backend: Add Layout

src/restic/backend/layout.go

@@ -0,0 +1,58 @@
+package backend
+
+import (
+	"restic"
+)
+
+// Layout computes paths for file name storage.
+type Layout interface {
+	Filename(restic.Handle) string
+	Dirname(restic.Handle) string
+	Paths() []string
+}
+
+// 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.DataFile:     "data",
+	restic.SnapshotFile: "snapshots",
+	restic.IndexFile:    "index",
+	restic.LockFile:     "locks",
+	restic.KeyFile:      "keys",
+}
+
+// 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.DataFile && 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 {
+		name = "config"
+	}
+
+	return l.Join(l.Dirname(h), name)
+}
+
+// Paths returns all directory names
+func (l *DefaultLayout) Paths() (dirs []string) {
+	for _, p := range defaultLayoutPaths {
+		dirs = append(dirs, l.Join(l.Path, p))
+	}
+	return dirs
+}

src/restic/backend/layout_test.go

@@ -0,0 +1,79 @@
+package backend
+
+import (
+	"fmt"
+	"path/filepath"
+	"reflect"
+	"restic"
+	"restic/test"
+	"sort"
+	"testing"
+)
+
+func TestDefaultLayout(t *testing.T) {
+	path, cleanup := test.TempDir(t)
+	defer cleanup()
+
+	var tests = []struct {
+		restic.Handle
+		filename string
+	}{
+		{
+			restic.Handle{Type: restic.DataFile, Name: "0123456"},
+			filepath.Join(path, "data", "01", "0123456"),
+		},
+		{
+			restic.Handle{Type: restic.ConfigFile, Name: "CFG"},
+			filepath.Join(path, "config"),
+		},
+		{
+			restic.Handle{Type: restic.SnapshotFile, Name: "123456"},
+			filepath.Join(path, "snapshots", "123456"),
+		},
+		{
+			restic.Handle{Type: restic.IndexFile, Name: "123456"},
+			filepath.Join(path, "index", "123456"),
+		},
+		{
+			restic.Handle{Type: restic.LockFile, Name: "123456"},
+			filepath.Join(path, "locks", "123456"),
+		},
+		{
+			restic.Handle{Type: restic.KeyFile, Name: "123456"},
+			filepath.Join(path, "keys", "123456"),
+		},
+	}
+
+	l := &DefaultLayout{
+		Path: path,
+		Join: filepath.Join,
+	}
+
+	t.Run("Paths", func(t *testing.T) {
+		dirs := l.Paths()
+
+		want := []string{
+			filepath.Join(path, "data"),
+			filepath.Join(path, "snapshots"),
+			filepath.Join(path, "index"),
+			filepath.Join(path, "locks"),
+			filepath.Join(path, "keys"),
+		}
+
+		sort.Sort(sort.StringSlice(want))
+		sort.Sort(sort.StringSlice(dirs))
+
+		if !reflect.DeepEqual(dirs, want) {
+			t.Fatalf("wrong paths returned, want:\v  %v\ngot:\n  %v", want, dirs)
+		}
+	})
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("%v/%v", test.Type, test.Handle.Name), func(t *testing.T) {
+			filename := l.Filename(test.Handle)
+			if filename != test.filename {
+				t.Fatalf("wrong filename, want %v, got %v", test.filename, filename)
+			}
+		})
+	}
+}