make the tar writer handle sharded ipfs directories

makes ipfs get work on sharded directories

fixes #4871

License: MIT
Signed-off-by: Steven Allen <steven@stebalien.com>

unixfs/archive/tar/writer.go

@@ -39,23 +39,25 @@ func NewWriter(ctx context.Context, dag ipld.DAGService, archive bool, compressi
 }
 
 func (w *Writer) writeDir(nd *mdag.ProtoNode, fpath string) error {
+	dir, err := uio.NewDirectoryFromNode(w.Dag, nd)
+	if err != nil {
+		return err
+	}
 	if err := writeDirHeader(w.TarW, fpath); err != nil {
 		return err
 	}
 
-	for i, ng := range ipld.GetDAG(w.ctx, w.Dag, nd) {
-		child, err := ng.Get(w.ctx)
+	return dir.ForEachLink(w.ctx, func(l *ipld.Link) error {
+		child, err := w.Dag.Get(w.ctx, l.Cid)
 		if err != nil {
 			return err
 		}
-
-		npath := path.Join(fpath, nd.Links()[i].Name)
+		npath := path.Join(fpath, l.Name)
 		if err := w.WriteNode(child, npath); err != nil {
 			return err
 		}
-	}
-
-	return nil
+		return nil
+	})
 }
 
 func (w *Writer) writeFile(nd *mdag.ProtoNode, pb *upb.Data, fpath string) error {
@@ -83,7 +85,7 @@ func (w *Writer) WriteNode(nd ipld.Node, fpath string) error {
 		switch pb.GetType() {
 		case upb.Data_Metadata:
 			fallthrough
-		case upb.Data_Directory:
+		case upb.Data_Directory, upb.Data_HAMTShard:
 			return w.writeDir(nd, fpath)
 		case upb.Data_Raw:
 			fallthrough