test/ti-agent/redefinition_helper.cc - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "common_helper.h"

 #include <cstdio>
 #include <deque>
 #include <map>
 #include <sstream>
 #include <string>
 #include <vector>

 #include "jni.h"
 #include "jvmti.h"

 #include "jvmti_helper.h"
 #include "test_env.h"

 namespace art {

 enum class RedefineType {
   kNormal,
   kStructural,
 };

 static void SetupCommonRedefine();
 static void SetupCommonRetransform(RedefineType type);
 static void SetupCommonTransform();
 template <bool is_redefine>
 static void throwCommonRedefinitionError(jvmtiEnv* jvmti,
                                          JNIEnv* env,
                                          jint num_targets,
                                          jclass* target,
                                          jvmtiError res) {
   std::stringstream err;
   char* error = nullptr;
   jvmti->GetErrorName(res, &error);
   err << "Failed to " << (is_redefine ? "redefine" : "retransform") << " class";
   if (num_targets > 1) {
     err << "es";
   }
   err << " <";
   for (jint i = 0; i < num_targets; i++) {
     char* signature = nullptr;
     char* generic = nullptr;
     jvmti->GetClassSignature(target[i], &signature, &generic);
     if (i != 0) {
       err << ", ";
     }
     err << signature;
     jvmti->Deallocate(reinterpret_cast<unsigned char*>(signature));
     jvmti->Deallocate(reinterpret_cast<unsigned char*>(generic));
   }
   err << "> due to " << error;
   std::string message = err.str();
   jvmti->Deallocate(reinterpret_cast<unsigned char*>(error));
   env->ThrowNew(env->FindClass("java/lang/Exception"), message.c_str());
 }

 #define CONFIGURATION_COMMON_REDEFINE 0
 #define CONFIGURATION_COMMON_RETRANSFORM 1
 #define CONFIGURATION_COMMON_TRANSFORM 2
 #define CONFIGURATION_STRUCTURAL_TRANSFORM 3

 extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_nativeSetTestConfiguration(JNIEnv*,
                                                                                    jclass,
                                                                                    jint type) {
   switch (type) {
     case CONFIGURATION_COMMON_REDEFINE: {
       SetupCommonRedefine();
       return;
     }
     case CONFIGURATION_COMMON_RETRANSFORM: {
       SetupCommonRetransform(RedefineType::kNormal);
       return;
     }
     case CONFIGURATION_COMMON_TRANSFORM: {
       SetupCommonTransform();
       return;
     }
     case CONFIGURATION_STRUCTURAL_TRANSFORM: {
       SetupCommonRetransform(RedefineType::kStructural);
       return;
     }
     default: {
       LOG(FATAL) << "Unknown test configuration: " << type;
     }
   }
 }

 template<RedefineType kType>
 static bool SupportsAndIsJVM() {
   if constexpr (kType == RedefineType::kStructural) {
     return false;
   } else {
     return IsJVM();
   }
 }


 namespace common_redefine {

 template <RedefineType kType>
 static jvmtiError CallRedefineEntrypoint(JNIEnv* env,
                                          jvmtiEnv* jvmti,
                                          jint num_defs,
                                          const jvmtiClassDefinition* defs) {
   decltype(jvmti->functions->RedefineClasses) entrypoint = nullptr;
   if constexpr (kType == RedefineType::kNormal) {
     entrypoint = jvmti->functions->RedefineClasses;
   } else {
     entrypoint = GetExtensionFunction<decltype(entrypoint)>(
         env, jvmti_env, "com.android.art.class.structurally_redefine_classes");
   }
   if (entrypoint == nullptr) {
     LOG(INFO) << "Could not find entrypoint!";
     return JVMTI_ERROR_NOT_AVAILABLE;
   }
   return entrypoint(jvmti, num_defs, defs);
 }

 static void throwRedefinitionError(jvmtiEnv* jvmti,
                                    JNIEnv* env,
                                    jint num_targets,
                                    jclass* target,
                                    jvmtiError res) {
   return throwCommonRedefinitionError<true>(jvmti, env, num_targets, target, res);
 }

 template<RedefineType kType>
 static void DoMultiClassRedefine(jvmtiEnv* jvmti_env,
                                  JNIEnv* env,
                                  jint num_redefines,
                                  jclass* targets,
                                  jbyteArray* class_file_bytes,
                                  jbyteArray* dex_file_bytes) {
   std::vector<jvmtiClassDefinition> defs;
   for (jint i = 0; i < num_redefines; i++) {
     jbyteArray desired_array = SupportsAndIsJVM<kType>() ? class_file_bytes[i] : dex_file_bytes[i];
     jint len = static_cast<jint>(env->GetArrayLength(desired_array));
     const unsigned char* redef_bytes = reinterpret_cast<const unsigned char*>(
         env->GetByteArrayElements(desired_array, nullptr));
     defs.push_back({targets[i], static_cast<jint>(len), redef_bytes});
   }
   jvmtiError res = CallRedefineEntrypoint<kType>(env, jvmti_env, num_redefines, defs.data());
   if (res != JVMTI_ERROR_NONE) {
     throwRedefinitionError(jvmti_env, env, num_redefines, targets, res);
   }
 }

