backend: split layout code into own subpackage

internal/backend/layout/layout_default.go

@@ -0,0 +1,79 @@
+package layout
+
+import (
+	"encoding/hex"
+
+	"github.com/restic/restic/internal/restic"
+)
+
+// DefaultLayout implements the default layout for local and sftp backends, as
+// described in the Design document. The `data` directory has one level of
+// subdirs, two characters each (taken from the first two characters of the
+// file name).
+type DefaultLayout struct {
+	Path string
+	Join func(...string) string
+}
+
+var defaultLayoutPaths = map[restic.FileType]string{
+	restic.PackFile:     "data",
+	restic.SnapshotFile: "snapshots",
+	restic.IndexFile:    "index",
+	restic.LockFile:     "locks",
+	restic.KeyFile:      "keys",
+}
+
+func (l *DefaultLayout) String() string {
+	return "<DefaultLayout>"
+}
+
+// Name returns the name for this layout.
+func (l *DefaultLayout) Name() string {
+	return "default"
+}
+
+// Dirname returns the directory path for a given file type and name.
+func (l *DefaultLayout) Dirname(h restic.Handle) string {
+	p := defaultLayoutPaths[h.Type]
+
+	if h.Type == restic.PackFile && len(h.Name) > 2 {
+		p = l.Join(p, h.Name[:2]) + "/"
+	}
+
+	return l.Join(l.Path, p) + "/"
+}
+
+// Filename returns a path to a file, including its name.
+func (l *DefaultLayout) Filename(h restic.Handle) string {
+	name := h.Name
+	if h.Type == restic.ConfigFile {
+		return l.Join(l.Path, "config")
+	}
+
+	return l.Join(l.Dirname(h), name)
+}
+
+// Paths returns all directory names needed for a repo.
+func (l *DefaultLayout) Paths() (dirs []string) {
+	for _, p := range defaultLayoutPaths {
+		dirs = append(dirs, l.Join(l.Path, p))
+	}
+
+	// also add subdirs
+	for i := 0; i < 256; i++ {
+		subdir := hex.EncodeToString([]byte{byte(i)})
+		dirs = append(dirs, l.Join(l.Path, defaultLayoutPaths[restic.PackFile], subdir))
+	}
+
+	return dirs
+}
+
+// Basedir returns the base dir name for type t.
+func (l *DefaultLayout) Basedir(t restic.FileType) (dirname string, subdirs bool) {
+	if t == restic.PackFile {
+		subdirs = true
+	}
+
+	dirname = l.Join(l.Path, defaultLayoutPaths[t])
+	return
+}