
  97 };
  98 
  99 jvmtiError
 100 JvmtiGetLoadedClasses::getLoadedClasses(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
 101 
 102   LoadedClassesClosure closure(env, false);
 103   {
 104     // To get a consistent list of classes we need MultiArray_lock to ensure
 105     // array classes aren't created.
 106     MutexLocker ma(MultiArray_lock);
 107 
 108     // Iterate through all classes in ClassLoaderDataGraph
 109     // and collect them using the LoadedClassesClosure
 110     MutexLocker mcld(ClassLoaderDataGraph_lock);
 111     ClassLoaderDataGraph::loaded_classes_do(&closure);
 112   }
 113 
 114   return closure.get_result(env, classCountPtr, classesPtr);
 115 }
 116 
 117 jvmtiError
 118 JvmtiGetLoadedClasses::getClassLoaderClasses(JvmtiEnv *env, jobject initiatingLoader,
 119                                              jint* classCountPtr, jclass** classesPtr) {
 120 
 121   LoadedClassesClosure closure(env, true);
 122   {
 123     // To get a consistent list of classes we need MultiArray_lock to ensure
 124     // array classes aren't created during this walk.
 125     MutexLocker ma(MultiArray_lock);
 126     MutexLocker sd(SystemDictionary_lock);
 127     oop loader = JNIHandles::resolve(initiatingLoader);
 128     // All classes loaded from this loader as initiating loader are
 129     // requested, so only need to walk this loader's ClassLoaderData
 130     // dictionary, or the NULL ClassLoaderData dictionary for bootstrap loader.
 131     if (loader != NULL) {
 132       ClassLoaderData* data = java_lang_ClassLoader::loader_data_acquire(loader);
 133       // ClassLoader may not be used yet for loading.
 134       if (data != NULL && data->dictionary() != NULL) {
 135         data->dictionary()->all_entries_do(&closure);
 136       }
 137     } else {
 138       ClassLoaderData::the_null_class_loader_data()->dictionary()->all_entries_do(&closure);
 139     }
 140     // Get basic arrays for all loaders.
 141     Universe::basic_type_classes_do(&closure);
 142   }
 143 
 144   return closure.get_result(env, classCountPtr, classesPtr);
 145 }
--- EOF ---