Fixing 'docker save' on Windows.

Save was failing file integrity checksums due to bugs in both
Windows and Docker. This commit includes fixes to file time handling
in tarexport and system.chtimes that are necessary along with
the Windows platform fixes to correctly support save. With this
change, sysfile_backups for windowsfilter driver are no longer
needed, so that code is removed.

Signed-off-by: Stefan J. Wernli <swernli@microsoft.com>

archive/changes_test.go

@@ -8,6 +8,8 @@ import (
 	"sort"
 	"testing"
 	"time"
+
+	"github.com/docker/docker/pkg/system"
 )
 
 func max(x, y int) int {
@@ -87,7 +89,7 @@ func createSampleDir(t *testing.T, root string) {
 
 		if info.filetype != Symlink {
 			// Set a consistent ctime, atime for all files and dirs
-			if err := os.Chtimes(p, now, now); err != nil {
+			if err := system.Chtimes(p, now, now); err != nil {
 				t.Fatal(err)
 			}
 		}
@@ -289,7 +291,7 @@ func mutateSampleDir(t *testing.T, root string) {
 	}
 
 	// Touch file
-	if err := os.Chtimes(path.Join(root, "file4"), time.Now().Add(time.Second), time.Now().Add(time.Second)); err != nil {
+	if err := system.Chtimes(path.Join(root, "file4"), time.Now().Add(time.Second), time.Now().Add(time.Second)); err != nil {
 		t.Fatal(err)
 	}
 
@@ -333,7 +335,7 @@ func mutateSampleDir(t *testing.T, root string) {
 	}
 
 	// Touch dir
-	if err := os.Chtimes(path.Join(root, "dir3"), time.Now().Add(time.Second), time.Now().Add(time.Second)); err != nil {
+	if err := system.Chtimes(path.Join(root, "dir3"), time.Now().Add(time.Second), time.Now().Add(time.Second)); err != nil {
 		t.Fatal(err)
 	}
 }

system/chtimes.go

@@ -43,5 +43,10 @@ func Chtimes(name string, atime time.Time, mtime time.Time) error {
 		return err
 	}
 
+	// Take platform specific action for setting create time.
+	if err := setCTime(name, mtime); err != nil {
+		return err
+	}
+
 	return nil
 }

system/chtimes_unix.go

@@ -0,0 +1,14 @@
+// +build !windows
+
+package system
+
+import (
+	"time"
+)
+
+//setCTime will set the create time on a file. On Unix, the create
+//time is updated as a side effect of setting the modified time, so
+//no action is required.
+func setCTime(path string, ctime time.Time) error {
+	return nil
+}

system/chtimes_unix_test.go

@@ -1,4 +1,4 @@
-// +build linux freebsd
+// +build !windows
 
 package system
 

system/chtimes_windows.go

@@ -0,0 +1,27 @@
+// +build windows
+
+package system
+
+import (
+	"syscall"
+	"time"
+)
+
+//setCTime will set the create time on a file. On Windows, this requires
+//calling SetFileTime and explicitly including the create time.
+func setCTime(path string, ctime time.Time) error {
+	ctimespec := syscall.NsecToTimespec(ctime.UnixNano())
+	pathp, e := syscall.UTF16PtrFromString(path)
+	if e != nil {
+		return e
+	}
+	h, e := syscall.CreateFile(pathp,
+		syscall.FILE_WRITE_ATTRIBUTES, syscall.FILE_SHARE_WRITE, nil,
+		syscall.OPEN_EXISTING, syscall.FILE_FLAG_BACKUP_SEMANTICS, 0)
+	if e != nil {
+		return e
+	}
+	defer syscall.Close(h)
+	c := syscall.NsecToFiletime(syscall.TimespecToNsec(ctimespec))
+	return syscall.SetFileTime(h, &c, nil, nil)
+}