user/file.go
func openDBFile(filename string, flag int) (*dbfile, error) {
	f, err := os.OpenFile(filename, flag, 0)
	if err != nil {
		return nil, err
	}

	db := &dbfile{file: f, rd: bufio.NewReader(f)}
	db.Lock()
	return db, nil
}
func openDBFile(filename string, flag int) (*dbfile, error) {
	f, err := os.OpenFile(filename, flag, 0)
	if err != nil {
		return nil, err
	}

	db := &dbfile{file: f, rd: bufio.NewReader(f)}
	db.Lock()
	return db, nil
}
// openDBFile opens a file.