 template<RedefineType kType>
 static void DoClassRedefine(jvmtiEnv* jvmti_env,
                             JNIEnv* env,
                             jclass target,
                             jbyteArray class_file_bytes,
                             jbyteArray dex_file_bytes) {
   return DoMultiClassRedefine<kType>(jvmti_env, env, 1, &target, &class_file_bytes, &dex_file_bytes);
 }

 extern "C" JNIEXPORT jboolean JNICALL
 Java_art_Redefinition_isStructurallyModifiable(JNIEnv* env, jclass, jclass target) {
   using ArtCanStructurallyRedefineClass =
       jvmtiError (*)(jvmtiEnv * env, jclass k, jboolean * result);
   ArtCanStructurallyRedefineClass can_redef = GetExtensionFunction<ArtCanStructurallyRedefineClass>(
       env, jvmti_env, "com.android.art.class.is_structurally_modifiable_class");
   if (can_redef == nullptr || env->ExceptionCheck()) {
     return false;
   }
   jboolean result = false;
   JvmtiErrorToException(env, jvmti_env, can_redef(jvmti_env, target, &result));
   return result;
 }

 extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonStructuralClassRedefinition(
     JNIEnv* env, jclass, jclass target, jbyteArray dex_file_bytes) {
   DoClassRedefine<RedefineType::kStructural>(jvmti_env, env, target, nullptr, dex_file_bytes);
 }

 // Magic JNI export that classes can use for redefining classes.
 // To use classes should declare this as a native function with signature (Ljava/lang/Class;[B[B)V
 extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonClassRedefinition(
     JNIEnv* env, jclass, jclass target, jbyteArray class_file_bytes, jbyteArray dex_file_bytes) {
   DoClassRedefine<RedefineType::kNormal>(jvmti_env, env, target, class_file_bytes, dex_file_bytes);
 }

 // Magic JNI export that classes can use for redefining classes.
 // To use classes should declare this as a native function with signature
 // ([Ljava/lang/Class;[[B[[B)V
 extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonMultiStructuralClassRedefinition(
     JNIEnv* env,
     jclass,
     jobjectArray targets,
     jobjectArray dex_file_bytes) {
   std::vector<jclass> classes;
   std::vector<jbyteArray> class_files;
   std::vector<jbyteArray> dex_files;
   jint len = env->GetArrayLength(targets);
   if (len != env->GetArrayLength(dex_file_bytes)) {
     env->ThrowNew(env->FindClass("java/lang/IllegalArgumentException"),
                   "the three array arguments passed to this function have different lengths!");
     return;
   }
   for (jint i = 0; i < len; i++) {
     classes.push_back(static_cast<jclass>(env->GetObjectArrayElement(targets, i)));
     dex_files.push_back(static_cast<jbyteArray>(env->GetObjectArrayElement(dex_file_bytes, i)));
     class_files.push_back(nullptr);
   }
   return DoMultiClassRedefine<RedefineType::kStructural>(jvmti_env,
                                                          env,
                                                          len,
                                                          classes.data(),
                                                          class_files.data(),
                                                          dex_files.data());
 }

 // Magic JNI export that classes can use for redefining classes.
 // To use classes should declare this as a native function with signature
 // ([Ljava/lang/Class;[[B[[B)V
 extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonMultiClassRedefinition(
     JNIEnv* env,
     jclass,
     jobjectArray targets,
     jobjectArray class_file_bytes,
     jobjectArray dex_file_bytes) {
   std::vector<jclass> classes;
   std::vector<jbyteArray> class_files;
   std::vector<jbyteArray> dex_files;
   jint len = env->GetArrayLength(targets);
   if (len != env->GetArrayLength(class_file_bytes) || len != env->GetArrayLength(dex_file_bytes)) {
     env->ThrowNew(env->FindClass("java/lang/IllegalArgumentException"),
                   "the three array arguments passed to this function have different lengths!");
     return;
   }
   for (jint i = 0; i < len; i++) {
     classes.push_back(static_cast<jclass>(env->GetObjectArrayElement(targets, i)));
     dex_files.push_back(static_cast<jbyteArray>(env->GetObjectArrayElement(dex_file_bytes, i)));
     class_files.push_back(static_cast<jbyteArray>(env->GetObjectArrayElement(class_file_bytes, i)));
   }
   return DoMultiClassRedefine<RedefineType::kNormal>(jvmti_env,
                                                      env,
                                                      len,
                                                      classes.data(),
                                                      class_files.data(),
                                                      dex_files.data());
 }

