Moves files

internal/backend/layout.go

@@ -0,0 +1,167 @@
+package backend
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"restic"
+	"restic/debug"
+	"restic/errors"
+	"restic/fs"
+)
+
+// Layout computes paths for file name storage.
+type Layout interface {
+	Filename(restic.Handle) string
+	Dirname(restic.Handle) string
+	Basedir(restic.FileType) string
+	Paths() []string
+	Name() string
+}
+
+// Filesystem is the abstraction of a file system used for a backend.
+type Filesystem interface {
+	Join(...string) string
+	ReadDir(string) ([]os.FileInfo, error)
+	IsNotExist(error) bool
+}
+
+// ensure statically that *LocalFilesystem implements Filesystem.
+var _ Filesystem = &LocalFilesystem{}
+
+// LocalFilesystem implements Filesystem in a local path.
+type LocalFilesystem struct {
+}
+
+// ReadDir returns all entries of a directory.
+func (l *LocalFilesystem) ReadDir(dir string) ([]os.FileInfo, error) {
+	f, err := fs.Open(dir)
+	if err != nil {
+		return nil, err
+	}
+
+	entries, err := f.Readdir(-1)
+	if err != nil {
+		return nil, errors.Wrap(err, "Readdir")
+	}
+
+	err = f.Close()
+	if err != nil {
+		return nil, errors.Wrap(err, "Close")
+	}
+
+	return entries, nil
+}
+
+// Join combines several path components to one.
+func (l *LocalFilesystem) Join(paths ...string) string {
+	return filepath.Join(paths...)
+}
+
+// IsNotExist returns true for errors that are caused by not existing files.
+func (l *LocalFilesystem) IsNotExist(err error) bool {
+	return os.IsNotExist(err)
+}
+
+var backendFilenameLength = len(restic.ID{}) * 2
+var backendFilename = regexp.MustCompile(fmt.Sprintf("^[a-fA-F0-9]{%d}$", backendFilenameLength))
+
+func hasBackendFile(fs Filesystem, dir string) (bool, error) {
+	entries, err := fs.ReadDir(dir)
+	if err != nil && fs.IsNotExist(errors.Cause(err)) {
+		return false, nil
+	}
+
+	if err != nil {
+		return false, errors.Wrap(err, "ReadDir")
+	}
+
+	for _, e := range entries {
+		if backendFilename.MatchString(e.Name()) {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
+// ErrLayoutDetectionFailed is returned by DetectLayout() when the layout
+// cannot be detected automatically.
+var ErrLayoutDetectionFailed = errors.New("auto-detecting the filesystem layout failed")
+
+// DetectLayout tries to find out which layout is used in a local (or sftp)
+// filesystem at the given path. If repo is nil, an instance of LocalFilesystem
+// is used.
+func DetectLayout(repo Filesystem, dir string) (Layout, error) {
+	debug.Log("detect layout at %v", dir)
+	if repo == nil {
+		repo = &LocalFilesystem{}
+	}
+
+	// key file in the "keys" dir (DefaultLayout)
+	foundKeysFile, err := hasBackendFile(repo, repo.Join(dir, defaultLayoutPaths[restic.KeyFile]))
+	if err != nil {
+		return nil, err
+	}
+
+	// key file in the "key" dir (S3LegacyLayout)
+	foundKeyFile, err := hasBackendFile(repo, repo.Join(dir, s3LayoutPaths[restic.KeyFile]))
+	if err != nil {
+		return nil, err
+	}
+
+	if foundKeysFile && !foundKeyFile {
+		debug.Log("found default layout at %v", dir)
+		return &DefaultLayout{
+			Path: dir,
+			Join: repo.Join,
+		}, nil
+	}
+
+	if foundKeyFile && !foundKeysFile {
+		debug.Log("found s3 layout at %v", dir)
+		return &S3LegacyLayout{
+			Path: dir,
+			Join: repo.Join,
+		}, nil
+	}
+
+	debug.Log("layout detection failed")
+	return nil, ErrLayoutDetectionFailed
+}
+
+// ParseLayout parses the config string and returns a Layout. When layout is
+// the empty string, DetectLayout is used. If that fails, defaultLayout is used.
+func ParseLayout(repo Filesystem, layout, defaultLayout, path string) (l Layout, err error) {
+	debug.Log("parse layout string %q for backend at %v", layout, path)
+	switch layout {
+	case "default":
+		l = &DefaultLayout{
+			Path: path,
+			Join: repo.Join,
+		}
+	case "s3legacy":
+		l = &S3LegacyLayout{
+			Path: path,
+			Join: repo.Join,
+		}
+	case "":
+		l, err = DetectLayout(repo, path)
+
+		// use the default layout if auto detection failed
+		if errors.Cause(err) == ErrLayoutDetectionFailed && defaultLayout != "" {
+			debug.Log("error: %v, use default layout %v", err, defaultLayout)
+			return ParseLayout(repo, defaultLayout, "", path)
+		}
+
+		if err != nil {
+			return nil, err
+		}
+		debug.Log("layout detected: %v", l)
+	default:
+		return nil, errors.Errorf("unknown backend layout string %q, may be one of: default, s3legacy", layout)
+	}
+
+	return l, nil
+}