Add Windows node support.

The syscall.Stat_t doesn't exist on Windows, so it is replaced by an interface,
which Windows can fill out, and field access is replaced by function calls.

Common Unix functionality is put into "node_unix.go", so there is less boilerplate.

Symlinks are skipped on Windows, since they require admin privileges.

node.go

@@ -15,6 +15,7 @@ import (
 	"github.com/restic/restic/debug"
 	"github.com/restic/restic/pack"
 	"github.com/restic/restic/repository"
+	"runtime"
 )
 
 // Node is a file, directory or other item in a backup.
@@ -148,7 +149,7 @@ func (node *Node) CreateAt(path string, repo *repository.Repository) error {
 func (node Node) restoreMetadata(path string) error {
 	var err error
 
-	err = os.Lchown(path, int(node.UID), int(node.GID))
+	err = lchown(path, int(node.UID), int(node.GID))
 	if err != nil {
 		return errors.Annotate(err, "Lchown")
 	}
@@ -236,6 +237,10 @@ func (node Node) createFileAt(path string, repo *repository.Repository) error {
 }
 
 func (node Node) createSymlinkAt(path string) error {
+	// Windows does not allow non-admins to create soft links.
+	if runtime.GOOS == "windows" {
+		return nil
+	}
 	err := os.Symlink(node.LinkTarget, path)
 	if err != nil {
 		return errors.Annotate(err, "Symlink")
@@ -245,15 +250,15 @@ func (node Node) createSymlinkAt(path string) error {
 }
 
 func (node *Node) createDevAt(path string) error {
-	return syscall.Mknod(path, syscall.S_IFBLK|0600, int(node.Device))
+	return mknod(path, syscall.S_IFBLK|0600, int(node.Device))
 }
 
 func (node *Node) createCharDevAt(path string) error {
-	return syscall.Mknod(path, syscall.S_IFCHR|0600, int(node.Device))
+	return mknod(path, syscall.S_IFCHR|0600, int(node.Device))
 }
 
 func (node *Node) createFifoAt(path string) error {
-	return syscall.Mkfifo(path, 0600)
+	return mkfifo(path, 0600)
 }
 
 func (node Node) MarshalJSON() ([]byte, error) {
@@ -381,9 +386,19 @@ func (node *Node) isNewer(path string, fi os.FileInfo) bool {
 		return true
 	}
 
-	extendedStat := fi.Sys().(*syscall.Stat_t)
-	inode := extendedStat.Ino
-	size := uint64(extendedStat.Size)
+	size := uint64(fi.Size())
+
+	extendedStat, ok := toStatT(fi.Sys())
+	if !ok {
+		if node.ModTime != fi.ModTime() ||
+			node.Size != size {
+			debug.Log("node.isNewer", "node %v is newer: timestamp, size or inode changed", path)
+			return true
+		}
+		return false
+	}
+
+	inode := extendedStat.ino()
 
 	if node.ModTime != fi.ModTime() ||
 		node.ChangeTime != changeTime(extendedStat) ||
@@ -397,11 +412,11 @@ func (node *Node) isNewer(path string, fi os.FileInfo) bool {
 	return false
 }
 
-func (node *Node) fillUser(stat *syscall.Stat_t) error {
-	node.UID = stat.Uid
-	node.GID = stat.Gid
+func (node *Node) fillUser(stat statT) error {
+	node.UID = stat.uid()
+	node.GID = stat.gid()
 
-	username, err := lookupUsername(strconv.Itoa(int(stat.Uid)))
+	username, err := lookupUsername(strconv.Itoa(int(stat.uid())))
 	if err != nil {
 		return errors.Annotate(err, "fillUser")
 	}
@@ -439,12 +454,12 @@ func lookupUsername(uid string) (string, error) {
 }
 
 func (node *Node) fillExtra(path string, fi os.FileInfo) error {
-	stat, ok := fi.Sys().(*syscall.Stat_t)
+	stat, ok := toStatT(fi.Sys())
 	if !ok {
 		return nil
 	}
 
-	node.Inode = uint64(stat.Ino)
+	node.Inode = uint64(stat.ino())
 
 	node.fillTimes(stat)
 
@@ -456,15 +471,15 @@ func (node *Node) fillExtra(path string, fi os.FileInfo) error {
 
 	switch node.Type {
 	case "file":
-		node.Size = uint64(stat.Size)
-		node.Links = uint64(stat.Nlink)
+		node.Size = uint64(stat.size())
+		node.Links = uint64(stat.nlink())
 	case "dir":
 	case "symlink":
 		node.LinkTarget, err = os.Readlink(path)
 	case "dev":
-		node.Device = uint64(stat.Rdev)
+		node.Device = uint64(stat.rdev())
 	case "chardev":
-		node.Device = uint64(stat.Rdev)
+		node.Device = uint64(stat.rdev())
 	case "fifo":
 	case "socket":
 	default:
@@ -473,3 +488,32 @@ func (node *Node) fillExtra(path string, fi os.FileInfo) error {
 