 // Get all capabilities except those related to retransformation.
 jint OnLoad(JavaVM* vm,
             [[maybe_unused]] char* options,
             [[maybe_unused]] void* reserved) {
   if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
     printf("Unable to get jvmti env!\n");
     return 1;
   }
   SetupCommonRedefine();
   return 0;
 }

 }  // namespace common_redefine

 namespace common_retransform {

 struct CommonTransformationResult {
   std::vector<unsigned char> class_bytes;
   std::vector<unsigned char> dex_bytes;

   CommonTransformationResult(size_t class_size, size_t dex_size)
       : class_bytes(class_size), dex_bytes(dex_size) {}

   CommonTransformationResult() = default;
   CommonTransformationResult(CommonTransformationResult&&) = default;
   CommonTransformationResult(CommonTransformationResult&) = default;
 };

 // Map from class name to transformation result.
 std::map<std::string, std::deque<CommonTransformationResult>> gTransformations;
 bool gPopTransformations = true;

 extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_addCommonTransformationResult(
     JNIEnv* env, jclass, jstring class_name, jbyteArray class_array, jbyteArray dex_array) {
   const char* name_chrs = env->GetStringUTFChars(class_name, nullptr);
   std::string name_str(name_chrs);
   env->ReleaseStringUTFChars(class_name, name_chrs);
   CommonTransformationResult trans(env->GetArrayLength(class_array),
                                    env->GetArrayLength(dex_array));
   if (env->ExceptionOccurred()) {
     return;
   }
   env->GetByteArrayRegion(class_array,
                           0,
                           env->GetArrayLength(class_array),
                           reinterpret_cast<jbyte*>(trans.class_bytes.data()));
   if (env->ExceptionOccurred()) {
     return;
   }
   env->GetByteArrayRegion(dex_array,
                           0,
                           env->GetArrayLength(dex_array),
                           reinterpret_cast<jbyte*>(trans.dex_bytes.data()));
   if (env->ExceptionOccurred()) {
     return;
   }
   if (gTransformations.find(name_str) == gTransformations.end()) {
     std::deque<CommonTransformationResult> list;
     gTransformations[name_str] = std::move(list);
   }
   gTransformations[name_str].push_back(std::move(trans));
 }

 // The hook we are using.
 void JNICALL CommonClassFileLoadHookRetransformable(jvmtiEnv* jvmti_env,
                                                     [[maybe_unused]] JNIEnv* jni_env,
                                                     [[maybe_unused]] jclass class_being_redefined,
                                                     [[maybe_unused]] jobject loader,
                                                     const char* name,
                                                     [[maybe_unused]] jobject protection_domain,
                                                     [[maybe_unused]] jint class_data_len,
                                                     [[maybe_unused]] const unsigned char* class_dat,
                                                     jint* new_class_data_len,
                                                     unsigned char** new_class_data) {
   std::string name_str(name);
   if (gTransformations.find(name_str) != gTransformations.end() &&
       gTransformations[name_str].size() > 0) {
     CommonTransformationResult& res = gTransformations[name_str][0];
     const std::vector<unsigned char>& desired_array = IsJVM() ? res.class_bytes : res.dex_bytes;
     unsigned char* new_data;
     CHECK_EQ(JVMTI_ERROR_NONE, jvmti_env->Allocate(desired_array.size(), &new_data));
     memcpy(new_data, desired_array.data(), desired_array.size());
     *new_class_data = new_data;
     *new_class_data_len = desired_array.size();
     if (gPopTransformations) {
       gTransformations[name_str].pop_front();
     }
   }
 }

 extern "C" JNIEXPORT void Java_art_Redefinition_setPopRetransformations(JNIEnv*,
                                                                         jclass,
                                                                         jboolean enable) {
   gPopTransformations = enable;
 }

 extern "C" JNIEXPORT void Java_art_Redefinition_popTransformationFor(JNIEnv* env,
                                                                          jclass,
                                                                          jstring class_name) {
   const char* name_chrs = env->GetStringUTFChars(class_name, nullptr);
   std::string name_str(name_chrs);
   env->ReleaseStringUTFChars(class_name, name_chrs);
   if (gTransformations.find(name_str) != gTransformations.end() &&
       gTransformations[name_str].size() > 0) {
     gTransformations[name_str].pop_front();
   } else {
     std::stringstream err;
     err << "No transformations found for class " << name_str;
     std::string message = err.str();
     env->ThrowNew(env->FindClass("java/lang/Exception"), message.c_str());
   }
 }

 extern "C" JNIEXPORT void Java_art_Redefinition_enableCommonRetransformation(JNIEnv* env,
                                                                                  jclass,
                                                                                  jboolean enable) {
   jvmtiError res = jvmti_env->SetEventNotificationMode(enable ? JVMTI_ENABLE : JVMTI_DISABLE,
                                                        JVMTI_EVENT_CLASS_FILE_LOAD_HOOK,
                                                        nullptr);
   if (res != JVMTI_ERROR_NONE) {
     JvmtiErrorToException(env, jvmti_env, res);
   }
 }

