Merge pull request #2875 from fgma/issue2699

issue2699: restore symlinks on windows when run as admin user

changelog/unreleased/issue-2699

@@ -0,0 +1,9 @@
+Bugfix: Restore symbolic links on windows
+
+We've added support to restore symbolic links on windows.
+Because of windows specific restrictions this is only possible when running
+restic having SeCreateSymbolicLinkPrivilege privilege or when running as admin.
+
+https://github.com/restic/restic/issues/1078
+https://github.com/restic/restic/issues/2699
+https://github.com/restic/restic/pull/2875

doc/050_restore.rst

@@ -56,6 +56,10 @@ There are case insensitive variants of ``--exclude`` and ``--include`` called
 ``--iexclude`` and ``--iinclude``. These options will behave the same way but
 ignore the casing of paths.
 
+Restoring symbolic links on windows is only possible when the user has
+``SeCreateSymbolicLinkPrivilege`` privilege or is running as admin. This is a
+restriction of windows not restic.
+
 Restore using mount
 ===================
 

internal/archiver/testing.go

@@ -78,10 +78,6 @@ func TestCreateFiles(t testing.TB, target string, dir TestDir) {
 				t.Fatal(err)
 			}
 		case TestSymlink:
-			if runtime.GOOS == "windows" {
-				continue
-			}
-
 			err := fs.Symlink(filepath.FromSlash(it.Target), targetPath)
 			if err != nil {
 				t.Fatal(err)
@@ -139,16 +135,6 @@ func TestEnsureFiles(t testing.TB, target string, dir TestDir) {
 
 	// first, test that all items are there
 	TestWalkFiles(t, target, dir, func(path string, item interface{}) error {
-		// ignore symlinks on Windows
-		if _, ok := item.(TestSymlink); ok && runtime.GOOS == "windows" {
-			// mark paths and parents as checked
-			pathsChecked[path] = struct{}{}
-			for parent := filepath.Dir(path); parent != target; parent = filepath.Dir(parent) {
-				pathsChecked[parent] = struct{}{}
-			}
-			return nil
-		}
-
 		fi, err := fs.Lstat(path)
 		if err != nil {
 			return err
@@ -298,10 +284,6 @@ func TestEnsureTree(ctx context.Context, t testing.TB, prefix string, repo resti
 			}
 			TestEnsureFileContent(ctx, t, repo, nodePrefix, node, e)
 		case TestSymlink:
-			// skip symlinks on windows
-			if runtime.GOOS == "windows" {
-				continue
-			}
 			if node.Type != "symlink" {
 				t.Errorf("tree node %v has wrong type %q, want %q", nodePrefix, node.Type, "file")
 			}
@@ -313,12 +295,6 @@ func TestEnsureTree(ctx context.Context, t testing.TB, prefix string, repo resti
 	}
 
 	for name := range dir {
-		// skip checking symlinks on Windows
-		entry := dir[name]
-		if _, ok := entry.(TestSymlink); ok && runtime.GOOS == "windows" {
-			continue
-		}
-
 		_, ok := checked[name]
 		if !ok {
 			t.Errorf("tree %v: expected node %q not found, has: %v", prefix, name, nodeNames)

internal/archiver/testing_test.go

@@ -6,7 +6,6 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"runtime"
 	"testing"
 	"time"
 
@@ -68,10 +67,6 @@ func createFilesAt(t testing.TB, targetdir string, files map[string]interface{})
 				t.Fatal(err)
 			}
 		case TestSymlink:
-			// ignore symlinks on windows
-			if runtime.GOOS == "windows" {
-				continue
-			}
 			err := fs.Symlink(filepath.FromSlash(it.Target), target)
 			if err != nil {
 				t.Fatal(err)
@@ -93,7 +88,7 @@ func TestTestCreateFiles(t *testing.T) {
 				},
 				"sub": TestDir{
 					"subsub": TestDir{
-						"link": TestSymlink{Target: "x/y/z"},
+						"link": TestSymlink{Target: filepath.Clean("x/y/z")},
 					},
 				},
 			},
@@ -101,7 +96,7 @@ func TestTestCreateFiles(t *testing.T) {
 				"foo":             TestFile{Content: "foo"},
 				"subdir":          TestDir{},
 				"subdir/subfile":  TestFile{Content: "bar"},
-				"sub/subsub/link": TestSymlink{Target: "x/y/z"},
+				"sub/subsub/link": TestSymlink{Target: filepath.Clean("x/y/z")},
 			},
 		},
 	}
@@ -120,13 +115,6 @@ func TestTestCreateFiles(t *testing.T) {
 			TestCreateFiles(t, tempdir, test.dir)
 
