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// Copyright 2014 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/lock_state.h"
#include <windows.h>
#include <wtsapi32.h>
#include "base/functional/bind.h"
#include "base/no_destructor.h"
#include "ui/base/win/session_change_observer.h"
namespace ui {
namespace {
// Checks if the current session is locked.
bool IsSessionLocked() {
bool is_locked = false;
LPWSTR buffer = nullptr;
DWORD buffer_length = 0;
if (::WTSQuerySessionInformation(WTS_CURRENT_SERVER, WTS_CURRENT_SESSION,
WTSSessionInfoEx, &buffer, &buffer_length) &&
buffer_length >= sizeof(WTSINFOEXW)) {
auto* info = reinterpret_cast<WTSINFOEXW*>(buffer);
is_locked =
info->Data.WTSInfoExLevel1.SessionFlags == WTS_SESSIONSTATE_LOCK;
}
if (buffer)
::WTSFreeMemory(buffer);
return is_locked;
}
// Observes the screen lock state of Windows and caches the current state. This
// is necessary as IsSessionLocked uses WTSQuerySessionInformation internally,
// which is an expensive syscall and causes a performance regression as we query
// the current state quite often. http://crbug.com/940607.
class SessionLockedObserver {
public:
SessionLockedObserver()
: session_change_observer_(
base::BindRepeating(&SessionLockedObserver::OnSessionChange,
base::Unretained(this))),
screen_locked_(IsSessionLocked()) {}
SessionLockedObserver(const SessionLockedObserver&) = delete;
SessionLockedObserver& operator=(const SessionLockedObserver&) = delete;
bool IsLocked() const { return screen_locked_; }
private:
void OnSessionChange(WPARAM status_code, const bool* is_current_session) {
if (is_current_session && !*is_current_session)
return;
if (status_code == WTS_SESSION_UNLOCK)
screen_locked_ = false;
else if (status_code == WTS_SESSION_LOCK && is_current_session)
screen_locked_ = true;
}
SessionChangeObserver session_change_observer_;
bool screen_locked_;
};
} // namespace
bool IsWorkstationLocked() {
static const base::NoDestructor<SessionLockedObserver> observer;
return observer->IsLocked();
}
} // namespace ui
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