Get MD5 hash with TeeReader

md5_tee.go

        // Make new md5
        hasher := md5.New()

        // Make a new file
        image, err := os.Create(imagefile)
        if err != nil {
                err = errors.New("problem creating file")
                return
        }

        // Save file and also read into hasher for md5
        _, err = io.Copy(image, io.TeeReader(file, hasher))
        if err != nil {
                os.RemoveAll(imagefile)
                err = errors.New("problem copying file")
                return
        }

        // Set md5sum from hasher
        md5sum = hex.EncodeToString(hasher.Sum(nil))