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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "dbus/exported_object.h"
#include <stdint.h>
#include <string>
#include <utility>
#include "base/check.h"
#include "base/containers/contains.h"
#include "base/debug/crash_logging.h"
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/task_runner.h"
#include "base/threading/thread_restrictions.h"
#include "dbus/bus.h"
#include "dbus/error.h"
#include "dbus/message.h"
#include "dbus/object_path.h"
#include "dbus/scoped_dbus_error.h"
#include "dbus/util.h"
namespace dbus {
namespace {
// Helper to ensure the wrapped `ResponseSender` is invoked. To use it, use the
// factory method to create wrapping callback owning an instance of this class.
// The wrapping callback must run. Otherwise, CHECK in destructor will trigger.
class ResponseSenderWrapper {
public:
ResponseSenderWrapper(std::string interface,
std::string member,
ExportedObject::ResponseSender sender)
: interface_(std::move(interface)),
member_(std::move(member)),
sender_(std::move(sender)) {}
ResponseSenderWrapper(ResponseSenderWrapper&) = delete;
ResponseSenderWrapper& operator&(ResponseSenderWrapper&) = delete;
~ResponseSenderWrapper() {
SCOPED_CRASH_KEY_STRING32("ResponseSenderWrapper", "DBusInterface",
interface_);
SCOPED_CRASH_KEY_STRING32("ResponseSenderWrapper", "DBusMember", member_);
// `sender_` must have run (or not set).
LOG_IF(FATAL, !sender_.is_null())
<< "ResponseSender did not run for " << interface_ << "." << member_;
}
// Convenience factory.
static ExportedObject::ResponseSender Create(
std::string interface,
std::string member,
ExportedObject::ResponseSender sender) {
return base::BindOnce(
&ResponseSenderWrapper::RunSender,
std::make_unique<ResponseSenderWrapper>(
std::move(interface), std::move(member), std::move(sender)));
}
private:
void RunSender(std::unique_ptr<Response> response) {
CHECK(sender_);
std::move(sender_).Run(std::move(response));
}
const std::string interface_;
const std::string member_;
ExportedObject::ResponseSender sender_;
};
} // namespace
ExportedObject::ExportedObject(Bus* bus,
const ObjectPath& object_path)
: bus_(bus),
object_path_(object_path),
object_is_registered_(false) {
LOG_IF(FATAL, !object_path_.IsValid()) << object_path_.value();
}
ExportedObject::~ExportedObject() {
DCHECK(!object_is_registered_);
}
bool ExportedObject::ExportMethodAndBlock(
const std::string& interface_name,
const std::string& method_name,
const MethodCallCallback& method_call_callback) {
bus_->AssertOnDBusThread();
// Check if the method is already exported.
const std::string absolute_method_name =
GetAbsoluteMemberName(interface_name, method_name);
if (base::Contains(method_table_, absolute_method_name)) {
LOG(ERROR) << absolute_method_name << " is already exported";
return false;
}
if (!bus_->Connect())
return false;
if (!bus_->SetUpAsyncOperations())
return false;
if (!Register())
return false;
// Add the method callback to the method table.
method_table_[absolute_method_name] = method_call_callback;
return true;
}
bool ExportedObject::UnexportMethodAndBlock(const std::string& interface_name,
const std::string& method_name) {
bus_->AssertOnDBusThread();
const std::string absolute_method_name =
GetAbsoluteMemberName(interface_name, method_name);
MethodTable::const_iterator iter = method_table_.find(absolute_method_name);
if (iter == method_table_.end()) {
LOG(ERROR) << absolute_method_name << " is not exported";
return false;
}
method_table_.erase(iter);
return true;
}
void ExportedObject::ExportMethod(
const std::string& interface_name,
const std::string& method_name,
const MethodCallCallback& method_call_callback,
OnExportedCallback on_exported_callback) {
bus_->AssertOnOriginThread();
base::OnceClosure task = base::BindOnce(
&ExportedObject::ExportMethodInternal, this, interface_name, method_name,
method_call_callback, std::move(on_exported_callback));
bus_->GetDBusTaskRunner()->PostTask(FROM_HERE, std::move(task));
}
void ExportedObject::UnexportMethod(
const std::string& interface_name,
const std::string& method_name,
OnUnexportedCallback on_unexported_callback) {
bus_->AssertOnOriginThread();
base::OnceClosure task = base::BindOnce(
&ExportedObject::UnexportMethodInternal, this, interface_name,
method_name, std::move(on_unexported_callback));
bus_->GetDBusTaskRunner()->PostTask(FROM_HERE, std::move(task));
}
void ExportedObject::SendSignal(Signal* signal) {
// For signals, the object path should be set to the path to the sender
// object, which is this exported object here.
