etc_getpwuid(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
#if defined(HAVE_GETPWENT)
    VALUE id;
    uid_t uid;
    struct passwd *pwd;

    rb_secure(4);
    if (rb_scan_args(argc, argv, "01", &id) == 1) {
	uid = PW_VAL2UID(id);
    }
    else {
	uid = getuid();
    }
    pwd = getpwuid(uid);
    if (pwd == 0) rb_raise(rb_eArgError, "can't find user for %d", uid);
    return setup_passwd(pwd);
#else
    return Qnil;
#endif
}