未来在IEnumWbemClassObject调用挂起应用

Question

我有一个简单的函数，得到使用WMI的硬盘序列号，但下面的调用将挂起应用程序一样，如果它进入了一个无限循环：

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

完整的代码是：

std::string GetHarddiskSerialNumber() 
{ 
     HRESULT hres; 

     // No need to initialize COM in openFL, as it seems that its already initialized when starting windows 
     // 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 "Failed to initialize COM library. Error code = 0x";     // 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 "Failed to initialize security. Error code = 0x";     // 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 (for example, 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_OperatingSystem"), 
      WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, 
      NULL, 
      &pEnumerator); 

     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; 
     std::string result= ""; 
     while (pEnumerator) 
     { 
      // this call will hang the app: 
      HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1, &pclsObj, &uReturn); 


      if(0 == uReturn) 
      { 
       break; 
      } 

      VARIANT vtProp; 

      // Get the value of the Name property 
      hr = pclsObj->Get(L"SerialNumber", 0, &vtProp, 0, 0); 
      wstring ws(vtProp.bstrVal, SysStringLen(vtProp.bstrVal)); 
      result = string(ws.begin(), ws.end()); 
      VariantClear(&vtProp); 

      hr = pclsObj->Get(L"Manufacturer", 0, &vtProp, 0, 0); 
      wstring ws2(vtProp.bstrVal, SysStringLen(vtProp.bstrVal)); 
      result+=","; 
      result+= string(ws2.begin(), ws2.end()); 
      VariantClear(&vtProp); 





      pclsObj->Release(); 
     } 

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

     pSvc->Release(); 
     pLoc->Release(); 
     pEnumerator->Release(); 
     //pclsObj->Release(); 
     CoUninitialize(); 
     return result; 

    } 
}// name space 

有什么想法吗？

Answer 1

我不是很肯定，但也可以使用搭售使用0超时：

HRESULT hr = pEnumerator->Next(WBEM_NO_WAIT, 1, &pclsObj, &uReturn); 

从MSDN：

指定以毫秒为单位的最大时间量的调用返回之前 块。如果使用常量WBEM_INFINITE （0xFFFFFFFF），则会阻止呼叫，直到对象可用。如果使用 值0（WBEM_NO_WAIT），则该呼叫立即返回，是否有任何 对象可用。