[Rd] Segfault: .Call and classes with logical slots

[torsten at hothorn.de]

On Mon, 26 Apr 2004, John Chambers wrote:

> I think you need to PROTECT the vector you're putting in the slot as
> well as the overall object.  At any rate, the problem goes away for me
> with the revised version of dummy.c below.

yes, and it seems that PROTECT'ing the logical variable is sufficient
while PROTECT'ing the class but not the logical variable causes a
segfault again. I tried with numeric slots too: No problems.

> (Empirically, PROTECT'ing
> the class definition didn't seem to be needed, but experience suggests
> that too much protection  is better than too little.)

I tried to save (UN)PROTECT calls because of efficiency reasons. Anyway,
this helps me a lot, thanks!

Torsten

>




> #include <Rdefines.h>
>
> SEXP foo() {
>
>     SEXP ans, cl, el;
>
>     PROTECT(cl = MAKE_CLASS("test"));
>     PROTECT(ans = NEW_OBJECT(cl));
>     PROTECT(el = allocVector(LGLSXP, 1));
>     SET_SLOT(ans, install("lgl"), el);
>     LOGICAL(GET_SLOT(ans, install("lgl")))[0] = TRUE;
>     UNPROTECT(3);
>     return(ans);
> }
>
>
> Torsten Hothorn wrote:
> >
> > Hi,
> >
> > the following example aiming at a class containing a logical slot
> > segfaults under R-1.9.0 when `gctorture(on = TRUE)' is used:
> >
> > Code code (dummy.c):
> >
> > #include <Rdefines.h>
> >
> > SEXP foo() {
> >
> >     SEXP ans;
> >
> >     PROTECT(ans = NEW_OBJECT(MAKE_CLASS("test")));
> >     SET_SLOT(ans, install("lgl"), allocVector(LGLSXP, 1));
> >     LOGICAL(GET_SLOT(ans, install("lgl")))[0] = TRUE;
> >     UNPROTECT(1);
> >     return(ans);
> > }
> >
> > R code (dummy.R):
> >
> > dyn.load("dummy.so")
> >
> > setClass("test", representation = representation(lgl = "logical"))
> >
> > a = .Call("foo")
> > a # OK
> >
> > gctorture(on = TRUE)
> > a = .Call("foo")
> > gctorture(on = FALSE)
> > a # segfault
> >
> > which gives
> >
> > R>
> > R>
> > R> dyn.load("dummy.so")
> > R>
> > R> setClass("test", representation = representation(lgl = "logical"))
> > [1] "test"
> > R>
> > R> a = .Call("foo")
> > R> a
> > An object of class "test"
> > Slot "lgl":
> > [1] TRUE
> >
> > R>
> > R> gctorture(on = TRUE)
> > R> a = .Call("foo")
> > R> gctorture(on = FALSE)
> > Segmentation fault
> >
> > Best,
> >
> > Torsten
> >
> > R> version
> >          _
> > platform i686-pc-linux-gnu
> > arch     i686
> > os       linux-gnu
> > system   i686, linux-gnu
> > status
> > major    1
> > minor    9.0
> > year     2004
> > month    04
> > day      12
> > language R
> > R>
> >
> >  _______________________________________________________________________
> > |                                                                       |
> > |       Dr. rer. nat. Torsten Hothorn                                   |
> > |       Institut fuer Medizininformatik, Biometrie und Epidemiologie    |
> > |       Waldstrasse 6, D-91054 Erlangen, Deutschland                    |
> > |       Tel: ++49-9131-85-22707 (dienstl.)                              |
> > |       Fax: ++49-9131-85-25740                                         |
> > |       Email:  Torsten.Hothorn at rzmail.uni-erlangen.de                  |
> > |               PLEASE send emails cc to torsten at hothorn.de             |
> > |       Web: http://www.imbe.med.uni-erlangen.de/~hothorn               |
> > |_______________________________________________________________________|
> >
> > ______________________________________________
> > R-devel at stat.math.ethz.ch mailing list
> > https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
>
> --
> John M. Chambers                  jmc at bell-labs.com
> Bell Labs, Lucent Technologies    office: (908)582-2681
> 700 Mountain Avenue, Room 2C-282  fax:    (908)582-3340
> Murray Hill, NJ  07974            web: http://www.cs.bell-labs.com/~jmc
>