CHECK(signal->SetPath(object_path_));
// Increment the reference count so we can safely reference the
// underlying signal message until the signal sending is complete. This
// will be unref'ed in SendSignalInternal().
DBusMessage* signal_message = signal->raw_message();
dbus_message_ref(signal_message);
if (bus_->GetDBusTaskRunner()->RunsTasksInCurrentSequence()) {
// The Chrome OS power manager doesn't use a dedicated TaskRunner for
// sending DBus messages. Sending signals asynchronously can cause an
// inversion in the message order if the power manager calls
// ObjectProxy::CallMethodAndBlock() before going back to the top level of
// the MessageLoop: crbug.com/472361.
SendSignalInternal(signal_message);
} else {
bus_->GetDBusTaskRunner()->PostTask(
FROM_HERE, base::BindOnce(&ExportedObject::SendSignalInternal, this,
signal_message));
}
}
void ExportedObject::Unregister() {
bus_->AssertOnDBusThread();
if (!object_is_registered_)
return;
bus_->UnregisterObjectPath(object_path_);
object_is_registered_ = false;
}
void ExportedObject::ExportMethodInternal(
const std::string& interface_name,
const std::string& method_name,
const MethodCallCallback& method_call_callback,
OnExportedCallback on_exported_callback) {
bus_->AssertOnDBusThread();
const bool success = ExportMethodAndBlock(interface_name,
method_name,
method_call_callback);
bus_->GetOriginTaskRunner()->PostTask(
FROM_HERE, base::BindOnce(&ExportedObject::OnExported, this,
std::move(on_exported_callback), interface_name,
method_name, success));
}
void ExportedObject::UnexportMethodInternal(
const std::string& interface_name,
const std::string& method_name,
OnUnexportedCallback on_unexported_callback) {
bus_->AssertOnDBusThread();
const bool success = UnexportMethodAndBlock(interface_name, method_name);
bus_->GetOriginTaskRunner()->PostTask(
FROM_HERE, base::BindOnce(&ExportedObject::OnUnexported, this,
std::move(on_unexported_callback),
interface_name, method_name, success));
}
void ExportedObject::OnExported(OnExportedCallback on_exported_callback,
const std::string& interface_name,
const std::string& method_name,
bool success) {
bus_->AssertOnOriginThread();
std::move(on_exported_callback).Run(interface_name, method_name, success);
}
void ExportedObject::OnUnexported(OnExportedCallback on_unexported_callback,
const std::string& interface_name,
const std::string& method_name,
bool success) {
bus_->AssertOnOriginThread();
std::move(on_unexported_callback).Run(interface_name, method_name, success);
}
void ExportedObject::SendSignalInternal(DBusMessage* signal_message) {
uint32_t serial = 0;
bus_->Send(signal_message, &serial);
dbus_message_unref(signal_message);
}
bool ExportedObject::Register() {
bus_->AssertOnDBusThread();
if (object_is_registered_)
return true;
Error error;
DBusObjectPathVTable vtable = {};
vtable.message_function = &ExportedObject::HandleMessageThunk;
vtable.unregister_function = &ExportedObject::OnUnregisteredThunk;
const bool success =
bus_->TryRegisterObjectPath(object_path_, &vtable, this, &error);
if (!success) {
LOG(ERROR) << "Failed to register the object: " << object_path_.value()
<< ": " << error.message();
return false;
}
object_is_registered_ = true;
return true;
}
DBusHandlerResult ExportedObject::HandleMessage(
DBusConnection* connection,
DBusMessage* raw_message) {
bus_->AssertOnDBusThread();
// ExportedObject only handles method calls. Ignore other message types (e.g.
