是否可以检测到 Windows 上的注销已中止？

Question

我想知道是否可以以编程方式重新启动在关闭开始时已终止的应用程序，该应用程序将在以后取消。
在 Windows 上，如果应用程序在关机时调用 ShutdownBlockReasonCreate，它可以通过检查 ENDSESSION_CRITICAL 位是否设置来了解用户是否取消了或没有 lParam.
就我而言，我不想想要阻止任何关机。

这可能吗？感谢您的任何建议。

Answer 1

我想我找到了解决方案：

我使用CreateWindowEx 创建了一个隐藏窗口来处理WM_QUERYENDSESSION 和WM_ENDSESSION 消息：

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_QUERYENDSESSION:
        {
            //clean up ...

            ShutdownBlockReasonCreate(hwnd, L"      ");
            // What ? You said you don't want to block the shutdown ?
            // Yes I do. It seems to work different with a hidden window.

            return 1;
        }
        case WM_ENDSESSION:
        {
            // GetSystemMetrics(SM_SHUTTINGDOWN) return Nonzero if the current session is shutting down
            // This loop waits for the user to cancel the shutdown
            while(GetSystemMetrics(SM_SHUTTINGDOWN) != 0)
               Sleep(100);
            // The user has cancelled the shutdown here
            // I can run the process again using CreateProcess or what ever...
            // Once this line is executed this instance will be terminated

        return 0;
        }
        default:
        return DefWindowProc(hwnd, msg, wParam, lParam);
    }
}

return 值非常重要（请参阅this）。
出乎我的意料，一个没有顶层可见窗口的进程，即使调用ShutdownBlockReasonCreate（带有隐藏窗口句柄），也不会显示在阻止关机的应用程序列表中。如果没有其他应用程序阻止关闭，Windows 只会等待几秒钟，然后关闭。

对于循环，我从here 获得了这个想法。不知道有没有更好的选择。

就是这样。

请测试一下，如果我错了，请纠正我。 谢谢。

[编辑] 这是准备测试的主要程序：

#include <string>
#include <Windows.h>

using namespace std;

string getExePath()
{
    TCHAR wpath[MAX_PATH];
    GetModuleFileName (NULL, wpath, MAX_PATH);
    size_t i;
    char path[MAX_PATH];
    wcstombs_s(&i, path, MAX_PATH, wpath, MAX_PATH);

    return path;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_QUERYENDSESSION:
        {
            // A shutdown has been initiated
            ShutdownBlockReasonCreate(hwnd, L"      ");

            return 1;
        }
        case WM_ENDSESSION:
        {
            // GetSystemMetrics(SM_SHUTTINGDOWN) return Nonzero if the current session is shutting down
            // This loop waits for the user to cancel the shutdown

            while(GetSystemMetrics(SM_SHUTTINGDOWN) != 0)
               Sleep(100);            

            // The user has cancelled the shutdown here
            // I can run the process again

            WinExec(string("\"" + getExePath() + "\"").c_str(), SW_HIDE);

            TerminateProcess(OpenProcess(PROCESS_TERMINATE, FALSE, GetCurrentProcessId()), 0);

        return 0;
        }
        default:
        return DefWindowProc(hwnd, msg, wParam, lParam);
    }
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    HWND hwnd;
    WNDCLASSEXA wc;

    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wc.lpszClassName = "TestShutDownAbortClass";
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    if( RegisterClassExA(&wc) == 0 )
        return 1;

    hwnd = CreateWindowExA(0,"TestShutDownAbortClass", "", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,NULL, NULL, hInstance, NULL);

    if(hwnd == NULL)
        return 1;

    MSG msg;
    while(GetMessageA(&msg, hwnd, 0, 0) > 0)
    {
        TranslateMessage(&msg);
        DispatchMessageA(&msg);
    }


    return 0;
}