fix overread on scanforlinks

utils.go

@@ -48,7 +48,7 @@ func scanForLinksRec(br io.Reader, cb func(cid.Cid), scratch []byte) error {
 				return fmt.Errorf("string in cbor input too long")
 			}
 
-			if _, err := io.ReadAtLeast(br, scratch, int(extra)); err != nil {
+			if _, err := io.ReadAtLeast(br, scratch[:extra], int(extra)); err != nil {
 				return err
 			}
 
@@ -103,7 +103,7 @@ type CBORMarshaler interface {
 }
 
 type Deferred struct {
-	Raw []byte
+	Raw         []byte
 	nestedLevel int
 }
 

utils_test.go

@@ -2,9 +2,29 @@ package typegen
 
 import (
 	"bytes"
+	"encoding/hex"
+	"fmt"
 	"testing"
+
+	cid "github.com/ipfs/go-cid"
 )
 
+func TestLinkScan(t *testing.T) {
+	inp := "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"
+	inpb, err := hex.DecodeString(inp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var cids []cid.Cid
+	if err := ScanForLinks(bytes.NewReader(inpb), func(c cid.Cid) {
+		cids = append(cids, c)
+	}); err != nil {
+		t.Fatal(err)
+	}
+	fmt.Println(cids)
+}
+
 func TestDeferredMaxLengthSingle(t *testing.T) {
 	var header bytes.Buffer
 	if err := WriteMajorTypeHeader(&header, MajByteString, ByteArrayMaxLen+1); err != nil {