fix unmarshaling of empty nodes

Author: whyrusleeping

cbor_gen.go

@@ -83,6 +83,8 @@ func (t *Node) UnmarshalCBOR(br io.Reader) error {
 			return err
 		}
 		t.Bitfield = big.NewInt(0).SetBytes(buf)
+	} else {
+		t.Bitfield = big.NewInt(0)
 	}
 	// t.t.Pointers ([]*hamt.Pointer)
 
@@ -125,8 +127,7 @@ func (t *KV) MarshalCBOR(w io.Writer) error {
 		return err
 	}
 
-	// t.t.Value (typegen.Deferred)
-
+	// t.t.Value (cbg.Deferred)
 	if err := t.Value.MarshalCBOR(w); err != nil {
 		return err
 	}
@@ -149,28 +150,15 @@ func (t *KV) UnmarshalCBOR(br io.Reader) error {
 
 	// t.t.Key (string)
 
-	maj, extra, err = cbg.CborReadHeader(br)
-	if err != nil {
-		return err
-	}
-
-	if maj != cbg.MajTextString {
-		return fmt.Errorf("expected cbor type 'text string' in input")
-	}
-
-	if extra > 256*1024 {
-		return fmt.Errorf("string in cbor input too long")
-	}
-
 	{
-		buf := make([]byte, extra)
-		if _, err := io.ReadFull(br, buf); err != nil {
+		sval, err := cbg.ReadString(br)
+		if err != nil {
 			return err
 		}
 
-		t.Key = string(buf)
+		t.Key = string(sval)
 	}
-	// t.t.Value (typegen.Deferred)
+	// t.t.Value (cbg.Deferred)
 
 	t.Value = new(cbg.Deferred)
 

gen/main.go

@@ -22,7 +22,6 @@ func main() {
 	t := []interface{}{
 		hamt.Node{},
 		hamt.KV{},
-		hamt.Pointer{},
 	}
 
 	for _, t := range t {

go.mod

@@ -7,6 +7,6 @@ require (
 	github.com/multiformats/go-multihash v0.0.1
 	github.com/polydawn/refmt v0.0.0-20190221155625-df39d6c2d992
 	github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72
-	github.com/whyrusleeping/cbor-gen v0.0.0-20190822231004-8db835b09a5a
+	github.com/whyrusleeping/cbor-gen v0.0.0-20190910031516-c1cbffdb01bb
 	golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7
 )

go.sum

@@ -39,6 +39,8 @@ github.com/whyrusleeping/cbor-gen v0.0.0-20190822002707-4e02357de5c1 h1:wDIXmhgP
 github.com/whyrusleeping/cbor-gen v0.0.0-20190822002707-4e02357de5c1/go.mod h1:xdlJQaiqipF0HW+Mzpg7XRM3fWbGvfgFlcppuvlkIvY=
 github.com/whyrusleeping/cbor-gen v0.0.0-20190822231004-8db835b09a5a h1:9oEQR9eq2H2JDmglMcrCa+TxUEYy3HKSiNoLIkPNy/U=
 github.com/whyrusleeping/cbor-gen v0.0.0-20190822231004-8db835b09a5a/go.mod h1:xdlJQaiqipF0HW+Mzpg7XRM3fWbGvfgFlcppuvlkIvY=
+github.com/whyrusleeping/cbor-gen v0.0.0-20190910031516-c1cbffdb01bb h1:8yBVx6dgk1GfkiWOQ+RbeDDBLCOZxOtmZ949O2uj5H4=
+github.com/whyrusleeping/cbor-gen v0.0.0-20190910031516-c1cbffdb01bb/go.mod h1:xdlJQaiqipF0HW+Mzpg7XRM3fWbGvfgFlcppuvlkIvY=
 golang.org/x/crypto v0.0.0-20190211182817-74369b46fc67 h1:ng3VDlRp5/DHpSWl02R4rM9I+8M2rhmsuLwAMmkLQWE=
 golang.org/x/crypto v0.0.0-20190211182817-74369b46fc67/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/sys v0.0.0-20190219092855-153ac476189d h1:Z0Ahzd7HltpJtjAHHxX8QFP3j1yYgiuvjbjRzDj/KH0=

hamt_test.go

@@ -382,6 +382,26 @@ func nodesEqual(t *testing.T, store *CborIpldStore, n1, n2 *Node) bool {
 	return n1Cid.Equals(n2Cid)
 }
 
+func TestReloadEmpty(t *testing.T) {
+	ctx := context.Background()
+	cs := NewCborStore()
+
+	n := NewNode(cs)
+	c, err := cs.Put(ctx, n)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	on, err := LoadNode(ctx, cs, c)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := on.Set(ctx, "foo", "bar"); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestCopy(t *testing.T) {
 	ctx := context.Background()
 	cs := NewCborStore()