From d6edae95e96b661fbb81a71e388136a18ad786ae Mon Sep 17 00:00:00 2001
From: Carlo Alberto Ferraris <cafxx@strayorange.com>
Date: Sun, 9 Jan 2022 08:07:18 +0000
Subject: [PATCH] utimes

---
 README.md                    |  2 ++
 atomicfile.go                | 63 ++++++++++++++++++++++++++++++++----
 cmd/atomicfile/atomicfile.go | 17 ++++++++++
 3 files changed, 76 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 8e7e746..d0f1668 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,8 @@ Flags:
   --perm=PERM            File permissions
   --uid=UID              File owner user
   --gid=GID              File owner group
+  --mtime=MTIME          File modification time (RFC 3339)
+  --atime=ATIME          File access time (RFC 3339)
 
 Args:
   <filename>  Name of the file to create
diff --git a/atomicfile.go b/atomicfile.go
index 2593568..4f303ba 100644
--- a/atomicfile.go
+++ b/atomicfile.go
@@ -9,6 +9,8 @@ import (
 	"path"
 	"strconv"
 	"strings"
+	"time"
+	"unsafe"
 
 	"golang.org/x/sys/unix"
 )
@@ -83,6 +85,34 @@ func Ownership(uid, gid int) Option {
 	})
 }
 
+func ModificationTime(t time.Time) Option {
+	return optionFunc(func(c *config) error {
+		if c.mtime != defaultConfig().mtime {
+			return &werror{"multiple modification times", nil}
+		}
+		ts, err := unix.TimeToTimespec(t)
+		if err != nil {
+			return &werror{"invalid modification time", err}
+		}
+		c.mtime = ts
+		return nil
+	})
+}
+
+func AccessTime(t time.Time) Option {
+	return optionFunc(func(c *config) error {
+		if c.atime != defaultConfig().atime {
+			return &werror{"multiple access times", nil}
+		}
+		ts, err := unix.TimeToTimespec(t)
+		if err != nil {
+			return &werror{"invalid access time", err}
+		}
+		c.atime = ts
+		return nil
+	})
+}
+
 // TODO: owner/group, permissions, file times, lock, xattr, fadvise flags, fsync, ...
 
 type config struct {
@@ -93,16 +123,20 @@ type config struct {
 		name  string
 		value []byte
 	}
-	perm uint32
-	uid  int
-	gid  int
+	perm  uint32
+	uid   int
+	gid   int
+	mtime unix.Timespec
+	atime unix.Timespec
 }
 
 func defaultConfig() config {
 	return config{
-		perm: ^uint32(0),
-		uid:  -1,
-		gid:  -1,
+		perm:  ^uint32(0),
+		uid:   -1,
+		gid:   -1,
+		mtime: unix.Timespec{Nsec: unix.UTIME_OMIT},
+		atime: unix.Timespec{Nsec: unix.UTIME_OMIT},
 	}
 }
 
@@ -173,6 +207,14 @@ func Create(filename string, options ...Option) error {
 			return &werror{"setting xattr", err}
 		}
 	}
+
+	if cfg.mtime != defaultConfig().mtime || cfg.atime != defaultConfig().atime {
+		err := futimens(int(f.Fd()), &[2]unix.Timespec{cfg.atime, cfg.mtime})
+		if err != nil {
+			return &werror{"setting access/modification time", err}
+		}
+	}
+
 	if cfg.flushData {
 		err := f.Sync()
 		if err != nil {
@@ -247,3 +289,12 @@ func guessContentSize(r io.Reader) int64 {
 	}
 	return 0
 }
+
+// https://github.com/golang/go/issues/49699
+func futimens(fd int, times *[2]unix.Timespec) (err error) {
+	_, _, e1 := unix.Syscall6(unix.SYS_UTIMENSAT, uintptr(fd), 0, uintptr(unsafe.Pointer(times)), 0, 0, 0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
diff --git a/cmd/atomicfile/atomicfile.go b/cmd/atomicfile/atomicfile.go
index 6c5a2f8..5bfa515 100644
--- a/cmd/atomicfile/atomicfile.go
+++ b/cmd/atomicfile/atomicfile.go
@@ -3,6 +3,7 @@ package main
 import (
 	"os"
 	"strconv"
+	"time"
 
 	"github.com/CAFxX/atomicfile"
 	"gopkg.in/alecthomas/kingpin.v2"
@@ -16,6 +17,8 @@ func main() {
 	perm := kingpin.Flag("perm", "File permissions").String()
 	uid := kingpin.Flag("uid", "File owner user").Default("-1").PlaceHolder("UID").Int()
 	gid := kingpin.Flag("gid", "File owner group").Default("-1").PlaceHolder("GID").Int()
+	mtime := kingpin.Flag("mtime", "File modification time (RFC 3339)").String()
+	atime := kingpin.Flag("atime", "File access time (RFC 3339)").String()
 	kingpin.Parse()
 
 	opts := []atomicfile.Option{
@@ -40,6 +43,20 @@ func main() {
 	if *uid != -1 || *gid != -1 {
 		opts = append(opts, atomicfile.Ownership(*uid, *gid))
 	}
+	if *mtime != "" {
+		t, err := time.Parse(time.RFC3339Nano, *mtime)
+		if err != nil {
+			fatal(err)
+		}
+		opts = append(opts, atomicfile.ModificationTime(t))
+	}
+	if *atime != "" {
+		t, err := time.Parse(time.RFC3339Nano, *atime)
+		if err != nil {
+			fatal(err)
+		}
+		opts = append(opts, atomicfile.AccessTime(t))
+	}
 
 	err := atomicfile.Create(*filename, opts...)
 	if err != nil {