I am trying to get my program to set the system time (Windows 10) using a GPS as a source of truth.

However, despite getting a valid time string from the GPS and converting it to SYSTEMTIME, the clock doesn’t actually update. I confirmed this by setting the clock manually to some wildly incorrect time, hoping my program would then update the clock back to the correct time.

I have the following code, which I’ve cobbled together by looking around online:

// Enable the required privilege
HANDLE hToken;
TOKEN_PRIVILEGES tkp;
LookupPrivilegeValue(NULL, SE_SYSTEMTIME_NAME, &tkp.Privileges[0].Luid);
tkp.PrivilegeCount = 1;
tkp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
AdjustTokenPrivileges(hToken, FALSE, &tkp, 0, (PTOKEN_PRIVILEGES)NULL, 0);
if (GetLastError() != ERROR_SUCCESS)
{
  // Update the system time
  SYSTEMTIME* time = &convertDateTimeToSystemTime(gpsTime);
  if (SetSystemTime(time) != NO_ERROR)
  {
    std::stringstream logStream;
    logStream << "Successfully updated system time to: " << timeString;
    std::cout << logStream.str() << std::endl;
  }
  else
  {
    std::stringstream logStream;
    logStream << "Failed to update system time, error code: " << GetLastError();
    std::cout << logStream.str() << std::endl;
  }
}
else
{
  std::stringstream logStream;
  logStream << "Failed to adjust token privileges, error code: " << GetLastError();
  std::cout << logStream.str() << std::endl;
}

And here’s where I convert my time from the GPS to SYSTEMTIME:

SYSTEMTIME GpsMessageProcessor::convertDateTimeToSystemTime(const Poco::DateTime time)
  {
    SYSTEMTIME convertedTime;
    convertedTime.wYear = time.year();
    convertedTime.wMonth = time.month();
    convertedTime.wDay = time.day();
    convertedTime.wHour = time.hour();
    convertedTime.wMinute = time.minute();
    convertedTime.wSecond = time.second();
    convertedTime.wMilliseconds = time.millisecond();

    return convertedTime;
  }

The code above outputs:

Failed to update system time, error code : 1314

Which is in the else block of the if (SetSystemTime(time) != NO_ERROR) condition.