tools/jvmti-agents/breakpoint-logger/breakpoint_logger.cc - LeafOS-Project/android_art - Gitiles

 // Copyright (C) 2017 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 <android-base/logging.h>
 #include <atomic>
 #include <iostream>
 #include <iomanip>
 #include <jni.h>
 #include <jvmti.h>
 #include <memory>
 #include <string>
 #include <vector>

 namespace breakpoint_logger {

 struct SingleBreakpointTarget {
   std::string class_name;
   std::string method_name;
   std::string method_sig;
   jlocation location;
 };

 struct BreakpointTargets {
   std::vector<SingleBreakpointTarget> bps;
 };

 static void VMInitCB(jvmtiEnv* jvmti, JNIEnv* env, jthread thr ATTRIBUTE_UNUSED) {
   BreakpointTargets* all_targets = nullptr;
   jvmtiError err = jvmti->GetEnvironmentLocalStorage(reinterpret_cast<void**>(&all_targets));
   if (err != JVMTI_ERROR_NONE || all_targets == nullptr) {
     env->FatalError("unable to get breakpoint targets");
   }
   for (const SingleBreakpointTarget& target : all_targets->bps) {
     jclass k = env->FindClass(target.class_name.c_str());
     if (env->ExceptionCheck()) {
       env->ExceptionDescribe();
       env->FatalError("Could not find class!");
       return;
     }
     jmethodID m = env->GetMethodID(k, target.method_name.c_str(), target.method_sig.c_str());
     if (env->ExceptionCheck()) {
       env->ExceptionClear();
       m = env->GetStaticMethodID(k, target.method_name.c_str(), target.method_sig.c_str());
       if (env->ExceptionCheck()) {
         env->ExceptionDescribe();
         env->FatalError("Could not find method!");
         return;
       }
     }
     err = jvmti->SetBreakpoint(m, target.location);
     if (err != JVMTI_ERROR_NONE) {
       env->FatalError("unable to set breakpoint");
       return;
     }
     env->DeleteLocalRef(k);
   }
 }

 class ScopedThreadInfo {
  public:
   ScopedThreadInfo(jvmtiEnv* jvmti_env, JNIEnv* env, jthread thread)
       : jvmti_env_(jvmti_env), env_(env), free_name_(false) {
     memset(&info_, 0, sizeof(info_));
     if (thread == nullptr) {
       info_.name = const_cast<char*>("<NULLPTR>");
     } else if (jvmti_env->GetThreadInfo(thread, &info_) != JVMTI_ERROR_NONE) {
       info_.name = const_cast<char*>("<UNKNOWN THREAD>");
     } else {
       free_name_ = true;
     }
   }

   ~ScopedThreadInfo() {
     if (free_name_) {
       jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(info_.name));
     }
     env_->DeleteLocalRef(info_.thread_group);
     env_->DeleteLocalRef(info_.context_class_loader);
   }

   const char* GetName() const {
     return info_.name;
   }

  private:
   jvmtiEnv* jvmti_env_;
   JNIEnv* env_;
   bool free_name_;
   jvmtiThreadInfo info_;
 };

 class ScopedClassInfo {
  public:
   ScopedClassInfo(jvmtiEnv* jvmti_env, jclass c)
       : jvmti_env_(jvmti_env),
         class_(c),
         name_(nullptr),
         generic_(nullptr),
         file_(nullptr),
         debug_ext_(nullptr) {}

   ~ScopedClassInfo() {
     if (class_ != nullptr) {
       jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(name_));
       jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(generic_));
       jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(file_));
       jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(debug_ext_));
     }
   }

   bool Init() {
     if (class_ == nullptr) {
       name_ = const_cast<char*>("<NONE>");
       generic_ = const_cast<char*>("<NONE>");
       return true;
     } else {
       jvmtiError ret1 = jvmti_env_->GetSourceFileName(class_, &file_);
       jvmtiError ret2 = jvmti_env_->GetSourceDebugExtension(class_, &debug_ext_);
       return jvmti_env_->GetClassSignature(class_, &name_, &generic_) == JVMTI_ERROR_NONE &&
           ret1 != JVMTI_ERROR_MUST_POSSESS_CAPABILITY &&
           ret1 != JVMTI_ERROR_INVALID_CLASS &&
           ret2 != JVMTI_ERROR_MUST_POSSESS_CAPABILITY &&
           ret2 != JVMTI_ERROR_INVALID_CLASS;
     }
   }

