使用Visual C++查询操作系统信息

Question

以下代码是msdn（link）中有关如何使用WMI查询操作信息的示例代码。当运行在Visual C++ 2010的代码，我得到以下错误：

“在0x5a2c47af（msvcr100d.dll）未处理异常ProjectTest.exe： 0000005：访问冲突读取位置0xccccffff。”

有谁能帮我解决这个问题吗？

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

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

int main() 
{ 
    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 (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 = NULL; 
    ULONG uReturn = 0; 

    while (pEnumerator) 
    { 
     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"PAEEnabled", 0, &vtProp, 0, 0); 
     wcout << " Is PAE enabled? : " << vtProp.bstrVal << endl; 
     VariantClear(&vtProp); 

     pclsObj->Release(); 
    } 

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

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

    system("PAUSE"); 

    return 0; // Program successfully completed. 

} 

Answer 1

实际上，它确实返回完全有效的数据。 它只是它只会为您的调用返回一个布尔值，并且不会返回bstrVal。

根据VT_BOOLEAN检查vtProp.vt属性。 在VARIANT中，你总是必须检查VARIANT拥有的数据类型的vt属性。

---

原来的答案：

你vtProp是nullptr连寿pclsObj-的HRESULT>获取（）调用S_OK。很可能它找不到PAEEnabled属性。

当您使用MSDN示例中使用“名称”而不是“PAEEnabled”的原始代码时，它的工作原理很好。