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120 lines
3.7 KiB
120 lines
3.7 KiB
// Copyright (C) 2020 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <android-base/logging.h>
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#include <jni.h>
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#include <jvmti.h>
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#include <iostream>
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#include <string_view>
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namespace enablevlog {
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namespace {
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// Special art ti-version number. We will use this as a fallback if we cannot get a regular JVMTI
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// env.
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static constexpr jint kArtTiVersion = JVMTI_VERSION_1_2 | 0x40000000;
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// The extension that lets us change the VLOG flags.
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static constexpr std::string_view kSetVerboseExtensionName =
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"com.android.art.misc.set_verbose_flag_ext";
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// Extension prototype
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using SetVerboseFlagExt = jvmtiError (*)(jvmtiEnv*, const char*, jboolean);
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template <typename T>
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static inline jvmtiError Deallocate(jvmtiEnv* env, T* mem) {
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return env->Deallocate(reinterpret_cast<unsigned char*>(mem));
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}
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template <typename T>
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void Dealloc(jvmtiEnv* env, T* t) {
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env->Deallocate(reinterpret_cast<unsigned char*>(t));
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}
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template <typename T, typename... Rest>
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void Dealloc(jvmtiEnv* env, T* t, Rest... rs) {
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Dealloc(env, t);
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Dealloc(env, rs...);
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}
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void DeallocParams(jvmtiEnv* env, jvmtiParamInfo* params, jint n_params) {
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for (jint i = 0; i < n_params; i++) {
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Dealloc(env, params[i].name);
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}
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}
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template <typename T>
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T GetExtensionFunction(jvmtiEnv* jvmti, const std::string_view& name) {
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jint n_ext = 0;
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void* res = nullptr;
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jvmtiExtensionFunctionInfo* infos = nullptr;
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if (jvmti->GetExtensionFunctions(&n_ext, &infos) != JVMTI_ERROR_NONE) {
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LOG(FATAL) << "Unable to get extensions";
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}
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for (jint i = 0; i < n_ext; i++) {
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const jvmtiExtensionFunctionInfo& info = infos[i];
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if (name == info.id) {
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res = reinterpret_cast<void*>(info.func);
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}
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DeallocParams(jvmti, info.params, info.param_count);
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Dealloc(jvmti, info.short_description, info.errors, info.id, info.params);
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}
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Dealloc(jvmti, infos);
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return reinterpret_cast<T>(res);
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}
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static jint SetupJvmtiEnv(JavaVM* vm, jvmtiEnv** jvmti) {
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jint res = 0;
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res = vm->GetEnv(reinterpret_cast<void**>(jvmti), JVMTI_VERSION_1_1);
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if (res != JNI_OK || *jvmti == nullptr) {
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LOG(ERROR) << "Unable to access JVMTI, error code " << res;
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return vm->GetEnv(reinterpret_cast<void**>(jvmti), kArtTiVersion);
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}
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return res;
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}
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} // namespace
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static jint AgentStart(JavaVM* vm, char* options, void* reserved ATTRIBUTE_UNUSED) {
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jvmtiEnv* jvmti = nullptr;
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if (SetupJvmtiEnv(vm, &jvmti) != JNI_OK) {
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LOG(ERROR) << "Could not get JVMTI env or ArtTiEnv!";
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return JNI_ERR;
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}
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SetVerboseFlagExt svfe = GetExtensionFunction<SetVerboseFlagExt>(jvmti, kSetVerboseExtensionName);
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if (svfe == nullptr) {
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LOG(ERROR) << "Could not find extension " << kSetVerboseExtensionName;
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return JNI_ERR;
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} else if (svfe(jvmti, options, true) != JVMTI_ERROR_NONE) {
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return JNI_ERR;
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} else {
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return JNI_OK;
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}
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}
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// Late attachment (e.g. 'am attach-agent').
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extern "C" JNIEXPORT jint JNICALL Agent_OnAttach(JavaVM* vm, char* options, void* reserved) {
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return AgentStart(vm, options, reserved);
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}
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// Early attachment
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extern "C" JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* jvm, char* options, void* reserved) {
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return AgentStart(jvm, options, reserved);
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}
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} // namespace enablevlog
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