RE: tolua crashes

["Fabian Lemke" <lemkef@...>]

I am using the tolua class bindings from inside the scripts..  I just added
that awhile ago actually.  The problem didn't show up until recently, so I
did not think it was related.

I tried the patch, and basic tests seem to have passed!
I have to run it through some more to be sure, but so far, so good!

Thanks!,

Fabian

> -----Original Message-----
> From: Christian Vogler [mailto:cvogler@gradient.cis.upenn.edu]
> Sent: Sunday, October 21, 2001 10:50 AM
> To: lua-l@tecgraf.puc-rio.br
> Cc: lemkef@charter.net
> Subject: tolua crashes
>
>
> On Sun, Oct 21, 2001 at 08:14:25AM -0500, Fabian Lemke wrote:
> > It is C++.
> >
> > I have explicitly declared the destructor, but it did't seem to help.
> > (tried it before posting originally actually)
>
> > I tried the destructer both with and without the (void).
> > The behavior is kind of strange.  if I do a "new" in place of the
> > GetPos (in the lua script calling it), and still no delete call, it
> > doesn't have a problem either.  Could it have something to do with
> > the copying of the object?
>
> Tolua copies and takes ownership of objects that are returned by
> value, so it should be deleted properly when the garbage collection
> kicks in. The explicit delete() is actually *wrong*, because tolua
> will still think that it owns the object, which now does not exist
> anymore. Eventually, this could cause crashes of the memory management
> subsystem during a gc cycle.
>
> I don't see anything wrong with your pkg snippet, and the code that
> tolua generates looks correct to me, too. At this point I have no idea
> whether you have uncovered a bug in the tolua libraries, your
> compiler, or whether there is something else in the rest of your code
> that may corrupt things. We use tolua a lot for the kind of task that
> you are describing, including return by value and taking of ownership
> and never had any problems, so your problem is kind of weird.
>
> Can you get a stack backtrace of the point where your program crashes
> with an illegal instruction?
>
> Another shot in the dark: are you using the tolua class or module
> bindings from lua itself (i.e., the tolua_class, tolua_instance,
> etc. functions)?  These *do* contain a bug that causes corruption of
> the heap, but if you don't use them in your scripts, it will not
> trigger. And your symptoms don't really match the profile of the bug
> anyway. But just in case, also try this patch to tolua:
>
> --- snip ---
> RCS file: /home3/cvogler/src/cvs/3rdParty/tolua/src/lib/tolua_gp.c,v
> retrieving revision 1.1.1.1.4.1
> retrieving revision 1.1.1.1.4.2
> diff -u -r1.1.1.1.4.1 -r1.1.1.1.4.2
> --- src/lib/tolua_gp.c  2001/03/06 03:50:09     1.1.1.1.4.1
> +++ src/lib/tolua_gp.c  2001/03/11 23:43:29     1.1.1.1.4.2
> @@ -40,7 +40,13 @@
>
>  int tolua_getvalue (lua_State* L, int narg, int def)
>  {
> - return lua_gettop(L)<abs(narg) ? def : narg;
> + if (lua_gettop(L)<abs(narg))
> + {
> +  lua_pushnil(L);
> +  return lua_gettop(L);
> + }
> + else
> +  return narg;
>  }
>
>  int tolua_getbool (lua_State* L, int narg, int def)
> --- snip ---
>
> - Christian