/*
* 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/strlcpy.h"
#include "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?
android::CloseNativeLibrary(dlopen_handle, needs_native_bridge);
*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)
: dlopen_handle_(nullptr),
onload_(nullptr),
onattach_(nullptr),
onunload_(nullptr) {
*this = std::move(other);
}
Agent& Agent::operator=(Agent&& other) {
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