Question

I’m using Windows 7 and now I want to develop a program with WMI.

I’ve read MSDN and found this example code.

#include "stdafx.h"
#define _WIN32_DCOM
#include <iostream>
using namespace std;
#include <comdef.h>
#include <Wbemidl.h>
#include <conio.h>


# pragma comment(lib, "wbemuuid.lib")

BOOL ManageWMI();
int main(int argc, char* argv[])
{
    if(ManageWMI()) printf("%WMI Error!");
 _getch(); 
 return 0;
}

BOOL ManageWMI()
{
    HRESULT hres;

    // Step 1: --------------------------------------------------
    // Initialize COM. ------------------------------------------

    hres =  CoInitializeEx(0, COINIT_MULTITHREADED); 
    if (FAILED(hres))
    {
        cout << "Failed to initialize COM library. Error code = 0x" 
            << hex << hres << endl;
        return 1;                  // Program has failed.
    }
    cout << "step 1" << endl;
    // Step 2: --------------------------------------------------
    // Set general COM security levels --------------------------
    // Note: If you are using Windows 2000, you need to specify -
    // the default authentication credentials for a user by using
    // a SOLE_AUTHENTICATION_LIST structure in the pAuthList ----
    // parameter of CoInitializeSecurity ------------------------

    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
        );


    if (FAILED(hres))
    {
        cout << "Failed to initialize security. Error code = 0x" 
            << hex << hres << endl;
        CoUninitialize();
        return 1;                    // Program has failed.
    }

    cout << "step 2 " << endl;
    // Step 3: ---------------------------------------------------
    // Obtain the initial locator to WMI -------------------------

    IWbemLocator *pLoc = NULL;

    hres = CoCreateInstance(
        CLSID_WbemLocator,             
        0, 
        CLSCTX_INPROC_SERVER, 
        IID_IWbemLocator, (LPVOID *) &pLoc);

    if (FAILED(hres))
    {
        cout << "Failed to create IWbemLocator object."
            << " Err code = 0x"
            << hex << hres << endl;
        CoUninitialize();
        return 1;                 // Program has failed.
    }
    cout << "step 3" << endl;
    // Step 4: -----------------------------------------------------
    // Connect to WMI through the IWbemLocator::ConnectServer method

    IWbemServices *pSvc = NULL;

    // Connect to the root/cimv2 namespace with
    // the current user and obtain pointer pSvc
    // to make IWbemServices calls.
    hres = 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 
         &pSvc                    // pointer to IWbemServices proxy
         );

    if (FAILED(hres))
    {
        cout << "Could not connect. Error code = 0x" 
             << hex << hres << endl;
        pLoc->Release();     
        cout << "released!!" << endl;
        CoUninitialize();
        cout << "counitialized !!" << endl;
        return 1;                // Program has failed.
    }
    cout<< "step 4" << endl;
    cout << "Connected to ROOT//CIMV2 WMI namespace" << endl;


    // Step 5: --------------------------------------------------
    // Set security levels on the proxy -------------------------

    hres = CoSetProxyBlanket(
       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 
    );
    cout << "step 5" << endl;
    if (FAILED(hres))
    {
        cout << "Could not set proxy blanket. Error code = 0x" 
            << hex << hres << endl;
        pSvc->Release();
        pLoc->Release();     
        CoUninitialize();
        return 1;               // Program has failed.
    }

    // Step 6: --------------------------------------------------
    // Use the IWbemServices pointer to make requests of WMI ----

    // For example, get the name of the operating system
    IEnumWbemClassObject* pEnumerator = NULL;
    hres = pSvc->ExecQuery(
        bstr_t("WQL"), 
        bstr_t("SELECT * FROM Win32_NetworkAdapterConfiguration WHERE IPEnabled = ''TRUE''"),
        WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, 
        NULL,
        &pEnumerator);

    if (FAILED(hres))
    {
        cout << "Query for Network Adapter Configuration failed."
            << " Error code = 0x" 
            << hex << hres << endl;
        pSvc->Release();
        pLoc->Release();
        CoUninitialize();
        return 1;               // Program has failed.
    }

    // Step 7: -------------------------------------------------
    // Get the data from the query in step 6 -------------------

    IWbemClassObject *pclsObj;
    ULONG uReturn = 0;

    while (pEnumerator)
    {
        HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1, 
            &pclsObj, &uReturn);

        if(0 == uReturn)
        {
            break;
        }

        VARIANT vtProp;
  VariantInit(&vtProp);


  //hr = pclsObj->Get(L"IPSubnet", 0, &vtProp, 0, 0);
        // Get the value of the Enable property
  hr = pclsObj->Get(L"IPEnabled", 0, &vtProp, 0, 0);
        // Get the value of the MacAddress property
  if(vtProp.boolVal)
  {
   hr = pclsObj->Get(L"MacAddress", 0, &vtProp, 0, 0);
   wcout << " MacAddress : " << vtProp.bstrVal << endl;
  }

  hr = pclsObj->Get(L"IPEnabled", 0, &vtProp, 0, 0);
  if(vtProp.boolVal)
  { 
   LONG lstart, lend;
   LONG idx = -1;
   BSTR* pbstr;
   SAFEARRAY *sa;
   hr = pclsObj->Get(L"Description", 0, &vtProp, 0, 0);
   if(!FAILED(hr))
   {
    wcout << "Description: " << vtProp.bstrVal << endl; 
   }
   hr = pclsObj->Get(L"DNSHostName", 0, &vtProp, 0, 0);
   if(!FAILED(hr))
   {
    cout << "DNS:" << vtProp.bstrVal << endl;
   }
   hr = pclsObj->Get(L"IPAddress", 0, &vtProp, 0, 0);
   if(!FAILED(hr))
   {   
    SAFEARRAY *psa = vtProp.parray;
    cout << "IP Address::" << psa << endl;
   }
  }


        VariantClear(&vtProp);
    }

    // Cleanup
    // ========

    pSvc->Release();
    pLoc->Release();
    pEnumerator->Release();
    pclsObj->Release();
    CoUninitialize();

    return 0;   // Program successfully completed.

}

However, these code doesn’t work on my computer.

It failed in “step4” with error code 0x8004100e.
I googled and restart my WMI service but doesn’t work either.

Does anyone had the same experience and solved that? Hope you give me some help. Thanks…

Answer 1

You are using a wrong syntax for the ROOT//CIMV2 namespace try changing to ROOT\\CIMV2

hres = 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 
     &pSvc                    // pointer to IWbemServices proxy
     );

Btw the 0x8004100E value is the code for the WBEM_E_INVALID_NAMESPACE (Namespace specified cannot be found.) error.