ZIP archives in Golang

compress.go

import (
	"archive/zip"
	"io"
	"os"
	"path/filepath"
	"strings"
)

func zipit(source, target string) error {
	zipfile, err := os.Create(target)
	if err != nil {
		return err
	}
	defer zipfile.Close()

	archive := zip.NewWriter(zipfile)
	defer archive.Close()

	info, err := os.Stat(source)
	if err != nil {
		return nil
	}

	var baseDir string
	if info.IsDir() {
		baseDir = filepath.Base(source)
	}

	filepath.Walk(source, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

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

		if baseDir != "" {
			header.Name = filepath.Join(baseDir, strings.TrimPrefix(path, source))
		}

		if info.IsDir() {
			header.Name += "/"
		} else {
			header.Method = zip.Deflate
		}

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

		if info.IsDir() {
			return nil
		}

		file, err := os.Open(path)
		if err != nil {
			return err
		}
		defer file.Close()
		_, err = io.Copy(writer, file)
		return err
	})

	return err
}

extract.go

import (
	"archive/zip"
	"io"
	"os"
	"path/filepath"
	"strings"
)

func unzip(archive, target string) error {
	reader, err := zip.OpenReader(archive)
	if err != nil {
		return err
	}

	if err := os.MkdirAll(target, 0755); err != nil {
		return err
	}

	for _, file := range reader.File {
		path := filepath.Join(target, file.Name)
		if file.FileInfo().IsDir() {
			os.MkdirAll(path, file.Mode())
			continue
		}

		fileReader, err := file.Open()
		if err != nil {
			return err
		}
		defer fileReader.Close()

		targetFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.Mode())
		if err != nil {
			return err
		}
		defer targetFile.Close()

		if _, err := io.Copy(targetFile, fileReader); err != nil {
			return err
		}
	}

	return nil
}

@Svett, thanks for the very useful code. I have a question on line 21 in compress.go. Is there any reason to return nil instead of err in this case?

The extract function will generate too many open file issue as the defer is only called once the function return, here an altered version:

func Unzip(archive, target string) error {
    reader, err := zip.OpenReader(archive)
    if err != nil {
        return err
    }

    if err := os.MkdirAll(target, 0755); err != nil {
        return err
    }

    for _, file := range reader.File {
        path := filepath.Join(target, file.Name)
        if file.FileInfo().IsDir() {
            os.MkdirAll(path, file.Mode())
            continue
        }

        fileReader, err := file.Open()
        if err != nil {

            if fileReader != nil {
                fileReader.Close()
            }

            return err
        }

        targetFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.Mode())
        if err != nil {
            fileReader.Close()

            if targetFile != nil {
                targetFile.Close()
            }

            return err
        }

        if _, err := io.Copy(targetFile, fileReader); err != nil {
            fileReader.Close()
            targetFile.Close()

            return err
        }

        fileReader.Close()
        targetFile.Close()
    }

    return nil
}

The zipit function throws an error if the .zip file does not already exist. How do i remedy this?

	// Check file
	if _, err := os.Stat(archive); os.IsNotExist(err) {
		return err
	}

License?

If have a large files in multiple directory, the filepath.Walk would take a long time to process. Any possible to use goroutine to improve performance?

hi all, if I have some sub directories, in the code previous, it just make directory of sub directories, how can i restore those files in sub directories?

if r.File[f].FileInfo().IsDir() {
if err := os.MkdirAll(dstpath, os.ModePerm); err != nil {
return nil, err
}
}
in this piece of code, how could i copy those files which are in this directory?

You have to walk through the directories until you reach a regular file.