use io.WriterTo instead of custom save interface ti serialize metadata and rolie.

cmd/csaf_provider/files.go

@@ -138,16 +138,12 @@ func writeHashedFile(fname, name string, data []byte, armored string) error {
 	return nil
 }
 
-type saver interface {
-	Save(io.Writer) error
-}
-
-func saveToFile(fname string, s saver) error {
+func saveToFile(fname string, wt io.WriterTo) error {
 	f, err1 := os.Create(fname)
 	if err1 != nil {
 		return err1
 	}
-	err1 = s.Save(f)
+	_, err1 = wt.WriteTo(f)
 	err2 := f.Close()
 	if err1 != nil {
 		return err1

cmd/csaf_provider/transaction.go

@@ -67,7 +67,7 @@ func doTransaction(
 			return err
 		}
 
-		if err := pmd.Save(newMetaFile); err != nil {
+		if _, err := pmd.WriteTo(newMetaFile); err != nil {
 			newMetaFile.Close()
 			os.Remove(newMetaName)
 			os.RemoveAll(newDir)

csaf/models.go

@@ -420,11 +420,24 @@ func NewProviderMetadataDomain(domain string, tlps []TLPLabel) *ProviderMetadata
 	return pm
 }
 
-// Save saves a metadata provider to a writer.
-func (pmd *ProviderMetadata) Save(w io.Writer) error {
+type nWriter struct {
+	io.Writer
+	n int64
+}
+
+func (nw *nWriter) Write(p []byte) (int, error) {
+	n, err := nw.Write(p)
+	nw.n += int64(n)
+	return n, err
+}
+
+// WriteTo saves a metadata provider to a writer.
+func (pmd *ProviderMetadata) WriteTo(w io.Writer) (int64, error) {
 	enc := json.NewEncoder(w)
 	enc.SetIndent("", "  ")
-	return enc.Encode(pmd)
+	nw := nWriter{w, 0}
+	err := enc.Encode(&nw)
+	return nw.n, err
 }
 
 // LoadProviderMetadata loads a metadata provider from a reader.

csaf/rolie.go

@@ -68,11 +68,13 @@ func LoadROLIEFeed(r io.Reader) (*ROLIEFeed, error) {
 	return &rf, nil
 }
 
-// Save saves a ROLIE feed to a writer.
-func (rf *ROLIEFeed) Save(w io.Writer) error {
+// WriteTo saves a ROLIE feed to a writer.
+func (rf *ROLIEFeed) WriteTo(w io.Writer) (int64, error) {
 	enc := json.NewEncoder(w)
 	enc.SetIndent("", "  ")
-	return enc.Encode(rf)
+	nw := nWriter{w, 0}
+	err := enc.Encode(&nw)
+	return nw.n, err
 }
 
 // EntryByID looks up an entry by its ID.