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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/base/win/session_change_observer.h"
#include <wtsapi32.h>
#include <memory>
#include <utility>
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/functional/callback_helpers.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/memory/singleton.h"
#include "base/observer_list.h"
#include "base/task/thread_pool.h"
#include "ui/gfx/win/singleton_hwnd.h"
#include "ui/gfx/win/singleton_hwnd_observer.h"
namespace ui {
class SessionChangeObserver::WtsRegistrationNotificationManager {
public:
static WtsRegistrationNotificationManager* GetInstance() {
return base::Singleton<WtsRegistrationNotificationManager>::get();
}
WtsRegistrationNotificationManager() {
DCHECK(!singleton_hwnd_observer_);
singleton_hwnd_observer_ = std::make_unique<gfx::SingletonHwndObserver>(
base::BindRepeating(&WtsRegistrationNotificationManager::OnWndProc,
base::Unretained(this)));
base::OnceClosure wts_register =
base::BindOnce(base::IgnoreResult(&WTSRegisterSessionNotification),
gfx::SingletonHwnd::GetInstance()->hwnd(),
DWORD{NOTIFY_FOR_THIS_SESSION});
base::ThreadPool::CreateCOMSTATaskRunner({})->PostTask(
FROM_HERE, std::move(wts_register));
}
WtsRegistrationNotificationManager(
const WtsRegistrationNotificationManager&) = delete;
WtsRegistrationNotificationManager& operator=(
const WtsRegistrationNotificationManager&) = delete;
~WtsRegistrationNotificationManager() { RemoveSingletonHwndObserver(); }
void AddObserver(SessionChangeObserver* observer) {
DCHECK(singleton_hwnd_observer_);
observer_list_.AddObserver(observer);
}
void RemoveObserver(SessionChangeObserver* observer) {
observer_list_.RemoveObserver(observer);
}
private:
friend struct base::DefaultSingletonTraits<
WtsRegistrationNotificationManager>;
void OnWndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
switch (message) {
case WM_WTSSESSION_CHANGE:
if (wparam == WTS_SESSION_LOCK || wparam == WTS_SESSION_UNLOCK) {
bool is_current_session;
const bool* is_current_session_ptr = &is_current_session;
DWORD current_session_id = 0;
if (!::ProcessIdToSessionId(::GetCurrentProcessId(),
¤t_session_id)) {
PLOG(ERROR) << "ProcessIdToSessionId failed";
is_current_session_ptr = nullptr;
} else {
is_current_session =
(static_cast<DWORD>(lparam) == current_session_id);
}
for (SessionChangeObserver& observer : observer_list_)
observer.OnSessionChange(wparam, is_current_session_ptr);
}
break;
case WM_DESTROY:
RemoveSingletonHwndObserver();
break;
}
}
void RemoveSingletonHwndObserver() {
if (!singleton_hwnd_observer_)
return;
singleton_hwnd_observer_.reset(nullptr);
// There is no race condition between this code and the worker thread.
// RemoveSingletonHwndObserver is only called from two places:
// 1) Destruction due to Singleton Destruction.
// 2) WM_DESTROY fired by SingletonHwnd.
// Under both cases we are in shutdown, which means no other worker threads
// can be running.
WTSUnRegisterSessionNotification(gfx::SingletonHwnd::GetInstance()->hwnd());
for (SessionChangeObserver& observer : observer_list_)
observer.ClearCallback();
}
base::ObserverList<SessionChangeObserver, true>::Unchecked observer_list_;
std::unique_ptr<gfx::SingletonHwndObserver> singleton_hwnd_observer_;
};
SessionChangeObserver::SessionChangeObserver(const WtsCallback& callback)
: callback_(callback) {
DCHECK(!callback_.is_null());
WtsRegistrationNotificationManager::GetInstance()->AddObserver(this);
}
SessionChangeObserver::~SessionChangeObserver() {
ClearCallback();
}
void SessionChangeObserver::OnSessionChange(WPARAM wparam,
const bool* is_current_session) {
callback_.Run(wparam, is_current_session);
}
void SessionChangeObserver::ClearCallback() {
if (!callback_.is_null()) {
callback_.Reset();
WtsRegistrationNotificationManager::GetInstance()->RemoveObserver(this);
}
}
} // namespace ui
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