runtime/ti/agent.cc - platform/art - Git at Google

 /*
  * 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 "agent.h"

 #include "android-base/stringprintf.h"
 #include "nativehelper/scoped_local_ref.h"
 #include "nativeloader/native_loader.h"

 #include "base/logging.h"
 #include "base/strlcpy.h"
 #include "jni/java_vm_ext.h"
 #include "runtime.h"
 #include "thread-current-inl.h"
 #include "scoped_thread_state_change-inl.h"

 namespace art {
 namespace ti {

 using android::base::StringPrintf;

 const char* AGENT_ON_LOAD_FUNCTION_NAME = "Agent_OnLoad";
 const char* AGENT_ON_ATTACH_FUNCTION_NAME = "Agent_OnAttach";
 const char* AGENT_ON_UNLOAD_FUNCTION_NAME = "Agent_OnUnload";

 AgentSpec::AgentSpec(const std::string& arg) {
   size_t eq = arg.find_first_of('=');
   if (eq == std::string::npos) {
     name_ = arg;
   } else {
     name_ = arg.substr(0, eq);
     args_ = arg.substr(eq + 1, arg.length());
   }
 }

 std::unique_ptr<Agent> AgentSpec::Load(/*out*/jint* call_res,
                                        /*out*/LoadError* error,
                                        /*out*/std::string* error_msg) {
   VLOG(agents) << "Loading agent: " << name_ << " " << args_;
   return DoLoadHelper(nullptr, false, nullptr, call_res, error, error_msg);
 }

 // Tries to attach the agent using its OnAttach method. Returns true on success.
 std::unique_ptr<Agent> AgentSpec::Attach(JNIEnv* env,
                                          jobject class_loader,
                                          /*out*/jint* call_res,
                                          /*out*/LoadError* error,
                                          /*out*/std::string* error_msg) {
   VLOG(agents) << "Attaching agent: " << name_ << " " << args_;
   return DoLoadHelper(env, true, class_loader, call_res, error, error_msg);
 }


 // TODO We need to acquire some locks probably.
 std::unique_ptr<Agent> AgentSpec::DoLoadHelper(JNIEnv* env,
                                                bool attaching,
                                                jobject class_loader,
                                                /*out*/jint* call_res,
                                                /*out*/LoadError* error,
                                                /*out*/std::string* error_msg) {
   ScopedThreadStateChange stsc(Thread::Current(), ThreadState::kNative);
   DCHECK(call_res != nullptr);
   DCHECK(error_msg != nullptr);

   std::unique_ptr<Agent> agent = DoDlOpen(env, class_loader, error, error_msg);
   if (agent == nullptr) {
     VLOG(agents) << "err: " << *error_msg;
     return nullptr;
   }
   AgentOnLoadFunction callback = attaching ? agent->onattach_ : agent->onload_;
   if (callback == nullptr) {
     *error_msg = StringPrintf("Unable to start agent %s: No %s callback found",
                               (attaching ? "attach" : "load"),
                               name_.c_str());
     VLOG(agents) << "err: " << *error_msg;
     *error = kLoadingError;
     return nullptr;
   }
   // Need to let the function fiddle with the array.
   std::unique_ptr<char[]> copied_args(new char[args_.size() + 1]);
   strlcpy(copied_args.get(), args_.c_str(), args_.size() + 1);
   // TODO Need to do some checks that we are at a good spot etc.
   *call_res = callback(Runtime::Current()->GetJavaVM(),
                        copied_args.get(),
                        nullptr);
   if (*call_res != 0) {
     *error_msg = StringPrintf("Initialization of %s returned non-zero value of %d",
                               name_.c_str(), *call_res);
     VLOG(agents) << "err: " << *error_msg;
     *error = kInitializationError;
     return nullptr;
   }
   return agent;
 }

 std::unique_ptr<Agent> AgentSpec::DoDlOpen(JNIEnv* env,
                                            jobject class_loader,
                                            /*out*/LoadError* error,
                                            /*out*/std::string* error_msg) {
   DCHECK(error_msg != nullptr);

