unix: add unix.TimeToPtpClockTime on Linux

Add time conversion helpers for PtpClockTime similar to those
existing for Timespec and Timeval.

unix/timestruct_linux.go

@@ -0,0 +1,26 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux
+
+package unix
+
+import "time"
+
+// TimeToPtpClockTime returns t as PtpClockTime
+func TimeToPtpClockTime(t time.Time) PtpClockTime {
+	sec := t.Unix()
+	nsec := uint32(t.Nanosecond())
+	return PtpClockTime{Sec: sec, Nsec: nsec}
+}
+
+// Time returns PTPClockTime as time.Time
+func (t *PtpClockTime) Time() time.Time {
+	return time.Unix(t.Sec, int64(t.Nsec))
+}
+
+// Unix returns the time stored in t as seconds plus nanoseconds.
+func (t *PtpClockTime) Unix() (sec int64, nsec int64) {
+	return t.Sec, int64(t.Nsec)
+}

unix/timestruct_linux_test.go

@@ -0,0 +1,42 @@
+// Copyright 2017 The Go Authors. All right reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux
+
+package unix_test
+
+import (
+	"testing"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+func TestTimeToPtpClockTime(t *testing.T) {
+	testcases := []struct {
+		time  time.Time
+	}{
+		{time.Unix(0, 0)},
+		{time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)},
+		{time.Date(2262, time.December, 31, 23, 0, 0, 0, time.UTC)},
+		{time.Unix(0x7FFFFFFF, 0)},
+		{time.Unix(0x80000000, 0)},
+		{time.Unix(0x7FFFFFFF, 1000000000)},
+		{time.Unix(0x7FFFFFFF, 999999999)},
+		{time.Unix(-0x80000000, 0)},
+		{time.Unix(-0x80000001, 0)},
+		{time.Date(2038, time.January, 19, 3, 14, 7, 0, time.UTC)},
+		{time.Date(2038, time.January, 19, 3, 14, 8, 0, time.UTC)},
+		{time.Date(1901, time.December, 13, 20, 45, 52, 0, time.UTC)},
+		{time.Date(1901, time.December, 13, 20, 45, 51, 0, time.UTC)},
+	}
+
+	for _, tc := range testcases {
+		ts := unix.TimeToPtpClockTime(tc.time)
+		tstime := time.Unix(int64(ts.Sec), int64(ts.Nsec))
+		if !tstime.Equal(tc.time) {
+			t.Errorf("TimeToPtpClockTime(%v) is the time %v", tc.time, tstime)
+		}
+	}
+}