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package assets
import (
"archive/tar"
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"io"
"io/fs"
"os"
"path"
"path/filepath"
"strings"
"github.com/johnandersen777/socialweb-computer-kcp/internal/kit/sha256sum"
)
func TreeDigest(dir string) (string, error) {
h := sha256.New()
err := filepath.WalkDir(dir, func(p string, d fs.DirEntry, err error) error {
if err != nil {
return err
}
rel, err := filepath.Rel(dir, p)
if err != nil {
return err
}
if rel == "." {
return nil
}
rel = filepath.ToSlash(rel)
info, err := os.Lstat(p)
if err != nil {
return err
}
switch {
case info.IsDir():
fmt.Fprintf(h, "d %s\n", rel)
case info.Mode()&fs.ModeSymlink != 0:
target, err := os.Readlink(p)
if err != nil {
return err
}
fmt.Fprintf(h, "l %s %s\n", filepath.ToSlash(target), rel)
case info.Mode().IsRegular():
sum, err := sha256sum.File(p)
if err != nil {
return err
}
x := "-"
if info.Mode().Perm()&0o111 != 0 {
x = "x"
}
fmt.Fprintf(h, "f %s %s %s\n", x, sum, rel)
default:
return fmt.Errorf("assets: %s is neither a file, a directory nor a symlink", p)
}
return nil
})
if err != nil {
return "", err
}
return hex.EncodeToString(h.Sum(nil)), nil
}
func WriteTar(w io.Writer, dir string) error {
tw := tar.NewWriter(w)
err := filepath.WalkDir(dir, func(p string, d fs.DirEntry, err error) error {
if err != nil {
return err
}
rel, err := filepath.Rel(dir, p)
if err != nil {
return err
}
if rel == "." {
return nil
}
rel = filepath.ToSlash(rel)
info, err := os.Lstat(p)
if err != nil {
return err
}
hdr := &tar.Header{Name: rel, Format: tar.FormatPAX}
switch {
case info.IsDir():
hdr.Typeflag, hdr.Name, hdr.Mode = tar.TypeDir, rel+"/", 0o755
case info.Mode()&fs.ModeSymlink != 0:
target, err := os.Readlink(p)
if err != nil {
return err
}
if err := safeLink(rel, target); err != nil {
return err
}
hdr.Typeflag, hdr.Linkname, hdr.Mode = tar.TypeSymlink, filepath.ToSlash(target), 0o777
case info.Mode().IsRegular():
hdr.Typeflag, hdr.Size, hdr.Mode = tar.TypeReg, info.Size(), 0o444
if info.Mode().Perm()&0o111 != 0 {
hdr.Mode = 0o555
}
default:
return fmt.Errorf("assets: %s is neither a file, a directory nor a symlink", p)
}
if err := tw.WriteHeader(hdr); err != nil {
return err
}
if hdr.Typeflag != tar.TypeReg {
return nil
}
f, err := os.Open(p)
if err != nil {
return err
}
defer f.Close()
_, err = io.Copy(tw, f)
return err
})
if err != nil {
return err
}
return tw.Close()
}
func safeRel(name string) (string, error) {
clean := path.Clean(strings.TrimSuffix(name, "/"))
if clean == "." || clean == ".." || path.IsAbs(clean) || strings.HasPrefix(clean, "../") {
return "", fmt.Errorf("assets: tar entry %q escapes the extraction root", name)
}
return clean, nil
}
func safeLink(rel, target string) error {
if path.IsAbs(target) {
return fmt.Errorf("assets: symlink %s -> %s is absolute", rel, target)
}
joined := path.Clean(path.Join(path.Dir(rel), target))
if joined == ".." || strings.HasPrefix(joined, "../") {
return fmt.Errorf("assets: symlink %s -> %s escapes the extraction root", rel, target)
}
return nil
}
func ExtractTar(r io.Reader, dir string) error { return extractTar(r, dir) }
func RemoveTree(dir string) error { return removeTree(dir) }
func extractTar(r io.Reader, dir string) error {
tr := tar.NewReader(r)
for {
hdr, err := tr.Next()
if errors.Is(err, io.EOF) {
return syncTree(dir)
}
if err != nil {
return err
}
rel, err := safeRel(hdr.Name)
if err != nil {
return err
}
dst := filepath.Join(dir, filepath.FromSlash(rel))
switch hdr.Typeflag {
case tar.TypeDir:
if err := os.MkdirAll(dst, 0o755); err != nil {
return err
}
case tar.TypeSymlink:
if err := safeLink(rel, hdr.Linkname); err != nil {
return err
}
if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
return err
}
if err := os.Symlink(filepath.FromSlash(hdr.Linkname), dst); err != nil {
return err
}
case tar.TypeReg:
if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
return err
}
mode := os.FileMode(0o444)
if hdr.Mode&0o111 != 0 {
mode = 0o555
}
f, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o600)
if err != nil {
return err
}
_, cerr := io.Copy(f, tr)
if err := errors.Join(cerr, f.Close()); err != nil {
return err
}
if err := os.Chmod(dst, mode); err != nil {
return err
}
default:
return fmt.Errorf("assets: tar entry %q has type %c; only files, directories and symlinks are assets", hdr.Name, hdr.Typeflag)
}
}
}
func removeTree(dir string) error {
filepath.WalkDir(dir, func(p string, d fs.DirEntry, err error) error {
if err == nil && d.IsDir() {
os.Chmod(p, 0o755)
}
return nil
})
return os.RemoveAll(dir)
}
