siva: skip locations still not done in repo iter

siva/location.go

@@ -103,9 +103,11 @@ func (l *Location) checkAndUpdate() error {
 		return err
 	}
 
-	err = l.updateCache(cp)
-	if err != nil {
-		return err
+	if cp.Offset() > 0 {
+		err = l.updateCache(cp)
+		if err != nil {
+			return err
+		}
 	}
 
 	l.checkpoint = cp
@@ -162,6 +164,9 @@ func (l *Location) FS(mode borges.Mode) (sivafs.SivaFS, error) {
 func (l *Location) fs(mode borges.Mode, cp *checkpoint) (sivafs.SivaFS, error) {
 	if mode == borges.ReadOnlyMode {
 		offset := cp.Offset()
+		if offset == 0 {
+			return nil, borges.ErrLocationNotExists.New(string(l.id))
+		}
 
 		if l.metadata != nil {
 			version := l.lib.Version()

util/iterator.go

@@ -23,27 +23,33 @@ func NewLocationRepositoryIterator(locs []borges.Location, mode borges.Mode) *Lo
 // Next returns the next repository from the iterator. If the iterator has
 // reached the end it will return io.EOF as an error.
 func (iter *LocationRepositoryIterator) Next() (borges.Repository, error) {
-	if len(iter.locs) == 0 {
-		return nil, io.EOF
-	}
+	for {
+		if len(iter.locs) == 0 {
+			return nil, io.EOF
+		}
 
-	if iter.iter == nil {
-		i, err := iter.locs[0].Repositories(iter.mode)
-		if err != nil {
-			iter.locs = iter.locs[1:]
-			return nil, err
+		if iter.iter == nil {
+			i, err := iter.locs[0].Repositories(iter.mode)
+			if err != nil {
+				iter.locs = iter.locs[1:]
+				return nil, err
+			}
+			iter.iter = i
 		}
-		iter.iter = i
-	}
 
-	r, err := iter.iter.Next()
-	if err == io.EOF {
-		iter.locs = iter.locs[1:]
-		iter.iter = nil
-		return iter.Next()
+		r, err := iter.iter.Next()
+		switch err {
+		case nil:
+			return r, err
+		case io.EOF:
+			iter.locs = iter.locs[1:]
+			iter.iter = nil
+		default:
+			if !borges.ErrLocationNotExists.Is(err) {
+				return nil, err
+			}
+		}
 	}
-
-	return r, err
 }
 
 // ForEach call the function for each object contained on this iter until