   jclass GetClass() const {
     return class_;
   }
   const char* GetName() const {
     return name_;
   }
   // Generic type parameters, whatever is in the <> for a class
   const char* GetGeneric() const {
     return generic_;
   }
   const char* GetSourceDebugExtension() const {
     if (debug_ext_ == nullptr) {
       return "<UNKNOWN_SOURCE_DEBUG_EXTENSION>";
     } else {
       return debug_ext_;
     }
   }
   const char* GetSourceFileName() const {
     if (file_ == nullptr) {
       return "<UNKNOWN_FILE>";
     } else {
       return file_;
     }
   }

  private:
   jvmtiEnv* jvmti_env_;
   jclass class_;
   char* name_;
   char* generic_;
   char* file_;
   char* debug_ext_;
 };

 class ScopedMethodInfo {
  public:
   ScopedMethodInfo(jvmtiEnv* jvmti_env, JNIEnv* env, jmethodID method)
       : jvmti_env_(jvmti_env),
         env_(env),
         method_(method),
         declaring_class_(nullptr),
         class_info_(nullptr),
         name_(nullptr),
         signature_(nullptr),
         generic_(nullptr),
         first_line_(-1) {}

   ~ScopedMethodInfo() {
     env_->DeleteLocalRef(declaring_class_);
     jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(name_));
     jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(signature_));
     jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(generic_));
   }

   bool Init() {
     if (jvmti_env_->GetMethodDeclaringClass(method_, &declaring_class_) != JVMTI_ERROR_NONE) {
       return false;
     }
     class_info_.reset(new ScopedClassInfo(jvmti_env_, declaring_class_));
     jint nlines;
     jvmtiLineNumberEntry* lines;
     jvmtiError err = jvmti_env_->GetLineNumberTable(method_, &nlines, &lines);
     if (err == JVMTI_ERROR_NONE) {
       if (nlines > 0) {
         first_line_ = lines[0].line_number;
       }
       jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(lines));
     } else if (err != JVMTI_ERROR_ABSENT_INFORMATION &&
                err != JVMTI_ERROR_NATIVE_METHOD) {
       return false;
     }
     return class_info_->Init() &&
         (jvmti_env_->GetMethodName(method_, &name_, &signature_, &generic_) == JVMTI_ERROR_NONE);
   }

   const ScopedClassInfo& GetDeclaringClassInfo() const {
     return *class_info_;
   }

   jclass GetDeclaringClass() const {
     return declaring_class_;
   }

   const char* GetName() const {
     return name_;
   }

   const char* GetSignature() const {
     return signature_;
   }

   const char* GetGeneric() const {
     return generic_;
   }

   jint GetFirstLine() const {
     return first_line_;
   }

  private:
   jvmtiEnv* jvmti_env_;
   JNIEnv* env_;
   jmethodID method_;
   jclass declaring_class_;
   std::unique_ptr<ScopedClassInfo> class_info_;
   char* name_;
   char* signature_;
   char* generic_;
   jint first_line_;

   friend std::ostream& operator<<(std::ostream& os, ScopedMethodInfo const& method);
 };

 std::ostream& operator<<(std::ostream& os, const ScopedMethodInfo* method) {
   return os << *method;
 }

 std::ostream& operator<<(std::ostream& os, ScopedMethodInfo const& method) {
   return os << method.GetDeclaringClassInfo().GetName() << "->" << method.GetName()
             << method.GetSignature() << " (source: "
             << method.GetDeclaringClassInfo().GetSourceFileName() << ":" << method.GetFirstLine()
             << ")";
 }

 static void BreakpointCB(jvmtiEnv* jvmti_env,
                          JNIEnv* env,
                          jthread thread,
                          jmethodID method,
                          jlocation location) {
   ScopedThreadInfo info(jvmti_env, env, thread);
   ScopedMethodInfo method_info(jvmti_env, env, method);
   if (!method_info.Init()) {
     LOG(ERROR) << "Unable to get method info!";
     return;
   }
   LOG(WARNING) << "Breakpoint at location: 0x" << std::setw(8) << std::setfill('0') << std::hex
             << location << " in method " << method_info << " thread: " << info.GetName();
 }

