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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 "chromeos/ash/components/dbus/services/cros_dbus_service.h"
#include <stddef.h>
#include <memory>
#include <utility>
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/memory/raw_ptr.h"
#include "base/system/sys_info.h"
#include "dbus/bus.h"
#include "dbus/exported_object.h"
#include "dbus/object_path.h"
namespace ash {
// The CrosDBusService implementation used in production, and unit tests.
class CrosDBusServiceImpl : public CrosDBusService {
public:
CrosDBusServiceImpl(dbus::Bus* bus,
const std::string& service_name,
const dbus::ObjectPath& object_path,
ServiceProviderList service_providers)
: service_started_(false),
origin_thread_id_(base::PlatformThread::CurrentId()),
bus_(bus),
service_name_(service_name),
object_path_(object_path),
service_providers_(std::move(service_providers)) {
DCHECK(bus);
DCHECK(!service_name_.empty());
DCHECK(object_path_.IsValid());
}
CrosDBusServiceImpl(const CrosDBusServiceImpl&) = delete;
CrosDBusServiceImpl& operator=(const CrosDBusServiceImpl&) = delete;
~CrosDBusServiceImpl() override = default;
// Starts the D-Bus service.
void Start() {
// Make sure we're running on the origin thread (i.e. the UI thread in
// production).
DCHECK(OnOriginThread());
DCHECK(!service_started_);
// Methods must be exported before RequestOwnership is called:
// https://crbug.com/874978
exported_object_ = bus_->GetExportedObject(object_path_);
for (const auto& provider : service_providers_)
provider->Start(exported_object_);
// There are some situations, described in http://crbug.com/234382#c27,
// where processes on Linux can wind up stuck in an uninterruptible state
// for tens of seconds. If this happens when Chrome is trying to exit, this
// unkillable process can wind up clinging to ownership of |service_name_|
// while the system is trying to restart the browser. This leads to a fatal
// situation if we don't allow the new browser instance to replace the old
// as the owner of |service_name_| as seen in http://crbug.com/234382.
// Hence, REQUIRE_PRIMARY_ALLOW_REPLACEMENT.
bus_->RequestOwnership(service_name_,
dbus::Bus::REQUIRE_PRIMARY_ALLOW_REPLACEMENT,
base::BindOnce(&CrosDBusServiceImpl::OnOwnership,
base::Unretained(this)));
service_started_ = true;
}
private:
// Returns true if the current thread is on the origin thread.
bool OnOriginThread() {
return base::PlatformThread::CurrentId() == origin_thread_id_;
}
// Called when an ownership request is completed.
void OnOwnership(const std::string& service_name,
bool success) {
LOG_IF(FATAL, !success) << "Failed to own: " << service_name;
}
bool service_started_;
base::PlatformThreadId origin_thread_id_;
raw_ptr<dbus::Bus> bus_;
std::string service_name_;
dbus::ObjectPath object_path_;
scoped_refptr<dbus::ExportedObject> exported_object_;
// Service providers that form CrosDBusService.
ServiceProviderList service_providers_;
};
// The stub CrosDBusService implementation used on Linux desktop,
// which does nothing as of now.
class CrosDBusServiceStubImpl : public CrosDBusService {
public:
CrosDBusServiceStubImpl() = default;
CrosDBusServiceStubImpl(const CrosDBusServiceStubImpl&) = delete;
CrosDBusServiceStubImpl& operator=(const CrosDBusServiceStubImpl&) = delete;
~CrosDBusServiceStubImpl() override = default;
};
// static
std::unique_ptr<CrosDBusService> CrosDBusService::Create(
dbus::Bus* system_bus,
const std::string& service_name,
const dbus::ObjectPath& object_path,
ServiceProviderList service_providers) {
if (!system_bus)
return std::make_unique<CrosDBusServiceStubImpl>();
return CreateRealImpl(system_bus, service_name, object_path,
std::move(service_providers));
}
// static
CrosDBusService::ServiceProviderList CrosDBusService::CreateServiceProviderList(
std::unique_ptr<ServiceProviderInterface> provider) {
ServiceProviderList list;
list.push_back(std::move(provider));
return list;
}
// static
std::unique_ptr<CrosDBusService> CrosDBusService::CreateRealImpl(
dbus::Bus* bus,
const std::string& service_name,
const dbus::ObjectPath& object_path,
ServiceProviderList service_providers) {
auto service = std::make_unique<CrosDBusServiceImpl>(
bus, service_name, object_path, std::move(service_providers));
service->Start();
return std::move(service);
}
CrosDBusService::~CrosDBusService() = default;
CrosDBusService::CrosDBusService() = default;
CrosDBusService::ServiceProviderInterface::~ServiceProviderInterface() =
default;
} // namespace ash
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