file.c:2424
static VALUE
rb_stat_r(obj)
    VALUE obj;
{
    struct stat *st = get_stat(obj);

#ifdef S_IRUSR
    if (rb_stat_owned(obj))
	return st->st_mode & S_IRUSR ? Qtrue : Qfalse;
#endif
#ifdef S_IRGRP
    if (rb_stat_grpowned(obj))
	return st->st_mode & S_IRGRP ? Qtrue : Qfalse;
#endif
#ifdef S_IROTH
    if (!(st->st_mode & S_IROTH)) return Qfalse;
#endif
    return Qtrue;
}
