Imagine you want to explore the world of WMI with C++ like that:
ManagementClass mc(_TEXT("Win32_NetworkAdapter"));
bool result = mc.GetInstances();
while (mc.MoveNext())
{
CNetworkCard card;
card.m_Name = mc.GetStringProperty(_TEXT("Name"));
card.m_MACAddress = mc.GetStringProperty(_TEXT("MACAddress"));
card.m_Speed = mc.GetStringProperty(_TEXT("Speed"));
m_data.m_NetworkCards.Add(card);
}
Here is the class you need:
class ManagementClass
{
public:
ManagementClass(const CString& adr);
~ManagementClass();
bool GetInstances();
bool MoveNext();
CString GetStringProperty(CString propName);
bool GetBoolProperty(CString propName);
int GetIntProperty(CString propName);
long GetLongProperty(CString propName);
protected:
CString m_wmiAdr;
IWbemLocator *m_pLoc;
CComPtr<IWbemServices> m_pSvc;
CComPtr<IEnumWbemClassObject> m_pEnumerator;
CComPtr<IWbemClassObject> m_pclsObj;
};
The implementation is a little by tricky. Look:
#include "stdafx.h"
#include "ManagementClass.h"
ManagementClass::ManagementClass(const CString& adr)
{
m_wmiAdr.Format(_TEXT("SELECT * From %s"), adr);
m_pLoc = nullptr;
m_pEnumerator = nullptr;
m_pclsObj = nullptr;
}
ManagementClass::~ManagementClass()
{
if (m_pLoc)
{
m_pLoc->Release();
m_pLoc = nullptr;
}
}
bool ManagementClass::GetInstances()
{
static bool bSecurity = false;
HRESULT hres;
if (bSecurity == false)
{
bSecurity = true;
hres = CoInitializeSecurity(
NULL,
-1, // COM authentication
NULL, // Authentication services
NULL, // Reserved
RPC_C_AUTHN_LEVEL_DEFAULT, // Default authentication
RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation
NULL, // Authentication info
EOAC_NONE, // Additional capabilities
NULL // Reserved
);
}
hres = CoCreateInstance(
CLSID_WbemLocator,
0,
CLSCTX_INPROC_SERVER,
IID_IWbemLocator, (LPVOID *)&m_pLoc);
if (FAILED(hres))
{
return false;
}
// Connect to WMI through the IWbemLocator::ConnectServer method
// Connect to the root\cimv2 namespace with
// the current user and obtain pointer pSvc
// to make IWbemServices calls.
hres = m_pLoc->ConnectServer(
_bstr_t(L"ROOT\\CIMV2"), // Object path of WMI namespace
NULL, // User name. NULL = current user
NULL, // User password. NULL = current
0, // Locale. NULL indicates current
NULL, // Security flags.
0, // Authority (e.g. Kerberos)
0, // Context object
&m_pSvc // pointer to IWbemServices proxy
);
if (FAILED(hres))
{
m_pLoc->Release();
return false; // Program has failed.
}
hres = CoSetProxyBlanket(
m_pSvc, // Indicates the proxy to set
RPC_C_AUTHN_WINNT, // RPC_C_AUTHN_xxx
RPC_C_AUTHZ_NONE, // RPC_C_AUTHZ_xxx
NULL, // Server principal name
RPC_C_AUTHN_LEVEL_CALL, // RPC_C_AUTHN_LEVEL_xxx
RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
NULL, // client identity
EOAC_NONE // proxy capabilities
);
if (FAILED(hres))
{
m_pLoc->Release();
return false;
}
// Use the IWbemServices pointer to make requests of WMI ----
// For example, get the name of the operating system
//IEnumWbemClassObject* pEnumerator = NULL;
//CComPtr<IEnumWbemClassObject> pEnumerator = NULL;
hres = m_pSvc->ExecQuery(
bstr_t("WQL"),
bstr_t((LPTSTR)(LPCTSTR)m_wmiAdr),
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
NULL,
&m_pEnumerator);
if (m_pEnumerator == NULL)
{
return false;
}
if (FAILED(hres))
{
m_pLoc->Release();
return false;
}
return true;
}
bool ManagementClass::MoveNext()
{
ULONG uReturn = 0;
if (m_pEnumerator)
{
CComPtr<IWbemClassObject> pclsObj = nullptr;
HRESULT hr = m_pEnumerator->Next(WBEM_INFINITE, 1, &pclsObj, &uReturn);
if (hr == S_FALSE)
{
return false;
}
m_pclsObj = pclsObj;
}
else
{
return false;
}
return true;
}
CString ManagementClass::GetStringProperty(CString propName)
{
ASSERT(m_pclsObj != NULL);
CComVariant vtProp;
HRESULT hr = m_pclsObj->Get(propName, 0, &vtProp, 0, 0);
CString data;
AfxBSTR2CString(&data, vtProp.bstrVal);
return data;
}
bool ManagementClass::GetBoolProperty(CString propName)
{
ASSERT(m_pclsObj != NULL);
bool result = false;
CComVariant vtProp;
HRESULT hr = m_pclsObj->Get(propName, 0, &vtProp, 0, 0);
if (vtProp.boolVal == 1)
result = true;
return result;
}
int ManagementClass::GetIntProperty(CString propName)
{
ASSERT(m_pclsObj != NULL);
CComVariant vtProp;
HRESULT hr = m_pclsObj->Get(propName, 0, &vtProp, 0, 0);
int i = vtProp.iVal;
return i;
}
long ManagementClass::GetLongProperty(CString propName)
{
ASSERT(m_pclsObj != NULL);
CComVariant vtProp;
HRESULT hr = m_pclsObj->Get(propName, 0, &vtProp, 0, 0);
long l = vtProp.lVal;
return l;
}
Don’t forget the include stuff in the stdafx.h:
#include <Wbemidl.h>
#pragma comment(lib, “wbemuuid.lib”)
ChristopheP on Microsoft Technologies 