c - SetWindowLongPtr 似乎不起作用

Question

我尝试子类化另一个窗口(在另一个进程中)，因此我注入(inject)了一个 dll，它调用 SetWindowLongPtr，但它失败并且 GetLastError 返回 5。

BOOL APIENTRY DllMain (HANDLE hDll, DWORD dwReason, LPVOID lpReserved)
{
    switch (dwReason)
    {
        case DLL_PROCESS_ATTACH:
        {
            HWND hwnd = GetHwndProc();

            if (!(orgWndProc = (WNDPROC)SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR)SubclassProc)))
            {
                char buf[40];
                sprintf(buf, "Error code: %d", GetLastError());
                MessageBox(hwnd, buf, "Error", MB_OK);
            }   
            break;
        }
    }
    return TRUE;
}

编辑:它绝对是正确的 PID。

编辑2:我得到了错误的HWND，但现在已修复(也编辑了代码)我不再收到错误 5(来自 GetLastError)

    HWND GetHwndProc()
{
    HWND hwnd = GetTopWindow(NULL);
    DWORD currentPID = GetCurrentProcessId();
    do
    {
        char title[256];
        if ((GetWindowText(hwnd, title, 256) > 0) && (IsWindowVisible(hwnd)))
        {
            DWORD procId;
            GetWindowThreadProcessId(hwnd, &procId);

            if (procId == currentPID)   
            {
                MessageBox(hwnd, title, "", MB_OK);
                return hwnd;
            }
        }

        hwnd = GetNextWindow(hwnd, GW_HWNDNEXT);
    } while (hwnd);
}

WNDPROC orgWndProc;
LRESULT APIENTRY SubclassProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
        case WM_LBUTTONDOWN:
            MessageBox(0, "Subclass", "", 0);
            return TRUE;

        default:
            return CallWindowProc(orgWndProc, hwnd, msg, wParam, lParam);
    }
}

感谢您的阅读!

Answer 1

您需要从创建窗口的线程调用SetWindowSubclass，与之关联的消息队列在该线程中运行。来自SetWindowSubclass reference :

Warning You cannot use the subclassing helper functions to subclass a window across threads.

反过来，SetWindowLongPtr 必须从创建窗口的进程中调用。来自SetWindowLongPtr reference :

Windows XP/2000: The SetWindowLongPtr function fails if the window specified by the hWnd parameter does not belong to the same process as the calling thread.

还有用户界面权限隔离，它进一步限制访问。