   ScopedLocalRef<jstring> library_path(env,
                                        class_loader == nullptr
                                            ? nullptr
                                            : JavaVMExt::GetLibrarySearchPath(env, class_loader));

   bool needs_native_bridge = false;
   std::string nativeloader_error_msg;
   void* dlopen_handle = android::OpenNativeLibrary(env,
                                                    Runtime::Current()->GetTargetSdkVersion(),
                                                    name_.c_str(),
                                                    class_loader,
                                                    library_path.get(),
                                                    &needs_native_bridge,
                                                    &nativeloader_error_msg);
   if (dlopen_handle == nullptr) {
     *error_msg = StringPrintf("Unable to dlopen %s: %s",
                               name_.c_str(),
                               nativeloader_error_msg.c_str());
     *error = kLoadingError;
     return nullptr;
   }
   if (needs_native_bridge) {
     // TODO: Consider support?
     // The result of this call and error_msg is ignored because the most
     // relevant error is that native bridge is unsupported.
     android::CloseNativeLibrary(dlopen_handle, needs_native_bridge, error_msg);
     *error_msg = StringPrintf("Native-bridge agents unsupported: %s", name_.c_str());
     *error = kLoadingError;
     return nullptr;
   }

   std::unique_ptr<Agent> agent(new Agent(name_, dlopen_handle));
   agent->PopulateFunctions();
   *error = kNoError;
   return agent;
 }

 std::ostream& operator<<(std::ostream &os, AgentSpec const& m) {
   return os << "AgentSpec { name=\"" << m.name_ << "\", args=\"" << m.args_ << "\" }";
 }


 void* Agent::FindSymbol(const std::string& name) const {
   CHECK(dlopen_handle_ != nullptr) << "Cannot find symbols in an unloaded agent library " << this;
   return dlsym(dlopen_handle_, name.c_str());
 }

 // TODO Lock some stuff probably.
 void Agent::Unload() {
   if (dlopen_handle_ != nullptr) {
     if (onunload_ != nullptr) {
       onunload_(Runtime::Current()->GetJavaVM());
     }
     // Don't actually android::CloseNativeLibrary since some agents assume they will never get
     // unloaded. Since this only happens when the runtime is shutting down anyway this isn't a big
     // deal.
     dlopen_handle_ = nullptr;
     onload_ = nullptr;
     onattach_ = nullptr;
     onunload_ = nullptr;
   } else {
     VLOG(agents) << this << " is not currently loaded!";
   }
 }

 Agent::Agent(Agent&& other) noexcept
     : dlopen_handle_(nullptr),
       onload_(nullptr),
       onattach_(nullptr),
       onunload_(nullptr) {
   *this = std::move(other);
 }

 Agent& Agent::operator=(Agent&& other) noexcept {
   if (this != &other) {
     if (dlopen_handle_ != nullptr) {
       Unload();
     }
     name_ = std::move(other.name_);
     dlopen_handle_ = other.dlopen_handle_;
     onload_ = other.onload_;
     onattach_ = other.onattach_;
     onunload_ = other.onunload_;
     other.dlopen_handle_ = nullptr;
     other.onload_ = nullptr;
     other.onattach_ = nullptr;
     other.onunload_ = nullptr;
   }
   return *this;
 }

 void Agent::PopulateFunctions() {
   onload_ = reinterpret_cast<AgentOnLoadFunction>(FindSymbol(AGENT_ON_LOAD_FUNCTION_NAME));
   if (onload_ == nullptr) {
     VLOG(agents) << "Unable to find 'Agent_OnLoad' symbol in " << this;
   }
   onattach_ = reinterpret_cast<AgentOnLoadFunction>(FindSymbol(AGENT_ON_ATTACH_FUNCTION_NAME));
   if (onattach_ == nullptr) {
     VLOG(agents) << "Unable to find 'Agent_OnAttach' symbol in " << this;
   }
   onunload_ = reinterpret_cast<AgentOnUnloadFunction>(FindSymbol(AGENT_ON_UNLOAD_FUNCTION_NAME));
   if (onunload_ == nullptr) {
     VLOG(agents) << "Unable to find 'Agent_OnUnload' symbol in " << this;
   }
 }

 Agent::~Agent() {
   if (dlopen_handle_ != nullptr) {
     Unload();
   }
 }

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

 std::ostream& operator<<(std::ostream &os, Agent const& m) {
   return os << "Agent { name=\"" << m.name_ << "\", handle=" << m.dlopen_handle_ << " }";
 }

