integer divide by zero in CreateDlgIndirect()

From:

".rhavin grobert" <clqrq@yahoo.de>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 23 Oct 2008 08:45:02 -0700 (PDT)

Message-ID:

<cd04b6e2-b9e9-4f72-bda8-522e5b1c56af@m74g2000hsh.googlegroups.com>

I experience an integer divide by zero while trying to create a
modeless
dialog from an mfc-dll that is called from a windowless exe. I tried
to
give a step-by-step overview and hope someone can explain what causes
this error and what can be done about it. TIA, ~.rhavin;)

=====================================================

1. windowless exe loads dll, calling InitInstance()
    HINSTANCE is 0x10000000.
2. InitInstance() registers HWND_MESSAGE-parent'ed msg-window
3. Msg-window opened (only window that app has now)
4. Message send to msg-window "please open dialog (whatever)"
5. Message correctly received by msg-loop and appropriate fn called,
    that looks like the following:
_______________________________________________________

void CFZGUIManager::DlgMessage()
{
    CQDlgMessage* pDlg = new CQDlgMessage;
    VERIFY(pDlg->Create());
    // ... //
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

6. Dialog allocated (new) CQDlgMessage ctor called.
7. CQDlgMessage is a public CQDialog that is a public CDialog
    CQDialog has following ctor and saves its ResourceID:
_______________________________________________________
CQDialog::CQDialog(UINT nResourceID, CWnd* pParent) :
m_nResourceID(nResourceID), CDialog(nResourceID, pParent) {}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

7. CQDialog has a Create() fn that looks like this:
______________________________________________________

bool CQDialog::Create(CWnd* pParent)
    if (pParent == NULL)
        pParent = AfxGetMainWnd();

    if (pParent == NULL)
        pParent = GetDesktopWindow();

    // #: * see below* //

    return (CDialog::Create(m_nResourceID, pParent) != FALSE);
};
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

8. At "#", the pParent is set to desktop, because app has no
    main window (pParent = [CTempWnd hWnd=0x00010014]).
9. CDialog::Create() is called with correct RsrcID.
10. in CDialog::Create(), AfxFindResourceHandle() is called,
    returning HINSTANCE 0x10000000, then FindResource() and
    LoadResource() are called, both returning values != NULL
11. Now CreateIndirect() is called.
    hDialogTemplate is 0x101b52b0
    pParentWnd is 0x0099d5c0 (hWnd = 0x00010014, Desktop)
    hInstance is 0x10000000
12. hDialogTemplate is locked (LockResource()) and another
    CreateIndirect() overload is called witch calles (finally!)
    CreateDlgIndirect(), where the following happens:
    ( a # marks my own comments ...)
______________________________________________________

BOOL CWnd::CreateDlgIndirect(LPCDLGTEMPLATE
    lpDialogTemplate, CWnd* pParentWnd, HINSTANCE hInst)
{
    ASSERT(lpDialogTemplate != NULL); //# -> OK
    if (pParentWnd != NULL)
        ASSERT_VALID(pParentWnd); //# -> OK

    if (hInst == NULL) //# -> hInst != NULL
        hInst = AfxGetInstanceHandle();

    _AFX_OCC_DIALOG_INFO occDialogInfo;
    COccManager* pOccManager = afxOccManager; //# ->NULL

    HGLOBAL hTemplate = NULL;

    HWND hWnd = NULL;
    DWORD dwError = 0;

    TRY
    {
        VERIFY(AfxDeferRegisterClass(
            AFX_WNDCOMMCTLS_REG)
        ); //# -> OK

        AfxDeferRegisterClass(
            AFX_WNDCOMMCTLSNEW_REG
        ); //# -> seems ok

        if (pOccManager != NULL)
        {
            //# ... is NULL, so nothing done here! ... #//
        }

        if (lpDialogTemplate == NULL) //# -> is != NULL
            return FALSE;

        // If no font specified, set the system font.
        CString strFace;
        WORD wSize = 0;
        BOOL bSetSysFont = !CDialogTemplate::GetFont(
            lpDialogTemplate, strFace, wSize);
        //# -> bSetSysFont set to FALSE

        //#... some stuff not called omitted here ... #//

        // setup for modal loop and creation
        m_nModalResult = -1;
        m_nFlags |= WF_CONTINUEMODAL;

        //# m_nFlags now == WF_CONTINUEMODAL;

        // create modeless dialog
        AfxHookWindowCreate(this); //# -> seems OK

//# ++++++++++++++++++++++++++++++++++++++++++++
//# following call (cant trace it any further) gives this message:
//# "Unhandled exeption in [myApp] (NTDLL.DLL):
//# 0xC0000094: Integer Divide by Zero"
//# ++++++++++++++++++++++++++++++++++++++++++++

        hWnd = ::CreateDialogIndirect(hInst, lpDialogTemplate,
            pParentWnd->GetSafeHwnd(), AfxDlgProc);
        // ...... //
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~