package restic import ( "errors" "fmt" "io" "os" "path/filepath" "strings" "github.com/restic/restic/backend" "github.com/restic/restic/debug" "github.com/restic/restic/server" ) // Cache is used to locally cache items from a server. type Cache struct { base string } func NewCache(s *server.Server) (*Cache, error) { cacheDir, err := getCacheDir() if err != nil { return nil, err } basedir := filepath.Join(cacheDir, s.ID()) debug.Log("Cache.New", "opened cache at %v", basedir) return &Cache{base: basedir}, nil } // Has checks if the local cache has the id. func (c *Cache) Has(t backend.Type, subtype string, id backend.ID) (bool, error) { filename, err := c.filename(t, subtype, id) if err != nil { return false, err } fd, err := os.Open(filename) defer fd.Close() if err != nil { if os.IsNotExist(err) { debug.Log("Cache.Has", "test for file %v: not cached", filename) return false, nil } debug.Log("Cache.Has", "test for file %v: error %v", filename, err) return false, err } debug.Log("Cache.Has", "test for file %v: is cached", filename) return true, nil } // Store returns an io.WriteCloser that is used to save new information to the // cache. The returned io.WriteCloser must be closed by the caller after all // data has been written. func (c *Cache) Store(t backend.Type, subtype string, id backend.ID) (io.WriteCloser, error) { filename, err := c.filename(t, subtype, id) if err != nil { return nil, err } dirname := filepath.Dir(filename) err = os.MkdirAll(dirname, 0700) if err != nil { return nil, err } file, err := os.Create(filename) if err != nil { debug.Log("Cache.Store", "error creating file %v: %v", filename, err) return nil, err } debug.Log("Cache.Store", "created file %v", filename) return file, nil } // Load returns information from the cache. The returned io.ReadCloser must be // closed by the caller. func (c *Cache) Load(t backend.Type, subtype string, id backend.ID) (io.ReadCloser, error) { filename, err := c.filename(t, subtype, id) if err != nil { return nil, err } return os.Open(filename) } func (c *Cache) purge(t backend.Type, subtype string, id backend.ID) error { filename, err := c.filename(t, subtype, id) if err != nil { return err } err = os.Remove(filename) debug.Log("Cache.purge", "Remove file %v: %v", filename, err) if err != nil && os.IsNotExist(err) { return nil } return err } // Clear removes information from the cache that isn't present in the server any more. func (c *Cache) Clear(s *server.Server) error { list, err := c.list(backend.Snapshot) if err != nil { return err } for _, entry := range list { debug.Log("Cache.Clear", "found entry %v", entry) if ok, err := s.Test(backend.Snapshot, entry.ID.String()); !ok || err != nil { debug.Log("Cache.Clear", "snapshot %v doesn't exist any more, removing %v", entry.ID, entry) err = c.purge(backend.Snapshot, entry.Subtype, entry.ID) if err != nil { return err } } } return nil } type cacheEntry struct { ID backend.ID Subtype string } func (c cacheEntry) String() string { if c.Subtype != "" { return c.ID.Str() + "." + c.Subtype } return c.ID.Str() } func (c *Cache) list(t backend.Type) ([]cacheEntry, error) { var dir string switch t { case backend.Snapshot: dir = filepath.Join(c.base, "snapshots") default: return nil, fmt.Errorf("cache not supported for type %v", t) } fd, err := os.Open(dir) if err != nil { if os.IsNotExist(err) { return []cacheEntry{}, nil } return nil, err } defer fd.Close() fis, err := fd.Readdir(-1) if err != nil { return nil, err } entries := make([]cacheEntry, 0, len(fis)) for _, fi := range fis { parts := strings.SplitN(fi.Name(), ".", 2) id, err := backend.ParseID(parts[0]) // ignore invalid cache entries for now if err != nil { debug.Log("Cache.List", "unable to parse name %v as id: %v", parts[0], err) continue } e := cacheEntry{ID: id} if len(parts) == 2 { e.Subtype = parts[1] } entries = append(entries, e) } return entries, nil } func (c *Cache) filename(t backend.Type, subtype string, id backend.ID) (string, error) { filename := id.String() if subtype != "" { filename += "." + subtype } switch t { case backend.Snapshot: return filepath.Join(c.base, "snapshots", filename), nil } return "", fmt.Errorf("cache not supported for type %v", t) } func getCacheDir() (string, error) { if dir := os.Getenv("RESTIC_CACHE"); dir != "" { return dir, nil } return getXDGCacheDir() } // getXDGCacheDir returns the cache directory according to XDG basedir spec, see // http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html func getXDGCacheDir() (string, error) { xdgcache := os.Getenv("XDG_CACHE_HOME") home := os.Getenv("HOME") if xdgcache == "" && home == "" { return "", errors.New("unable to locate cache directory (XDG_CACHE_HOME and HOME unset)") } cachedir := "" if xdgcache != "" { cachedir = filepath.Join(xdgcache, "restic") } else if home != "" { cachedir = filepath.Join(home, ".cache", "restic") } fi, err := os.Stat(cachedir) if os.IsNotExist(err) { err = os.MkdirAll(cachedir, 0700) if err != nil { return "", err } fi, err = os.Stat(cachedir) debug.Log("getCacheDir", "create cache dir %v", cachedir) } if err != nil { return "", err } if !fi.IsDir() { return "", fmt.Errorf("cache dir %v is not a directory", cachedir) } return cachedir, nil }