Add in stream wrapper to adder

core/coreunix/add.go

@@ -85,6 +85,7 @@ type Adder struct {
 	Wrap        bool
 	NoCopy      bool
 	Chunker     string
+	FileWrapper func(io.Reader) (io.Reader, error)
 	root        ipld.Node
 	mroot       *mfs.Root
 	unlocker    bstore.Unlocker
@@ -114,6 +115,14 @@ func (adder *Adder) SetMfsRoot(r *mfs.Root) {
 
 // Constructs a node from reader's data, and adds it. Doesn't pin.
 func (adder *Adder) add(reader io.Reader) (ipld.Node, error) {
+	if adder.FileWrapper != nil {
+		wr, err := adder.FileWrapper(reader)
+		if err != nil {
+			return nil, err
+		}
+		reader = wr
+	}
+
 	chnk, err := chunker.FromString(reader, adder.Chunker)
 	if err != nil {
 		return nil, err