1 /* Copyright (C) 2017 The Android Open Source Project
2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3  *
4  * This file implements interfaces from the file jvmti.h. This implementation
5  * is licensed under the same terms as the file jvmti.h.  The
6  * copyright and license information for the file jvmti.h follows.
7  *
8  * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
9  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
10  *
11  * This code is free software; you can redistribute it and/or modify it
12  * under the terms of the GNU General Public License version 2 only, as
13  * published by the Free Software Foundation.  Oracle designates this
14  * particular file as subject to the "Classpath" exception as provided
15  * by Oracle in the LICENSE file that accompanied this code.
16  *
17  * This code is distributed in the hope that it will be useful, but WITHOUT
18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
20  * version 2 for more details (a copy is included in the LICENSE file that
21  * accompanied this code).
22  *
23  * You should have received a copy of the GNU General Public License version
24  * 2 along with this work; if not, write to the Free Software Foundation,
25  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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30  */
31 
32 #include "ti_threadgroup.h"
33 
34 #include "art_field-inl.h"
35 #include "art_jvmti.h"
36 #include "base/logging.h"
37 #include "base/macros.h"
38 #include "base/mutex.h"
39 #include "handle_scope-inl.h"
40 #include "jni_internal.h"
41 #include "mirror/class.h"
42 #include "mirror/object-inl.h"
43 #include "mirror/string.h"
44 #include "obj_ptr.h"
45 #include "object_lock.h"
46 #include "runtime.h"
47 #include "scoped_thread_state_change-inl.h"
48 #include "thread-current-inl.h"
49 #include "thread_list.h"
50 #include "well_known_classes.h"
51 
52 namespace openjdkjvmti {
53 
54 
GetTopThreadGroups(jvmtiEnv * env,jint * group_count_ptr,jthreadGroup ** groups_ptr)55 jvmtiError ThreadGroupUtil::GetTopThreadGroups(jvmtiEnv* env,
56                                                jint* group_count_ptr,
57                                                jthreadGroup** groups_ptr) {
58   // We only have a single top group. So we can take the current thread and move upwards.
59   if (group_count_ptr == nullptr || groups_ptr == nullptr) {
60     return ERR(NULL_POINTER);
61   }
62 
63   art::Runtime* runtime = art::Runtime::Current();
64   if (runtime == nullptr) {
65     // Must be starting the runtime, or dying.
66     return ERR(WRONG_PHASE);
67   }
68 
69   jobject sys_thread_group = runtime->GetSystemThreadGroup();
70   if (sys_thread_group == nullptr) {
71     // Seems we're still starting up.
72     return ERR(WRONG_PHASE);
73   }
74 
75   unsigned char* data;
76   jvmtiError result = env->Allocate(sizeof(jthreadGroup), &data);
77   if (result != ERR(NONE)) {
78     return result;
79   }
80 
81   jthreadGroup* groups = reinterpret_cast<jthreadGroup*>(data);
82   *groups =
83       reinterpret_cast<JNIEnv*>(art::Thread::Current()->GetJniEnv())->NewLocalRef(sys_thread_group);
84   *groups_ptr = groups;
85   *group_count_ptr = 1;
86 
87   return ERR(NONE);
88 }
89 
GetThreadGroupInfo(jvmtiEnv * env,jthreadGroup group,jvmtiThreadGroupInfo * info_ptr)90 jvmtiError ThreadGroupUtil::GetThreadGroupInfo(jvmtiEnv* env,
91                                                jthreadGroup group,
92                                                jvmtiThreadGroupInfo* info_ptr) {
93   if (group == nullptr) {
94     return ERR(INVALID_THREAD_GROUP);
95   }
96 
97   art::ScopedObjectAccess soa(art::Thread::Current());
98   if (soa.Env()->IsInstanceOf(group, art::WellKnownClasses::java_lang_ThreadGroup) == JNI_FALSE) {
99     return ERR(INVALID_THREAD_GROUP);
100   }
101 
102   art::ObjPtr<art::mirror::Object> obj = soa.Decode<art::mirror::Object>(group);
103 
104   // Do the name first. It's the only thing that can fail.
