Question

为什么以下程序会崩溃？

#include <QApplication>

#include <windows.h>
#include <QFrame>


uint MSGFLT_ADD = 1;
uint WM_COPYGLOBALDATA = 0x0049;

int main(int argc, char *argv[])
{
    BOOL (*ChangeWindowMessageFilter)(UINT,DWORD) = NULL;

    HINSTANCE hDLL = LoadLibraryA("User32.dll");               // Handle to DLL
    if (hDLL != NULL){
        ChangeWindowMessageFilter = (BOOL (*)(UINT,DWORD))GetProcAddress(hDLL, "ChangeWindowMessageFilter");
    }

    if (ChangeWindowMessageFilter != NULL){
        if (!(*ChangeWindowMessageFilter)(WM_DROPFILES, MSGFLT_ADD)){
            printf("Failed to add exception for WM_DROPFILES\n");
        }
        if (!(*ChangeWindowMessageFilter)(WM_COPYDATA, MSGFLT_ADD)){
            printf("Failed to add exception for WM_COPYDATA");
        }
        if (!(*ChangeWindowMessageFilter)(WM_COPYGLOBALDATA, MSGFLT_ADD)){
            printf("Failed to add exception for WM_COPYGLOBALDATA");
        }
        printf("Added filters\n");
        fflush(0);
    }
    if (hDLL != NULL){
        FreeLibrary(hDLL);
    }

    QApplication a(argc, argv);
    QFrame w; //debug crashes here
    w.show();

    return a.exec();
}

QFrame::QFrame(QWidget* parent, Qt::WindowFlags f)
    : QWidget(*new QFramePrivate, parent, f) //on this line in particular
{
    Q_D(QFrame);
    d->init();
}

编辑：

if (!(*ChangeWindowMessageFilter)(WM_COPYDATA, MSGFLT_ADD)){ //if i disable this everything works
    printf("Failed to add exception for WM_COPYDATA");
}

Answer 1

   BOOL (*ChangeWindowMessageFilter)(UINT,DWORD) = NULL;

您的函数指针声明错误。 Winapi函数总是__stdcall。毫无疑问，您的编译器使用默认的__cdecl。通过函数指针调用时获得的堆栈不平衡可能会产生许多副作用。如果您使用MSVC ++并运行Debug构建，那么您将始终立即获得诊断。修正：

   BOOL (WINAPI * ChangeWindowMessageFilter)(UINT,DWORD) = NULL;

Fwiw，如果这是为了实现拖放式升级程序，那么只需删除所有这些，它就不会起作用。 D + D是基于COM的，它不使用消息。

为什么ChangeWindowMessageFilter导致Qt崩溃？

1 个答案: