c++ - (WMI) ExecMethod out parameter - ResultingSnapshot is NULL irrespective of the result of the call, Why?

Question

I am using WMI to create an RCT Checkpoint. Below is the code snippet. The problem is when I call the method Create Snapshot using ExecMethodthe checkpoint gets created but the ResultingSnapshot to still points to NULL.

Since the call is asynchronous (as the return value from pOutParameters is 4096) I have also waited till the job gets completed in WaitForJobCompletion but pOutParameters is not updated and still, the ResultingSnapshot is NULL.

Basically, I need this ResultingSnapshot for creating a reference point. If there is any other way to do it, I can write it, need guidance though.

I am new to WMI, any help or lead is appreciated.

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 << "
Snpshot Complete" << endl;
}

EDIT I found that the SnapshotType Parameter is not set correctly it should be 32768 and I have used the following way to convert uint16 to Variant but no Success and I get 0x80070057 Incorrect Parameter Error.

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);