I can use the perl runtime from a C application using the recipes written in the documentation, e.g. (trivial lines left out for brevity):

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

void boot_DynaLoader (pTHX_ CV* cv);

void xs_init(pTHX) {
    static const char file[] = __FILE__;
    dXSUB_SYS;
    PERL_UNUSED_CONTEXT;
    newXS( "DynaLoader::boot_DynaLoader", boot_DynaLoader, file );
}

int main( int argc, char **argv, char **env ) {
  PerlInterpreter *my_perl;
  PERL_SYS_INIT3( &argc, &argv, &env );
  my_perl = perl_alloc();
  perl_construct(my_perl);
  perl_parse( my_perl, xs_init, argc, argv, env );
  int result = perl_run(my_perl);
  perl_destruct(my_perl);
  perl_free(my_perl);
  PERL_SYS_TERM();
  return result;
}
[download]

This works great, however this requires that the application program is linked against the perl shared library. I want to distribute this application with a custom perl shared library. Still not a problem, I link the application with --rpath=. and place the shared library next to the application, for example:

$ cd /tmp/foo
$ ls
myapp    myperl.so
$ ./myapp
Hello, world!
[download]

Still fine. But I want to be able to call the application from arbitrary places, e.g.

$ cd
$ ls /tmp/foo
myapp    myperl.so
$ /tmp/foo/myapp
/tmp/foo/myapp: error while loading shared libraries: myperl.so: canno
+t open shared object file: No such file or directory
[download]

This is as it should be. When linking with --rpath=. the shared library must be in the current directory. What I would want is that the shared library is looked up there where the application is. I can use a wrapper script that sets LD_LIBRARY_PATH before calling the application but I'd rather want to solve this within the application itself. Fortunately, there is such a thing as dlopen:

int main( int argc, char **argv, char **env ) {
  /* find path to shared library */
  /* open shared lib */
  void *handle = dlopen(...);

  /* Get entry point for perl_alloc */
  void* (*perl_alloc)();
  perl_alloc = (void*())dlsym(handle, "perl_alloc")
  /* Call perl_alloc */
  my_perl = (*perl_alloc)();

  /* and so on */
  /* ... */
}
[download]

This, too, works nice ... except for one detail: I cannot get the second argument to perl_parse (xs_init above, to set up the DynaLoader) right. Can anyone shed some light on how to get this working?

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