type FileLike interface {
	Name() string
	Stat() (fs.FileInfo, error)
	Read([]byte) (int, error)
	Close() error
}

// addFile adds a single file to the archive
func (ar *Archive) addFile(fd FileLike) {
	// Format the entry.
	// First, get its info.
	info, err := fd.Stat()
	if err != nil {
		log.Fatal(err)
	}

	readFile := pass.ReadFile
	if readFile == nil {
		readFile = os.ReadFile
	}
	content, err := readFile(filename)
	if err != nil {
		return nil, nil, err
	}
	tf := pass.Fset.AddFile(filename, -1, len(content))
	tf.SetLinesForContent(content)
	return content, tf, nil
}

// LineStart returns the position of the start of the specified line
// within file f, or NoPos if there is no line of that number.

	// all positions have been calculated (by way of fakeFileSet.setLines), so
	// that we can avoid setting unnecessary lines. See also golang/go#46586.
	f := s.files[file]
	if f == nil {
		f = &fileInfo{file: s.fset.AddFile(file, -1, maxlines)}
		s.files[file] = f
	}

	if line > maxlines {
		line = 1
	}
	if line > f.lastline {
		f.lastline = line
	}