body_limiter.go
func NewBodyLimiter(w http.ResponseWriter, r *http.Request, n int64) *BodyLimiter {
	return &BodyLimiter{
		Original:   r.Body,
		ReadCloser: http.MaxBytesReader(w, r.Body, n),
	}
}
func NewBodyLimiter(w http.ResponseWriter, r *http.Request, n int64) *BodyLimiter {
	return &BodyLimiter{
		Original:   r.Body,
		ReadCloser: http.MaxBytesReader(w, r.Body, n),
	}
}
// NewBodyLimiter returns a new body limiter for the specified request.