105   {
106     art::ArtField* name_field =
107         art::jni::DecodeArtField(art::WellKnownClasses::java_lang_ThreadGroup_name);
108     CHECK(name_field != nullptr);
109     art::ObjPtr<art::mirror::String> name_obj =
110         art::ObjPtr<art::mirror::String>::DownCast(name_field->GetObject(obj));
111     std::string tmp_str;
112     const char* tmp_cstr;
113     if (name_obj == nullptr) {
114       tmp_cstr = "";
115     } else {
116       tmp_str = name_obj->ToModifiedUtf8();
117       tmp_cstr = tmp_str.c_str();
118     }
119     jvmtiError result;
120     JvmtiUniquePtr<char[]> copy = CopyString(env, tmp_cstr, &result);
121     if (copy == nullptr) {
122       return result;
123     }
124     info_ptr->name = copy.release();
125   }
126 
127   // Parent.
128   {
129     art::ArtField* parent_field =
130         art::jni::DecodeArtField(art::WellKnownClasses::java_lang_ThreadGroup_parent);
131     CHECK(parent_field != nullptr);
132     art::ObjPtr<art::mirror::Object> parent_group = parent_field->GetObject(obj);
133     info_ptr->parent = parent_group == nullptr
134                            ? nullptr
135                            : soa.AddLocalReference<jthreadGroup>(parent_group);
136   }
137 
138   // Max priority.
139   {
140     art::ArtField* prio_field = obj->GetClass()->FindDeclaredInstanceField("maxPriority", "I");
141     CHECK(prio_field != nullptr);
142     info_ptr->max_priority = static_cast<jint>(prio_field->GetInt(obj));
143   }
144 
145   // Daemon.
146   {
147     art::ArtField* daemon_field = obj->GetClass()->FindDeclaredInstanceField("daemon", "Z");
148     CHECK(daemon_field != nullptr);
149     info_ptr->is_daemon = daemon_field->GetBoolean(obj) == 0 ? JNI_FALSE : JNI_TRUE;
150   }
151 
152   return ERR(NONE);
153 }
154 
155 
IsInDesiredThreadGroup(art::Handle<art::mirror::Object> desired_thread_group,art::ObjPtr<art::mirror::Object> peer)156 static bool IsInDesiredThreadGroup(art::Handle<art::mirror::Object> desired_thread_group,
157                                    art::ObjPtr<art::mirror::Object> peer)
158     REQUIRES_SHARED(art::Locks::mutator_lock_) {
159   CHECK(desired_thread_group != nullptr);
160 
161   art::ArtField* thread_group_field =
162       art::jni::DecodeArtField(art::WellKnownClasses::java_lang_Thread_group);
163   DCHECK(thread_group_field != nullptr);
164   art::ObjPtr<art::mirror::Object> group = thread_group_field->GetObject(peer);
165   return (group == desired_thread_group.Get());
166 }
167 
GetThreads(art::Handle<art::mirror::Object> thread_group,std::vector<art::ObjPtr<art::mirror::Object>> * thread_peers)168 static void GetThreads(art::Handle<art::mirror::Object> thread_group,
169                        std::vector<art::ObjPtr<art::mirror::Object>>* thread_peers)
170     REQUIRES_SHARED(art::Locks::mutator_lock_) REQUIRES(!art::Locks::thread_list_lock_) {
171   CHECK(thread_group != nullptr);
172 
173   art::MutexLock mu(art::Thread::Current(), *art::Locks::thread_list_lock_);
174   for (art::Thread* t : art::Runtime::Current()->GetThreadList()->GetList()) {
175     if (t->IsStillStarting()) {
176       continue;
177     }
178     art::ObjPtr<art::mirror::Object> peer = t->GetPeerFromOtherThread();
179     if (peer == nullptr) {
180       continue;
181     }
182     if (IsInDesiredThreadGroup(thread_group, peer)) {
183       thread_peers->push_back(peer);
184     }
185   }
186 }
187 
GetChildThreadGroups(art::Handle<art::mirror::Object> thread_group,std::vector<art::ObjPtr<art::mirror::Object>> * thread_groups)188 static void GetChildThreadGroups(art::Handle<art::mirror::Object> thread_group,
189                                  std::vector<art::ObjPtr<art::mirror::Object>>* thread_groups)
190     REQUIRES_SHARED(art::Locks::mutator_lock_) {
191   CHECK(thread_group != nullptr);
192 
193   // Get the ThreadGroup[] "groups" out of this thread group...
