檢查是否已安裝服務
此示例顯示如何檢查服務是否已存在（ 即，是否已安裝在計算機上）。此程式碼僅需要最低許可權，因此每個程序都可以執行檢查，無論它執行的安全級別如何。
#define UNICODE
#define _UNICODE
#include <Windows.h>
#include <string>
#include <iostream>
enum Result
{
unknown,
serviceManager_AccessDenied,
serviceManager_DatabaseDoesNotExist,
service_AccessDenied,
service_InvalidServiceManagerHandle,
service_InvalidServiceName,
service_DoesNotExist,
service_Exist
};
Result ServiceExists(const std::wstring &serviceName)
{
Result r = unknown;
// Get a handle to the SCM database
SC_HANDLE manager = OpenSCManager(NULL, SERVICES_ACTIVE_DATABASE, GENERIC_READ);
if (manager == NULL)
{
DWORD lastError = GetLastError();
// At this point, we can return directly because no handles need to be closed.
if (lastError == ERROR_ACCESS_DENIED)
return serviceManager_AccessDenied;
else if (lastError == ERROR_DATABASE_DOES_NOT_EXIST)
return serviceManager_DatabaseDoesNotExist;
else
return unknown;
}
SC_HANDLE service = OpenService(manager, serviceName.c_str(), GENERIC_READ);
if (service == NULL)
{
DWORD error = GetLastError();
if (error == ERROR_ACCESS_DENIED)
r = service_AccessDenied;
else if (error == ERROR_INVALID_HANDLE)
r = service_InvalidServiceManagerHandle;
else if (error == ERROR_INVALID_NAME)
r = service_InvalidServiceName;
else if (error == ERROR_SERVICE_DOES_NOT_EXIST)
r = service_DoesNotExist;
else
r = unknown;
}
else
r = service_Exist;
if (service != NULL)
CloseServiceHandle(service);
if (manager != NULL)
CloseServiceHandle(manager);
return r;
}
int main()
{
std::wstring serviceName = L"MSSQL$SQLEXPRESS"; // name of the service to check
Result result = ServiceExists(serviceName);
if (result == service_Exist)
std::wcout << L"The service '" << serviceName << "' exists." << std::endl;
else if (result == service_DoesNotExist)
std::wcout << L"The service '" << serviceName << "' does not exist." << std::endl;
else
std::wcout << L"An error has occurred, and it could not be determined whether the service '" << serviceName << "' exists or not." << std::endl;
}