[clisp-list] Re: saveinitmem and ffi

[Tomas Z. <zel...@gm...>]

Thanks, I'll try the patch and report.
Looking at it for another time, I should probably try it again without
calling (init) - my intention was to create the callback at
*init-hooks* time anyway.
I am still a bit confused - I thought the call to init before image
saving would have no effect when loading image, as clisp has no way of
knowing what was saved by another library (readline), and I do not
understand why calling the function to get callback at *init-hooks*
time should produce invalid reference.

As I've said, I'll report about result of patch.
BTW, replacing :default with library name string did not help.

Thanks,

Tomas Zellerin


2005/9/30, Sam Steingold <sd...@gn...>:
> > * Tomas Zellerin <mryyreva@tznvy.pbz> [2005-09-29 08:14:30 +0200]:
> >
> > while trying to make more from included readline, I encountered a
> > problem that can be shown on this example:
> >
> > (use-package 'ffi)
> > (def-call-out add-defun
> >   (:name "rl_add_defun")
> >   (:library :default)
> >   (:arguments (name c-string :in :malloc-free)
> >             (callback (c-function (:language :stdc)
> >                        (:arguments (rep int) (char  int)))
> >              :in :malloc-free)
> >             (key int))
> >   (:language :stdc)
> >   (:return-type int))
> > (defun init ()
> >  (labels ((edit-history (key rep)
> >   (print key)
> >   (print rep)))
> >   (add-defun "edit-history" #'edit-history -1)))
> > (init)
> > (push #'init *init-hooks*)
> > (saveinitmem "foo")
> >
> > That is, a function with callback to linux is defined and then called.
> > Now, this works fine when loaded (compiled or not), but when later
> > loaded from image, it makes problem when compiled:
> >
> > $ clisp -norc  -C problem.lisp
> > $ clisp -q -M foo.mem
> >
> > *** - FFI::FOREIGN-CALL-OUT: #<INVALID FOREIGN-POINTER #x00000000> come=
s from
> >       a previous Lisp session and is invalid
> > The following restarts are available:
> > SKIP           :R1      skip (SAVEINITMEM foo)
> > STOP           :R2      stop loading file /home/tomas/src/misc/problem.=
lisp
> > ABORT          :R3      ABORT
> > $ clisp -norc problem.lisp
> > $ clisp -q -M foo.mem
> > [1]>
> >
> > When read-history is defined with defun, it makes same problem even
> > when not compiled.
>
> a callback is allocated on the heap (with malloc) and it cannot be saved
> into an image.
> the reason you are not getting the error under some conditions is that
> there is no attempt made to re-use the saved callback because the lisp
> function corresponding to the callback was not found in the callback
> hash table.
>
> PROPOSED SOLUTION:
>
> 1. exit_ffi() should release all callbacks and replace them in
>   O(foreign_callin_vector) with NIL.
>   this is not strictly necessary (you do not have to free all your
>   mallocs before exit, but I think this is "good taste").
>   Bruno, Joerg, should we do this?
>
> 2. when convert_function_to_foreign() finds in invalid (or NIL)
>   triple[1], it should just call alloc_callback();
>   see the appended patch.
>   Tomas, could you please try this patch?
>   it appears to fix the bug you reported.
>
> --
> Sam Steingold (http://www.podval.org/~sds) running w2k
> <http://www.memri.org/> <http://truepeace.org> <http://www.honestreportin=
g.com>
> <http://www.camera.org> <http://www.savegushkatif.org> <http://pmw.org.il=
/>
> If abortion is murder, then oral sex is cannibalism.
>
>
> --- foreign.d   21 Sep 2005 14:10:34 -0400      1.144
> +++ foreign.d   29 Sep 2005 18:20:45 -0400
> @@ -442,12 +442,23 @@
>         if (equal_fvd(resulttype,Car(acons))
>             && equal_argfvds(argtypes,Car(Cdr(acons)))
>             && eq(flags,Car(Cdr(Cdr(acons))))) {
> -          var gcv_object_t* triple =3D &TheSvector(TheIarray(O(foreign_c=
allin_vector))->data)->data[3*posfixnum_to_V(Cdr(Cdr(Cdr(acons))))-2];
> -          triple[2] =3D fixnum_inc(triple[2],1); /* increment reference =
count */
> +          var uintV f_index =3D posfixnum_to_V(Cdr(Cdr(Cdr(acons))));
> +          var gcv_object_t* triple =3D &TheSvector(TheIarray(O(foreign_c=
allin_vector))->data)->data[3*f_index-2];
>           var object ffun =3D triple[1];
>           ASSERT(equal_fvd(resulttype,TheFfunction(ffun)->ff_resulttype))=
;
>           ASSERT(equal_argfvds(argtypes,TheFfunction(ffun)->ff_argtypes))=
;
>           ASSERT(eq(flags,TheFfunction(ffun)->ff_flags));
> +          var object faddress =3D TheFfunction(ffun)->ff_address;
> +          if (fp_validp(TheFpointer(TheFaddress(faddress)->fa_base))) {
> +            triple[2] =3D fixnum_inc(triple[2],1); /* increment referenc=
e count */
> +          } else {     /* callback from the previous session -- renew */
> +            /* leave the reference count alone */
> +            begin_system_call();
> +            TheFaddress(faddress)->fa_offset =3D
> +              (uintP)alloc_callback(&callback,(void*)(uintP)f_index);
> +            end_system_call();
> +            TheFaddress(faddress)->fa_base =3D O(fp_zero);
> +          }
>           return ffun;
>         }
>       }
>