// signal).
if (dbus_message_get_type(raw_message) != DBUS_MESSAGE_TYPE_METHOD_CALL)
return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
// raw_message will be unrefed on exit of the function. Increment the
// reference so we can use it in MethodCall.
dbus_message_ref(raw_message);
std::unique_ptr<MethodCall> method_call(
MethodCall::FromRawMessage(raw_message));
std::string interface = method_call->GetInterface();
std::string member = method_call->GetMember();
if (interface.empty()) {
// We don't support method calls without interface.
LOG(WARNING) << "Interface is missing: " << method_call->ToString();
return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
}
// Check if we know about the method.
const std::string absolute_method_name = GetAbsoluteMemberName(
interface, member);
MethodTable::const_iterator iter = method_table_.find(absolute_method_name);
if (iter == method_table_.end()) {
// Don't know about the method.
LOG(WARNING) << "Unknown method: " << method_call->ToString();
return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
}
if (bus_->HasDBusThread()) {
// Post a task to run the method in the origin thread.
bus_->GetOriginTaskRunner()->PostTask(
FROM_HERE, base::BindOnce(&ExportedObject::RunMethod, this,
iter->second, std::move(method_call)));
} else {
// If the D-Bus thread is not used, just call the method directly.
RunMethod(iter->second, std::move(method_call));
}
// It's valid to say HANDLED here, and send a method response at a later
// time from OnMethodCompleted() asynchronously.
return DBUS_HANDLER_RESULT_HANDLED;
}
void ExportedObject::RunMethod(const MethodCallCallback& method_call_callback,
std::unique_ptr<MethodCall> method_call) {
bus_->AssertOnOriginThread();
MethodCall* method = method_call.get();
// Edge case that `method_call_callback` may be canceled when the method
// call message is processed. Send an error response.
if (method_call_callback.IsCancelled()) {
SendResponse(std::move(method_call), ErrorResponse::FromMethodCall(
method, DBUS_ERROR_UNKNOWN_METHOD,
"Method is no longer available"));
return;
}
method_call_callback.Run(
method, ResponseSenderWrapper::Create(
method->GetInterface(), method->GetMember(),
base::BindOnce(&ExportedObject::SendResponse, this,
std::move(method_call))));
}
void ExportedObject::SendResponse(std::unique_ptr<MethodCall> method_call,
std::unique_ptr<Response> response) {
DCHECK(method_call);
if (bus_->HasDBusThread()) {
bus_->GetDBusTaskRunner()->PostTask(
FROM_HERE, base::BindOnce(&ExportedObject::OnMethodCompleted, this,
std::move(method_call), std::move(response)));
} else {
OnMethodCompleted(std::move(method_call), std::move(response));
}
}
void ExportedObject::OnMethodCompleted(std::unique_ptr<MethodCall> method_call,
std::unique_ptr<Response> response) {
bus_->AssertOnDBusThread();
// Check if the bus is still connected. If the method takes long to
// complete, the bus may be shut down meanwhile.
if (!bus_->IsConnected())
return;
if (!response) {
// Something bad happened in the method call.
std::unique_ptr<ErrorResponse> error_response(ErrorResponse::FromMethodCall(
method_call.get(), DBUS_ERROR_FAILED,
"error occurred in " + method_call->GetMember()));
bus_->Send(error_response->raw_message(), nullptr);
return;
}
// The method call was successful.
bus_->Send(response->raw_message(), nullptr);
}
void ExportedObject::OnUnregistered(DBusConnection* connection) {
}
DBusHandlerResult ExportedObject::HandleMessageThunk(
DBusConnection* connection,
DBusMessage* raw_message,
void* user_data) {
ExportedObject* self = reinterpret_cast<ExportedObject*>(user_data);
return self->HandleMessage(connection, raw_message);
}
void ExportedObject::OnUnregisteredThunk(DBusConnection *connection,
void* user_data) {
ExportedObject* self = reinterpret_cast<ExportedObject*>(user_data);
return self->OnUnregistered(connection);
}
} // namespace dbus
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