slight refactor odl.go

odl.go

@@ -43,7 +43,6 @@ func download(n int, root, name, uri string) error {
 	if err != nil {
 		return fmt.Errorf("parsing uri %s: %v", uri, err)
 	}
-	ext := filepath.Ext(u.Path)
 
 	response, err := http.Get(uri)
 	switch {
@@ -51,14 +50,14 @@ func download(n int, root, name, uri string) error {
 		return fmt.Errorf("downloading file %s: %v", uri, err)
 	case response.StatusCode != http.StatusOK:
 		return fmt.Errorf("downloading file %s: status code %d", uri, response.StatusCode)
-	default:
-		defer response.Body.Close()
 	}
 
+	defer response.Body.Close()
+
 	var r io.Reader = response.Body
+	ext := filepath.Ext(u.Path)
 	if ext == "" {
-		var err error
-		ext, r, err = guessExt(response.Body)
+		ext, r, err = guessExt(r)
 		if err != nil {
 			return err
 		}
@@ -66,11 +65,10 @@ func download(n int, root, name, uri string) error {
 
 	filename := filepath.Join(root, name+strconv.Itoa(n)+ext)
 	f, err := os.Create(filename)
-	if err != nil {
-		return err
+	if err == nil {
+		_, err = io.Copy(f, r)
 	}
 
-	_, err = io.Copy(f, r)
 	return err
 }