Create zip archive of files

zip.go

package zip

import (
	"archive/zip"
	"io"
	"os"
)

// Service represents a service that knows about compressing files into zip
// archives.
type Service struct{}

// New returns a new zip service.
func New() *Service {
	return &Service{}
}

// ZipFiles compresses one or many files into a single zip archive file.
func (s *Service) ZipFiles(filename string, files []string) error {
	newZipFile, err := os.Create(filename)
	if err != nil {
		return err
	}
	defer newZipFile.Close()

	zipWriter := zip.NewWriter(newZipFile)
	defer zipWriter.Close()

	// Add files to zip
	for _, file := range files {
		if err := AddFileToZip(zipWriter, file); err != nil {
			return err
		}
	}

	return nil
}

// AddFileToZip takes a zip writer and a filename (path on disk) to include in
// the final zip file.
func AddFileToZip(zipWriter *zip.Writer, filename string) error {
	fileToZip, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer fileToZip.Close()

	// Get the file information
	info, err := fileToZip.Stat()
	if err != nil {
		return err
	}

	header, err := zip.FileInfoHeader(info)
	if err != nil {
		return err
	}

	// Using FileInfoHeader() above only uses the basename of the file. If we want
	// to preserve the folder structure we can overwrite this with the full path.
	header.Name = filename

	// Change to deflate to gain better compression
	// see http://golang.org/pkg/archive/zip/#pkg-constants
	header.Method = zip.Deflate

	writer, err := zipWriter.CreateHeader(header)
	if err != nil {
		return err
	}

	_, err = io.Copy(writer, fileToZip)

	return err
}