VC++根据explorer.exe进程检测用户是否已登录

void CALLBACK timeCall(UINT timeid, UINT umsg, DWORD_PTR dwUser, DWORD dw1, DWORD_PTR dw2)
{
 DWORD dwSessionId = WTSGetActiveConsoleSessionId();        //获取控制台的session
 HANDLE hSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);    //为创建环境快照
 if (hSnap == INVALID_HANDLE_VALUE)
  return;

 //遍历快照，通过快照的 procEntry.szExeFile 获取应用程序名字,从而取得相应的PID
 PROCESSENTRY32 procEntry;
 procEntry.dwSize = sizeof(PROCESSENTRY32);
 Process32First(hSnap, &procEntry);

 DWORD dwExplorerPid = -1;
 do
 {
  if (strcmp(procEntry.szExeFile, "explorer.exe") == 0)
  {
   DWORD dwExplorerSessId = 0;
   if (ProcessIdToSessionId(procEntry.th32ProcessID, &dwExplorerSessId) && dwExplorerSessId == dwSessionId)
   {
    dwExplorerPid = procEntry.th32ProcessID;
    break;
   }
  }
 } while (Process32Next(hSnap, &procEntry));

 LOG_INFO("检测用户是否已经登录 : %s", (dwExplorerPid == -1) ? "未登录" : "已经登录");
 if (dwExplorerPid != -1)
 {
  //已登录
  DoSomething();
 }
}