 static void throwRetransformationError(jvmtiEnv* jvmti,
                                        JNIEnv* env,
                                        jint num_targets,
                                        jclass* targets,
                                        jvmtiError res) {
   return throwCommonRedefinitionError<false>(jvmti, env, num_targets, targets, res);
 }

 static void DoClassRetransformation(jvmtiEnv* jvmti_env, JNIEnv* env, jobjectArray targets) {
   std::vector<jclass> classes;
   jint len = env->GetArrayLength(targets);
   classes.reserve(len);
   for (jint i = 0; i < len; i++) {
     classes.push_back(static_cast<jclass>(env->GetObjectArrayElement(targets, i)));
   }
   jvmtiError res = jvmti_env->RetransformClasses(len, classes.data());
   if (res != JVMTI_ERROR_NONE) {
     throwRetransformationError(jvmti_env, env, len, classes.data(), res);
   }
 }

 extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonClassRetransformation(
     JNIEnv* env, jclass, jobjectArray targets) {
   jvmtiCapabilities caps;
   jvmtiError caps_err = jvmti_env->GetCapabilities(&caps);
   if (caps_err != JVMTI_ERROR_NONE) {
     env->ThrowNew(env->FindClass("java/lang/Exception"),
                   "Unable to get current jvmtiEnv capabilities");
     return;
   }

   // Allocate a new environment if we don't have the can_retransform_classes capability needed to
   // call the RetransformClasses function.
   jvmtiEnv* real_env = nullptr;
   if (caps.can_retransform_classes != 1) {
     JavaVM* vm = nullptr;
     if (env->GetJavaVM(&vm) != 0 ||
         vm->GetEnv(reinterpret_cast<void**>(&real_env), JVMTI_VERSION_1_0) != 0) {
       env->ThrowNew(env->FindClass("java/lang/Exception"),
                     "Unable to create temporary jvmtiEnv for RetransformClasses call.");
       return;
     }
     SetStandardCapabilities(real_env);
   } else {
     real_env = jvmti_env;
   }
   DoClassRetransformation(real_env, env, targets);
   if (caps.can_retransform_classes != 1) {
     real_env->DisposeEnvironment();
   }
 }

 // Get all capabilities except those related to retransformation.
 jint OnLoad(JavaVM* vm,
             [[maybe_unused]] char* options,
             [[maybe_unused]] void* reserved) {
   if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
     printf("Unable to get jvmti env!\n");
     return 1;
   }
   SetupCommonRetransform(RedefineType::kNormal);
   return 0;
 }

 }  // namespace common_retransform

 namespace common_transform {

 // Get all capabilities except those related to retransformation.
 jint OnLoad(JavaVM* vm,
             [[maybe_unused]] char* options,
             [[maybe_unused]] void* reserved) {
   if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
     printf("Unable to get jvmti env!\n");
     return 1;
   }
   SetupCommonTransform();
   return 0;
 }

 }  // namespace common_transform

 static void SetupCommonRedefine() {
   jvmtiCapabilities caps = GetStandardCapabilities();
   caps.can_retransform_classes = 0;
   caps.can_retransform_any_class = 0;
   jvmti_env->AddCapabilities(&caps);
 }

 static void SetupCommonRetransform(RedefineType type) {
   SetStandardCapabilities(jvmti_env);
   if (type == RedefineType::kNormal) {
     current_callbacks.ClassFileLoadHook =
         common_retransform::CommonClassFileLoadHookRetransformable;
     jvmtiError res = jvmti_env->SetEventCallbacks(&current_callbacks, sizeof(current_callbacks));
     CHECK_EQ(res, JVMTI_ERROR_NONE);
   } else {
     jvmtiError res = jvmti_env->SetExtensionEventCallback(
         GetExtensionEventId(jvmti_env, "com.android.art.class.structural_dex_file_load_hook"),
         reinterpret_cast<jvmtiExtensionEvent>(
             common_retransform::CommonClassFileLoadHookRetransformable));
     CHECK_EQ(res, JVMTI_ERROR_NONE);
   }
   common_retransform::gTransformations.clear();
 }

 static void SetupCommonTransform() {
   // Don't set the retransform caps
   jvmtiCapabilities caps = GetStandardCapabilities();
   caps.can_retransform_classes = 0;
   caps.can_retransform_any_class = 0;
   jvmti_env->AddCapabilities(&caps);

   // Use the same callback as the retransform test.
   current_callbacks.ClassFileLoadHook = common_retransform::CommonClassFileLoadHookRetransformable;
   jvmtiError res = jvmti_env->SetEventCallbacks(&current_callbacks, sizeof(current_callbacks));
   CHECK_EQ(res, JVMTI_ERROR_NONE);
   common_retransform::gTransformations.clear();
 }