194   art::ArtField* groups_field =
195       art::jni::DecodeArtField(art::WellKnownClasses::java_lang_ThreadGroup_groups);
196   art::ObjPtr<art::mirror::Object> groups_array = groups_field->GetObject(thread_group.Get());
197 
198   if (groups_array == nullptr) {
199     return;
200   }
201   CHECK(groups_array->IsObjectArray());
202 
203   art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> groups_array_as_array =
204       groups_array->AsObjectArray<art::mirror::Object>();
205 
206   // Copy all non-null elements.
207   for (int32_t i = 0; i < groups_array_as_array->GetLength(); ++i) {
208     art::ObjPtr<art::mirror::Object> entry = groups_array_as_array->Get(i);
209     if (entry != nullptr) {
210       thread_groups->push_back(entry);
211     }
212   }
213 }
214 
GetThreadGroupChildren(jvmtiEnv * env,jthreadGroup group,jint * thread_count_ptr,jthread ** threads_ptr,jint * group_count_ptr,jthreadGroup ** groups_ptr)215 jvmtiError ThreadGroupUtil::GetThreadGroupChildren(jvmtiEnv* env,
216                                                    jthreadGroup group,
217                                                    jint* thread_count_ptr,
218                                                    jthread** threads_ptr,
219                                                    jint* group_count_ptr,
220                                                    jthreadGroup** groups_ptr) {
221   if (group == nullptr) {
222     return ERR(INVALID_THREAD_GROUP);
223   }
224 
225   art::ScopedObjectAccess soa(art::Thread::Current());
226 
227   if (!soa.Env()->IsInstanceOf(group, art::WellKnownClasses::java_lang_ThreadGroup)) {
228     return ERR(INVALID_THREAD_GROUP);
229   }
230 
231   art::StackHandleScope<1> hs(soa.Self());
232   art::Handle<art::mirror::Object> thread_group = hs.NewHandle(
233       soa.Decode<art::mirror::Object>(group));
234 
235   art::ObjectLock<art::mirror::Object> thread_group_lock(soa.Self(), thread_group);
236 
237   std::vector<art::ObjPtr<art::mirror::Object>> thread_peers;
238   GetThreads(thread_group, &thread_peers);
239 
240   std::vector<art::ObjPtr<art::mirror::Object>> thread_groups;
241   GetChildThreadGroups(thread_group, &thread_groups);
242 
243   JvmtiUniquePtr<jthread[]> peers_uptr;
244   if (!thread_peers.empty()) {
245     jvmtiError res;
246     peers_uptr = AllocJvmtiUniquePtr<jthread[]>(env, thread_peers.size(), &res);
247     if (peers_uptr == nullptr) {
248       return res;
249     }
250   }
251 
252   JvmtiUniquePtr<jthreadGroup[]> group_uptr;
253   if (!thread_groups.empty()) {
254     jvmtiError res;
255     group_uptr = AllocJvmtiUniquePtr<jthreadGroup[]>(env, thread_groups.size(), &res);
256     if (group_uptr == nullptr) {
257       return res;
258     }
259   }
260 
261   // Can't fail anymore from here on.
262 
263   // Copy data into out buffers.
264   for (size_t i = 0; i != thread_peers.size(); ++i) {
265     peers_uptr[i] = soa.AddLocalReference<jthread>(thread_peers[i]);
266   }
267   for (size_t i = 0; i != thread_groups.size(); ++i) {
268     group_uptr[i] = soa.AddLocalReference<jthreadGroup>(thread_groups[i]);
269   }
270 
271   *thread_count_ptr = static_cast<jint>(thread_peers.size());
272   *threads_ptr = peers_uptr.release();
273   *group_count_ptr = static_cast<jint>(thread_groups.size());
274   *groups_ptr = group_uptr.release();
275 
276   return ERR(NONE);
277 }
278 
279 }  // namespace openjdkjvmti
280