// Copyright 2021 The Gitea Authors. All rights reserved.// SPDX-License-Identifier: MIT package util import (	"bytes"	"errors"	"io") // ReadAtMost reads at most len(buf) bytes from r into buf.// It returns the number of bytes copied. n is only less than len(buf) if r provides fewer bytes.// If EOF or ErrUnexpectedEOF occurs while reading, err will be nil.func ReadAtMost(r io.Reader, buf []byte) (n int, err error) {	n, err = io.ReadFull(r, buf)	if err == io.EOF || err == io.ErrUnexpectedEOF {		err = nil	}	return n, err} // ReadWithLimit reads at most "limit" bytes from r into buf.// If EOF or ErrUnexpectedEOF occurs while reading, err will be nil.func ReadWithLimit(r io.Reader, n int) (buf []byte, err error) {	return readWithLimit(r, 1024, n)} func readWithLimit(r io.Reader, batch, limit int) ([]byte, error) {	if limit <= batch {		buf := make([]byte, limit)		n, err := ReadAtMost(r, buf)		if err != nil {			return nil, err		}		return buf[:n], nil	}	res := bytes.NewBuffer(make([]byte, 0, batch))	bufFix := make([]byte, batch)	eof := false	for res.Len() < limit && !eof {		bufTmp := bufFix		if res.Len()+batch > limit {			bufTmp = bufFix[:limit-res.Len()]		}		n, err := io.ReadFull(r, bufTmp)		if err == io.EOF || err == io.ErrUnexpectedEOF {			eof = true		} else if err != nil {			return nil, err		}		if _, err = res.Write(bufTmp[:n]); err != nil {			return nil, err		}	}	return res.Bytes(), nil} // ErrNotEmpty is an error reported when there is a non-empty readervar ErrNotEmpty = errors.New("not-empty") // IsEmptyReader reads a reader and ensures it is emptyfunc IsEmptyReader(r io.Reader) (err error) {	var buf [1]byte 	for {		n, err := r.Read(buf[:])		if err != nil {			if err == io.EOF {				return nil			}			return err		}		if n > 0 {			return ErrNotEmpty		}	}}