 }  // namespace art
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "common_helper.h"

	#include <cstdio>
	#include <deque>
	#include <map>
	#include <sstream>
	#include <string>
	#include <vector>

	#include "jni.h"
	#include "jvmti.h"

	#include "jvmti_helper.h"
	#include "test_env.h"

	namespace art {

	enum class RedefineType {
	kNormal,
	kStructural,
	};

	static void SetupCommonRedefine();
	static void SetupCommonRetransform(RedefineType type);
	static void SetupCommonTransform();
	template <bool is_redefine>
	static void throwCommonRedefinitionError(jvmtiEnv* jvmti,
	JNIEnv* env,
	jint num_targets,
	jclass* target,
	jvmtiError res) {
	std::stringstream err;
	char* error = nullptr;
	jvmti->GetErrorName(res, &error);
	err << "Failed to " << (is_redefine ? "redefine" : "retransform") << " class";
	if (num_targets > 1) {
	err << "es";
	}
	err << " <";
	for (jint i = 0; i < num_targets; i++) {
	char* signature = nullptr;
	char* generic = nullptr;
	jvmti->GetClassSignature(target[i], &signature, &generic);
	if (i != 0) {
	err << ", ";
	}
	err << signature;
	jvmti->Deallocate(reinterpret_cast<unsigned char*>(signature));
	jvmti->Deallocate(reinterpret_cast<unsigned char*>(generic));
	}
	err << "> due to " << error;
	std::string message = err.str();
	jvmti->Deallocate(reinterpret_cast<unsigned char*>(error));
	env->ThrowNew(env->FindClass("java/lang/Exception"), message.c_str());
	}

	#define CONFIGURATION_COMMON_REDEFINE 0
	#define CONFIGURATION_COMMON_RETRANSFORM 1
	#define CONFIGURATION_COMMON_TRANSFORM 2
	#define CONFIGURATION_STRUCTURAL_TRANSFORM 3

	extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_nativeSetTestConfiguration(JNIEnv*,
	jclass,
	jint type) {
	switch (type) {
	case CONFIGURATION_COMMON_REDEFINE: {
	SetupCommonRedefine();
	return;
	}
	case CONFIGURATION_COMMON_RETRANSFORM: {
	SetupCommonRetransform(RedefineType::kNormal);
	return;
	}
	case CONFIGURATION_COMMON_TRANSFORM: {
	SetupCommonTransform();
	return;
	}
	case CONFIGURATION_STRUCTURAL_TRANSFORM: {
	SetupCommonRetransform(RedefineType::kStructural);
	return;
	}
	default: {
	LOG(FATAL) << "Unknown test configuration: " << type;
	}
	}
	}

	template<RedefineType kType>
	static bool SupportsAndIsJVM() {
	if constexpr (kType == RedefineType::kStructural) {
	return false;
	} else {
	return IsJVM();
	}
	}


	namespace common_redefine {

	template <RedefineType kType>
	static jvmtiError CallRedefineEntrypoint(JNIEnv* env,
	jvmtiEnv* jvmti,
	jint num_defs,
	const jvmtiClassDefinition* defs) {
	decltype(jvmti->functions->RedefineClasses) entrypoint = nullptr;
	if constexpr (kType == RedefineType::kNormal) {
	entrypoint = jvmti->functions->RedefineClasses;
	} else {
	entrypoint = GetExtensionFunction<decltype(entrypoint)>(
	env, jvmti_env, "com.android.art.class.structurally_redefine_classes");
	}
	if (entrypoint == nullptr) {
	LOG(INFO) << "Could not find entrypoint!";
	return JVMTI_ERROR_NOT_AVAILABLE;
	}
	return entrypoint(jvmti, num_defs, defs);
	}

	static void throwRedefinitionError(jvmtiEnv* jvmti,
	JNIEnv* env,
	jint num_targets,
	jclass* target,
	jvmtiError res) {
	return throwCommonRedefinitionError<true>(jvmti, env, num_targets, target, res);
	}

	template<RedefineType kType>
	static void DoMultiClassRedefine(jvmtiEnv* jvmti_env,
	JNIEnv* env,
	jint num_redefines,
	jclass* targets,
	jbyteArray* class_file_bytes,
	jbyteArray* dex_file_bytes) {
	std::vector<jvmtiClassDefinition> defs;
	for (jint i = 0; i < num_redefines; i++) {
	jbyteArray desired_array = SupportsAndIsJVM<kType>() ? class_file_bytes[i] : dex_file_bytes[i];
	jint len = static_cast<jint>(env->GetArrayLength(desired_array));
	const unsigned char* redef_bytes = reinterpret_cast<const unsigned char*>(
	env->GetByteArrayElements(desired_array, nullptr));
	defs.push_back({targets[i], static_cast<jint>(len), redef_bytes});
	}
	jvmtiError res = CallRedefineEntrypoint<kType>(env, jvmti_env, num_redefines, defs.data());
	if (res != JVMTI_ERROR_NONE) {
	throwRedefinitionError(jvmti_env, env, num_redefines, targets, res);
	}
	}