 }  // namespace ti
 }  // 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 "agent.h"

	#include "android-base/stringprintf.h"
	#include "nativehelper/scoped_local_ref.h"
	#include "nativeloader/native_loader.h"

	#include "base/logging.h"
	#include "base/strlcpy.h"
	#include "jni/java_vm_ext.h"
	#include "runtime.h"
	#include "thread-current-inl.h"
	#include "scoped_thread_state_change-inl.h"

	namespace art {
	namespace ti {

	using android::base::StringPrintf;

	const char* AGENT_ON_LOAD_FUNCTION_NAME = "Agent_OnLoad";
	const char* AGENT_ON_ATTACH_FUNCTION_NAME = "Agent_OnAttach";
	const char* AGENT_ON_UNLOAD_FUNCTION_NAME = "Agent_OnUnload";

	AgentSpec::AgentSpec(const std::string& arg) {
	size_t eq = arg.find_first_of('=');
	if (eq == std::string::npos) {
	name_ = arg;
	} else {
	name_ = arg.substr(0, eq);
	args_ = arg.substr(eq + 1, arg.length());
	}
	}

	std::unique_ptr<Agent> AgentSpec::Load(/out/jint* call_res,
	/out/LoadError* error,
	/out/std::string* error_msg) {
	VLOG(agents) << "Loading agent: " << name_ << " " << args_;
	return DoLoadHelper(nullptr, false, nullptr, call_res, error, error_msg);
	}

	// Tries to attach the agent using its OnAttach method. Returns true on success.
	std::unique_ptr<Agent> AgentSpec::Attach(JNIEnv* env,
	jobject class_loader,
	/out/jint* call_res,
	/out/LoadError* error,
	/out/std::string* error_msg) {
	VLOG(agents) << "Attaching agent: " << name_ << " " << args_;
	return DoLoadHelper(env, true, class_loader, call_res, error, error_msg);
	}


	// TODO We need to acquire some locks probably.
	std::unique_ptr<Agent> AgentSpec::DoLoadHelper(JNIEnv* env,
	bool attaching,
	jobject class_loader,
	/out/jint* call_res,
	/out/LoadError* error,
	/out/std::string* error_msg) {
	ScopedThreadStateChange stsc(Thread::Current(), ThreadState::kNative);
	DCHECK(call_res != nullptr);
	DCHECK(error_msg != nullptr);

	std::unique_ptr<Agent> agent = DoDlOpen(env, class_loader, error, error_msg);
	if (agent == nullptr) {
	VLOG(agents) << "err: " << *error_msg;
	return nullptr;
	}
	AgentOnLoadFunction callback = attaching ? agent->onattach_ : agent->onload_;
	if (callback == nullptr) {
	*error_msg = StringPrintf("Unable to start agent %s: No %s callback found",
	(attaching ? "attach" : "load"),
	name_.c_str());
	VLOG(agents) << "err: " << *error_msg;
	*error = kLoadingError;
	return nullptr;
	}
	// Need to let the function fiddle with the array.
	std::unique_ptr<char[]> copied_args(new char[args_.size() + 1]);
	strlcpy(copied_args.get(), args_.c_str(), args_.size() + 1);
	// TODO Need to do some checks that we are at a good spot etc.
	*call_res = callback(Runtime::Current()->GetJavaVM(),
	copied_args.get(),
	nullptr);
	if (*call_res != 0) {
	*error_msg = StringPrintf("Initialization of %s returned non-zero value of %d",
	name_.c_str(), *call_res);
	VLOG(agents) << "err: " << *error_msg;
	*error = kInitializationError;
	return nullptr;
	}
	return agent;
	}

	std::unique_ptr<Agent> AgentSpec::DoDlOpen(JNIEnv* env,
	jobject class_loader,
	/out/LoadError* error,
	/out/std::string* error_msg) {
	DCHECK(error_msg != nullptr);

