private static Path getCanonicalPath(Path path) {
        try {
            return path.toRealPath();
        } catch (IOException e) {
            return getCanonicalPath(path.getParent()).resolve(path.getFileName());
        }
    }

    static class ExitException extends Exception {
        int exitCode;

        ExitException(int exitCode) {
            this.exitCode = exitCode;
        }