 static std::string SubstrOf(const std::string& s, size_t start, size_t end) {
   if (end == std::string::npos) {
     end = s.size();
   }
   if (end == start) {
     return "";
   }
   CHECK_GT(end, start) << "cannot get substr of " << s;
   return s.substr(start, end - start);
 }

 static bool ParseSingleBreakpoint(const std::string& bp, /*out*/SingleBreakpointTarget* target) {
   std::string option = bp;
   if (option.empty() || option[0] != 'L' || option.find(';') == std::string::npos) {
     LOG(ERROR) << option << " doesn't look like it has a class name";
     return false;
   }
   target->class_name = SubstrOf(option, 1, option.find(';'));

   option = SubstrOf(option, option.find(';') + 1, std::string::npos);
   if (option.size() < 2 || option[0] != '-' || option[1] != '>') {
     LOG(ERROR) << bp << " doesn't seem to indicate a method, expected ->";
     return false;
   }
   option = SubstrOf(option, 2, std::string::npos);
   size_t sig_start = option.find('(');
   size_t loc_start = option.find('@');
   if (option.empty() || sig_start == std::string::npos) {
     LOG(ERROR) << bp << " doesn't seem to have a method sig!";
     return false;
   } else if (loc_start == std::string::npos ||
              loc_start < sig_start ||
              loc_start + 1 >= option.size()) {
     LOG(ERROR) << bp << " doesn't seem to have a valid location!";
     return false;
   }
   target->method_name = SubstrOf(option, 0, sig_start);
   target->method_sig = SubstrOf(option, sig_start, loc_start);
   target->location = std::stol(SubstrOf(option, loc_start + 1, std::string::npos));
   return true;
 }

 static std::string RemoveLastOption(const std::string& op) {
   if (op.find(',') == std::string::npos) {
     return "";
   } else {
     return SubstrOf(op, op.find(',') + 1, std::string::npos);
   }
 }

 // Fills targets with the breakpoints to add.
 // Lname/of/Klass;->methodName(Lsig/of/Method)Lreturn/Type;@location,<...>
 static bool ParseArgs(const std::string& start_options,
                       /*out*/BreakpointTargets* targets) {
   for (std::string options = start_options;
        !options.empty();
        options = RemoveLastOption(options)) {
     SingleBreakpointTarget target;
     std::string next = SubstrOf(options, 0, options.find(','));
     if (!ParseSingleBreakpoint(next, /*out*/ &target)) {
       LOG(ERROR) << "Unable to parse breakpoint from " << next;
       return false;
     }
     targets->bps.push_back(target);
   }
   return true;
 }

 enum class StartType {
   OnAttach, OnLoad,
 };

 static jint AgentStart(StartType start,
                        JavaVM* vm,
                        char* options,
                        void* reserved ATTRIBUTE_UNUSED) {
   jvmtiEnv* jvmti = nullptr;
   jvmtiError error = JVMTI_ERROR_NONE;
   {
     jint res = 0;
     res = vm->GetEnv(reinterpret_cast<void**>(&jvmti), JVMTI_VERSION_1_1);

     if (res != JNI_OK || jvmti == nullptr) {
       LOG(ERROR) << "Unable to access JVMTI, error code " << res;
       return JNI_ERR;
     }
   }

   void* bp_target_mem = nullptr;
   error = jvmti->Allocate(sizeof(BreakpointTargets),
                           reinterpret_cast<unsigned char**>(&bp_target_mem));
   if (error != JVMTI_ERROR_NONE) {
     LOG(ERROR) << "Unable to alloc memory for breakpoint target data";
     return JNI_ERR;
   }

   BreakpointTargets* data = new(bp_target_mem) BreakpointTargets;
   error = jvmti->SetEnvironmentLocalStorage(data);
   if (error != JVMTI_ERROR_NONE) {
     LOG(ERROR) << "Unable to set local storage";
     return JNI_ERR;
   }

   if (!ParseArgs(options, /*out*/data)) {
     LOG(ERROR) << "failed to parse breakpoint list!";
     return JNI_ERR;
   }

