1 files changed, 69 insertions, 0 deletions
diff --git a/plumbing/protocol/packp/advrefs.go b/plumbing/protocol/packp/advrefs.go
index c54f9d8..b36b180 100644
--- a/plumbing/protocol/packp/advrefs.go
+++ b/plumbing/protocol/packp/advrefs.go
@@ -1,7 +1,16 @@
 package packp
 
 import (
+	"fmt"
+	"strings"
+
 	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/storer"
+	"gopkg.in/src-d/go-git.v4/storage/memory"
+)
+
+const (
+	symref = "symref"
 )
 
 // AdvRefs values represent the information transmitted on an
@@ -38,3 +47,63 @@ func NewAdvRefs() *AdvRefs {
 		Shallows:     []plumbing.Hash{},
 	}
 }
+
+func (a *AdvRefs) AddReference(r *plumbing.Reference) error {
+	switch r.Type() {
+	case plumbing.SymbolicReference:
+		v := fmt.Sprintf("%s:%s", r.Name().String(), r.Target().String())
+		a.Capabilities.Add(symref, v)
+	case plumbing.HashReference:
+		a.References[r.Name().String()] = r.Hash()
+	default:
+		return plumbing.ErrInvalidType
+	}
+
+	return nil
+}
+
+func (a *AdvRefs) AllReferences() (memory.ReferenceStorage, error) {
+	s := memory.ReferenceStorage{}
+	if err := addRefs(s, a); err != nil {
+		return s, plumbing.NewUnexpectedError(err)
+	}
+
+	return s, nil
+}
+
+func addRefs(s storer.ReferenceStorer, ar *AdvRefs) error {
+	for name, hash := range ar.References {
+		ref := plumbing.NewReferenceFromStrings(name, hash.String())
+		if err := s.SetReference(ref); err != nil {
+			return err
+		}
+	}
+
+	return addSymbolicRefs(s, ar)
+}
+
+func addSymbolicRefs(s storer.ReferenceStorer, ar *AdvRefs) error {
+	if !hasSymrefs(ar) {
+		return nil
+	}
+
+	for _, symref := range ar.Capabilities.Get(symref).Values {
+		chunks := strings.Split(symref, ":")
+		if len(chunks) != 2 {
+			err := fmt.Errorf("bad number of `:` in symref value (%q)", symref)
+			return plumbing.NewUnexpectedError(err)
+		}
+		name := plumbing.ReferenceName(chunks[0])
+		target := plumbing.ReferenceName(chunks[1])
+		ref := plumbing.NewSymbolicReference(name, target)
+		if err := s.SetReference(ref); err != nil {
+			return nil
+		}
+	}
+
+	return nil
+}
+
+func hasSymrefs(ar *AdvRefs) bool {
+	return ar.Capabilities.Supports(symref)
+}