	ScopedLocalRef<jstring> library_path(env,
	class_loader == nullptr
	? nullptr
	: JavaVMExt::GetLibrarySearchPath(env, class_loader));

	bool needs_native_bridge = false;
	std::string nativeloader_error_msg;
	void* dlopen_handle = android::OpenNativeLibrary(env,
	Runtime::Current()->GetTargetSdkVersion(),
	name_.c_str(),
	class_loader,
	library_path.get(),
	&needs_native_bridge,
	&nativeloader_error_msg);
	if (dlopen_handle == nullptr) {
	*error_msg = StringPrintf("Unable to dlopen %s: %s",
	name_.c_str(),
	nativeloader_error_msg.c_str());
	*error = kLoadingError;
	return nullptr;
	}
	if (needs_native_bridge) {
	// TODO: Consider support?
	// The result of this call and error_msg is ignored because the most
	// relevant error is that native bridge is unsupported.
	android::CloseNativeLibrary(dlopen_handle, needs_native_bridge, error_msg);
	*error_msg = StringPrintf("Native-bridge agents unsupported: %s", name_.c_str());
	*error = kLoadingError;
	return nullptr;
	}

	std::unique_ptr<Agent> agent(new Agent(name_, dlopen_handle));
	agent->PopulateFunctions();
	*error = kNoError;
	return agent;
	}

	std::ostream& operator<<(std::ostream &os, AgentSpec const& m) {
	return os << "AgentSpec { name=\"" << m.name_ << "\", args=\"" << m.args_ << "\" }";
	}


	void* Agent::FindSymbol(const std::string& name) const {
	CHECK(dlopen_handle_ != nullptr) << "Cannot find symbols in an unloaded agent library " << this;
	return dlsym(dlopen_handle_, name.c_str());
	}

	// TODO Lock some stuff probably.
	void Agent::Unload() {
	if (dlopen_handle_ != nullptr) {
	if (onunload_ != nullptr) {
	onunload_(Runtime::Current()->GetJavaVM());
	}
	// Don't actually android::CloseNativeLibrary since some agents assume they will never get
	// unloaded. Since this only happens when the runtime is shutting down anyway this isn't a big
	// deal.
	dlopen_handle_ = nullptr;
	onload_ = nullptr;
	onattach_ = nullptr;
	onunload_ = nullptr;
	} else {
	VLOG(agents) << this << " is not currently loaded!";
	}
	}

	Agent::Agent(Agent&& other) noexcept
	: dlopen_handle_(nullptr),
	onload_(nullptr),
	onattach_(nullptr),
	onunload_(nullptr) {
	*this = std::move(other);
	}

	Agent& Agent::operator=(Agent&& other) noexcept {
	if (this != &other) {
	if (dlopen_handle_ != nullptr) {
	Unload();
	}
	name_ = std::move(other.name_);
	dlopen_handle_ = other.dlopen_handle_;
	onload_ = other.onload_;
	onattach_ = other.onattach_;
	onunload_ = other.onunload_;
	other.dlopen_handle_ = nullptr;
	other.onload_ = nullptr;
	other.onattach_ = nullptr;
	other.onunload_ = nullptr;
	}
	return *this;
	}

	void Agent::PopulateFunctions() {
	onload_ = reinterpret_cast<AgentOnLoadFunction>(FindSymbol(AGENT_ON_LOAD_FUNCTION_NAME));
	if (onload_ == nullptr) {
	VLOG(agents) << "Unable to find 'Agent_OnLoad' symbol in " << this;
	}
	onattach_ = reinterpret_cast<AgentOnLoadFunction>(FindSymbol(AGENT_ON_ATTACH_FUNCTION_NAME));
	if (onattach_ == nullptr) {
	VLOG(agents) << "Unable to find 'Agent_OnAttach' symbol in " << this;
	}
	onunload_ = reinterpret_cast<AgentOnUnloadFunction>(FindSymbol(AGENT_ON_UNLOAD_FUNCTION_NAME));
	if (onunload_ == nullptr) {
	VLOG(agents) << "Unable to find 'Agent_OnUnload' symbol in " << this;
	}
	}

	Agent::~Agent() {
	if (dlopen_handle_ != nullptr) {
	Unload();
	}
	}

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

	std::ostream& operator<<(std::ostream &os, Agent const& m) {
	return os << "Agent { name=\"" << m.name_ << "\", handle=" << m.dlopen_handle_ << " }";
	}

	} // namespace ti
	} // namespace art