	template<RedefineType kType>
	static void DoClassRedefine(jvmtiEnv* jvmti_env,
	JNIEnv* env,
	jclass target,
	jbyteArray class_file_bytes,
	jbyteArray dex_file_bytes) {
	return DoMultiClassRedefine<kType>(jvmti_env, env, 1, &target, &class_file_bytes, &dex_file_bytes);
	}

	extern "C" JNIEXPORT jboolean JNICALL
	Java_art_Redefinition_isStructurallyModifiable(JNIEnv* env, jclass, jclass target) {
	using ArtCanStructurallyRedefineClass =
	jvmtiError ()(jvmtiEnv env, jclass k, jboolean * result);
	ArtCanStructurallyRedefineClass can_redef = GetExtensionFunction<ArtCanStructurallyRedefineClass>(
	env, jvmti_env, "com.android.art.class.is_structurally_modifiable_class");
	if (can_redef == nullptr \|\| env->ExceptionCheck()) {
	return false;
	}
	jboolean result = false;
	JvmtiErrorToException(env, jvmti_env, can_redef(jvmti_env, target, &result));
	return result;
	}

	extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonStructuralClassRedefinition(
	JNIEnv* env, jclass, jclass target, jbyteArray dex_file_bytes) {
	DoClassRedefine<RedefineType::kStructural>(jvmti_env, env, target, nullptr, dex_file_bytes);
	}

	// Magic JNI export that classes can use for redefining classes.
	// To use classes should declare this as a native function with signature (Ljava/lang/Class;[B[B)V
	extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonClassRedefinition(
	JNIEnv* env, jclass, jclass target, jbyteArray class_file_bytes, jbyteArray dex_file_bytes) {
	DoClassRedefine<RedefineType::kNormal>(jvmti_env, env, target, class_file_bytes, dex_file_bytes);
	}

	// Magic JNI export that classes can use for redefining classes.
	// To use classes should declare this as a native function with signature
	// ([Ljava/lang/Class;[[B[[B)V
	extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonMultiStructuralClassRedefinition(
	JNIEnv* env,
	jclass,
	jobjectArray targets,
	jobjectArray dex_file_bytes) {
	std::vector<jclass> classes;
	std::vector<jbyteArray> class_files;
	std::vector<jbyteArray> dex_files;
	jint len = env->GetArrayLength(targets);
	if (len != env->GetArrayLength(dex_file_bytes)) {
	env->ThrowNew(env->FindClass("java/lang/IllegalArgumentException"),
	"the three array arguments passed to this function have different lengths!");
	return;
	}
	for (jint i = 0; i < len; i++) {
	classes.push_back(static_cast<jclass>(env->GetObjectArrayElement(targets, i)));
	dex_files.push_back(static_cast<jbyteArray>(env->GetObjectArrayElement(dex_file_bytes, i)));
	class_files.push_back(nullptr);
	}
	return DoMultiClassRedefine<RedefineType::kStructural>(jvmti_env,
	env,
	len,
	classes.data(),
	class_files.data(),
	dex_files.data());
	}

	// Magic JNI export that classes can use for redefining classes.
	// To use classes should declare this as a native function with signature
	// ([Ljava/lang/Class;[[B[[B)V
	extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonMultiClassRedefinition(
	JNIEnv* env,
	jclass,
	jobjectArray targets,
	jobjectArray class_file_bytes,
	jobjectArray dex_file_bytes) {
	std::vector<jclass> classes;
	std::vector<jbyteArray> class_files;
	std::vector<jbyteArray> dex_files;
	jint len = env->GetArrayLength(targets);
	if (len != env->GetArrayLength(class_file_bytes) \|\| len != env->GetArrayLength(dex_file_bytes)) {
	env->ThrowNew(env->FindClass("java/lang/IllegalArgumentException"),
	"the three array arguments passed to this function have different lengths!");
	return;
	}
	for (jint i = 0; i < len; i++) {
	classes.push_back(static_cast<jclass>(env->GetObjectArrayElement(targets, i)));
	dex_files.push_back(static_cast<jbyteArray>(env->GetObjectArrayElement(dex_file_bytes, i)));
	class_files.push_back(static_cast<jbyteArray>(env->GetObjectArrayElement(class_file_bytes, i)));
	}
	return DoMultiClassRedefine<RedefineType::kNormal>(jvmti_env,
	env,
	len,
	classes.data(),
	class_files.data(),
	dex_files.data());
	}

