apkovl-cli/compression/compression.go

package compression

import (
	"archive/tar"
	"compress/gzip"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	log "github.com/s00500/env_logger"
)

func isSymlink(fi os.FileInfo) bool {
	return fi.Mode()&os.ModeSymlink != 0
}

func Compress(inputPath, outputPath string) error {
	var file *os.File
	var err error
	var writer *gzip.Writer

	if file, err = os.OpenFile(outputPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
		return err
	}
	defer file.Close()

	if writer, err = gzip.NewWriterLevel(file, gzip.BestCompression); err != nil {
		return err
	}
	defer writer.Close()

	tw := tar.NewWriter(writer)
	defer tw.Close()

	err = filepath.Walk(inputPath, func(file string, fi os.FileInfo, err error) error {
		log.Should(err)
		if inputPath == file {
			return nil
		}

		// Skip some strange systemfiles
		if strings.Contains(file, ".DS_Store") || strings.Contains(file, ".Trash") || strings.Contains(file, "._") {
			return nil
		}

		log.Trace("Compressing ", inputPath, " : Got: ", file)
		// generate tar header
		header, err := tar.FileInfoHeader(fi, file)
		// set to numeric only
		if err != nil {
			return err
		}

		if isSymlink(fi) {
			linkTarget, err := os.Readlink(file)
			if err != nil {
				return fmt.Errorf("%s: readlink: %v", fi.Name(), err)
			}
			header, err = tar.FileInfoHeader(fi, filepath.ToSlash(linkTarget))
			if err != nil {
				return fmt.Errorf("%s: making header: %v", fi.Name(), err)
			}
		}

		header.Name = "./" + strings.TrimPrefix(filepath.ToSlash(file), filepath.ToSlash(inputPath)+"/")

		header.Uname = ""
		header.Gname = ""

		// write header
		if err := tw.WriteHeader(header); err != nil {
			return err
		}
		// if not a dir, write file content
		if !fi.IsDir() && !isSymlink(fi) {
			data, err := os.Open(file)
			if err != nil {
				return err
			}
			if _, err := io.Copy(tw, data); err != nil {
				return err
			}
		}
		return nil
	})
	return err
}

func ExtractTarGz(gzipStream io.Reader, extractDir string) error {
	uncompressedStream, err := gzip.NewReader(gzipStream)
	if err != nil {
		return fmt.Errorf("extractTarGz: NewReader failed: %w", err)
	}

	tarReader := tar.NewReader(uncompressedStream)

	for {
		header, err := tarReader.Next()

		if err == io.EOF {
			break
		}

		if err != nil {
			return fmt.Errorf("extractTarGz: Next() failed: %w", err)
		}

		switch header.Typeflag {
		case tar.TypeDir:
			//log.Info("DIr!", header.Name)
			if err := os.Mkdir(filepath.Join(extractDir, header.Name), 0755); err != nil {
				return fmt.Errorf("extractTarGz: Mkdir() failed: %w", err)
			}
		case tar.TypeReg:
			//log.Info("File!", header.Name)
			if err := os.MkdirAll(filepath.Join(extractDir, filepath.Dir(header.Name)), 0755); err != nil {
				return fmt.Errorf("extractTarGz: File Mkdir() failed: %w", err)
			}
			outFile, err := os.OpenFile(filepath.Join(extractDir, header.Name), os.O_CREATE|os.O_RDWR, os.FileMode(header.Mode))
			if err != nil {
				return fmt.Errorf("extractTarGz: OpenFile() failed: %w", err)
			}
			if _, err := io.Copy(outFile, tarReader); err != nil {
				return fmt.Errorf("extractTarGz: Copy() failed: %w", err)
			}
			outFile.Close()
		case tar.TypeSymlink:
			if err := os.MkdirAll(filepath.Join(extractDir, filepath.Dir(header.Name)), 0755); err != nil {
				return fmt.Errorf("extractTarGz: File Mkdir() failed: %w", err)
			}
			if err := os.Symlink(header.Linkname, filepath.Join(extractDir, header.Name)); err != nil {
				log.Errorf("failed writing symbolic link: %s", err)
				//return fmt.Errorf("failed writing symbolic link: %s", err)
			}
			//log.Infof("Skip symlink in: %b in %s",
			//	header.Typeflag,
			//	header.Name)
		default:
			return fmt.Errorf("extractTarGz: uknown type: %d in %s",
				header.Typeflag,
				header.Name)
		}

	}
	return nil
}

func Exists(name string) bool {
	_, err := os.Stat(name)
	return !os.IsNotExist(err)
}