package backend import ( "fmt" "os" "path/filepath" "regexp" "github.com/restic/restic/internal/debug" "github.com/restic/restic/internal/errors" "github.com/restic/restic/internal/fs" "github.com/restic/restic/internal/restic" ) // 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 }