[Olsr-dev] Loading plugin fails, undefined symbol for olsrd functions

[Jonathan P. Chapman]

Hi!

Am 23.03.2010 22:16, schrieb Henning Rogge:
> Sorry, that was in the master branch. In the stable branch you will find an 
> example for using dlsym() at line 160+ in the same file.
>   
>> around is easier). The easiest way would be to use the pointer to your
>> function as a parameter to set a callback.
>>     
I do not want to be overly optimistic since I still get segfaults, but
they seem to be caused by something else (~3000 lines of untested code
;-), so this may well have solved my problem :-)

So this is what I did:
Include the header for dlopen, dlysn
#include <dlfcn.h>

Define a function pointer for each function I use:
void (*create_lq_hello) (struct lq_hello_message *lq_hello, struct
interface *outif) = NULL;

In the LQ Plugins init-function: Create a handler and open the olsrd binary:
void *dynamic_link_handler;
dynamic_link_handler = dlopen ("olsrd", RTLD_NOW);

Then assign the function pointers to the corresponding symbol:
create_lq_hello = dlsym (dynamic_link_handler, "create_lq_hello");

Use the function pointer where appropriate:
(*create_lq_hello) (&my_hello, &some_interface);


Caveat:
I used a static name for the olsrd binary, since argv[0] appears not to
be available to the plugin (neither olsr_argv[0]), a proper version
should determine the actual path of the calling binary and open that.
Any ideas on how to do that are very welcome ;-)

Thanks and best regards!

Jonathan

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