QCroreApplication QApplication with WMI

[newb]

Dear all,

I have serached for using WMI with Qt.

I found some WMI C++ Application Examples in MSDN website.

I have tried the code form the below link

http://msdn.microsoft.com/en-us/libr...=VS.85%29.aspx

when i copied and run the application as win32 console application it worked well.

the same code i ut into the Qt application ,

When i use QApplication anApplication ( argc, argv ); in my code it is not working

But if i use QCroreApplication anApplication ( argc, argv ); it is working

Any suggestions or help

[tbscope]

Post your source code

[squidge]

and please use [ code ] tags this time

[newb]

when i change QCroreApplication to QApplication The below source code not works and gives me errror like " Failed to initialize COM library. Error code = 0x80010106 "

#define _WIN32_DCOM
#include <iostream>
using namespace std;
#include <comdef.h>
#include <Wbemidl.h>
 
# pragma comment(lib, "wbemuuid.lib")
 
// Qt Includes
#include <QtCore>
#include <QtGui>
 
 
 //----------------------------------------------------------------------------
 
// Main Function
int main( int a_argc, char *a_argv[] )
//************************************
{
	// initialize the application
	QApplication anapplication( a_argc, a_argv );
 
	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.
    }
 
    // 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.
    }
 
    // 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.
    }
 
    // 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();     
        CoUninitialize();
        return 1;                // Program has failed.
    }
 
    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 
    );
 
    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_USBControllerDevice"),
        WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, 
        NULL,
        &pEnumerator);
 
//ExecQuery(L"WQL", L"SELECT * FROM Win32_LogicalDisk", WBEM_FLAG_FORWARD_ONLY, NULL, &iter);
 
    if (FAILED(hres))
    {
        cout << "Query for operating system name 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(FAILED(hr)||0 == uReturn)
        {
            break;
        }
 
        VARIANT vtProp;
 
        // Get the value of the Name property
        /*hr = pclsObj->Get(L"VolumeName", 0, &vtProp, 0, 0);
        wcout << " VolumeName : " << vtProp.bstrVal << endl;
        VariantClear(&vtProp);*/
 
 
        if (FAILED(pclsObj->Get(L"Antecedent", 0, &vtProp, 0, 0)))
		{
			cout<<"The specified property is not found."<<endl;
		}
		else
		{
			wcout <<vtProp.bstrVal << endl;
		}
 
        pclsObj->Release();
    }
 
    // Cleanup
    // ========
 
    pSvc->Release();
    pLoc->Release();
    pEnumerator->Release();
   // pclsObj->Release();
    CoUninitialize();
 
 
   // return 0;   // Program successfully completed.
 
	//execute the application
	int anInt = anapplication.exec();
 
	return anInt;
}
//-----------------------------------------------------------------------------

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

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

// Qt Includes
#include <QtCore>
#include <QtGui>


 //----------------------------------------------------------------------------

// Main Function
int main( int a_argc, char *a_argv[] )
//************************************
{
	// initialize the application
	QApplication anapplication( a_argc, a_argv );

	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.
    }

    // 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.
    }
    
    // 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.
    }

    // 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();     
        CoUninitialize();
        return 1;                // Program has failed.
    }

    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 
    );

    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_USBControllerDevice"),
        WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, 
        NULL,
        &pEnumerator);

//ExecQuery(L"WQL", L"SELECT * FROM Win32_LogicalDisk", WBEM_FLAG_FORWARD_ONLY, NULL, &iter);

    if (FAILED(hres))
    {
        cout << "Query for operating system name 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(FAILED(hr)||0 == uReturn)
        {
            break;
        }

        VARIANT vtProp;

        // Get the value of the Name property
        /*hr = pclsObj->Get(L"VolumeName", 0, &vtProp, 0, 0);
        wcout << " VolumeName : " << vtProp.bstrVal << endl;
        VariantClear(&vtProp);*/

	
        if (FAILED(pclsObj->Get(L"Antecedent", 0, &vtProp, 0, 0)))
		{
			cout<<"The specified property is not found."<<endl;
		}
		else
		{
			wcout <<vtProp.bstrVal << endl;
		}

        pclsObj->Release();
    }

    // Cleanup
    // ========
    
    pSvc->Release();
    pLoc->Release();
    pEnumerator->Release();
   // pclsObj->Release();
    CoUninitialize();


   // return 0;   // Program successfully completed.

