setuid?()
public
Returns true if stat has the set-user-id permission bit set, false
if it doesn’t or if the operating system doesn’t support this feature.
File.stat("/bin/su").setuid?
static VALUE
rb_stat_suid(VALUE obj)
{
#ifdef S_ISUID
if (get_stat(obj)->st_mode & S_ISUID) return Qtrue;
#endif
return Qfalse;
}