1 // Copyright (C) 2019 The Android Open Source Project
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 //
15
16 #include <android-base/logging.h>
17
18 #include <jni.h>
19 #include <jvmti.h>
20
21 namespace dumpjvmti {
22
23 namespace {
24
25 // Special art ti-version number. We will use this as a fallback if we cannot get a regular JVMTI
26 // env.
27 static constexpr jint kArtTiVersion = JVMTI_VERSION_1_2 | 0x40000000;
28
Dealloc(jvmtiEnv * env,T * t)29 template <typename T> static void Dealloc(jvmtiEnv* env, T* t) {
30 env->Deallocate(reinterpret_cast<unsigned char*>(t));
31 }
32
Dealloc(jvmtiEnv * env,T * t,Rest...rs)33 template <typename T, typename... Rest> static void Dealloc(jvmtiEnv* env, T* t, Rest... rs) {
34 Dealloc(env, t);
35 Dealloc(env, rs...);
36 }
37
DeallocParams(jvmtiEnv * env,jvmtiParamInfo * params,jint n_params)38 static void DeallocParams(jvmtiEnv* env, jvmtiParamInfo* params, jint n_params) {
39 for (jint i = 0; i < n_params; i++) {
40 Dealloc(env, params[i].name);
41 }
42 }
43
44 // The extension function to get the internal data
45 static jvmtiError (*GetInternalData)(jvmtiEnv* env, unsigned char** data) = nullptr;
46
SetupJvmtiEnv(JavaVM * vm,jvmtiEnv ** jvmti)47 static jint SetupJvmtiEnv(JavaVM* vm, jvmtiEnv** jvmti) {
48 jint res = 0;
49 res = vm->GetEnv(reinterpret_cast<void**>(jvmti), JVMTI_VERSION_1_1);
50
51 if (res != JNI_OK || *jvmti == nullptr) {
52 LOG(ERROR) << "Unable to access JVMTI, error code " << res;
53 res = vm->GetEnv(reinterpret_cast<void**>(jvmti), kArtTiVersion);
54 if (res != JNI_OK) {
55 return res;
56 }
57 }
58
59 jvmtiEnv* env = *jvmti;
60
61 // Get the extensions.
62 jint n_ext = 0;
63 jvmtiExtensionFunctionInfo* infos = nullptr;
64 if (env->GetExtensionFunctions(&n_ext, &infos) != JVMTI_ERROR_NONE) {
65 return JNI_ERR;
66 }
67 for (jint i = 0; i < n_ext; i++) {
68 jvmtiExtensionFunctionInfo* cur_info = &infos[i];
69 if (strcmp("com.android.art.misc.get_plugin_internal_state", cur_info->id) == 0) {
70 GetInternalData = reinterpret_cast<decltype(GetInternalData)>(cur_info->func);
71 }
72 // Cleanup the cur_info
73 DeallocParams(env, cur_info->params, cur_info->param_count);
74 Dealloc(env, cur_info->id, cur_info->short_description, cur_info->params, cur_info->errors);
75 }
76 // Cleanup the array.
77 Dealloc(env, infos);
78 return GetInternalData != nullptr ? JNI_OK : JNI_ERR;
79 }
80
CbDataDump(jvmtiEnv * jvmti)81 static void CbDataDump(jvmtiEnv* jvmti) {
82 unsigned char* data = nullptr;
83 if (JVMTI_ERROR_NONE == GetInternalData(jvmti, &data)) {
84 LOG(INFO) << data;
85 Dealloc(jvmti, data);
86 }
87 }
88
89 } // namespace
90
AgentStart(JavaVM * vm,char * options ATTRIBUTE_UNUSED,void * reserved ATTRIBUTE_UNUSED)91 static jint AgentStart(JavaVM* vm, char* options ATTRIBUTE_UNUSED, void* reserved ATTRIBUTE_UNUSED) {
92 jvmtiEnv* jvmti = nullptr;
93 if (SetupJvmtiEnv(vm, &jvmti) != JNI_OK) {
94 LOG(ERROR) << "Could not get JVMTI env or ArtTiEnv!";
95 return JNI_ERR;
96 }
97 jvmtiEventCallbacks cb{
98 .DataDumpRequest = CbDataDump,
99 };
100 jvmti->SetEventCallbacks(&cb, sizeof(cb));
101 jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_DATA_DUMP_REQUEST, nullptr);
102 return JNI_OK;
103 }
104
105 // Late attachment (e.g. 'am attach-agent').
Agent_OnAttach(JavaVM * vm,char * options,void * reserved)106 extern "C" JNIEXPORT jint JNICALL Agent_OnAttach(JavaVM* vm, char* options, void* reserved) {
107 return AgentStart(vm, options, reserved);
108 }
109
110 // Early attachment
Agent_OnLoad(JavaVM * jvm,char * options,void * reserved)111 extern "C" JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* jvm, char* options, void* reserved) {
112 return AgentStart(jvm, options, reserved);
113 }
114
115 } // namespace dumpjvmti
116