}

func (f *File) readFrom(r io.Reader) (written int64, handled bool, err error) {
	// Neither copy_file_range(2) nor splice(2) supports destinations opened with
	// O_APPEND, so don't bother to try zero-copy with these system calls.
	//
	// Visit https://man7.org/linux/man-pages/man2/copy_file_range.2.html#ERRORS and
	// https://man7.org/linux/man-pages/man2/splice.2.html#ERRORS for details.
	if f.appendMode {