PackageManager/Archive/Unarchive.go

package Archive

import (
	"archive/tar"
	"bufio"
	"bytes"
	"compress/gzip"
	"io"
	"io/fs"
	"os"
	"path/filepath"
)

func ExtractArchive(source, target string) error {
	var (
		inFile     *os.File
		gzipReader *gzip.Reader
		tarReader  *tar.Reader
		e          error
	)

	inFile, e = os.Open(source)
	if e != nil {
		return e
	}
	defer inFile.Close()

	gzipReader, e = gzip.NewReader(inFile)
	defer gzipReader.Close()
	tarReader = tar.NewReader(gzipReader)

	return extractFromArchive(tarReader, target)
}

func extractFromArchive(tarReader *tar.Reader, target string) error {
	var (
		header         *tar.Header
		info           fs.FileInfo
		file           *os.File
		path, basePath string
		e              error
	)

	for {
		header, e = tarReader.Next()
		if e == io.EOF {
			break
		}
		if e != nil {
			return e
		}

		path = filepath.Join(target, header.Name)

		info = header.FileInfo()
		if filepath.Base(info.Name()) == "manifest.yml" {
			continue
		}

		if info.IsDir() {
			e = os.MkdirAll(path, info.Mode())
			if e != nil {
				return e
			}
			continue
		}

		basePath, e = filepath.Abs(filepath.Dir(path))
		if e != nil {
			return e
		}

		_, e = os.Stat(basePath)
		if os.IsNotExist(e) {
			e = os.MkdirAll(basePath, info.Mode())
			if e != nil {
				return e
			}
		}

		file, e = os.OpenFile(path, os.O_CREATE|os.O_RDWR, info.Mode())
		if e != nil {
			return e
		}

		defer file.Close()

		_, e = io.Copy(file, tarReader)
		if e != nil {
			return e
		}
	}

	return nil

}

func ExtractManifestFile(source string) (string, error) {
	var (
		inFile     *os.File
		gzipReader *gzip.Reader
		tarReader  *tar.Reader
		e          error
	)

	inFile, e = os.Open(source)
	if e != nil {
		return "", e
	}
	defer inFile.Close()

	gzipReader, e = gzip.NewReader(inFile)
	defer gzipReader.Close()
	tarReader = tar.NewReader(gzipReader)

	return extractManifestFromArchive(tarReader)
}

func extractManifestFromArchive(tarReader *tar.Reader) (string, error) {
	var (
		header         *tar.Header
		info           fs.FileInfo
		manifestWriter *bufio.Writer
		manifestBytes  bytes.Buffer
		e              error
	)

	for {
		header, e = tarReader.Next()
		if e == io.EOF {
			break
		}
		if e != nil {
			return manifestBytes.String(), e
		}

		info = header.FileInfo()
		if filepath.Base(info.Name()) != "manifest.yml" {
			continue
		}

		manifestWriter = bufio.NewWriter(&manifestBytes)

		_, e = io.Copy(manifestWriter, tarReader)
		if e != nil {
			return manifestBytes.String(), e
		}
	}

	return manifestBytes.String(), nil
}