(WMI)ExecMethod out 参数 - 无论调用的结果如何，ResultingSnapshot 都是 NULL

Question

我正在使用WMI创建一个RCT检查点。下面是代码片段。问题是当我使用ExecMethod调用方法Create Snapshot时，检查点被创建，但ResultingSnapshot仍然指向NULL。

由于调用是异步的(因为 pOutParameters 的返回值为 4096(，我也等到作业在 WaitForJobCompletion 中完成，但pOutParameters没有更新，ResultingSnapshot仍然是 NULL。

基本上，我需要这个ResultingSnapshot来创建参考点。如果有其他方法可以做到这一点，我可以写出来，但需要指导。

我是WMI的新手，任何帮助或领导都值得赞赏。

HRESULT hr;
CComPtr<IWbemClassObject> pInParams;
CComPtr<IWbemClassObject> pOutParameters;
IWbemCallResult *pResult = 0;
// Set Method Paramters
this->GetMethodParams(L"Msvm_VirtualSystemSnapshotService", L"CreateSnapshot", &pInParams);
IWbemClassObject * pVirtualSystemSnaphotSettingData = NULL;
hr = m_pWbemServices->GetObject(L"Msvm_VirtualSystemSnapshotSettingData", 0, NULL, &pVirtualSystemSnaphotSettingData, &pResult);
IWbemClassObject * pInpInstOfSnapshotSettingData = NULL;
hr = pVirtualSystemSnaphotSettingData->SpawnInstance(0, &pInpInstOfSnapshotSettingData);
VARIANT consistencyLevel;
VariantInit(&consistencyLevel);
V_VT(&consistencyLevel) = VT_BSTR;
V_BSTR(&consistencyLevel) = SysAllocString(L"1");
hr = pInpInstOfSnapshotSettingData->Put(L"ConsistencyLevel", 0, &consistencyLevel, 0);
VariantClear(&consistencyLevel);
VARIANT elementName;
VariantInit(&elementName);
V_VT(&elementName) = VT_BSTR;
V_BSTR(&elementName) = SysAllocString(L"rhel-1");
hr = pInpInstOfSnapshotSettingData->Put(L"ElementName", 0, &elementName, 0);
VariantClear(&elementName);
hr = m_pWbemServices->PutInstance(pInpInstOfSnapshotSettingData, 0, NULL, &pResult);
BSTR objString = NULL;
hr = pInpInstOfSnapshotSettingData->GetObjectText(0, &objString);
BSTR ArgNameTwo = SysAllocString(L"SnapshotSettings");
VARIANT v;
V_VT(&v) = VT_BSTR;
V_BSTR(&v) = objString; 
hr = pInParams->Put(ArgNameTwo, 0, &v, 0);
VARIANT vtProp;
m_pVmWbemClassObject->Get(L"__Path", 0, &vtProp, 0, 0);
wprintf(L"Affected System : : %ls", (LPWSTR)vtProp.bstrVal);
HRESULT hres = pInParams->Put(L"AffectedSystem", 0 , &vtProp, NULL);
VARIANT var;
VariantInit(&var);
V_VT(&var) = VT_BSTR;
V_BSTR(&var) = SysAllocString(L"2");

CHK_HRES(pInParams->Put(L"SnapshotType", 0, &var, 0));

IEnumWbemClassObject* pEnumOb = NULL;
hr = m_pWbemServices->ExecQuery(
BSTR(L"WQL"),
BSTR(L"select * from Msvm_VirtualSystemSnapshotService"),
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
NULL,
&pEnumOb);
IWbemClassObject *pclsObj1 = NULL;
ULONG uReturn1 = 0;
while (1)
{
    HRESULT hr = pEnumOb->Next(WBEM_INFINITE, 1, &pclsObj1, &uReturn1);
    if (0 == uReturn1)
    {
        break;
    }
    IWbemCallResult *pCallResult = NULL;
    IWbemClassObject *pResObj = NULL;
    CComBSTR path(this->GetStrProperty(L"__PATH", pclsObj1));
    hr = m_pWbemServices->ExecMethod(path, L"CreateSnapshot", 0, NULL, pInParams, &pOutParameters, &pCallResult);