   jvmtiCapabilities caps{};
   caps.can_generate_breakpoint_events = JNI_TRUE;
   caps.can_get_line_numbers           = JNI_TRUE;
   caps.can_get_source_file_name       = JNI_TRUE;
   caps.can_get_source_debug_extension = JNI_TRUE;
   error = jvmti->AddCapabilities(&caps);
   if (error != JVMTI_ERROR_NONE) {
     LOG(ERROR) << "Unable to set caps";
     return JNI_ERR;
   }

   jvmtiEventCallbacks callbacks{};
   callbacks.Breakpoint = &BreakpointCB;
   callbacks.VMInit = &VMInitCB;

   error = jvmti->SetEventCallbacks(&callbacks, static_cast<jint>(sizeof(callbacks)));

   if (error != JVMTI_ERROR_NONE) {
     LOG(ERROR) << "Unable to set event callbacks.";
     return JNI_ERR;
   }

   error = jvmti->SetEventNotificationMode(JVMTI_ENABLE,
                                           JVMTI_EVENT_BREAKPOINT,
                                           nullptr /* all threads */);
   if (error != JVMTI_ERROR_NONE) {
     LOG(ERROR) << "Unable to enable breakpoint event";
     return JNI_ERR;
   }
   if (start == StartType::OnAttach) {
     JNIEnv* env = nullptr;
     jint res = 0;
     res = vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_2);
     if (res != JNI_OK || env == nullptr) {
       LOG(ERROR) << "Unable to get jnienv";
       return JNI_ERR;
     }
     VMInitCB(jvmti, env, nullptr);
   } else {
     error = jvmti->SetEventNotificationMode(JVMTI_ENABLE,
                                             JVMTI_EVENT_VM_INIT,
                                             nullptr /* all threads */);
     if (error != JVMTI_ERROR_NONE) {
       LOG(ERROR) << "Unable to set event vminit";
       return JNI_ERR;
     }
   }
   return JNI_OK;
 }

 // Late attachment (e.g. 'am attach-agent').
 extern "C" JNIEXPORT jint JNICALL Agent_OnAttach(JavaVM *vm, char* options, void* reserved) {
   return AgentStart(StartType::OnAttach, vm, options, reserved);
 }

 // Early attachment
 extern "C" JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* jvm, char* options, void* reserved) {
   return AgentStart(StartType::OnLoad, jvm, options, reserved);
 }

 }  // namespace breakpoint_logger
	// Copyright (C) 2017 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 <android-base/logging.h>
	#include <atomic>
	#include <iostream>
	#include <iomanip>
	#include <jni.h>
	#include <jvmti.h>
	#include <memory>
	#include <string>
	#include <vector>

	namespace breakpoint_logger {

	struct SingleBreakpointTarget {
	std::string class_name;
	std::string method_name;
	std::string method_sig;
	jlocation location;
	};

	struct BreakpointTargets {
	std::vector<SingleBreakpointTarget> bps;
	};

	static void VMInitCB(jvmtiEnv* jvmti, JNIEnv* env, jthread thr ATTRIBUTE_UNUSED) {
	BreakpointTargets* all_targets = nullptr;
	jvmtiError err = jvmti->GetEnvironmentLocalStorage(reinterpret_cast<void**>(&all_targets));
	if (err != JVMTI_ERROR_NONE \|\| all_targets == nullptr) {
	env->FatalError("unable to get breakpoint targets");
	}
	for (const SingleBreakpointTarget& target : all_targets->bps) {
	jclass k = env->FindClass(target.class_name.c_str());
	if (env->ExceptionCheck()) {
	env->ExceptionDescribe();
	env->FatalError("Could not find class!");
	return;
	}
	jmethodID m = env->GetMethodID(k, target.method_name.c_str(), target.method_sig.c_str());
	if (env->ExceptionCheck()) {
	env->ExceptionClear();
	m = env->GetStaticMethodID(k, target.method_name.c_str(), target.method_sig.c_str());
	if (env->ExceptionCheck()) {
	env->ExceptionDescribe();
	env->FatalError("Could not find method!");
	return;
	}
	}
	err = jvmti->SetBreakpoint(m, target.location);
	if (err != JVMTI_ERROR_NONE) {
	env->FatalError("unable to set breakpoint");
	return;
	}
	env->DeleteLocalRef(k);
	}
	}

	class ScopedThreadInfo {
	public:
	ScopedThreadInfo(jvmtiEnv* jvmti_env, JNIEnv* env, jthread thread)
	: jvmti_env_(jvmti_env), env_(env), free_name_(false) {
	memset(&info_, 0, sizeof(info_));
	if (thread == nullptr) {
	info_.name = const_cast<char*>("<NULLPTR>");
	} else if (jvmti_env->GetThreadInfo(thread, &info_) != JVMTI_ERROR_NONE) {
	info_.name = const_cast<char*>("<UNKNOWN THREAD>");
	} else {
	free_name_ = true;
	}
	}

	~ScopedThreadInfo() {
	if (free_name_) {
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(info_.name));
	}
	env_->DeleteLocalRef(info_.thread_group);
	env_->DeleteLocalRef(info_.context_class_loader);
	}

	const char* GetName() const {
	return info_.name;
	}

	private:
	jvmtiEnv* jvmti_env_;
	JNIEnv* env_;
	bool free_name_;
	jvmtiThreadInfo info_;
	};

	class ScopedClassInfo {
	public:
	ScopedClassInfo(jvmtiEnv* jvmti_env, jclass c)
	: jvmti_env_(jvmti_env),
	class_(c),
	name_(nullptr),
	generic_(nullptr),
	file_(nullptr),
	debug_ext_(nullptr) {}

	~ScopedClassInfo() {
	if (class_ != nullptr) {
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(name_));
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(generic_));
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(file_));
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(debug_ext_));
	}
	}

	bool Init() {
	if (class_ == nullptr) {
	name_ = const_cast<char*>("<NONE>");
	generic_ = const_cast<char*>("<NONE>");
	return true;
	} else {
	jvmtiError ret1 = jvmti_env_->GetSourceFileName(class_, &file_);
	jvmtiError ret2 = jvmti_env_->GetSourceDebugExtension(class_, &debug_ext_);
	return jvmti_env_->GetClassSignature(class_, &name_, &generic_) == JVMTI_ERROR_NONE &&
	ret1 != JVMTI_ERROR_MUST_POSSESS_CAPABILITY &&
	ret1 != JVMTI_ERROR_INVALID_CLASS &&
	ret2 != JVMTI_ERROR_MUST_POSSESS_CAPABILITY &&
	ret2 != JVMTI_ERROR_INVALID_CLASS;
	}
	}

	jclass GetClass() const {
	return class_;
	}
	const char* GetName() const {
	return name_;
	}
	// Generic type parameters, whatever is in the <> for a class
	const char* GetGeneric() const {
	return generic_;
	}
	const char* GetSourceDebugExtension() const {
	if (debug_ext_ == nullptr) {
	return "<UNKNOWN_SOURCE_DEBUG_EXTENSION>";
	} else {
	return debug_ext_;
	}
	}
	const char* GetSourceFileName() const {
	if (file_ == nullptr) {
	return "<UNKNOWN_FILE>";
	} else {
	return file_;
	}
	}

	private:
	jvmtiEnv* jvmti_env_;
	jclass class_;
	char* name_;
	char* generic_;
	char* file_;
	char* debug_ext_;
	};

	class ScopedMethodInfo {
	public:
	ScopedMethodInfo(jvmtiEnv* jvmti_env, JNIEnv* env, jmethodID method)
	: jvmti_env_(jvmti_env),
	env_(env),
	method_(method),
	declaring_class_(nullptr),
	class_info_(nullptr),
	name_(nullptr),
	signature_(nullptr),
	generic_(nullptr),
	first_line_(-1) {}

	~ScopedMethodInfo() {
	env_->DeleteLocalRef(declaring_class_);
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(name_));
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(signature_));
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(generic_));
	}

	bool Init() {
	if (jvmti_env_->GetMethodDeclaringClass(method_, &declaring_class_) != JVMTI_ERROR_NONE) {
	return false;
	}
	class_info_.reset(new ScopedClassInfo(jvmti_env_, declaring_class_));
	jint nlines;
	jvmtiLineNumberEntry* lines;
	jvmtiError err = jvmti_env_->GetLineNumberTable(method_, &nlines, &lines);
	if (err == JVMTI_ERROR_NONE) {
	if (nlines > 0) {
	first_line_ = lines[0].line_number;
	}
	jvmti_env_->Deallocate(reinterpret_cast<unsigned char*>(lines));
	} else if (err != JVMTI_ERROR_ABSENT_INFORMATION &&
	err != JVMTI_ERROR_NATIVE_METHOD) {
	return false;
	}
	return class_info_->Init() &&
	(jvmti_env_->GetMethodName(method_, &name_, &signature_, &generic_) == JVMTI_ERROR_NONE);
	}

