I'm struggling to learn how to embed the perl interpreter into c. I've pieced together the following test but I don't understand what I'm doing wrong. I'm clearly not passing arguments from perl back to c correctly, as the string that I expect to get back is missing the first 4 characters (and those chars are being replaced by, what looks to me like, garbage).

Will anyone please let me know what I'm doing wrong?

thanks

-- Jonathan

jrs@madrona emperl$ ls -la

total 24
drwxrwxr-x   2 jrs jrs  4096 Jun 13 08:14 .
drwx------  80 jrs jrs 12288 Jun 12 19:54 ..
-rw-rw-r--   1 jrs jrs   756 Jun 13 08:07 main.c
-rw-rw-r--   1 jrs jrs   127 Jun 13 08:14 test.pl
[download]

jrs@madrona emperl$ cat test.pl

#!/usr/bin/perl -w
 
use strict;
 
sub reverse_string {
    my ($string) = @_;
    my $rev = reverse $string;
    return $rev;
}
[download]

jrs@madrona emperl$ cat main.c

#include <stdio.h>
#include <EXTERN.h>
#include <perl.h>
 
static PerlInterpreter *my_perl;
 
int main(int argc, char **argv, char **env) {
    char in_string[] = "abcdefg";
    char *out_string;
    char *embedding[] = { "", "test.pl" };
 
    PERL_SYS_INIT3(&argc,&argv,&env);
    my_perl = perl_alloc();
    perl_construct(my_perl);
    perl_parse(my_perl, NULL, 2, embedding, NULL);
 
    dSP;
    ENTER;
    SAVETMPS;
    PUSHMARK(sp);
    XPUSHs(sv_2mortal(newSVpv(in_string, 0)));
    PUTBACK;
    perl_call_pv("reverse_string", G_SCALAR);
    SPAGAIN;
    out_string = POPp;
    PUTBACK;
    FREETMPS;
    LEAVE;
 
    printf ("reverse %s -> %s\n", in_string, out_string);
 
    perl_destruct(my_perl);
    perl_free(my_perl);
    PERL_SYS_TERM();
}
[download]

jrs@madrona emperl$ cc -o test main.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
main.c: In function `main':
main.c:17: warning: ISO C90 forbids mixed declarations and code
jrs@madrona emperl$ ./test
reverse abcdefg -> x�cba
jrs@madrona emperl$ ./test
reverse abcdefg -> x� cba
jrs@madrona emperl$ ./test
reverse abcdefg -> x� cba
jrs@madrona emperl$ ./test
reverse abcdefg -> x�cba
jrs@madrona emperl$ ./test
reverse abcdefg -> xR
jrs@madrona emperl$ ./test
reverse abcdefg -> x"cba
jrs@madrona emperl$ ./test
reverse abcdefg -> x�cba
jrs@madrona emperl$ ./test
reverse abcdefg -> x�cba
jrs@madrona emperl$ ./test
reverse abcdefg -> xb� cba
jrs@madrona emperl$ ./test
reverse abcdefg -> x�cba
jrs@madrona emperl$