Function TimeAndOffsetFromDevice

phc/offset.go:105–144

TimeAndOffsetFromDevice returns time we got from phc device + offset

(device string, method TimeMethod)

// TimeAndOffsetFromDevice returns time we got from phc device + offset
func TimeAndOffsetFromDevice(device string, method TimeMethod) (SysoffResult, error) {
	f, err := os.Open(device)
	if err != nil {
		return SysoffResult{}, err
	}
	defer f.Close()
	dev := FromFile(f)

	switch method {
	case MethodSyscallClockGettime:
		var ts unix.Timespec
		ts1 := time.Now()
		err = unix.ClockGettime(dev.ClockID(), &ts)
		ts2 := time.Now()
		if err != nil {
			return SysoffResult{}, fmt.Errorf("failed clock_gettime: %w", err)
		}

		return SysoffEstimateBasic(ts1, time.Unix(ts.Unix()), ts2), nil
	case MethodIoctlSysOffsetExtended:
		extended, err := dev.ReadSysoffExtended()
		if err != nil {
			return SysoffResult{}, err
		}
		return extended.BestSample(), nil
	case MethodIoctlSysOffsetExtendedRealTimeClock:
		extended, err := dev.ReadSysoffExtendedRealTimeClock1()
		if err != nil {
			return SysoffResult{}, err
		}
		return extended.BestSample(), nil
	case MethodIoctlSysOffsetPrecise:
		precise, err := dev.ReadSysoffPrecise()
		if err != nil {
			return SysoffResult{}, err
		}
		return SysoffFromPrecise(precise), nil
	}
	return SysoffResult{}, fmt.Errorf("unknown method to get PHC time %q", method)
}

// generics in standard library can't come soon enough...
func abs(value time.Duration) time.Duration {