	// Get all capabilities except those related to retransformation.
	jint OnLoad(JavaVM* vm,
	[[maybe_unused]] char* options,
	[[maybe_unused]] void* reserved) {
	if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
	printf("Unable to get jvmti env!\n");
	return 1;
	}
	SetupCommonRedefine();
	return 0;
	}

	} // namespace common_redefine

	namespace common_retransform {

	struct CommonTransformationResult {
	std::vector<unsigned char> class_bytes;
	std::vector<unsigned char> dex_bytes;

	CommonTransformationResult(size_t class_size, size_t dex_size)
	: class_bytes(class_size), dex_bytes(dex_size) {}

	CommonTransformationResult() = default;
	CommonTransformationResult(CommonTransformationResult&&) = default;
	CommonTransformationResult(CommonTransformationResult&) = default;
	};

	// Map from class name to transformation result.
	std::map<std::string, std::deque<CommonTransformationResult>> gTransformations;
	bool gPopTransformations = true;

	extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_addCommonTransformationResult(
	JNIEnv* env, jclass, jstring class_name, jbyteArray class_array, jbyteArray dex_array) {
	const char* name_chrs = env->GetStringUTFChars(class_name, nullptr);
	std::string name_str(name_chrs);
	env->ReleaseStringUTFChars(class_name, name_chrs);
	CommonTransformationResult trans(env->GetArrayLength(class_array),
	env->GetArrayLength(dex_array));
	if (env->ExceptionOccurred()) {
	return;
	}
	env->GetByteArrayRegion(class_array,
	0,
	env->GetArrayLength(class_array),
	reinterpret_cast<jbyte*>(trans.class_bytes.data()));
	if (env->ExceptionOccurred()) {
	return;
	}
	env->GetByteArrayRegion(dex_array,
	0,
	env->GetArrayLength(dex_array),
	reinterpret_cast<jbyte*>(trans.dex_bytes.data()));
	if (env->ExceptionOccurred()) {
	return;
	}
	if (gTransformations.find(name_str) == gTransformations.end()) {
	std::deque<CommonTransformationResult> list;
	gTransformations[name_str] = std::move(list);
	}
	gTransformations[name_str].push_back(std::move(trans));
	}

	// The hook we are using.
	void JNICALL CommonClassFileLoadHookRetransformable(jvmtiEnv* jvmti_env,
	[[maybe_unused]] JNIEnv* jni_env,
	[[maybe_unused]] jclass class_being_redefined,
	[[maybe_unused]] jobject loader,
	const char* name,
	[[maybe_unused]] jobject protection_domain,
	[[maybe_unused]] jint class_data_len,
	[[maybe_unused]] const unsigned char* class_dat,
	jint* new_class_data_len,
	unsigned char** new_class_data) {
	std::string name_str(name);
	if (gTransformations.find(name_str) != gTransformations.end() &&
	gTransformations[name_str].size() > 0) {
	CommonTransformationResult& res = gTransformations[name_str][0];
	const std::vector<unsigned char>& desired_array = IsJVM() ? res.class_bytes : res.dex_bytes;
	unsigned char* new_data;
	CHECK_EQ(JVMTI_ERROR_NONE, jvmti_env->Allocate(desired_array.size(), &new_data));
	memcpy(new_data, desired_array.data(), desired_array.size());
	*new_class_data = new_data;
	*new_class_data_len = desired_array.size();
	if (gPopTransformations) {
	gTransformations[name_str].pop_front();
	}
	}
	}

	extern "C" JNIEXPORT void Java_art_Redefinition_setPopRetransformations(JNIEnv*,
	jclass,
	jboolean enable) {
	gPopTransformations = enable;
	}

	extern "C" JNIEXPORT void Java_art_Redefinition_popTransformationFor(JNIEnv* env,
	jclass,
	jstring class_name) {
	const char* name_chrs = env->GetStringUTFChars(class_name, nullptr);
	std::string name_str(name_chrs);
	env->ReleaseStringUTFChars(class_name, name_chrs);
	if (gTransformations.find(name_str) != gTransformations.end() &&
	gTransformations[name_str].size() > 0) {
	gTransformations[name_str].pop_front();
	} else {
	std::stringstream err;
	err << "No transformations found for class " << name_str;
	std::string message = err.str();
	env->ThrowNew(env->FindClass("java/lang/Exception"), message.c_str());
	}
	}

	extern "C" JNIEXPORT void Java_art_Redefinition_enableCommonRetransformation(JNIEnv* env,
	jclass,
	jboolean enable) {
	jvmtiError res = jvmti_env->SetEventNotificationMode(enable ? JVMTI_ENABLE : JVMTI_DISABLE,
	JVMTI_EVENT_CLASS_FILE_LOAD_HOOK,
	nullptr);
	if (res != JVMTI_ERROR_NONE) {
	JvmtiErrorToException(env, jvmti_env, res);
	}
	}

