Set format in archiver

Prevent changing the tar output by setting the format to
PAX and keeping the times truncated.
Without this change the archiver will produce different tar
archives with different hashes with go 1.10.
The addition of the access and changetime timestamps would
also cause diff comparisons to fail.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/archive/archive.go

@@ -17,6 +17,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/docker/docker/pkg/fileutils"
 	"github.com/docker/docker/pkg/idtools"
@@ -360,6 +361,10 @@ func FileInfoHeader(name string, fi os.FileInfo, link string) (*tar.Header, erro
 	if err != nil {
 		return nil, err
 	}
+	hdr.Format = tar.FormatPAX
+	hdr.ModTime = hdr.ModTime.Truncate(time.Second)
+	hdr.AccessTime = time.Time{}
+	hdr.ChangeTime = time.Time{}
 	hdr.Mode = fillGo18FileTypeBits(int64(chmodTarEntry(os.FileMode(hdr.Mode))), fi)
 	name, err = canonicalTarName(name, fi.IsDir())
 	if err != nil {
@@ -1158,6 +1163,10 @@ func (archiver *Archiver) CopyFileWithTar(src, dst string) (err error) {
 			if err != nil {
 				return err
 			}
+			hdr.Format = tar.FormatPAX
+			hdr.ModTime = hdr.ModTime.Truncate(time.Second)
+			hdr.AccessTime = time.Time{}
+			hdr.ChangeTime = time.Time{}
 			hdr.Name = filepath.Base(dst)
 			hdr.Mode = int64(chmodTarEntry(os.FileMode(hdr.Mode)))
 

pkg/containerfs/archiver.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"time"
 
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/idtools"
@@ -138,6 +139,10 @@ func (archiver *Archiver) CopyFileWithTar(src, dst string) (err error) {
 			if err != nil {
 				return err
 			}
+			hdr.Format = tar.FormatPAX
+			hdr.ModTime = hdr.ModTime.Truncate(time.Second)
+			hdr.AccessTime = time.Time{}
+			hdr.ChangeTime = time.Time{}
 			hdr.Name = dstDriver.Base(dst)
 			if dstDriver.OS() == "windows" {
 				hdr.Mode = int64(chmodTarEntry(os.FileMode(hdr.Mode)))