C ++：响应Windows注销的清除操作 [英] C++: cleanup actions in response to Windows logoff

问题描述

我想捕捉Windows注销事件，以便我可以做一些清理。我的 WindowProc 看起来像这样：

I want to catch a Windows logoff event so that I can do some cleanup. My WindowProc looks like this:

switch (uMsg){
case WM_ENDSESSION:
case WM_DESTROY:
    PostQuitMessage(0);
    return 0;
// other messages
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);

并且 WinMain 中的消息循环看起来像this：

and the message loop in WinMain looks like this:

for(;;){
    bool bTerminate = false;
    while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)){
        if(msg.message == WM_QUIT){
            bTerminate = true;
        }
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    if(bTerminate){
        break;
    }
    // do other stuff
    Sleep(10);
}
FILE * fout;
fopen_s(&fout, "C:\\success.txt", "w"); // simulating cleanup actions
fclose(fout);
ExitProcess(0);

目的机制是 WindowProc code> PostQuitMessage ，导致主消息循环接收 WM_QUIT ，中断循环并将程序发送到清除。当我退出程序（因此发送 WM_DESTROY ）程序创建 success.txt ，但当程序运行时，我注销（发送 WM_ENDSESSION ），但没有。

The intended mechanism is that WindowProc does PostQuitMessage, causing the main message loop to receive WM_QUIT, breaking the loop and sending the program to cleanup. When I exit the program (thus sending WM_DESTROY) the program creates success.txt, but when the program is running and I log off (sending WM_ENDSESSION), it does not.

我看过 WM_QUERYENDSESSION ，但 MSDN 说每个应用程序应在收到此消息后立即返回 TRUE 或 FALSE ，并延迟任何清除操作，直到它收到 WM_ENDSESSION 消息。

I have looked at WM_QUERYENDSESSION as well, but MSDN says "Each application should return TRUE or FALSE immediately upon receiving this message, and defer any cleanup operations until it receives the WM_ENDSESSION message."

推荐答案

WM_ENDSESSION 处理实际上不会让应用程序退出消息循环。您应该假设系统在发送 WM_ENDSESSION 消息后调用TerminateProcess。

WM_ENDSESSION processing doesn't actually give your application a chance to exit the message loop. You should assume the system calls TerminateProcess after sending the WM_ENDSESSION message.

因此，您的应用程序需要清理要在从窗口过程返回之前执行。

Therefore, any clean-up your application needs to perform should be done before returning from the window procedure.

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