Question

我对 IShellDispatch COM界面有一个非常奇怪的问题，更具体地说是 FolderItemVerbs 对象，这让我疯了！

调用 FolderItemVerbs :: Release（），然后调用 CoUninitialze（）将导致崩溃。它显然是可重复的，但只发生在10次中的10次。

崩溃是“0xC0000005：访问冲突”错误。在循环中运行有问题的代码100％迟早会再现崩溃： - （

请参阅示例程序：

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

请下载完整的示例代码在这里： http://pastie.org/private/0xsnajpia9lsmgnlf2afa

请注意，我明确跟踪崩溃到 FolderItemVerbs ，因为如果我从未创建 FolderItemVerbs 对象，则崩溃立即消失。

此外，如果我从未在 CoUninitialize（）之前调用“pVerbs-＆gt; Release（）”，那么崩溃也会消失，但这显然会导致大量的memleak。

另一个奇怪的事情是，如果我在Debugger下运行程序，崩溃将不会发生！但我可以运行程序，等待崩溃，然后让调试器处理崩溃。

不幸的是，我得到的Stack Trace并没有多大帮助： http://pastie.org/private/cuwunlun2t5dc5lembpw

我不认为我在这里做错了什么。我在过去两天一遍又一遍地检查了代码。所以这一切似乎都是FolderItemVerbs中的一个错误！

之前是否有人遇到此问题和/或可以确认这是FolderItemVerbs中的错误？此外，该问题是否有解决方法？

提前致谢!!!

Answer 1

谢谢大家！

以下是执行显式消息调度的“已更正”代码：

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 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(); 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);
        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;
}

目前无法使用代码重现崩溃： - ）

IShellDisptach：为什么FolderItemVerbs :: Release（）+ CoUninitialize（）会崩溃？

1 个答案: