Confine cleanup and use held session locks

internal/fileops/cleanup.go

@@ -0,0 +1,165 @@
+package fileops
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+// RemoveAllUnderRoot removes target and its contents only after opening root and
+// every target ancestor without following symbolic links. target must name a
+// proper descendant of root. Symlinks are rejected rather than followed or
+// removed so a failed cleanup never silently changes its scope.
+func RemoveAllUnderRoot(rootPath, target string) error {
+	root, targetName, err := openConfinedCleanupTarget(rootPath, target)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = root.Close() }()
+	return removeConfinedEntry(root, targetName)
+}
+
+func openConfinedCleanupTarget(rootPath, target string) (*os.Root, string, error) {
+	if strings.TrimSpace(rootPath) == "" {
+		return nil, "", fmt.Errorf("cleanup root is required")
+	}
+	if strings.TrimSpace(target) == "" {
+		return nil, "", fmt.Errorf("cleanup target is required")
+	}
+	rootAbs, err := filepath.Abs(rootPath)
+	if err != nil {
+		return nil, "", fmt.Errorf("resolve cleanup root: %w", err)
+	}
+	targetAbs, err := filepath.Abs(target)
+	if err != nil {
+		return nil, "", fmt.Errorf("resolve cleanup target: %w", err)
+	}
+	relative, err := filepath.Rel(rootAbs, targetAbs)
+	if err != nil {
+		return nil, "", fmt.Errorf("resolve cleanup target below root: %w", err)
+	}
+	if relative == "." || relative == ".." || strings.HasPrefix(relative, ".."+string(filepath.Separator)) {
+		return nil, "", fmt.Errorf("cleanup target %q must be below root %q", targetAbs, rootAbs)
+	}
+	parts, err := relativePathParts(relative)
+	if err != nil {
+		return nil, "", err
+	}
+	root, err := openConfinedDirectory(rootAbs)
+	if err != nil {
+		return nil, "", err
+	}
+	for _, part := range parts[:len(parts)-1] {
+		child, err := openConfinedChild(root, part, false, 0)
+		if err != nil {
+			_ = root.Close()
+			return nil, "", err
+		}
+		_ = root.Close()
+		root = child
+	}
+	return root, parts[len(parts)-1], nil
+}
+
+func openConfinedDirectory(path string) (*os.Root, error) {
+	abs, err := filepath.Abs(path)
+	if err != nil {
+		return nil, fmt.Errorf("resolve directory: %w", err)
+	}
+	parts, err := absolutePathParts(abs)
+	if err != nil {
+		return nil, err
+	}
+	rootPath := filesystemRoot(abs)
+	root, err := os.OpenRoot(rootPath)
+	if err != nil {
+		return nil, fmt.Errorf("open filesystem root %q: %w", rootPath, err)
+	}
+	for _, part := range parts {
+		child, err := openConfinedChild(root, part, false, 0)
+		if err != nil {
+			_ = root.Close()
+			return nil, err
+		}
+		_ = root.Close()
+		root = child
+	}
+	return root, nil
+}
+
+func relativePathParts(path string) ([]string, error) {
+	parts := strings.FieldsFunc(path, func(r rune) bool { return r == filepath.Separator || r == '/' || r == '\\' })
+	if len(parts) == 0 {
+		return nil, fmt.Errorf("cleanup target is required")
+	}
+	for _, part := range parts {
+		if part == "" || part == "." || part == ".." {
+			return nil, fmt.Errorf("unsafe cleanup path component %q", part)
+		}
+	}
+	return parts, nil
+}
+
+func removeConfinedEntry(parent *os.Root, name string) error {
+	info, err := parent.Lstat(name)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("inspect cleanup entry %q: %w", name, err)
+	}
+	if info.Mode()&os.ModeSymlink != 0 {
+		return fmt.Errorf("refusing to delete symlink path %q", name)
+	}
+	if !info.IsDir() {
+		if err := parent.Remove(name); err != nil {
+			return fmt.Errorf("remove cleanup entry %q: %w", name, err)
+		}
+		return nil
+	}
+
+	child, err := openConfinedChild(parent, name, false, 0)
+	if err != nil {
+		return err
+	}
+	err = removeConfinedChildren(child)
+	closeErr := child.Close()
+	if err != nil {
+		if closeErr != nil {
+			return errors.Join(err, closeErr)
+		}
+		return err
+	}
+	if closeErr != nil {
+		return fmt.Errorf("close cleanup directory %q: %w", name, closeErr)
+	}
+	if err := parent.Remove(name); err != nil {
+		return fmt.Errorf("remove cleanup directory %q: %w", name, err)
+	}
+	return nil
+}
+
+func removeConfinedChildren(root *os.Root) error {
+	directory, err := root.Open(".")
+	if err != nil {
+		return fmt.Errorf("open cleanup directory: %w", err)
+	}
+	entries, readErr := directory.ReadDir(-1)
+	closeErr := directory.Close()
+	if readErr != nil {
+		return fmt.Errorf("read cleanup directory: %w", readErr)
+	}
+	if closeErr != nil {
+		return fmt.Errorf("close cleanup directory: %w", closeErr)
+	}
+	sort.Slice(entries, func(i, j int) bool { return entries[i].Name() < entries[j].Name() })
+	for _, entry := range entries {
+		if err := removeConfinedEntry(root, entry.Name()); err != nil {
+			return err
+		}
+	}
+	return nil
+}

internal/fileops/cleanup_test.go

@@ -0,0 +1,79 @@
+package fileops
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestRemoveAllUnderRootRemovesNestedTreeIdempotently(t *testing.T) {
+	root := t.TempDir()
+	target := filepath.Join(root, "runs", "run-1")
+	mustWriteFile(t, filepath.Join(target, "nested", "result.txt"), []byte("result"), 0o640)
+
+	if err := RemoveAllUnderRoot(root, target); err != nil {
+		t.Fatalf("RemoveAllUnderRoot() error = %v", err)
+	}
+	if _, err := os.Lstat(target); !os.IsNotExist(err) {
+		t.Fatalf("Lstat(%q) error = %v, want not exist", target, err)
+	}
+	if err := RemoveAllUnderRoot(root, target); err != nil {
+		t.Fatalf("second RemoveAllUnderRoot() error = %v", err)
+	}
+}
+
+func TestRemoveAllUnderRootRejectsUnsafeTargets(t *testing.T) {
+	root := t.TempDir()
+	outside := t.TempDir()
+	target := filepath.Join(root, "runs", "run-1")
+	mustWriteFile(t, filepath.Join(target, "result.txt"), []byte("result"), 0o640)
+	sentinel := filepath.Join(outside, "sentinel.txt")
+	mustWriteFile(t, sentinel, []byte("outside"), 0o640)
+
+	if err := RemoveAllUnderRoot(root, root); err == nil {
+		t.Fatal("RemoveAllUnderRoot(root, root) error = nil, want root rejection")
+	}
+	if err := RemoveAllUnderRoot(root, filepath.Join(outside, "target")); err == nil {
+		t.Fatal("RemoveAllUnderRoot(outside) error = nil, want outside-root rejection")
+	}
+	if err := os.Symlink(outside, filepath.Join(root, "runs")); err == nil {
+		t.Fatal("Symlink() error = nil, want collision because runs already exists")
+	}
+	if err := os.RemoveAll(filepath.Join(root, "runs")); err != nil {
+		t.Fatalf("RemoveAll(runs) error = %v", err)
+	}
+	if err := os.Symlink(outside, filepath.Join(root, "runs")); err != nil {
+		t.Fatalf("Symlink() error = %v", err)
+	}
+	if err := RemoveAllUnderRoot(root, target); err == nil {
+		t.Fatal("RemoveAllUnderRoot(symlinked ancestor) error = nil, want rejection")
+	}
+	data, err := os.ReadFile(sentinel)
+	if err != nil {
+		t.Fatalf("ReadFile(sentinel) error = %v", err)
+	}
+	if string(data) != "outside" {
+		t.Fatalf("sentinel content = %q, want outside", data)
+	}
+}
+
+func TestRemoveAllUnderRootRejectsSymlinkInTree(t *testing.T) {
+	root := t.TempDir()
+	outside := t.TempDir()
+	target := filepath.Join(root, "runs", "run-1")
+	if err := os.MkdirAll(target, 0o750); err != nil {
+		t.Fatalf("MkdirAll(target) error = %v", err)
+	}
+	sentinel := filepath.Join(outside, "sentinel.txt")
+	mustWriteFile(t, sentinel, []byte("outside"), 0o640)
+	if err := os.Symlink(outside, filepath.Join(target, "link")); err != nil {
+		t.Fatalf("Symlink() error = %v", err)
+	}
+
+	if err := RemoveAllUnderRoot(root, target); err == nil {
+		t.Fatal("RemoveAllUnderRoot() error = nil, want symlink rejection")
+	}
+	if _, err := os.Stat(sentinel); err != nil {
+		t.Fatalf("outside sentinel was changed: %v", err)
+	}
+}

internal/fileops/confined.go

@@ -183,6 +183,39 @@ func syncOpenedDirectory(parent *os.Root) error {
 	return syncDirectoryFile(directory, parent.Name())
 }
 
+// OpenFileConfined opens a file after verifying its parent hierarchy without
+// following symbolic links. Existing symbolic-link leaves are rejected.
+func OpenFileConfined(path string, flags int, mode os.FileMode) (*os.File, error) {
+	parent, name, err := openConfinedParent(path, false, 0)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = parent.Close() }()
+	if info, err := parent.Lstat(name); err == nil && info.Mode()&os.ModeSymlink != 0 {
+		return nil, fmt.Errorf("destination file %q is a symbolic link", name)
+	} else if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return nil, fmt.Errorf("inspect destination file %q: %w", name, err)
+	}
+	file, err := parent.OpenFile(name, flags, mode)
+	if err != nil {
+		return nil, err
+	}
+	opened, err := file.Stat()
+	if err != nil {
+		_ = file.Close()
+		return nil, fmt.Errorf("inspect opened destination file %q: %w", name, err)
+	}
+	current, err := parent.Lstat(name)
+	if err != nil || current.Mode()&os.ModeSymlink != 0 || !os.SameFile(opened, current) {
+		_ = file.Close()
+		if err != nil {
+			return nil, fmt.Errorf("reinspect destination file %q: %w", name, err)
+		}
+		return nil, fmt.Errorf("destination file %q changed while being opened", name)
+	}
+	return file, nil
+}
+
 // DownloadedTempFile is a completed, destination-confined temporary file. It
 // keeps its parent directory open until the caller installs or cleans it up.
 type DownloadedTempFile struct {

internal/fileops/directory.go

@@ -1,6 +1,8 @@
 package fileops
 
 import (
+	"crypto/rand"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -21,14 +23,257 @@ func PromoteDirectory(src, dst string) error {
 	if err := checkAtomicDirectoryPromotionSupport(); err != nil {
 		return err
 	}
-	parent, _, err := openConfinedParent(dst, false, 0)
+	parent, destinationName, err := openConfinedParent(dst, false, 0)
 	if err != nil {
 		return fmt.Errorf("open destination parent: %w", err)
 	}
-	if err := parent.Close(); err != nil {
-		return fmt.Errorf("close destination parent: %w", err)
+	defer func() { _ = parent.Close() }()
+	return promoteDirectoryConfined(src, dst, parent, destinationName, sourceTraversalHooks{})
+}
+
+func promoteDirectoryConfined(src, dst string, parent *os.Root, destinationName string, hooks sourceTraversalHooks) (resultErr error) {
+	if strings.TrimSpace(src) == "" || strings.TrimSpace(dst) == "" {
+		return fmt.Errorf("source and destination directory paths are required")
 	}
-	return promoteDirectory(src, dst, renameDirectoryNoReplace)
+	sourceInfo, err := os.Lstat(src)
+	if err != nil {
+		return fmt.Errorf("inspect source directory: %w", err)
+	}
+	if sourceInfo.Mode()&os.ModeSymlink != 0 || !sourceInfo.IsDir() {
+		return fmt.Errorf("source path %q is not a directory", src)
+	}
+	if _, err := parent.Lstat(destinationName); err == nil {
+		return fmt.Errorf("destination path %q already exists", dst)
+	} else if !errors.Is(err, os.ErrNotExist) {
+		return fmt.Errorf("inspect destination path: %w", err)
+	}
+	insideSource, err := pathWithin(src, dst)
+	if err != nil {
+		return err
+	}
+	if insideSource {
+		return fmt.Errorf("destination path %q must not be inside source directory %q", dst, src)
+	}
+
+	temporary, temporaryName, err := createSiblingTempDirectory(parent, destinationName)
+	if err != nil {
+		return err
+	}
+	removeTemporary := true
+	defer func() {
+		var closeErr error
+		if temporary != nil {
+			closeErr = temporary.Close()
+		}
+		if removeTemporary {
+			removeErr := removeConfinedEntry(parent, temporaryName)
+			if removeErr != nil {
+				resultErr = errors.Join(resultErr, fmt.Errorf("remove temporary destination directory: %w", removeErr))
+			}
+		}
+		if closeErr != nil {
+			resultErr = errors.Join(resultErr, fmt.Errorf("close temporary destination directory: %w", closeErr))
+		}
+	}()
+
+	sourceRoot, err := openVerifiedSourceRoot(src, sourceInfo, hooks)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = sourceRoot.Close() }()
+	if err := copyRegularTreeToRoot(sourceRoot, src, temporary, hooks); err != nil {
+		return err
+	}
+	if err := setOpenedDirectoryMode(temporary, WorkspaceDirectoryMode); err != nil {
+		return fmt.Errorf("set temporary root permissions: %w", err)
+	}
+	if err := syncOpenedDirectory(temporary); err != nil {
+		return fmt.Errorf("sync temporary root: %w", err)
+	}
+	if err := temporary.Close(); err != nil {
+		return fmt.Errorf("close temporary root: %w", err)
+	}
+	temporary = nil
+
+	directory, err := parent.Open(".")
+	if err != nil {
+		return fmt.Errorf("open destination parent for promotion: %w", err)
+	}
+	renameErr := renameDirectoryNoReplaceAt(directory, temporaryName, destinationName)
+	closeErr := directory.Close()
+	if renameErr != nil {
+		return fmt.Errorf("install promoted directory: %w", renameErr)
+	}
+	if closeErr != nil {
+		return fmt.Errorf("close destination parent after promotion: %w", closeErr)
+	}
+	removeTemporary = false
+	if err := syncOpenedDirectory(parent); err != nil {
+		return fmt.Errorf("sync destination parent: %w", err)
+	}
+	return nil
+}
+
+func createSiblingTempDirectory(parent *os.Root, base string) (*os.Root, string, error) {
+	for attempt := 0; attempt < 100; attempt++ {
+		var randomBytes [16]byte
+		if _, err := rand.Read(randomBytes[:]); err != nil {
+			return nil, "", fmt.Errorf("generate temporary directory name: %w", err)
+		}
+		name := "." + base + ".tmp-" + hex.EncodeToString(randomBytes[:])
+		if err := parent.Mkdir(name, WorkspaceDirectoryMode.Perm()); err != nil {
+			if errors.Is(err, os.ErrExist) {
+				continue
+			}
+			return nil, "", fmt.Errorf("create temporary destination directory: %w", err)
+		}
+		directory, err := openConfinedChild(parent, name, false, 0)
+		if err != nil {
+			_ = parent.Remove(name)
+			return nil, "", err
+		}
+		return directory, name, nil
+	}
+	return nil, "", fmt.Errorf("create unique temporary destination directory")
+}
+
+func copyRegularTreeToRoot(src *os.Root, sourcePath string, dst *os.Root, hooks sourceTraversalHooks) error {
+	directory, err := src.Open(".")
+	if err != nil {
+		return fmt.Errorf("open source directory %q for traversal: %w", sourcePath, err)
+	}
+	entries, readErr := directory.ReadDir(-1)
+	closeErr := directory.Close()
+	if readErr != nil {
+		return fmt.Errorf("read source directory %q: %w", sourcePath, readErr)
+	}
+	if closeErr != nil {
+		return fmt.Errorf("close source directory %q: %w", sourcePath, closeErr)
+	}
+	sort.Slice(entries, func(i, j int) bool { return entries[i].Name() < entries[j].Name() })
+	for _, entry := range entries {
+		entryPath := filepath.Join(sourcePath, entry.Name())
+		info, err := src.Lstat(entry.Name())
+		if err != nil {
+			return fmt.Errorf("inspect source entry %q: %w", entryPath, err)
+		}
+		if hooks.afterEntryInspect != nil {
+			hooks.afterEntryInspect(entryPath)
+		}
+		switch {
+		case info.Mode().IsRegular():
+			if err := copyRegularFileToRoot(src, dst, entry.Name(), entryPath, info); err != nil {
+				return err
+			}
+		case info.IsDir():
+			if err := copyRegularDirectoryToRoot(src, dst, entry.Name(), entryPath, info, hooks); err != nil {
+				return err
+			}
+		default:
+			return fmt.Errorf("source entry %q has unsupported file type %s", entryPath, info.Mode().Type())
+		}
+	}
+	return nil
+}
+
+func copyRegularDirectoryToRoot(sourceParent, destinationParent *os.Root, name, sourcePath string, inspected os.FileInfo, hooks sourceTraversalHooks) error {
+	source, err := openVerifiedChildDirectory(sourceParent, name, sourcePath, inspected)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = source.Close() }()
+	if err := destinationParent.Mkdir(name, WorkspaceDirectoryMode.Perm()); err != nil {
+		return fmt.Errorf("create destination directory %q: %w", sourcePath, err)
+	}
+	destination, err := openConfinedChild(destinationParent, name, false, 0)
+	if err != nil {
+		return err
+	}
+	err = copyRegularTreeToRoot(source, sourcePath, destination, hooks)
+	if err == nil {
+		err = setOpenedDirectoryMode(destination, WorkspaceDirectoryMode)
+	}
+	if err == nil {
+		err = syncOpenedDirectory(destination)
+	}
+	closeErr := destination.Close()
+	if err != nil {
+		return err
+	}
+	if closeErr != nil {
+		return fmt.Errorf("close destination directory %q: %w", sourcePath, closeErr)
+	}
+	return nil
+}
+
+func copyRegularFileToRoot(sourceRoot, destinationRoot *os.Root, name, sourcePath string, inspected os.FileInfo) error {
+	in, err := openVerifiedSourceFile(sourceRoot, name, sourcePath, inspected)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = in.Close() }()
+	out, err := destinationRoot.OpenFile(name, os.O_WRONLY|os.O_CREATE|os.O_EXCL, WorkspaceFileMode)
+	if err != nil {
+		return fmt.Errorf("create destination file %q: %w", sourcePath, err)
+	}
+	if _, err := io.Copy(out, in); err != nil {
+		_ = out.Close()
+		return fmt.Errorf("copy source file %q: %w", sourcePath, err)
+	}
+	if err := out.Chmod(WorkspaceFileMode); err != nil {
+		_ = out.Close()
+		return fmt.Errorf("set destination file permissions %q: %w", sourcePath, err)
+	}
+	if err := out.Sync(); err != nil {
+		_ = out.Close()
+		return fmt.Errorf("sync destination file %q: %w", sourcePath, err)
+	}
+	if err := out.Close(); err != nil {
+		return fmt.Errorf("close destination file %q: %w", sourcePath, err)
+	}
+	return nil
+}
+
+func openVerifiedChildDirectory(parent *os.Root, name, sourcePath string, inspected os.FileInfo) (*os.Root, error) {
+	child, err := parent.OpenRoot(name)
+	if err != nil {
+		return nil, fmt.Errorf("open source directory %q: %w", sourcePath, err)
+	}
+	opened, err := child.Stat(".")
+	if err != nil {
+		_ = child.Close()
+		return nil, fmt.Errorf("inspect opened source directory %q: %w", sourcePath, err)
+	}
+	current, err := parent.Lstat(name)
+	if err != nil || current.Mode()&os.ModeSymlink != 0 || !current.IsDir() || !os.SameFile(opened, current) {
+		_ = child.Close()
+		if err != nil {
+			return nil, fmt.Errorf("reinspect source directory %q: %w", sourcePath, err)
+		}
+		return nil, fmt.Errorf("source directory %q changed while being copied", sourcePath)
+	}
+	return child, nil
+}
+
+func openVerifiedSourceFile(root *os.Root, name, sourcePath string, inspected os.FileInfo) (*os.File, error) {
+	in, err := root.Open(name)
+	if err != nil {
+		return nil, fmt.Errorf("open source file %q: %w", sourcePath, err)
+	}
+	opened, err := in.Stat()
+	if err != nil {
+		_ = in.Close()
+		return nil, fmt.Errorf("inspect opened source file %q: %w", sourcePath, err)
+	}
+	current, err := root.Lstat(name)
+	if err != nil || current.Mode()&os.ModeSymlink != 0 || !current.Mode().IsRegular() || !os.SameFile(opened, current) {
+		_ = in.Close()
+		if err != nil {
+			return nil, fmt.Errorf("reinspect source file %q: %w", sourcePath, err)
+		}
+		return nil, fmt.Errorf("source file %q changed while being copied", sourcePath)
+	}
+	return in, nil
 }
 
