frostfs-s3-gw/playback/utils/utils.go

package utils

import (
	"bytes"
	"encoding/base64"
	"encoding/xml"
	"errors"
	"io"
)

const BodyRecognizeLimit int64 = 128

func DetectXML(reader io.Reader) (bool, []byte, error) {
	checkBuf := bytes.NewBuffer(nil)
	token, err := xml.NewDecoder(io.TeeReader(io.LimitReader(reader, BodyRecognizeLimit), checkBuf)).RawToken()
	if err != nil {
		var xmlErr *xml.SyntaxError
		if errors.Is(err, io.EOF) || errors.As(err, &xmlErr) {
			return false, checkBuf.Bytes(), nil
		}
		return false, checkBuf.Bytes(), err
	}

	switch token.(type) {
	case xml.StartElement, xml.ProcInst:
		return true, checkBuf.Bytes(), nil
	}
	return false, checkBuf.Bytes(), nil
}

func ChooseWriter(isXML bool, body *bytes.Buffer) io.Writer {
	if !isXML {
		return base64.NewEncoder(base64.StdEncoding, body)
	}
	return body
}

func ChooseReader(isXml bool, bodyReader io.Reader) io.Reader {
	if !isXml {
		return base64.NewDecoder(base64.StdEncoding, bodyReader)
	}
	return bodyReader
}