 	return err
 }
+
+type statT interface {
+	dev() uint64
+	ino() uint64
+	nlink() uint64
+	uid() uint32
+	gid() uint32
+	rdev() uint64
+	size() int64
+	atim() syscall.Timespec
+	mtim() syscall.Timespec
+	ctim() syscall.Timespec
+}
+
+func mkfifo(path string, mode uint32) (err error) {
+	return mknod(path, mode|syscall.S_IFIFO, 0)
+}
+
+func (node *Node) fillTimes(stat statT) {
+	ctim := stat.ctim()
+	atim := stat.atim()
+	node.ChangeTime = time.Unix(ctim.Unix())
+	node.AccessTime = time.Unix(atim.Unix())
+}
+
+func changeTime(stat statT) time.Time {
+	ctim := stat.ctim()
+	return time.Unix(ctim.Unix())
+}

node_darwin.go

@@ -3,22 +3,16 @@ package restic
 import (
 	"os"
 	"syscall"
-	"time"
 )
 
 func (node *Node) OpenForReading() (*os.File, error) {
 	return os.Open(node.path)
 }
 
-func changeTime(stat *syscall.Stat_t) time.Time {
-	return time.Unix(stat.Ctimespec.Unix())
-}
-
-func (node *Node) fillTimes(stat *syscall.Stat_t) {
-	node.ChangeTime = time.Unix(stat.Ctimespec.Unix())
-	node.AccessTime = time.Unix(stat.Atimespec.Unix())
-}
-
 func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespec) error {
 	return nil
 }
+
+func (s statUnix) atim() syscall.Timespec { return s.Atimespec }
+func (s statUnix) mtim() syscall.Timespec { return s.Mtimespec }
+func (s statUnix) ctim() syscall.Timespec { return s.Ctimespec }

node_freebsd.go

@@ -3,22 +3,16 @@ package restic
 import (
 	"os"
 	"syscall"
-	"time"
 )
 
 func (node *Node) OpenForReading() (*os.File, error) {
 	return os.OpenFile(node.path, os.O_RDONLY, 0)
 }
 
-func (node *Node) fillTimes(stat *syscall.Stat_t) {
-	node.ChangeTime = time.Unix(stat.Ctimespec.Unix())
-	node.AccessTime = time.Unix(stat.Atimespec.Unix())
-}
-
-func changeTime(stat *syscall.Stat_t) time.Time {
-	return time.Unix(stat.Ctimespec.Unix())
-}
-
 func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespec) error {
 	return nil
 }
+
+func (s statUnix) atim() syscall.Timespec { return s.Atimespec }
+func (s statUnix) mtim() syscall.Timespec { return s.Mtimespec }
+func (s statUnix) ctim() syscall.Timespec { return s.Ctimespec }

node_linux.go

@@ -4,7 +4,6 @@ import (
 	"os"
 	"path/filepath"
 	"syscall"
-	"time"
 	"unsafe"
 
 	"github.com/juju/errors"
@@ -18,15 +17,6 @@ func (node *Node) OpenForReading() (*os.File, error) {
 	return file, err
 }
 
-func (node *Node) fillTimes(stat *syscall.Stat_t) {
-	node.ChangeTime = time.Unix(stat.Ctim.Unix())
-	node.AccessTime = time.Unix(stat.Atim.Unix())
-}
-
-func changeTime(stat *syscall.Stat_t) time.Time {
-	return time.Unix(stat.Ctim.Unix())
-}
-
 func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespec) error {
 	dir, err := os.Open(filepath.Dir(path))
 	defer dir.Close()
@@ -65,3 +55,7 @@ func utimensat(dirfd int, path string, times *[2]syscall.Timespec, flags int) (e
 func utimesNanoAt(dirfd int, path string, ts [2]syscall.Timespec, flags int) (err error) {
 	return utimensat(dirfd, path, (*[2]syscall.Timespec)(unsafe.Pointer(&ts[0])), flags)
 }
+
+func (s statUnix) atim() syscall.Timespec { return s.Atim }
+func (s statUnix) mtim() syscall.Timespec { return s.Mtim }
+func (s statUnix) ctim() syscall.Timespec { return s.Ctim }

node_openbsd.go

@@ -3,7 +3,6 @@ package restic
 import (
 	"os"
 	"syscall"
-	"time"
 )
 
 func (node *Node) OpenForReading() (*os.File, error) {
@@ -14,15 +13,10 @@ func (node *Node) OpenForReading() (*os.File, error) {
 	return file, err
 }
 
-func (node *Node) fillTimes(stat *syscall.Stat_t) {
-	node.ChangeTime = time.Unix(stat.Ctim.Unix())
-	node.AccessTime = time.Unix(stat.Atim.Unix())
-}
-
-func changeTime(stat *syscall.Stat_t) time.Time {
-	return time.Unix(stat.Ctim.Unix())
-}
-
 func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespec) error {
 	return nil
 }
+
+func (s statUnix) atim() syscall.Timespec { return s.Atim }
+func (s statUnix) mtim() syscall.Timespec { return s.Mtim }
+func (s statUnix) ctim() syscall.Timespec { return s.Ctim }

node_test.go

@@ -119,6 +119,9 @@ func TestNodeRestoreAt(t *testing.T) {
 		nodePath := filepath.Join(tempdir, test.Name)
 		OK(t, test.CreateAt(nodePath, nil))
 
