Merge pull request #63 from Stebalien/fix/test-bad-cbor

fix: don't fail if we try to discard nothing at the end of an object

utils.go

@@ -21,6 +21,11 @@ const maxHeaderSize = 9
 // the most common readers we encounter in this library for a significant
 // performance boost.
 func discard(br io.Reader, n int) error {
+	// If we're expecting no bytes, don't even try to read. Otherwise, we may read an EOF.
+	if n == 0 {
+		return nil
+	}
+
 	switch r := br.(type) {
 	case *bytes.Buffer:
 		buf := r.Next(n)

utils_test.go

@@ -27,6 +27,22 @@ func TestLinkScan(t *testing.T) {
 	t.Log(cids)
 }
 
+func TestScanForLinksEOFRegression(t *testing.T) {
+	inp := "82442000000081818242005140"
+	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)
+	}
+	t.Log(cids)
+}
+
 func TestDeferredMaxLengthSingle(t *testing.T) {
 	var header bytes.Buffer
 	if err := WriteMajorTypeHeader(&header, MajByteString, ByteArrayMaxLen+1); err != nil {