奇怪的WMI查询结果

strange WMI query result

本文关键字:查询 结果 WMI      更新时间:2023-10-16

下面的代码显示了结果(编译器:VS 2008)

已连接到ROOT\CIMV2 WMI命名空间

操作系统名称:Microsoft Windows XP专业|C:\WINDOWS|\Device\Harddisk0\Partition1

这是正确的吗?代码是从这里复制的,并在帖子评论中进行了一些修改。替换";名称";用";版本";显示正确的结果,即5.1.2600

#define _WIN32_DCOM
#include <iostream>
using namespace std;
#include <comdef.h>
#include <Wbemidl.h>
# pragma comment(lib, "wbemuuid.lib")
int main(int iArgCnt, char ** 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 must 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 negotiates service
        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 local rootcimv2 namespace
    // and obtain pointer pSvc to make IWbemServices calls.
    hres = pLoc->ConnectServer(
        _bstr_t(L"ROOT\CIMV2"), 
        NULL,
        NULL, 
        0, 
        NULL, 
        0, 
        0, 
        &pSvc
    );
        
    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 for 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.
    }
 IWbemClassObject *pclsObj;
    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"Name", 0, &vtProp, 0, 0);
        wcout << " OS Name : " << vtProp.bstrVal << endl;
        VariantClear(&vtProp);
        pclsObj->Release();
    }
    // Clean up
    //--------------------------
 pSvc->Release();
    pLoc->Release();
    pEnumerator->Release();
    CoUninitialize();
    return 0;
}

输出代码错误地认为返回的BSTR值以null结尾。

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

您必须使用SysStringLen来确定BSTR的真实长度,然后编写考虑到这一点的输出逻辑。

通过helper类_bstr_t处理BSTR更简单,它将所有这些棘手的原始BSTR语义封装到一个更传统的C++包装器中。参见std::stringchar*

"Caption"代替Name工作。