	const ScopedClassInfo& GetDeclaringClassInfo() const {
	return *class_info_;
	}

	jclass GetDeclaringClass() const {
	return declaring_class_;
	}

	const char* GetName() const {
	return name_;
	}

	const char* GetSignature() const {
	return signature_;
	}

	const char* GetGeneric() const {
	return generic_;
	}

	jint GetFirstLine() const {
	return first_line_;
	}

	private:
	jvmtiEnv* jvmti_env_;
	JNIEnv* env_;
	jmethodID method_;
	jclass declaring_class_;
	std::unique_ptr<ScopedClassInfo> class_info_;
	char* name_;
	char* signature_;
	char* generic_;
	jint first_line_;

	friend std::ostream& operator<<(std::ostream& os, ScopedMethodInfo const& method);
	};

	std::ostream& operator<<(std::ostream& os, const ScopedMethodInfo* method) {
	return os << *method;
	}

	std::ostream& operator<<(std::ostream& os, ScopedMethodInfo const& method) {
	return os << method.GetDeclaringClassInfo().GetName() << "->" << method.GetName()
	<< method.GetSignature() << " (source: "
	<< method.GetDeclaringClassInfo().GetSourceFileName() << ":" << method.GetFirstLine()
	<< ")";
	}

	static void BreakpointCB(jvmtiEnv* jvmti_env,
	JNIEnv* env,
	jthread thread,
	jmethodID method,
	jlocation location) {
	ScopedThreadInfo info(jvmti_env, env, thread);
	ScopedMethodInfo method_info(jvmti_env, env, method);
	if (!method_info.Init()) {
	LOG(ERROR) << "Unable to get method info!";
	return;
	}
	LOG(WARNING) << "Breakpoint at location: 0x" << std::setw(8) << std::setfill('0') << std::hex
	<< location << " in method " << method_info << " thread: " << info.GetName();
	}

	static std::string SubstrOf(const std::string& s, size_t start, size_t end) {
	if (end == std::string::npos) {
	end = s.size();
	}
	if (end == start) {
	return "";
	}
	CHECK_GT(end, start) << "cannot get substr of " << s;
	return s.substr(start, end - start);
	}

	static bool ParseSingleBreakpoint(const std::string& bp, /out/SingleBreakpointTarget* target) {
	std::string option = bp;
	if (option.empty() \|\| option[0] != 'L' \|\| option.find(';') == std::string::npos) {
	LOG(ERROR) << option << " doesn't look like it has a class name";
	return false;
	}
	target->class_name = SubstrOf(option, 1, option.find(';'));

	option = SubstrOf(option, option.find(';') + 1, std::string::npos);
	if (option.size() < 2 \|\| option[0] != '-' \|\| option[1] != '>') {
	LOG(ERROR) << bp << " doesn't seem to indicate a method, expected ->";
	return false;
	}
	option = SubstrOf(option, 2, std::string::npos);
	size_t sig_start = option.find('(');
	size_t loc_start = option.find('@');
	if (option.empty() \|\| sig_start == std::string::npos) {
	LOG(ERROR) << bp << " doesn't seem to have a method sig!";
	return false;
	} else if (loc_start == std::string::npos \|\|
	loc_start < sig_start \|\|
	loc_start + 1 >= option.size()) {
	LOG(ERROR) << bp << " doesn't seem to have a valid location!";
	return false;
	}
	target->method_name = SubstrOf(option, 0, sig_start);
	target->method_sig = SubstrOf(option, sig_start, loc_start);
	target->location = std::stol(SubstrOf(option, loc_start + 1, std::string::npos));
	return true;
	}

	static std::string RemoveLastOption(const std::string& op) {
	if (op.find(',') == std::string::npos) {
	return "";
	} else {
	return SubstrOf(op, op.find(',') + 1, std::string::npos);
	}
	}

