github.com/pluralsh/plural-cli@v0.9.5/pkg/utils/tar.go

package utils

import (
	"archive/tar"
	"compress/gzip"
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	"github.com/pluralsh/plural-cli/pkg/utils/pathing"
)

func Tar(src string, w io.Writer, regex string) error {
	// ensure the src actually exists before trying to tar it
	dir := filepath.Dir(src)
	if _, err := os.Stat(src); err != nil {
		return fmt.Errorf("Unable to tar files: %w", err)
	}

	gzw := gzip.NewWriter(w)
	defer func(gzw *gzip.Writer) {
		_ = gzw.Close()
	}(gzw)

	tw := tar.NewWriter(gzw)
	defer func(tw *tar.Writer) {
		_ = tw.Close()
	}(tw)

	// walk path
	return filepath.Walk(src, func(file string, fi os.FileInfo, err error) error {
		if regex != "" {
			matched, err := regexp.MatchString(regex, file)
			if matched || err != nil {
				return err
			}
		}

		if err != nil {
			return err
		}

		if !fi.Mode().IsRegular() {
			return nil
		}

		// create a new dir/file header
		header, err := tar.FileInfoHeader(fi, fi.Name())
		if err != nil {
			return err
		}
		header.Name = strings.TrimPrefix(strings.ReplaceAll(file, dir, ""), string(filepath.Separator))

		if err := tw.WriteHeader(header); err != nil {
			return err
		}

		f, err := os.Open(file)
		if err != nil {
			return err
		}

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

		if err := f.Close(); err != nil {
			return err
		}

		return nil
	})
}

func Untar(r io.Reader, dir, relpath string) error {
	return untar(r, dir, relpath)
}

func untar(r io.Reader, dir, relpath string) (err error) {
	t0 := time.Now()
	nFiles := 0
	madeDir := map[string]bool{}
	zr, err := gzip.NewReader(r)
	if err != nil {
		return fmt.Errorf("requires gzip-compressed body: %w", err)
	}
	tr := tar.NewReader(zr)
	loggedChtimesError := false
	for {
		f, err := tr.Next()
		if errors.Is(err, io.EOF) {
			break
		}
		if err != nil {
			return fmt.Errorf("tar error: %w", err)
		}
		if !validRelPath(f.Name) {
			return fmt.Errorf("tar contained invalid name error %q", f.Name)
		}
		rel, err := filepath.Rel(relpath, filepath.FromSlash(f.Name))
		if err != nil {
			return err
		}
		abs := pathing.SanitizeFilepath(filepath.Join(dir, rel))

		fi := f.FileInfo()
		mode := fi.Mode()
		switch {
		case mode.IsRegular():
			// Make the directory. This is redundant because it should
			// already be made by a directory entry in the tar
			// beforehand. Thus, don't check for errors; the next
			// write will fail with the same error.
			dir := filepath.Dir(abs)
			if !madeDir[dir] {
				if err := os.MkdirAll(filepath.Dir(abs), 0755); err != nil {
					return err
				}
				madeDir[dir] = true
			}
			wf, err := os.OpenFile(abs, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode.Perm())
			if err != nil {
				return err
			}
			n, err := io.Copy(wf, tr)
			if closeErr := wf.Close(); closeErr != nil && err == nil {
				err = closeErr
			}
			if err != nil {
				return fmt.Errorf("error writing to %s: %w", abs, err)
			}
			if n != f.Size {
				return fmt.Errorf("only wrote %d bytes to %s; expected %d", n, abs, f.Size)
			}
			modTime := f.ModTime
			if modTime.After(t0) {
				// Clamp modtimes at system time. See
				// golang.org/issue/19062 when clock on
				// buildlet was behind the gitmirror server
				// doing the git-archive.
				modTime = t0
			}
			if !modTime.IsZero() {
				if err := os.Chtimes(abs, modTime, modTime); err != nil && !loggedChtimesError {
					// benign error. Gerrit doesn't even set the
					// modtime in these, and we don't end up relying
					// on it anywhere (the gomote push command relies
					// on digests only), so this is a little pointless
					// for now.
					log.Printf("error changing modtime: %v (further Chtimes errors suppressed)", err)
					loggedChtimesError = true // once is enough
				}
			}
			nFiles++
		case mode.IsDir():
			if err := os.MkdirAll(abs, 0755); err != nil {
				return err
			}
			madeDir[abs] = true
		default:
			return fmt.Errorf("tar file entry %s contained unsupported file type %v", f.Name, mode)
		}
	}
	return nil
}

func validRelPath(p string) bool {
	if p == "" || strings.Contains(p, `\`) || strings.HasPrefix(p, "/") || strings.Contains(p, "../") {
		return false
	}
	return true
}