	//execute the application
	int anInt = anapplication.exec();

	return anInt;
}
//-----------------------------------------------------------------------------

To copy to clipboard, switch view to plain text mode 

[high_flyer]

Do you have the code for CoInitializeEx()?
What happens if you initialize your QApplication object after CoInitializeEx()?

[newb]

Thank you

now i don get this error

but in my console it shows like Qt: Could not initialize OLE (error 80010106)

Any help

[high_flyer]

Which libs do you link to in your project?
EDIT:
I see now, at the top.
Try delay loading wbemuuid.dll.

[newb]

Thnaks for the reply..

i get the vid and pid of the usb devices plugged into my system using WMI.

Now i want to get the drive letter corresponding to the device vid and pid i retrievd.

code

hres = pSvc->ExecQuery(
bstr_t("WQL"),
bstr_t("SELECT * FROM Win32_USBControllerDevice"),
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
NULL,
&pEnumerator);

if (FAILED(pclsObj->Get(L"Dependent", 0, &vtProp, 0, 0)))
{
cout<<"The specified property is not found."<<endl;

}
else
{
wcout <<vtProp.bstrVal << endl;

}

i get like below

\NJ96\root\cimv2:Win32_PnPEntity.DeviceID="USB\VID _1A8D&PID_1000\35809402 0874450"

how can i map DRIVE LETTER to my above output using the WMI

please help me out

[high_flyer]

This is not a Qt question, and I am not really familiar with WMI.
You might get more help with this issue in forums dedicated to WMI development.

[newb]

Can any body help me out

[chesterx]

Hi.
Using WMI and WMI Query Language is not an easy thing, but if you read carefully and look at the examples on MSDN I'm sure you'll get the picture, for I also use WMI to get PIDs and VIDs for plugged devices.
http://msdn.microsoft.com/en-us/libr...(v=VS.85).aspx

But , about the CoInitializeEx , I had the very same problem as you... CoInitializeEx is not returning S_OK.. But's that an OK thing, according to MSDN
As long as CoInitializeEx doesn't return RPC_E_CHANGED_MODE you should be ok, and you should call CoUninitialize in both cases where CoInitializeEx return S_OK or S_FALSE

Now, the issue with the QApplication object, that I also ran into, is that somewhere very deep in the initialization of an QApp object a call to CoInitialize is being made with parameters that we can't control.. I know that coz I used an API spy that tell me wich api calls a process is making.

The problem with CoInitialize is that is the same as CoInitializeEx(0, COINIT_APARTMENTTHREADED) and a later call (after the QApplication's instantiation) fails if we try CoInitializeEx(0, COINIT_APARTMENTTHREADED) with a RPC_E_CHANGED_MODE error.

So it's ok if you call CoInitializeEx(0, COINIT_APARTMENTTHREADED) with a S_FALSE returned.. and then even with an S_FALSE returned you should call CoUninitialize;

I know that QAxBase calls CoInitializeEx but, does anybody out there know why CoInitialize is called by the QApplication's constructor?

Tks

Hernan

---

Added after 6 minutes:

Lol, I just found the villain myself looking for the Could not initialize OLE string within the Qt source
Lines 754-758 on qapplication_win.cpp... OleInitialize() is called but then we are stuck with a Single-Threaded model for using COM.. that's bad news.
If one reads the remarks on http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx one can guess that OleInitialize is called for Drag'n'Drop to work.