+		if test.Type == "symlink" && runtime.GOOS == "windows" {
+			continue
+		}
 		if test.Type == "dir" {
 			OK(t, test.RestoreTimestamps(nodePath))
 		}
@@ -135,15 +138,17 @@ func TestNodeRestoreAt(t *testing.T) {
 			"%v: type doesn't match (%v != %v)", test.Type, test.Type, n2.Type)
 		Assert(t, test.Size == n2.Size,
 			"%v: size doesn't match (%v != %v)", test.Size, test.Size, n2.Size)
+
+		if runtime.GOOS != "windows" {
 			Assert(t, test.UID == n2.UID,
 				"%v: UID doesn't match (%v != %v)", test.Type, test.UID, n2.UID)
 			Assert(t, test.GID == n2.GID,
 				"%v: GID doesn't match (%v != %v)", test.Type, test.GID, n2.GID)
-
 			if test.Type != "symlink" {
 				Assert(t, test.Mode == n2.Mode,
 					"%v: mode doesn't match (%v != %v)", test.Type, test.Mode, n2.Mode)
 			}
+		}
 
 		AssertFsTimeEqual(t, "AccessTime", test.Type, test.AccessTime, n2.AccessTime)
 		AssertFsTimeEqual(t, "ModTime", test.Type, test.ModTime, n2.ModTime)

node_unix.go

@@ -0,0 +1,34 @@
+//
+
+// +build dragonfly linux netbsd openbsd freebsd solaris darwin
+
+package restic
+
+import (
+	"os"
+	"syscall"
+)
+
+var mknod = syscall.Mknod
+var lchown = os.Lchown
+
+type statUnix syscall.Stat_t
+
+func toStatT(i interface{}) (statT, bool) {
+	if i == nil {
+		return nil, false
+	}
+	s, ok := i.(*syscall.Stat_t)
+	if ok && s != nil {
+		return statUnix(*s), true
+	}
+	return nil, false
+}
+
+func (s statUnix) dev() uint64   { return uint64(s.Dev) }
+func (s statUnix) ino() uint64   { return uint64(s.Ino) }
+func (s statUnix) nlink() uint64 { return uint64(s.Nlink) }
+func (s statUnix) uid() uint32   { return uint32(s.Uid) }
+func (s statUnix) gid() uint32   { return uint32(s.Gid) }
+func (s statUnix) rdev() uint64  { return uint64(s.Rdev) }
+func (s statUnix) size() int64   { return int64(s.Size) }

node_windows.go

@@ -0,0 +1,66 @@
+package restic
+
+import (
+	"os"
+	"syscall"
+)
+
+func (node *Node) OpenForReading() (*os.File, error) {
+	file, err := os.OpenFile(node.path, os.O_RDONLY, 0)
+	if os.IsPermission(err) {
+		return os.OpenFile(node.path, os.O_RDONLY, 0)
+	}
+	return file, err
+}
+
+// mknod() creates a filesystem node (file, device
+// special file, or named pipe) named pathname, with attributes
+// specified by mode and dev.
+var mknod = func(path string, mode uint32, dev int) (err error) {
+	panic("mknod not implemented")
+}
+
+// Windows doesn't need lchown
+var lchown = func(path string, uid int, gid int) (err error) {
+	return nil
+}
+
+func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespec) error {
+	return nil
+}
+
+type statWin syscall.Win32FileAttributeData
+
+func toStatT(i interface{}) (statT, bool) {
+	if i == nil {
+		return nil, false
+	}
+	s, ok := i.(*syscall.Win32FileAttributeData)
+	if ok && s != nil {
+		return statWin(*s), true
+	}
+	return nil, false
+}
+
+func (s statWin) dev() uint64   { return 0 }
+func (s statWin) ino() uint64   { return 0 }
+func (s statWin) nlink() uint64 { return 0 }
+func (s statWin) uid() uint32   { return 0 }
+func (s statWin) gid() uint32   { return 0 }
+func (s statWin) rdev() uint64  { return 0 }
+
+func (s statWin) size() int64 {
+	return int64(s.FileSizeLow) | (int64(s.FileSizeHigh) << 32)
+}
+
+func (s statWin) atim() syscall.Timespec {
+	return syscall.NsecToTimespec(s.LastAccessTime.Nanoseconds())
+}
+
+func (s statWin) mtim() syscall.Timespec {
+	return syscall.NsecToTimespec(s.LastWriteTime.Nanoseconds())
+}
+
+func (s statWin) ctim() syscall.Timespec {
+	return syscall.NsecToTimespec(s.CreationTime.Nanoseconds())
+}