[RESOLVED] IShellDispatch: FolderItemVerbs? (Getting bizarre crash with CoUninitaialize!)

[MuldeR2]

Hi!

I hope this is the correct sub-forum to post this issue.

I'm having a very bizarre problem with the IShellDispatch COM interface, more specifically with the FolderItemVerbs that drives me nuts!

Calling FolderItemVerbs::Release() followed by CoUninitialze() will result in crash. It's clearly reproducible, but only happens 1 out of 10 times

Running the problematic code in a loop 100% reproduces the crash

Please see the example program:

static int TestProc(const TCHAR *pcDirectoryName, const TCHAR *pcFileName)
{
	int iSuccess = 0;
	
	IShellDispatch *pShellDispatch = NULL;
	Folder *pFolder = NULL; FolderItem *pItem = NULL;
	FolderItemVerbs *pVerbs = NULL;
	
	HRESULT hr = CoCreateInstance(CLSID_Shell, NULL, CLSCTX_INPROC_SERVER, IID_IShellDispatch, (void**)&pShellDispatch);
	if(FAILED(hr) || (pShellDispatch ==  NULL))
	{
		iSuccess = -3;
		return iSuccess;
	}

	variant_t vaDirectory(pcDirectoryName);
	hr = pShellDispatch->NameSpace(vaDirectory, &pFolder);
	if(FAILED(hr) || (pFolder == NULL))
	{
		iSuccess = -4;
		pShellDispatch->Release();
		return iSuccess;
	}

	variant_t vaFileName(pcFileName);
	hr = pFolder->ParseName(vaFileName, &pItem);
	if(FAILED(hr) || (pItem == NULL))
	{
		iSuccess = -5;
		pFolder->Release();
		pShellDispatch->Release();
		return iSuccess;
	}
	
	hr = pItem->Verbs(&pVerbs);
	if(FAILED(hr) || (pVerbs == NULL))
	{
		iSuccess = -6;
		pItem->Release();
		pFolder->Release();
		pShellDispatch->Release();
		return iSuccess;
	}

	/* Here we would do something with the FolderItemVerbs */

	pVerbs->Release(); //If this line is commented out, we don't get a crash, but a massive memory leak!
	pVerbs = NULL;

	pItem->Release();
	pItem = NULL;

	pFolder->Release();
	pFolder = NULL;

	pShellDispatch->Release();
	pShellDispatch = NULL;
	
	iSuccess = 1;
	return iSuccess;
}

//-----------------------------------------------------------------------------

static unsigned __stdcall ThreadProc(void* pArguments)
{
	HRESULT hr = CoInitialize(NULL);
	if((hr == S_OK) || (hr == S_FALSE))
	{
		threadParam_t *params = (threadParam_t*) pArguments;
		params->returnValue = TestProc(params->pcDirectoryName, params->pcFileName);
		CoUninitialize();
	}
	else
	{
		if(threadParam_t *params = (threadParam_t*) pArguments)
		{
			params->returnValue = -10;
		}
	}

	return EXIT_SUCCESS;
}

Please download the *complete* example code is here:
http://pastie.org/private/0xsnajpia9lsmgnlf2afa


Please also note that I unambiguously tracked down to crash to FolderItemVerbs, because if I never create the FolderItemVerbs object, the crash is gone immediately.

Also if I never call "pVerbs->Release()" before CoUninitialize() the crash is gone too, but this will result in a massive memleak, obviously.

Another strange thing is that the crash will NOT happen, if I run the program under the Debugger! But I can run the program, wait for the crash and then let the Debugger handle the crash.

Unfortunately the Stack Trace that I get then doesn't help much:
http://pastie.org/private/cuwunlun2t5dc5lembpw


I don't think I'm doing anything wrong here. I have checked the code over and over again in the last two days. So this all seems to be a bug in FolderItemVerbs!

Has anybody encountered this before and/or can confirm that this is a bug in FolderItemVerbs? Also, is there any workaround for the problem?

Thanks in advance !!!

[MuldeR2]

Sorry, forgot to mention: The crash is an "0xC0000005: Access Violation" error.

(BTW: Am I blind or is there really no "Edit" button on this forum?)

[VictorN]

(BTW: Am I blind or is there really no "Edit" button on this forum?)

Edit button will appear after about five your posts.

And please:

1. use Code tags, not PHP ones
2. do NOT put more than one statements in one line

Otherwise your code is hard to read/understand!

[MuldeR2]

Okay, got the answer elsewehre.

It turns out this was caused by a "problematic" Shell Extension. In my case it was Tortoise GIT.

And it could be resolved by explicitely dispacthing all messages before CoUninitialize().

static int TestProc(const TCHAR *pcDirectoryName, const TCHAR *pcFileName)
{
    /*see above*/ 
}

static void DispatchPendingMessages(void)
{
    const DWORD uiTimeout = GetTickCount() + 10000;
    const HANDLE hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
    unsigned int counter = 0;
    if(hEvent)
    {
        for(;;)
        {
            MSG Message;
            while(PeekMessage(&Message, NULL, WM_NULL, WM_NULL, PM_REMOVE))
            {
                TranslateMessage(&Message);
                DispatchMessage(&Message);
            }
            const DWORD nWaitResult = MsgWaitForMultipleObjects(1, &hEvent, FALSE, 250, QS_ALLINPUT | QS_ALLPOSTMESSAGE);
            if((nWaitResult == WAIT_TIMEOUT) || (nWaitResult == WAIT_FAILED) || (GetTickCount() >= uiTimeout)) break;
        }
        CloseHandle(hEvent);
    }
}

static unsigned __stdcall ThreadProc(void* pArguments)
{
    HRESULT hr = CoInitialize(NULL);
    if((hr == S_OK) || (hr == S_FALSE))
    {
        threadParam_t *params = (threadParam_t*) pArguments;
        params->returnValue = TestProc(params->pcDirectoryName, params->pcFileName);
        DispatchPendingMessages(); //This is required before CoUninitialize() to avoid crash with certain Shell Extensions !!!
        CoUninitialize();
    }
    else
    {
        if(threadParam_t *params = (threadParam_t*) pArguments)
        {
            params->returnValue = -10;
        }
    }

    return EXIT_SUCCESS;
}