 func promoteDirectory(src, dst string, install func(string, string) error) error {
@@ -87,7 +332,7 @@ func promoteDirectoryWithHooks(
 	removeTemporary := true
 	defer func() {
 		if removeTemporary {
-			_ = os.RemoveAll(temporary)
+			_ = RemoveAllUnderRoot(destinationParent, temporary)
 		}
 	}()
 

internal/fileops/rename_noreplace_darwin.go

@@ -2,10 +2,18 @@
 
 package fileops
 
-import "golang.org/x/sys/unix"
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
 
 func checkAtomicDirectoryPromotionSupport() error { return nil }
 
 func renameDirectoryNoReplace(src, dst string) error {
 	return unix.RenamexNp(src, dst, unix.RENAME_EXCL)
 }
+
+func renameDirectoryNoReplaceAt(parent *os.File, src, dst string) error {
+	return unix.RenameatxNp(int(parent.Fd()), src, int(parent.Fd()), dst, unix.RENAME_EXCL)
+}

internal/fileops/rename_noreplace_linux.go

@@ -2,10 +2,18 @@
 
 package fileops
 
-import "golang.org/x/sys/unix"
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
 
 func checkAtomicDirectoryPromotionSupport() error { return nil }
 
 func renameDirectoryNoReplace(src, dst string) error {
 	return unix.Renameat2(unix.AT_FDCWD, src, unix.AT_FDCWD, dst, unix.RENAME_NOREPLACE)
 }
+
+func renameDirectoryNoReplaceAt(parent *os.File, src, dst string) error {
+	return unix.Renameat2(int(parent.Fd()), src, int(parent.Fd()), dst, unix.RENAME_NOREPLACE)
+}

internal/fileops/rename_noreplace_other.go

@@ -4,6 +4,7 @@ package fileops
 
 import (
 	"fmt"
+	"os"
 	"runtime"
 )
 
@@ -14,3 +15,7 @@ func checkAtomicDirectoryPromotionSupport() error {
 func renameDirectoryNoReplace(_, _ string) error {
 	return checkAtomicDirectoryPromotionSupport()
 }
+
+func renameDirectoryNoReplaceAt(_ *os.File, _, _ string) error {
+	return checkAtomicDirectoryPromotionSupport()
+}

internal/fileops/rename_noreplace_windows.go

@@ -2,18 +2,17 @@
 
 package fileops
 
-import "golang.org/x/sys/windows"
+import (
+	"fmt"
+	"os"
+)
 
-func checkAtomicDirectoryPromotionSupport() error { return nil }
-
-func renameDirectoryNoReplace(src, dst string) error {
-	from, err := windows.UTF16PtrFromString(src)
-	if err != nil {
-		return err
-	}
-	to, err := windows.UTF16PtrFromString(dst)
-	if err != nil {
-		return err
-	}
-	return windows.MoveFileEx(from, to, 0)
+func checkAtomicDirectoryPromotionSupport() error {
+	return fmt.Errorf("%w on windows", ErrAtomicDirectoryPromotionUnsupported)
+}
+
+func renameDirectoryNoReplace(src, dst string) error { return checkAtomicDirectoryPromotionSupport() }
+
+func renameDirectoryNoReplaceAt(parent *os.File, src, dst string) error {
+	return checkAtomicDirectoryPromotionSupport()
 }