    /* cout << "check1 : " << hex << hr << endl;
    hr = pCallResult->GetResultObject(0, &pResObj);
    cout << "check2" << endl;*/
    this->WaitForJobCompletion(pOutParameters);
   }
cout << "nSnpshot Complete" << endl;
}

编辑我发现快照类型参数设置不正确，它应该是 32768，我使用以下方法将 uint16 转换为变体但没有成功，我得到0x80070057 Incorrect Parameter错误。

VARIANT var;
VariantInit(&var);
V_VT(&var) = VT_BSTR;
V_BSTR(&var) = SysAllocString(L"32768");
hr = pInParams->Put(L"SnapshotType", 0, &var, CIM_UINT16);

Answer 1

HRESULT GetRelated(PWSTR sAssociatePath, PWSTR sResultClass, IWbemClassObject** ppResultObject)
{
CStringW query;
query.Format(L"associators of {%s} where ResultClass = %s", sAssociatePath, sResultClass);
CComPtr<IEnumWbemClassObject> pEnumOb;
HRESULT hr = m_pWbemServices->ExecQuery(
    BSTR(L"WQL"),
    CComBSTR(query),
    WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
    NULL,
    &pEnumOb));
ULONG uReturn = 0;
CComPtr<IWbemClassObject> pObject;
hr = pEnumOb->Next(WBEM_INFINITE, 1, &pObject, &uReturn);
return hr;
}
// Call the GetRelated function above with the __PATH parameter of JOB
CComPtr<IWbemClassObject> pOutParam = NULL;
CHK_HRES(this->ExecMethod(pHyperVObject, L"ConvertToReferencePoint", pInParams, &pOutParam, NULL));
CComVariant jobPath;
CHK_HRES(pOutParam->Get(L"Job", 0, &jobPath, NULL, NULL));
CComPtr<IWbemClassObject> pResult;
GetRelated(jobPath.bstrVal, L"Msvm_VirtualSystemReferencePoint", &pResult);

Answer 2

您提供一个ppCallResult参数。从文档中：

ppCallResult [out] 如果为 NULL，则不使用此功能。如果 ppCallResult 是 指定时，必须将其设置为在输入时指向 NULL。在这种情况下， 呼叫立即返回，并带有WBEM_S_NO_ERROR。ppCallResult 参数接收指向新 IWbemCallResult 对象的指针，该对象 必须轮询才能使用 GetCallStatus 方法。调用的 out 参数可通过 调用 IWbemCallResult：：GetResultObject。

因此，您需要在pCallResult上使用GetCallStatus，直到方法完成，然后GetResultObject获取 out 参数：

LONG status;
while ((hr = pCallResult->GetCallStatus(1000, &status)) == WBEM_S_TIMEDOUT);
/* check hr and status here */
hr = pCallResult->GetResultObject(0, &pResObj);

或使用WBEM_INFINITE：

LONG status;
hr = pCallResult->GetCallStatus(WBEM_INFINITE, &status);
/* check hr and status here */
hr = pCallResult->GetResultObject(0, &pResObj);

或者，提供NULL而不是pCallResult，这将是一个同步调用，其中将设置pOutParameters：

hr = m_pWbemServices->ExecMethod(path, L"CreateSnapshot", 0, NULL, pInParams, &pOutParameters, NULL);

Answer 3

快照类型=32768 是否给您带来了错误？因为使用此快照类型时不会创建快照。

正在创建以下日志：

"Ubuntu1"的检查点创建失败，因为指定了无效的检查点类型。(虚拟机 ID 5C773BB5-B630-48B4-AB9E-71C548F3FAE4(

编辑：我

不确定它是否有帮助，但这解决了我的问题：https://learn.microsoft.com/en-us/answers/questions/160321/wmi-createsnapshot-not-working-with-snapshottype-3.html