Computer

WMI Programming with VBScript

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WMI

Windows Management Instrumentation (WMI) 是 Microsoft 實做的 WBEM 及 CIM
它提供有彈性的介面讓電腦資訊便於管理及查詢

但儘管 Microsoft 宣稱 WMI 提供 Visual C++ 及 .Net Framework 相關語言的介面
很明顯它的設計僅為 .net-friendly
對於 Visual C++ 便依舊是苦工

在五月初的先期研究中
由於產出必須為綠色軟體的需求，我用 MFC 硬刻了一個雛型
但這樣的開發效率並不讓人滿意

為了有效提昇開發曲線，於是借助 Scripting Language 特性
將整體架構由 Pure-MFC 改為 MFC + VBScript

在此提出簡單範例，展示採用 Visual C++ 與 VBScript 對 WMI 查詢系統資訊的差異…

VBScript
若以 VBScript 實作，只需寥寥幾行便可完成：

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Dim objWMIService, colSettings, objOS
Dim strTmp
 
Set objWMIService = GetObject ("winmgmts:\\.\root\cimv2")
Set colSettings = objWMIService.ExecQuery("Select * from Win32_OperatingSystem")
 
For Each objOS in colSettings
    strTmp = objOS.Caption
Next
 
Wsh.echo strTmp

Visual C++
相較之下 Visual C++ 的 code 便顯得臃腫不堪
儘管扣掉引入檔、例外處理以及註解，行數打個對折好了；所花的 effort 仍舊是 VBScript 的數倍!!

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#define _WIN32_DCOM
#include< iostream >
using namespace std;
#include< comdef.h >
#include< Wbemidl.h >
#pragma comment(lib, "wbemuuid.lib")
 
int main(int argc, 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 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_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;
    
    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);
    }
 
    // Cleanup
    // ========
     
    pSvc->Release();
    pLoc->Release();
    pEnumerator->Release();
    pclsObj->Release();
    CoUninitialize();
 
    return 0;   // Program successfully completed.
}

圖片來源：Developer Fusion

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