upload_multipart.go

package main

import (
	"bufio"
  	"io"
	"io/ioutil"
  
  	"github.com/h2non/filetype"
)

func uploadToTmpFile(reader *multipart.Reader) (string, string, *er.Error) {

	var contentType string

	f, err := ioutil.TempFile("", "")
	if err != nil {
		return "", contentType, er.VideoUploadError
	}
	defer f.Close()

	for {
		p, err := reader.NextPart()
		if err != nil && err != io.EOF {
			return "", contentType, er.VideoUploadError
		}

		if err == io.EOF {
			break
		}

		buf := bufio.NewReader(p)
		sniff, _ := buf.Peek(3072)

		kind, _ := filetype.Match(sniff)
		if kind.MIME.Type != MIMETypeVideo {
			return "", contentType, er.WrongContentType
		}
		if kind == filetype.Unknown {
			return "", contentType, er.UnknownFileType
		}
		if contentType == "" {
			contentType = kind.MIME.Value
		}

		lmt := io.MultiReader(buf)
		_, err = io.Copy(f, lmt)
		if err != nil && err != io.EOF {
			return "", contentType, er.VideoUploadError
		}
	}

	if f.Name() == "" {
		return "", contentType, er.VideoUploadError
	}

	return f.Name(), contentType, nil
}