Re: Why does this cause "data abort" ?

From:

"Lisa Pearlson" <no@spam.plz>

Newsgroups:

microsoft.public.vc.language

Date:

Wed, 24 Oct 2007 17:57:29 +0200

Message-ID:

<#fVa7YlFIHA.1324@TK2MSFTNGP06.phx.gbl>

Should this be __stdcall?

No, MSFT documentation defines it without that..

Maybe there is some stack corruption due to uncorrect calling conventions?

Yes, I am wondering about something like this..
The exported function is called by its Ordinal, so that succeeds, but
unclear what happens with rest of the code.
It may be CE specific issue.

Lisa

"Giovanni Dicanio" <giovanni.dicanio@invalid.it> wrote in message
news:O8h5ohkFIHA.936@TK2MSFTNGP06.phx.gbl...

"Lisa Pearlson" <no@spam.plz> ha scritto nel messaggio
news:uyyHzvjFIHA.1204@TK2MSFTNGP03.phx.gbl...

// sample class
class CMyWnd
{
public:
   CMyWnd() :
           m_hWnd(NULL), m_lpszClassName(NULL),
           m_hInstance(NULL), m_hIcon(NULL) {};

   LPTSTR m_lpszClassName;

I don't like this data member here.
I would prefer storing the class name into a buffer using deep-copy (e.g.
TCHAR m_className[ 200 ];) or better use a robust string class, like
CString), e.g.:

CString m_className;

And adjust here:

BOOL RegisterWndClass(LPCTSTR lpszClassName, HINSTANCE hInstance,
WNDPROC wndProc) {
m_lpszClassName = lpszClassName;

// Deep copy
m_className = lpszClassName;

   void UnregisterWndClass() {
           UnregisterClass(m_lpszClassName, m_hInstance);
   }

I'm not sure if the class should be unregistered here...
I would *not* unregister the window class.

http://blogs.msdn.com/oldnewthing/archive/2007/02/12/1661754.aspx

// global vars. Do they need to be declared static???
static const g_szClassName[] = _T("MyClass");
static HINSTANCE g_hInstance = NULL;
static CMyWnd* pWnd = NULL;

LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM
lParam)
{
return pWnd->OnMessage(uMsg, wParam, lParam);

I would check if pWnd is not null here, e.g. using an assert:

_ASSERTE( pWnd != NULL );

   case DLL_PROCESS_DETACH :
           if (pWnd) {
                   pWnd->UnregisterWndClass();
                   delete pWnd;

Try not unregistering here, and after delete pWnd, set also pWnd = NULL
(just to avoid the use of a uninitialized pointer).

// .def file has EXPORTS Initialize @ 240 NONAME
HWND Initialize(HWND hWndParent)

Should this be __stdcall?
Maybe there is some stack corruption due to uncorrect calling conventions?

However, I would not use this kind of "mixed C - C++" code; I would go for
a more robust C++ code.
I would use ATL/WTL (I don't know embedded development, maybe you have
memory limits so you can't use MFC? But in that case I think you could use
ATL, because ATL is a very *thin* object-oriented wrapper to Win32 APIs -
and you can have the benefit of robust object-oriented code).

Giovanni