	static void throwRetransformationError(jvmtiEnv* jvmti,
	JNIEnv* env,
	jint num_targets,
	jclass* targets,
	jvmtiError res) {
	return throwCommonRedefinitionError<false>(jvmti, env, num_targets, targets, res);
	}

	static void DoClassRetransformation(jvmtiEnv* jvmti_env, JNIEnv* env, jobjectArray targets) {
	std::vector<jclass> classes;
	jint len = env->GetArrayLength(targets);
	classes.reserve(len);
	for (jint i = 0; i < len; i++) {
	classes.push_back(static_cast<jclass>(env->GetObjectArrayElement(targets, i)));
	}
	jvmtiError res = jvmti_env->RetransformClasses(len, classes.data());
	if (res != JVMTI_ERROR_NONE) {
	throwRetransformationError(jvmti_env, env, len, classes.data(), res);
	}
	}

	extern "C" JNIEXPORT void JNICALL Java_art_Redefinition_doCommonClassRetransformation(
	JNIEnv* env, jclass, jobjectArray targets) {
	jvmtiCapabilities caps;
	jvmtiError caps_err = jvmti_env->GetCapabilities(&caps);
	if (caps_err != JVMTI_ERROR_NONE) {
	env->ThrowNew(env->FindClass("java/lang/Exception"),
	"Unable to get current jvmtiEnv capabilities");
	return;
	}

	// Allocate a new environment if we don't have the can_retransform_classes capability needed to
	// call the RetransformClasses function.
	jvmtiEnv* real_env = nullptr;
	if (caps.can_retransform_classes != 1) {
	JavaVM* vm = nullptr;
	if (env->GetJavaVM(&vm) != 0 \|\|
	vm->GetEnv(reinterpret_cast<void**>(&real_env), JVMTI_VERSION_1_0) != 0) {
	env->ThrowNew(env->FindClass("java/lang/Exception"),
	"Unable to create temporary jvmtiEnv for RetransformClasses call.");
	return;
	}
	SetStandardCapabilities(real_env);
	} else {
	real_env = jvmti_env;
	}
	DoClassRetransformation(real_env, env, targets);
	if (caps.can_retransform_classes != 1) {
	real_env->DisposeEnvironment();
	}
	}

	// Get all capabilities except those related to retransformation.
	jint OnLoad(JavaVM* vm,
	[[maybe_unused]] char* options,
	[[maybe_unused]] void* reserved) {
	if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
	printf("Unable to get jvmti env!\n");
	return 1;
	}
	SetupCommonRetransform(RedefineType::kNormal);
	return 0;
	}

	} // namespace common_retransform

	namespace common_transform {

	// Get all capabilities except those related to retransformation.
	jint OnLoad(JavaVM* vm,
	[[maybe_unused]] char* options,
	[[maybe_unused]] void* reserved) {
	if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
	printf("Unable to get jvmti env!\n");
	return 1;
	}
	SetupCommonTransform();
	return 0;
	}

	} // namespace common_transform

	static void SetupCommonRedefine() {
	jvmtiCapabilities caps = GetStandardCapabilities();
	caps.can_retransform_classes = 0;
	caps.can_retransform_any_class = 0;
	jvmti_env->AddCapabilities(&caps);
	}

	static void SetupCommonRetransform(RedefineType type) {
	SetStandardCapabilities(jvmti_env);
	if (type == RedefineType::kNormal) {
	current_callbacks.ClassFileLoadHook =
	common_retransform::CommonClassFileLoadHookRetransformable;
	jvmtiError res = jvmti_env->SetEventCallbacks(&current_callbacks, sizeof(current_callbacks));
	CHECK_EQ(res, JVMTI_ERROR_NONE);
	} else {
	jvmtiError res = jvmti_env->SetExtensionEventCallback(
	GetExtensionEventId(jvmti_env, "com.android.art.class.structural_dex_file_load_hook"),
	reinterpret_cast<jvmtiExtensionEvent>(
	common_retransform::CommonClassFileLoadHookRetransformable));
	CHECK_EQ(res, JVMTI_ERROR_NONE);
	}
	common_retransform::gTransformations.clear();
	}

	static void SetupCommonTransform() {
	// Don't set the retransform caps
	jvmtiCapabilities caps = GetStandardCapabilities();
	caps.can_retransform_classes = 0;
	caps.can_retransform_any_class = 0;
	jvmti_env->AddCapabilities(&caps);

	// Use the same callback as the retransform test.
	current_callbacks.ClassFileLoadHook = common_retransform::CommonClassFileLoadHookRetransformable;
	jvmtiError res = jvmti_env->SetEventCallbacks(&current_callbacks, sizeof(current_callbacks));
	CHECK_EQ(res, JVMTI_ERROR_NONE);
	common_retransform::gTransformations.clear();
	}

	} // namespace art