Hello !

I am working with an existing appliciation (on RedHat EL5) which I would like to extend by an embedded Perl interpreter. To get started, I first successfully created a static library, then a shared one which I linked to a simple C program. Everything works fine until I am trying to load the shared library dynamically. Unfortunately the existing application which I want to extend with the Perl interpreter leaves me the only choice to dynamically load a shared library, so there is no alternative to this approach.

I tried to simplify to a maximum to be able to reproduce the problem. I also tried with different Perl versions (I compiled 5.8.8, 5.8.9, 5.10.0) on different servers, everytime the same issue.

The perl script I am trying to run is "hello.pl". 

use strict;
use warnings;
use IO::Socket;     # without this line, no crash !
print "** hello from hello.pl **\n";

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The shared library is based on the file 'perlLib.c' which embeds the Perl interpreter: 

// perlLib.c
#include <EXTERN.h>
#include <perl.h>
EXTERN_C void xs_init (pTHX);
PerlInterpreter *my_perl;
void myPerlFunc()
{
 char *largv[] = { "", "-f", "hello.pl", NULL };
 int largc=3;
 my_perl = perl_alloc();
 perl_construct(my_perl);
 perl_parse(my_perl, xs_init, largc, largv, environ);
 perl_run(my_perl);
 perl_destruct(my_perl);
 perl_free(my_perl);
}

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The test executable is based on perlEmbedDynamic.c 

// perlEmbedDynamic.c

#include <stdio.h>
#include <dlfcn.h>
int main(int argc, char **argv)
{
    void *handle;
    void (*theLibFunction)();
    handle = dlopen ("libDynamicPerl.so", RTLD_LAZY);
    theLibFunction = dlsym(handle, "myPerlFunc");
    (*theLibFunction)();
    dlclose(handle);
    return(0);
}

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Finally to compile and test I use a small shell script 

# compTest.sh

# generate and compile perxsi.c
perl -MExtUtils::Embed -e xsinit -- -o perlxsi.c
cc -Wall -fPIC -g -c perlxsi.c `perl -MExtUtils::Embed -e ccopts`

# perlLib contains the function myPerlFunc which embeds and runs the i
+nterpreter
cc -Wall -fPIC -g -c perlLib.c `perl -MExtUtils::Embed -e ccopts`
# generate the dynamic libray
cc -Wall -shared -Wl,-export-dynamic -o libDynamicPerl.so perlLib.o pe
+rlxsi.o `perl -MExtUtils::Embed -e ldopts`
# linking of the library
cc -Wall -L. -lDynamicPerl perlEmbedDynamic.c -o perlEmbedDynamicLinki
+ng

# execute with linking, works fine
./perlEmbedDynamicLinking

# dynamic loading of the library
cc -rdynamic -o perlEmbedDynamicLoading perlEmbedDynamic.c -ldl

# execute with dynamic loading, crashes
./perlEmbedDynamicLoading

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perlxsi.c is created by the script in the usual way. If the hello.pl scripts does not contain the line "use IO::Socket", there is no crash. I also wonder why linking the shared lib works nicely while loading it crashes (where is the internal difference, once the shared lib becomes active ?). Once this works I would like to extend the embedded Perl, so the IO::Socket was just used as an example to be able to easily reproduce the problem.

Any help would be really appreciated !

thanx, lorius

In reply to embedding perl in a shared library crashes if shared lib is load dynamically by lorius

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