#include <R.h>
#include <Rinternals.h>

static void cooked_goose(SEXP foo)
{
    if (TYPEOF(foo) != EXTPTRSXP)
        error("argument not external pointer");
    double *x = (double *) R_ExternalPtrAddr(foo);
    int blather = x[0];
    Free(x);
    if (blather)
        printf("finalizer ran\n");
}

SEXP blob(SEXP nin, SEXP blatherin)
{
    if (! isInteger(nin))
        error("n not integer");
    int n = INTEGER(nin)[0];
    if (! (n > 0))
        error("n not positive");
    if (! isLogical(blatherin))
        error("blather not logical");
    int blather = LOGICAL(blatherin)[0];

    double *x = Calloc(n + 2, double);

    GetRNGstate();
    for (int i = 0; i < n; ++i)
        x[i + 2] = norm_rand();
    PutRNGstate();
    x[1] = n;
    x[0] = blather;

    SEXP bar;
    PROTECT(bar = R_MakeExternalPtr(x, R_NilValue, R_NilValue));
    R_RegisterCFinalizer(bar, cooked_goose);
    UNPROTECT(1);
    return bar;
}

SEXP blub(SEXP foo)
{
    if (TYPEOF(foo) != EXTPTRSXP)
        error("argument not external pointer");

    double *x = (double *) R_ExternalPtrAddr(foo);
    int blather = x[0];
    int n = x[1];

    SEXP bar;
    PROTECT(bar = allocVector(REALSXP, n));
    for (int i = 0; i < n; ++i)
        REAL(bar)[i] = x[i + 2];
    UNPROTECT(1);
    return bar;
}