	// Fills targets with the breakpoints to add.
	// Lname/of/Klass;->methodName(Lsig/of/Method)Lreturn/Type;@location,<...>
	static bool ParseArgs(const std::string& start_options,
	/out/BreakpointTargets* targets) {
	for (std::string options = start_options;
	!options.empty();
	options = RemoveLastOption(options)) {
	SingleBreakpointTarget target;
	std::string next = SubstrOf(options, 0, options.find(','));
	if (!ParseSingleBreakpoint(next, /out/ &target)) {
	LOG(ERROR) << "Unable to parse breakpoint from " << next;
	return false;
	}
	targets->bps.push_back(target);
	}
	return true;
	}

	enum class StartType {
	OnAttach, OnLoad,
	};

	static jint AgentStart(StartType start,
	JavaVM* vm,
	char* options,
	void* reserved ATTRIBUTE_UNUSED) {
	jvmtiEnv* jvmti = nullptr;
	jvmtiError error = JVMTI_ERROR_NONE;
	{
	jint res = 0;
	res = vm->GetEnv(reinterpret_cast<void**>(&jvmti), JVMTI_VERSION_1_1);

	if (res != JNI_OK \|\| jvmti == nullptr) {
	LOG(ERROR) << "Unable to access JVMTI, error code " << res;
	return JNI_ERR;
	}
	}

	void* bp_target_mem = nullptr;
	error = jvmti->Allocate(sizeof(BreakpointTargets),
	reinterpret_cast<unsigned char**>(&bp_target_mem));
	if (error != JVMTI_ERROR_NONE) {
	LOG(ERROR) << "Unable to alloc memory for breakpoint target data";
	return JNI_ERR;
	}

	BreakpointTargets* data = new(bp_target_mem) BreakpointTargets;
	error = jvmti->SetEnvironmentLocalStorage(data);
	if (error != JVMTI_ERROR_NONE) {
	LOG(ERROR) << "Unable to set local storage";
	return JNI_ERR;
	}

	if (!ParseArgs(options, /out/data)) {
	LOG(ERROR) << "failed to parse breakpoint list!";
	return JNI_ERR;
	}

	jvmtiCapabilities caps{};
	caps.can_generate_breakpoint_events = JNI_TRUE;
	caps.can_get_line_numbers = JNI_TRUE;
	caps.can_get_source_file_name = JNI_TRUE;
	caps.can_get_source_debug_extension = JNI_TRUE;
	error = jvmti->AddCapabilities(&caps);
	if (error != JVMTI_ERROR_NONE) {
	LOG(ERROR) << "Unable to set caps";
	return JNI_ERR;
	}

	jvmtiEventCallbacks callbacks{};
	callbacks.Breakpoint = &BreakpointCB;
	callbacks.VMInit = &VMInitCB;

	error = jvmti->SetEventCallbacks(&callbacks, static_cast<jint>(sizeof(callbacks)));

	if (error != JVMTI_ERROR_NONE) {
	LOG(ERROR) << "Unable to set event callbacks.";
	return JNI_ERR;
	}

	error = jvmti->SetEventNotificationMode(JVMTI_ENABLE,
	JVMTI_EVENT_BREAKPOINT,
	nullptr /* all threads */);
	if (error != JVMTI_ERROR_NONE) {
	LOG(ERROR) << "Unable to enable breakpoint event";
	return JNI_ERR;
	}
	if (start == StartType::OnAttach) {
	JNIEnv* env = nullptr;
	jint res = 0;
	res = vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_2);
	if (res != JNI_OK \|\| env == nullptr) {
	LOG(ERROR) << "Unable to get jnienv";
	return JNI_ERR;
	}
	VMInitCB(jvmti, env, nullptr);
	} else {
	error = jvmti->SetEventNotificationMode(JVMTI_ENABLE,
	JVMTI_EVENT_VM_INIT,
	nullptr /* all threads */);
	if (error != JVMTI_ERROR_NONE) {
	LOG(ERROR) << "Unable to set event vminit";
	return JNI_ERR;
	}
	}
	return JNI_OK;
	}

	// Late attachment (e.g. 'am attach-agent').
	extern "C" JNIEXPORT jint JNICALL Agent_OnAttach(JavaVM vm, char options, void* reserved) {
	return AgentStart(StartType::OnAttach, vm, options, reserved);
	}

	// Early attachment
	extern "C" JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* jvm, char* options, void* reserved) {
	return AgentStart(StartType::OnLoad, jvm, options, reserved);
	}

	} // namespace breakpoint_logger