err:        err,
		readCloser: nil,
	}
}

// safeCloser will wrap a Reader as a ReadCloser.
// It is safe to call Close while the reader is being used.
type safeCloser struct {
	closed uint32
	r      io.Reader
}

func (s *safeCloser) Read(p []byte) (n int, err error) {
	if atomic.LoadUint32(&s.closed) == 1 {
		return 0, io.EOF
	}
	n, err = s.r.Read(p)