Get property's value of date - c

Question

I'm currently writing a C program which have to do WMI query.
I can issue a query without trouble, but it begin to be really hard when it come to retrieve property's value from the VARIANT variable.
I have a huge switch case, and for each case I just want to wprintf the value (the final purpose is to retrieve the value in a wchar_t string).
So far, for the integer type, it wasn't so difficult, but for the datetime type, I can't have something at all.
Here's the example i'm working on (there are no function check for the sake of lisibility, but I do it :
typedef struct cpwmi {
IWbemLocator *locator;
IWbemServices *services;
IEnumWbemClassObject *results;
IWbemClassObject *result;
} cpwmi_s;
void CpWmi_Constructor(cpwmi_s *self)
{
self->locator = NULL;
self->services = NULL;
self->results = NULL;
self->result = NULL;
}
void CpWmi_Destructor(cpwmi_s *self)
{
if (self->result) {
self->result->lpVtbl->Release(self->result);
}
if (self->results) {
self->results->lpVtbl->Release(self->results);
}
if (self->services) {
self->services->lpVtbl->Release(self->services);
}
if (self->locator) {
self->locator->lpVtbl->Release(self->locator);
}
}
void CpWmi_MinimalExample(cpwmi_s *self)
{
// Connection
CoCreateInstance(&CLSID_WbemLocator, NULL, CLSCTX_INPROC_SERVER, &IID_IWbemLocator, &self->locator);
BSTR ressource = SysAllocString(L"ROOT\\CIMV2");
self->locator->lpVtbl->ConnectServer(self->locator, ressource, NULL, NULL, NULL, 0, NULL, NULL, &self->services);
SysFreeString(ressource);
// Issue WMI query
BSTR query = SysAllocString(L"SELECT ReleaseDate FROM Win32_BIOS");
BSTR language = SysAllocString(L"WQL");
self->services->lpVtbl->ExecQuery(self->services, language, query, WBEM_FLAG_BIDIRECTIONAL, NULL, &self->results);
SysFreeString(query);
SysFreeString(language);
// Go to first result
ULONG count = 0;
self->results->lpVtbl->Next(self->results, WBEM_INFINITE, 1, &self->result, &count);
// Get propperty's value
BSTR propertyName = SysAllocString(L"ReleaseDate");
VARIANT propertyValue;
CIMTYPE propertyType;
self->result->lpVtbl->Get(self->result, propertyName, 0, &propertyValue, &propertyType, 0);
wprintf(L"%s: ", propertyName);
if (propertyValue.vt != VT_NULL && propertyValue.vt != VT_EMPTY) {
switch (propertyType) {
/* Many case here */
case CIM_DATETIME:
wprintf(L"%f", propertyValue.date);
break;
}
}
VariantClear(&propertyValue);
wprintf(L"\n");
}
int main(void)
{
cpwmi_s wmi;
CpWmi_Constructor(&wmi);
// initialize COM
CoInitializeEx(NULL, COINIT_MULTITHREADED);
CoInitializeSecurity(NULL, -1, NULL, NULL, RPC_C_AUTHN_LEVEL_DEFAULT, RPC_C_IMP_LEVEL_IMPERSONATE, NULL, EOAC_NONE, NULL);
CpWmi_MinimalExample(&wmi);
CpWmi_Destructor(&wmi);
// unwind everything else we've allocated
CoUninitialize();
printf("Stop\n");
getchar();
return;
}
I expect to have something like
ReleaseDate : 20140401000000.000000+000
but I end up with
ReleaseDate : -92559592126069970772275711289628980735378270670621907468943360.000000
I must misread msdn documentation or don't know how to search/read, because up to this point, I have no idea how to do that in C !
I'm also worried about CIM_REFERENCE_TYPE, CIM_OBJECT_TYPE and the alike.
Is there anyone who have a hint or know to do that ?

Answer 1

propertyValue.date is double, it needs "%g" print format, but it's probably not valid. Try bstrVal value instead:
case CIM_DATETIME:
//wprintf(L"%g\n", propertyValue.date);
wprintf(L"%s\n", propertyValue.bstrVal);
break;
Note, in debug mode you can move the cursor over propertyValue and it should show the values contained in propertyValue