Inject on-fly / in chunks

[gookie-dev]

I wrote a FUSE in fusepy to mount music files. It looks like this and works perfectly:

def read(self, path, size, offset, fh):
    headers = {'Range': 'bytes=%d-%d' % (offset, offset + size - 1)}
    response = requests.get(self.files[path.lstrip("/")], headers=headers)
    return response.content

My problem is that the FLAC files do not contain any metadata / audio tags. So I am trying to inject them with mutagen. I do not want to load the whole file though. My goal is to inject it on the fly. I have tried this:

  def read(self, path, size, offset, fh):
    download_size = max(size, 1024)
    headers = {'Range': 'bytes=%d-%d' % (offset, offset + download_size - 1)}
    response = requests.get(self.files[path.lstrip("/")], headers=headers)
    audio = FLAC(BytesIO(response.content))
    track_id = path.lstrip("/").split(".")[0]
    metadata = q.get_metadata(track_id)
    for key, value in metadata.items():
        audio[key] = value
    output = BytesIO()
    audio.save(output)
    output.seek(0)
    output.seek(offset)
    return output.read(size)

However, when I open the mounted FLAC file in VLC, I get an I/O error from VLC. Does anyone have any idea how to solve this problem?