[Rd] R_NilValue and segfault.
Guillaume Yziquel
guillaume.yziquel at citycable.ch
Wed Nov 18 02:45:53 CET 2009
Hello.
I've been trying to wrap up the R_NilValue into OCaml-R. I nevertheless
get a segfault.
As I gathered, R_NilValue is declared in Rinternals.h:
> /* Special Values */
> LibExtern SEXP R_NilValue; /* The nil object */
> LibExtern SEXP R_UnboundValue; /* Unbound marker */
> LibExtern SEXP R_MissingArg; /* Missing argument marker */
So, in my r_data.c file, I have:
-1- an #include directive.
> #include <Rinternals.h>
-2- the function wrapping R data in OCaml data
> CAMLprim value Val_sexp (SEXP sexp)
> {
> CAMLparam0();
> CAMLlocal1(result);
> result = caml_alloc(1, Abstract_tag);
> Field(result, 0) = (value) sexp;
> /* Do not use Val_long in the above statement,
> as it will drop the top bit. See mlvalues.h. */
> CAMLreturn(result);
> }
and a function taking no argument (in the sense of OCaml), and returning
an OCaml object encapsulating a pointer which is R_NilValue. (R_NilValue
is already a pointer, so we just copy it).
> /* The NULL constant in R... */
>
> CAMLprim value r_null (value unit) {
> CAMLparam1(unit);
> CAMLreturn(Val_sexp(R_NilValue));
> }
OCaml code is straightforward:
> external null_creator : unit -> sexp = "r_null"
> let null = null_creator ()
And I get a segfault:
> Objective Caml version 3.11.1
>
> # R.sexptype (R.sexp "1");;
> - : R.sexptype = R.RealSxp
> # R.sexptype Quantmod.getSymbols;;
> - : R.sexptype = R.PromSxp
The two above are fine, but inspecting the type of R.null gives me a
segfault.
> # R.sexptype R.null;;
> /usr/bin/ocaml-batteries: line 2: 3723 Erreur de segmentation "/usr/lib/ocaml/batteries/toplevel.top" "/usr/lib/ocaml/batteries/top.ml" $@
Please tell me if there's anything obvious which causes this. There's a
lot of conditional compilation directives in Rinternals.h, and I'm
wondering whether or not that might be an issue.
All the best,
--
Guillaume Yziquel
http://yziquel.homelinux.org/
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