Exception idea in C compatible library. Comments.

Hello, I'm building a library (in C) amd am wondering about handling exception information. I was thinking about something like this. What do you think?

Code:

// Functions look like this...
void ALibraryFunction() {
	LIB_ENTER(L"ALibraryFunction");

	// function work

	return LIB_EXIT_EX(hr, "what ever");
}


// exception code...
typedef struct tagLIB_EXCEPTION {

	UINT nStackCount;
	LPWSTR szInitialFunction;
	LPWSTR szInnerFunction;

	LPWSTR szErrorInfo;	

	// more exception info here.

	HRESULT hr;

} LIB_EXCEPTION, * LPLIB_EXCEPTION;

LIB_EXCEPTION g_LibException;

// =============================================
VOID LIB_ENTER(LPCWSTR szFunctionName) {

	LPLIB_EXCEPTION pLibException = &g_LibException;

	if (pLibException->nStackCount++ == 0) {
		ZeroMemory(pLibException, sizeof(LIB_EXCEPTION));
		pLibException->szInitialFunction = szFunctionName;
	}

	pLibException->szInnerFunction = szFunctionName;
}


//=============================================HRESULT LIB_EXITEX(HRESULT hr, LPCWSTR szErrorInfo) {

	if (szErrorInfo) wcsncpy(pLibException->szErrorInfo, szMember, 63);

	pLibException->hr = hr;

	if (--pLibException->nStackCount == 0 && FAILED(hr)) LibShowException();

	return hr;
}



// ============================================
HRESULT LibFormatException(LPWSTR szBuffer, UINT cchBufferSize) {

// format exception structure into nice string..

}


// =============================================
HRESULT LibShowException(void) {

	WCHAR szMessage[512];

	LibFormatException(szMessage, 512);

	MessageBoxW(NULL, szMessage, NULL, MB_ICONWARNING);

}

Don't know if you've looked into this already but structured exception handling may be of some interest to you.

Thanks a lot for the reply. The problem with seh is that it is not widely supported by C compilers(as far as I know). I've implemented my idea and I think it works quite well. It can be toggled at runtime and the exception code can be entirely excluded at compile time with a define.