file := r.Form.Get("file")
	if len(file) == 0 {
		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrInvalidRequest), r.URL)
		return
	}

	file = filepath.ToSlash(file)
	// Reject attempts to traverse parent or absolute paths.
	if hasBadPathComponent(volume) || hasBadPathComponent(file) {
		writeErrorResponse(r.Context(), w, errorCodes.ToAPIErr(ErrInvalidResourceName), r.URL)
		return
	}