@@ -133,7 +133,13 @@
 func (s *Writer) storeFile(urlID int64, file *storage.File) (int64, error) {
 	if file.ContentType == "" {
 		file.ContentType = http.DetectContentType(file.Encodings["identity"].Bytes())
-		s.log.Warn("file has no content type, sniffing", "path", file.Path, "sniffed", file.ContentType)
+		s.log.Warn(
+			"file has no content type, sniffing",
+			"path",
+			file.Path,
+			"sniffed",
+			file.ContentType,
+		)
 	}
 	r, err := s.queries.insertFile.Exec(
 		sql.Named("url_id", urlID),
@@ -178,38 +184,26 @@ func contentType(pathname string) string {
 	return mime.TypeByExtension(filepath.Ext(pathNameToFileName(pathname)))
 }
 
-func (s *Writer) WritePost(post *content.Post, content *buffer.Buffer) error {
-	s.log.Debug("storing post", "title", post.Title)
-	bytes := content.Bytes()
-	etag, err := etag(bytes)
-	if err != nil {
-		return errors.WithMessage(err, "calculating etag")
-	}
-
+func (s *Writer) NewFileFromPost(post *content.Post) *storage.File {
 	file := &storage.File{
 		Path:         post.URL,
-		ContentType:  contentType(post.URL),
 		LastModified: post.Date,
-		Etag:         etag,
 		Encodings:    map[string]*buffer.Buffer{},
 	}
 
-	return s.WriteFile(file, content)
+	return file
 }
 
-func (s *Writer) Write(pathname string, content *buffer.Buffer) error {
-	bytes := content.Bytes()
+func (s *Writer) WritePost(post *content.Post, content *buffer.Buffer) error {
+	s.log.Debug("storing post", "title", post.Title)
 
-	etag, err := etag(bytes)
-	if err != nil {
-		return errors.WithMessage(err, "calculating etag")
-	}
+	return s.WriteFile(s.NewFileFromPost(post), content)
+}
 
+func (s *Writer) Write(pathname string, content *buffer.Buffer) error {
 	file := &storage.File{
 		Path:         pathname,
-		ContentType:  contentType(pathname),
 		LastModified: time.Now(),
-		Etag:         etag,
 		Encodings:    map[string]*buffer.Buffer{},
 	}
 
@@ -228,6 +222,17 @@ if file.Encodings == nil {
 		file.Encodings = map[string]*buffer.Buffer{}
 	}
 	file.Encodings["identity"] = content
+
+	if file.ContentType == "" {
+		file.ContentType = contentType(file.Path)
+	}
+
+	if file.Etag == "" {
+		file.Etag, err = etag(content.Bytes())
+		if err != nil {
+			return errors.WithMessage(err, "could not calculate file etag")
+		}
+	}
 
 	err = file.CalculateStyleHash()
 	if err != nil {