From f5cc5150e40e50696a628f5d3d1f2a59965aa810 Mon Sep 17 00:00:00 2001
From: Daniel Rocha <daniel@rocha.io>
Date: Fri, 29 Apr 2022 00:35:11 +0200
Subject: [PATCH] refactor: use syscall to set time on Linux and macOS

---
 go.mod                       |  1 +
 go.sum                       |  2 ++
 pkg/htp/service.go           | 34 ----------------------------------
 pkg/htp/service_darwin.go    | 14 ++++++++++++++
 pkg/htp/service_linux_386.go | 14 ++++++++++++++
 pkg/htp/service_linux_x64.go | 14 ++++++++++++++
 pkg/htp/service_unknown.go   | 12 ++++++++++++
 pkg/htp/service_windows.go   | 13 +++++++++++++
 8 files changed, 70 insertions(+), 34 deletions(-)
 create mode 100644 pkg/htp/service_darwin.go
 create mode 100644 pkg/htp/service_linux_386.go
 create mode 100644 pkg/htp/service_linux_x64.go
 create mode 100644 pkg/htp/service_unknown.go
 create mode 100644 pkg/htp/service_windows.go

diff --git a/go.mod b/go.mod
index 1a2cad3..cce9d8c 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.18
 require (
 	github.com/spf13/cobra v1.4.0
 	golang.org/x/exp v0.0.0-20220414153411-bcd21879b8fd
+	golang.org/x/sys v0.0.0-20220422013727-9388b58f7150
 )
 
 require (
diff --git a/go.sum b/go.sum
index d7357a7..02200da 100644
--- a/go.sum
+++ b/go.sum
@@ -8,5 +8,7 @@ github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 golang.org/x/exp v0.0.0-20220414153411-bcd21879b8fd h1:zVFyTKZN/Q7mNRWSs1GOYnHM9NiFSJ54YVRsD0rNWT4=
 golang.org/x/exp v0.0.0-20220414153411-bcd21879b8fd/go.mod h1:lgLbSvA5ygNOMpwM/9anMpWVlVJ7Z+cHWq/eFuinpGE=
+golang.org/x/sys v0.0.0-20220422013727-9388b58f7150 h1:xHms4gcpe1YE7A3yIllJXP16CMAGuqwO2lX1mTyyRRc=
+golang.org/x/sys v0.0.0-20220422013727-9388b58f7150/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
diff --git a/pkg/htp/service.go b/pkg/htp/service.go
index 833b1e0..7b8f464 100644
--- a/pkg/htp/service.go
+++ b/pkg/htp/service.go
@@ -1,18 +1,5 @@
 package htp
 
-import (
-	"fmt"
-	"os/exec"
-	"runtime"
-	"time"
-)
-
-const (
-	// isoFormat   = "2006-01-02T15:04:05.000Z07:00"
-	// unixFormat  = "Mon Jan _2 15:04:05.000 MST 2006"
-	macosFormat = "0102150406.05"
-)
-
 type SyncTrace struct {
 	Before func(i int) bool
 	After  func(i int, round *SyncRound) bool
@@ -47,24 +34,3 @@ func Sync(client *SyncClient, model *SyncModel, trace *SyncTrace) error {
 
 	return nil
 }
-
-func SyncSystem(model *SyncModel) error {
-	switch runtime.GOOS {
-	case "windows":
-		arg := fmt.Sprintf("Set-Date -Adjust $([TimeSpan]::FromSeconds(%+.3f))", -model.Offset().Sec())
-		return exec.Command("powershell", "-Command", arg).Run()
-
-	case "linux":
-		arg := fmt.Sprintf("%+.3f seconds", -model.Offset().Sec())
-		return exec.Command("date", "-s", arg).Run()
-
-	case "darwin":
-		arg := model.Now().Add(time.Second).Format(macosFormat)
-		sleep := time.Duration(int(time.Second) - model.Now().Nanosecond())
-		time.Sleep(sleep)
-		return exec.Command("date", arg).Run()
-
-	default:
-		return fmt.Errorf("system not supported: %s", runtime.GOOS)
-	}
-}
diff --git a/pkg/htp/service_darwin.go b/pkg/htp/service_darwin.go
new file mode 100644
index 0000000..5b196b8
--- /dev/null
+++ b/pkg/htp/service_darwin.go
@@ -0,0 +1,14 @@
+//go:build darwin
+
+package htp
+
+import "golang.org/x/sys/unix"
+
+func SyncSystem(model *SyncModel) error {
+	now := model.Now()
+	tv := &unix.Timeval{
+		Sec:  now.Unix(),
+		Usec: int32(now.UnixMicro() % 1_000_000),
+	}
+	return unix.Settimeofday(tv)
+}
diff --git a/pkg/htp/service_linux_386.go b/pkg/htp/service_linux_386.go
new file mode 100644
index 0000000..174694e
--- /dev/null
+++ b/pkg/htp/service_linux_386.go
@@ -0,0 +1,14 @@
+//go:build linux && 386
+
+package htp
+
+import "golang.org/x/sys/unix"
+
+func SyncSystem(model *SyncModel) error {
+	now := model.Now()
+	tv := &unix.Timeval{
+		Sec:  int32(now.Unix()),
+		Usec: int32(now.UnixMicro() % 1_000_000),
+	}
+	return unix.Settimeofday(tv)
+}
diff --git a/pkg/htp/service_linux_x64.go b/pkg/htp/service_linux_x64.go
new file mode 100644
index 0000000..c57242e
--- /dev/null
+++ b/pkg/htp/service_linux_x64.go
@@ -0,0 +1,14 @@
+//go:build linux && (amd64 || arm64)
+
+package htp
+
+import "golang.org/x/sys/unix"
+
+func SyncSystem(model *SyncModel) error {
+	now := model.Now()
+	tv := &unix.Timeval{
+		Sec:  now.Unix(),
+		Usec: now.UnixMicro() % 1_000_000,
+	}
+	return unix.Settimeofday(tv)
+}
diff --git a/pkg/htp/service_unknown.go b/pkg/htp/service_unknown.go
new file mode 100644
index 0000000..139f1ad
--- /dev/null
+++ b/pkg/htp/service_unknown.go
@@ -0,0 +1,12 @@
+//go:build !(darwin || (linux && (amd64 || arm64 || 386)) || windows)
+
+package htp
+
+import (
+	"fmt"
+	"runtime"
+)
+
+func SyncSystem(model *SyncModel) error {
+	return fmt.Errorf("system not supported: %s", runtime.GOOS)
+}
diff --git a/pkg/htp/service_windows.go b/pkg/htp/service_windows.go
new file mode 100644
index 0000000..b1ae66f
--- /dev/null
+++ b/pkg/htp/service_windows.go
@@ -0,0 +1,13 @@
+//go:build windows
+
+package htp
+
+import (
+	"fmt"
+	"os/exec"
+)
+
+func SyncSystem(model *SyncModel) error {
+	arg := fmt.Sprintf("Set-Date -Adjust $([TimeSpan]::FromSeconds(%+.3f))", -model.Offset().Sec())
+	return exec.Command("powershell", "-Command", arg).Run()
+}