我在使用 WMI 和 C 時遇到了一個問題。
這是我第一次使用它，所以我采用了基本檔案示例。但是運行它對我不起作用。
我試圖從 Win32_OperatingSystem 中提取作業系統名稱，但是當我顯示它時，我得到了0x9a2fec.
然后我嘗試使用 MaxNumberOfProcesses，我得到了“-1”。
我在 Windows 10 上，我不知道發生了什么。
我的代碼：
#include <iostream>
#define _WIN32_DCOM
#include <windows.h>
#include <Wbemidl.h>
#include <comdef.h>
# pragma comment(lib, "wbemuuid.lib")
bool initializeCom(){
// Step 1: --------------------------------------------------
// Initialize COM. ------------------------------------------
HRESULT hres = CoInitializeEx(0, COINIT_MULTITHREADED);
if (FAILED(hres))
{
std::cout << "Failed to initialize COM library. Error code = 0x"
<< std::hex << hres << std::endl;
return false; // Program has failed.
}
// Step 2: --------------------------------------------------
// Set general COM security levels --------------------------
hres = CoInitializeSecurity(
nullptr,
-1, // COM authentication
nullptr, // Authentication services
nullptr, // Reserved
RPC_C_AUTHN_LEVEL_DEFAULT, // Default authentication
RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation
nullptr, // Authentication info
EOAC_NONE, // Additional capabilities
nullptr // Reserved
);
if (FAILED(hres))
{
std::cout << "Failed to initialize security. Error code = 0x"
<< std::hex << hres << std::endl;
CoUninitialize();
return false; // Program has failed.
}
return true;
}
bool setUpWBEM(IWbemLocator*& wbemLocator, IWbemServices*& wbemServices){
// Step 3: ---------------------------------------------------
// Obtain the initial locator to WMI -------------------------
HRESULT hres = CoCreateInstance(
CLSID_WbemLocator,
0,
CLSCTX_INPROC_SERVER,
IID_IWbemLocator, (LPVOID *) &wbemLocator);
if (FAILED(hres))
{
std::cout << "Failed to create IWbemLocator object."
<< " Err code = 0x"
<< std::hex << hres << std::endl;
CoUninitialize();
return false; // Program has failed.
}
// Step 4: -----------------------------------------------------
// Connect to WMI through the IWbemLocator::ConnectServer method
// Connect to the root\cimv2 namespace with
// the current user and obtain pointer wbemServices
// to make IWbemServices calls.
hres = wbemLocator->ConnectServer(
_bstr_t(L"ROOT\\CIMV2"), // Object path of WMI namespace
nullptr, // User name. NULL = current user
nullptr, // User password. NULL = current
0, // Locale. NULL indicates current
0, // Security flags.
0, // Authority (for example, Kerberos)
0, // Context object
&wbemServices // pointer to IWbemServices proxy
);
if (FAILED(hres))
{
std::cout << "Could not connect. Error code = 0x" << std::hex << hres << std::endl;
wbemLocator->Release();
CoUninitialize();
return false; // Program has failed.
}
std::cout << "Connected to ROOT\\CIMV2 WMI namespace" << std::endl;
// Step 5: --------------------------------------------------
// Set security levels on the proxy -------------------------
hres = CoSetProxyBlanket(
wbemServices, // Indicates the proxy to set
RPC_C_AUTHN_WINNT, // RPC_C_AUTHN_xxx
RPC_C_AUTHZ_NONE, // RPC_C_AUTHZ_xxx
nullptr, // Server principal name
RPC_C_AUTHN_LEVEL_CALL, // RPC_C_AUTHN_LEVEL_xxx
RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
nullptr, // client identity
EOAC_NONE // proxy capabilities
);
if (FAILED(hres))
{
std::cout << "Could not set proxy blanket. Error code = 0x"
<< std::hex << hres << std::endl;
wbemServices->Release();
wbemLocator->Release();
CoUninitialize();
return false; // Program has failed.
}
return true;
}
int main() {
std::cout << "HelloWorld" << std::endl;
IWbemLocator* wbemLocator{nullptr};
IWbemServices* wbemServices{nullptr};
try{
if(!initializeCom())
throw "initializeCom failed";
if(!setUpWBEM(wbemLocator,wbemServices))
throw "setUpWBEM failed";
// Step 6: --------------------------------------------------
// Use the IWbemServices pointer to make requests of WMI ----
BSTR bstr_wql = SysAllocString(L"WQL" );
BSTR bstr_sql = SysAllocString(L"SELECT * FROM Win32_OperatingSystem" );
// For example, get the name of the operating system
IEnumWbemClassObject* pEnumerator{nullptr};
HRESULT hres = wbemServices->ExecQuery(
bstr_wql,
bstr_sql,
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
nullptr,
&pEnumerator);
if (FAILED(hres))
{
std::cout << "Query for operating system name failed."
<< " Error code = 0x"
<< std::hex << hres << std::endl;
wbemServices->Release();
wbemLocator->Release();
CoUninitialize();
throw "ExecQuery failed";; // Program has failed.
}
// Step 7: -------------------------------------------------
// Get the data from the query in step 6 -------------------
IWbemClassObject *pclsObj{nullptr};
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);
if(FAILED(hr))
std::cout << "Failed to get name " << std::endl;
std::cout << " OS Name : " << vtProp.bstrVal << std::endl;
VariantClear(&vtProp);
pclsObj->Release();
}
// Cleanup
// ========
wbemServices->Release();
wbemLocator->Release();
pEnumerator->Release();
CoUninitialize();
} catch(const std::string& error){
std::cout << error << std::endl;
}
return 0;
}
如果您有任何想法，請告訴我。
uj5u.com熱心網友回復：
問題出在程式的（幾乎）最后階段：顯示檢索到的“作業系統名稱”的代碼：
std::cout << " OS Name : " << vtProp.bstrVal << std::endl; // Prints pointer address
這里的問題是該BSTR型別使用 awchar_t*作為其緩沖區1并且std::cout流（std::ostream類的一個物件）沒有<<帶wchar_t*引數的多載（它有一個 for char*）——所以它使用帶 a 的版本const void*（作為最佳匹配），它列印地址本身，而不是指向的字串。
在您的情況下，有一個簡單的解決方法：使用std::wcout流（一個std::wostream物件），而不是2，它確實有一個<<帶wchar_t*引數的多載：
std::wcout << L" OS Name : " << vtProp.bstrVal << std::endl; // Prints the wchar_t* string
只需將您的輸出行替換為上述內容，在我的平臺上，將顯示的輸出從指標值（如您所見）更改為以下內容：
OS Name : Microsoft Windows 10 Pro|C:\WINDOWS|\Device\Harddisk0\Partition3
我不確定這是否正是您想要的，但這似乎是一個很大的改進。我相信您可以很容易地添加代碼來將該字串編輯為您想要的確切格式。
1請注意，雖然BSTR型別被定義為 a wchar_t*，但在某些方面它并不是完全相同的東西。有關更多資訊，請參閱此答案。
2重新閱讀您鏈接的檔案時，我看到wcout那里使用了它，用于顯示作業系統名稱。
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