Zip a directory in Golang with error handling, ignoring symlinks and file checking

main.go

func zipDirectory(zipfilename string) error {
	outFile, err := os.Create(zipfilename)
	if err != nil {
		return err
	}

	w := zip.NewWriter(outFile)

	if err := addFilesToZip(w, zipfilename, ""); err != nil {
		_ = outFile.Close()
		return err
	}

	if err := w.Close(); err != nil {
		_ = outFile.Close()
		return errors.New("Warning: closing zipfile writer failed: " + err.Error())
	}

	if err := outFile.Close(); err != nil {
		return errors.New("Warning: closing zipfile failed: " + err.Error())
	}

	return nil
}

func addFilesToZip(w *zip.Writer, basePath, baseInZip string) error {
	files, err := ioutil.ReadDir(basePath)
	if err != nil {
		return err
	}

	for _, file := range files {
		fullfilepath := filepath.Join(basePath, file.Name())
		if _, err := os.Stat(fullfilepath); os.IsNotExist(err) {
			// ensure the file exists. For example a symlink pointing to a non-existing location might be listed but not actually exist
			continue
		}

		if file.Mode() & os.ModeSymlink != 0 {
			// ignore symlinks alltogether
			continue
		}

		if file.IsDir() {
			if err := addFilesToZip(w, fullfilepath, filepath.Join(baseInZip, file.Name())); err != nil {
				return err
			}
		} else if file.Mode().IsRegular() {
			dat, err := ioutil.ReadFile(fullfilepath)
			if err != nil {
				return err
			}
			f, err := w.Create(filepath.Join(baseInZip, file.Name()))
			if err != nil {
				return err
			}
			_, err = f.Write(dat)
			if err != nil {
				return err
			}
		} else {
			// we ignore non-regular files because they are scary
		}
	}
	return nil
}