That sounds like a good idea.

$ ./reverse
var is narf!
Segmentation fault

Eh?

cat reverse.c

#include <EXTERN.h>
#include <perl.h>

static PerlInterpreter *my_perl;

static SV *
  do_reverse(x)
SV *x;
{
    dSP;
    int count;
    SV *var;
    ENTER; SAVETMPS;
    PUSHMARK(SP); XPUSHs(sv_mortalcopy(x)); PUTBACK;
    count = perl_call_pv("CORE::reverse", G_SCALAR);
    SPAGAIN;
    if (count != 1) croak("Aieee!");
    var = POPs;
    PUTBACK;
    FREETMPS;
    LEAVE;
}

main (int argc, char **argv, char **env)
{
    STRLEN len;
    SV *var;
    my_perl = perl_alloc();
    perl_construct(my_perl);
    var = newSVpvf("%s", "narf!");
    printf("var is %s\n", SvPV(var, len));
    var = do_reverse(sv_2mortal(var));
    printf("var is %s\n", SvPV(var, len));
    perl_destruct(my_perl);
    perl_free(my_perl);
}
[download]

According to gdb, it's segfaulting on the perl_call_pv. What am I doing wrong?

(Running perl, v5.6.1, built for i686-linux-multi.)