f, err := os.Open(name)
	if err != nil {
		return nil, err
	}
	arch, err := NewArchive(f)
	if err != nil {
		f.Close()
		return nil, err
	}
	arch.closer = f
	return arch, nil
}

// Close closes the Archive.
// If the Archive was created using NewArchive directly instead of OpenArchive,
// Close has no effect.
func (a *Archive) Close() error {
	var err error

func (i fileInfo) Sys() any           { return nil }

func (i fileInfo) String() string {
	return fs.FormatFileInfo(i)
}

// NewArchive returns a new Archive containing all the files in the directory dir.
// The archive can be amended afterward using methods like Add and Filter.
func NewArchive(dir string) (*Archive, error) {
	a := new(Archive)
	err := fs.WalkDir(os.DirFS(dir), ".", func(name string, d fs.DirEntry, err error) error {

	}

	newID := 0
	readAndRemoveCgoFlags := func(archive string) (string, error) {
		newID++
		newArchive := root.Objdir + fmt.Sprintf("_pkg%d_.a", newID)
		if err := sh.CopyFile(newArchive, archive, 0666, false); err != nil {
			return "", err
		}
		if cfg.BuildN || cfg.BuildX {
			sh.ShowCmd("", "ar d %s _cgo_flags", newArchive)
			if cfg.BuildN {
				// TODO(rsc): We could do better about showing the right _cgo_flags even in -n mode.

}

// aixBigArExportData returns export data from an AIX big archive.
func aixBigArExportData(archive io.ReadSeeker) (io.ReadSeeker, error) {
	archiveAt := readerAtFromSeeker(archive)
	arch, err := xcoff.NewArchive(archiveAt)
	if err != nil {
		return nil, err
	}

	for _, mem := range arch.Members {
		f, err := arch.GetFile(mem.Name)
		if err != nil {
			return nil, err
		}
		sdat := f.CSect(".go_export")

	exe := ""
	if goos == "windows" {
		exe = ".exe"
	}
	version, versionTime := readVERSION(goroot)

	// Start with files from GOROOT, filtering out non-distribution files.
	base, err := NewArchive(goroot)
	if err != nil {
		log.Fatal(err)
	}
	base.SetTime(versionTime)
	base.SetMode(mode)
	base.Remove(
		".git/**",
		".gitattributes",
		".github/**",
		".gitignore",

		AssertRebuilt(t, "new source", target)
		AssertRebuilt(t, "new source", shlib)
	})

	// If the .a file is newer than the .so, the .so is rebuilt (but not the .a)
	t.Run("newarchive", func(t *testing.T) {
		resetFileStamps()
		AssertNotRebuilt(t, "new .a file before build", target)
		goCmd(t, "list", "-linkshared", "-f={{.ImportPath}} {{.Stale}} {{.StaleReason}} {{.Target}}", "./depBase")