#399

backend/app/services/post_thumbnail_upload_validator.rb

@@ -11,10 +11,15 @@ class PostThumbnailUploadValidator
     end
     raise InvalidUpload, 'thumbnail file size が大きすぎます．' if thumbnail.size > MAX_THUMBNAIL_BYTES
     raise InvalidUpload, 'サムネイル画像の形式が不正です．' unless allowed_content_type?(thumbnail.content_type)
-    raise InvalidUpload, 'サムネイル画像の形式が不正です．' if Post.svg_document_bytes?(thumbnail.read)
-    thumbnail.rewind
+    bytes = thumbnail.read
+    raise InvalidUpload, 'サムネイル画像の形式が不正です．' if Post.svg_document_bytes?(bytes)
+    unless Post.raster_thumbnail_bytes?(bytes)
+      raise InvalidUpload, 'サムネイル画像の形式が不正です．'
+    end
 
-    attachment = Post.resized_thumbnail_attachment(thumbnail, content_type: thumbnail.content_type)
+    attachment = Post.resized_thumbnail_attachment(
+        StringIO.new(bytes),
+        content_type: thumbnail.content_type)
     attachment[:io].close if attachment[:io].respond_to?(:close)
   rescue MiniMagick::Error, Timeout::Error
     raise InvalidUpload, 'サムネイル画像の変換に失敗しました．'