 			for name, item := range test.files {
-				// don't check symlinks on windows
-				if runtime.GOOS == "windows" {
-					if _, ok := item.(TestSymlink); ok {
-						continue
-					}
-				}
-
 				targetPath := filepath.Join(tempdir, filepath.FromSlash(name))
 				fi, err := fs.Lstat(targetPath)
 				if err != nil {
@@ -233,13 +221,12 @@ func TestTestEnsureFiles(t *testing.T) {
 		expectFailure bool
 		files         map[string]interface{}
 		want          TestDir
-		unixOnly      bool
 	}{
 		{
 			files: map[string]interface{}{
 				"foo":            TestFile{Content: "foo"},
 				"subdir/subfile": TestFile{Content: "bar"},
-				"x/y/link":       TestSymlink{Target: "../../foo"},
+				"x/y/link":       TestSymlink{Target: filepath.Clean("../../foo")},
 			},
 			want: TestDir{
 				"foo": TestFile{Content: "foo"},
@@ -248,7 +235,7 @@ func TestTestEnsureFiles(t *testing.T) {
 				},
 				"x": TestDir{
 					"y": TestDir{
-						"link": TestSymlink{Target: "../../foo"},
+						"link": TestSymlink{Target: filepath.Clean("../../foo")},
 					},
 				},
 			},
@@ -295,7 +282,6 @@ func TestTestEnsureFiles(t *testing.T) {
 		},
 		{
 			expectFailure: true,
-			unixOnly:      true,
 			files: map[string]interface{}{
 				"foo": TestFile{Content: "foo"},
 			},
@@ -305,7 +291,6 @@ func TestTestEnsureFiles(t *testing.T) {
 		},
 		{
 			expectFailure: true,
-			unixOnly:      true,
 			files: map[string]interface{}{
 				"foo": TestSymlink{Target: "xxx"},
 			},
@@ -339,11 +324,6 @@ func TestTestEnsureFiles(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run("", func(t *testing.T) {
-			if test.unixOnly && runtime.GOOS == "windows" {
-				t.Skip("skip on Windows")
-				return
-			}
-
 			tempdir, cleanup := restictest.TempDir(t)
 			defer cleanup()
 
@@ -368,7 +348,6 @@ func TestTestEnsureSnapshot(t *testing.T) {
 		expectFailure bool
 		files         map[string]interface{}
 		want          TestDir
-		unixOnly      bool
 	}{
 		{
 			files: map[string]interface{}{
@@ -451,7 +430,6 @@ func TestTestEnsureSnapshot(t *testing.T) {
 		},
 		{
 			expectFailure: true,
-			unixOnly:      true,
 			files: map[string]interface{}{
 				"foo": TestSymlink{Target: filepath.FromSlash("x/y/z")},
 			},
@@ -476,11 +454,6 @@ func TestTestEnsureSnapshot(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run("", func(t *testing.T) {
-			if test.unixOnly && runtime.GOOS == "windows" {
-				t.Skip("skip on Windows")
-				return
-			}
-
 			ctx, cancel := context.WithCancel(context.Background())
 			defer cancel()
 

internal/fs/file.go

@@ -51,7 +51,7 @@ func Rename(oldpath, newpath string) error {
 // Symlink creates newname as a symbolic link to oldname.
 // If there is an error, it will be of type *LinkError.
 func Symlink(oldname, newname string) error {
-	return os.Symlink(fixpath(oldname), fixpath(newname))
+	return os.Symlink(oldname, fixpath(newname))
 }
 
 // Link creates newname as a hard link to oldname.

internal/restic/node.go

@@ -14,7 +14,6 @@ import (
 	"github.com/restic/restic/internal/errors"
 
 	"bytes"
-	"runtime"
 
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/fs"
@@ -295,10 +294,6 @@ func (node Node) writeNodeContent(ctx context.Context, repo Repository, f *os.Fi
 }
 
 func (node Node) createSymlinkAt(path string) error {
-	// Windows does not allow non-admins to create soft links.
-	if runtime.GOOS == "windows" {
-		return nil
-	}
 
 	if err := os.Remove(path); err != nil && !errors.Is(err, os.ErrNotExist) {
 		return errors.Wrap(err, "Symlink")

internal/restic/node_test.go

@@ -183,9 +183,6 @@ func TestNodeRestoreAt(t *testing.T) {
 		rtest.OK(t, test.CreateAt(context.TODO(), nodePath, nil))
 		rtest.OK(t, test.RestoreMetadata(nodePath))
 
-		if test.Type == "symlink" && runtime.GOOS == "windows" {
-			continue
-		}
 		if test.Type == "dir" {
 			rtest.OK(t, test.RestoreTimestamps(nodePath))
 		}

internal/restic/node_windows.go

@@ -17,7 +17,21 @@ func lchown(path string, uid int, gid int) (err error) {
 }
 
 func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespec) error {
-	return nil
+	// tweaked version of UtimesNano from go/src/syscall/syscall_windows.go
+	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|syscall.FILE_FLAG_OPEN_REPARSE_POINT, 0)
+	if e != nil {
+		return e
+	}
+	defer syscall.Close(h)
+	a := syscall.NsecToFiletime(syscall.TimespecToNsec(utimes[0]))
+	w := syscall.NsecToFiletime(syscall.TimespecToNsec(utimes[1]))
+	return syscall.SetFileTime(h, nil, &a, &w)
 }
 
 // Getxattr retrieves extended attribute data associated with path.