package cache import ( "io" "os" "path/filepath" "github.com/pkg/errors" "github.com/restic/restic/internal/crypto" "github.com/restic/restic/internal/debug" "github.com/restic/restic/internal/fs" "github.com/restic/restic/internal/restic" ) func (c *Cache) filename(h restic.Handle) string { if len(h.Name) < 2 { panic("Name is empty or too short") } subdir := h.Name[:2] return filepath.Join(c.path, cacheLayoutPaths[h.Type], subdir, h.Name) } func (c *Cache) canBeCached(t restic.FileType) bool { if c == nil { return false } if _, ok := cacheLayoutPaths[t]; !ok { return false } return true } type readCloser struct { io.Reader io.Closer } // Load returns a reader that yields the contents of the file with the // given handle. rd must be closed after use. If an error is returned, the // ReadCloser is nil. func (c *Cache) load(h restic.Handle, length int, offset int64) (io.ReadCloser, error) { debug.Log("Load from cache: %v", h) if !c.canBeCached(h.Type) { return nil, errors.New("cannot be cached") } f, err := fs.Open(c.filename(h)) if err != nil { return nil, errors.Wrap(err, "Open") } fi, err := f.Stat() if err != nil { _ = f.Close() return nil, errors.Wrap(err, "Stat") } if fi.Size() <= crypto.Extension { _ = f.Close() _ = c.remove(h) return nil, errors.Errorf("cached file %v is truncated, removing", h) } if fi.Size() < offset+int64(length) { _ = f.Close() _ = c.remove(h) return nil, errors.Errorf("cached file %v is too small, removing", h) } if offset > 0 { if _, err = f.Seek(offset, io.SeekStart); err != nil { _ = f.Close() return nil, err } } rd := readCloser{Reader: f, Closer: f} if length > 0 { rd.Reader = io.LimitReader(f, int64(length)) } return rd, nil } // SaveWriter returns a writer for the cache object h. It must be closed after writing is finished. func (c *Cache) saveWriter(h restic.Handle) (io.WriteCloser, error) { debug.Log("Save to cache: %v", h) if !c.canBeCached(h.Type) { return nil, errors.New("cannot be cached") } p := c.filename(h) err := fs.MkdirAll(filepath.Dir(p), 0700) if err != nil { return nil, errors.Wrap(err, "MkdirAll") } f, err := fs.OpenFile(p, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0400) if err != nil { return nil, errors.Wrap(err, "Create") } return f, err } // Save saves a file in the cache. func (c *Cache) Save(h restic.Handle, rd io.Reader) error { debug.Log("Save to cache: %v", h) if rd == nil { return errors.New("Save() called with nil reader") } f, err := c.saveWriter(h) if err != nil { return err } n, err := io.Copy(f, rd) if err != nil { _ = f.Close() _ = c.remove(h) return errors.Wrap(err, "Copy") } if n <= crypto.Extension { _ = f.Close() _ = c.remove(h) debug.Log("trying to cache truncated file %v, removing", h) return nil } if err = f.Close(); err != nil { _ = c.remove(h) return errors.Wrap(err, "Close") } return nil } // Remove deletes a file. When the file is not cache, no error is returned. func (c *Cache) remove(h restic.Handle) error { if !c.Has(h) { return nil } return fs.Remove(c.filename(h)) } // Clear removes all files of type t from the cache that are not contained in // the set valid. func (c *Cache) Clear(t restic.FileType, valid restic.IDSet) error { debug.Log("Clearing cache for %v: %v valid files", t, len(valid)) if !c.canBeCached(t) { return nil } list, err := c.list(t) if err != nil { return err } for id := range list { if valid.Has(id) { continue } if err = fs.Remove(c.filename(restic.Handle{Type: t, Name: id.String()})); err != nil { return err } } return nil } func isFile(fi os.FileInfo) bool { return fi.Mode()&(os.ModeType|os.ModeCharDevice) == 0 } // list returns a list of all files of type T in the cache. func (c *Cache) list(t restic.FileType) (restic.IDSet, error) { if !c.canBeCached(t) { return nil, errors.New("cannot be cached") } list := restic.NewIDSet() dir := filepath.Join(c.path, cacheLayoutPaths[t]) err := filepath.Walk(dir, func(name string, fi os.FileInfo, err error) error { if err != nil { return errors.Wrap(err, "Walk") } if !isFile(fi) { return nil } id, err := restic.ParseID(filepath.Base(name)) if err != nil { return nil } list.Insert(id) return nil }) return list, err } // Has returns true if the file is cached. func (c *Cache) Has(h restic.Handle) bool { if !c.canBeCached(h.Type) { return false } _, err := fs.Stat(c.filename(h)) return err == nil }