diff --git a/internal/cache/backend.go b/internal/cache/backend.go index 89aae51dc..9f545f309 100644 --- a/internal/cache/backend.go +++ b/internal/cache/backend.go @@ -5,6 +5,7 @@ import ( "io" "sync" + "github.com/pkg/errors" "github.com/restic/restic/internal/debug" "github.com/restic/restic/internal/restic" ) @@ -43,52 +44,50 @@ func (b *Backend) Remove(ctx context.Context, h restic.Handle) error { return b.Cache.Remove(h) } -type teeReader struct { - rd io.Reader - wr io.Writer - err error -} - -func (t *teeReader) Read(p []byte) (n int, err error) { - n, err = t.rd.Read(p) - if t.err == nil && n > 0 { - _, t.err = t.wr.Write(p[:n]) - } - - return n, err -} - var autoCacheTypes = map[restic.FileType]struct{}{ restic.IndexFile: struct{}{}, restic.SnapshotFile: struct{}{}, } -// Save stores a new file is the backend and the cache. +// Save stores a new file in the backend and the cache. func (b *Backend) Save(ctx context.Context, h restic.Handle, rd io.Reader) (err error) { if _, ok := autoCacheTypes[h.Type]; !ok { return b.Backend.Save(ctx, h, rd) } debug.Log("Save(%v): auto-store in the cache", h) - wr, err := b.Cache.SaveWriter(h) - if err != nil { - debug.Log("unable to save %v to cache: %v", h, err) - return b.Backend.Save(ctx, h, rd) + + seeker, ok := rd.(io.Seeker) + if !ok { + return errors.New("reader is not a seeker") } - tr := &teeReader{rd: rd, wr: wr} - err = b.Backend.Save(ctx, h, tr) + pos, err := seeker.Seek(0, io.SeekCurrent) + if err != nil { + return errors.Wrapf(err, "Seek") + } + + if pos != 0 { + return errors.Errorf("reader is not rewind (pos %d)", pos) + } + + err = b.Backend.Save(ctx, h, rd) if err != nil { - wr.Close() - b.Cache.Remove(h) return err } - err = wr.Close() + _, err = seeker.Seek(pos, io.SeekStart) if err != nil { - debug.Log("cache writer returned error: %v", err) - _ = b.Cache.Remove(h) + return errors.Wrapf(err, "Seek") } + + err = b.Cache.Save(h, rd) + if err != nil { + debug.Log("unable to save %v to cache: %v", h, err) + _ = b.Cache.Remove(h) + return nil + } + return nil }