main app <-> module.so bi-direct access C / linux

[netdrake]

Hi everyone!
I have some functions in main application (for example: log(), uppercase(), ...) and some in created module.so(counter() ...) But how can functions in module.so access to functions in main apllication ?

My first idea was create another module (util.so) and access module.so -> util.so. But that is nasty Too many modules ...

My next idea is send to the module.so pointers to functions which are in main app. But is normal or safe? Have functions log() and uppercase() static addresses while running main ?

Thanks for advice or any other ideas

[Banfa]

Are the *.so files the compiled objects

you can just declare extern any functions you wish to call from other modules

 
// main.c
 
#include "main.h"
 
void log(char *msg)
{
  // write msg to file here
}
 
 
//  main.h
 
extern void log(char *msg);
 
 
// module.c
 
voif fn(fn)
{
  log("Start of fn");
 
  // do something here
 
  log("end of fn");
}
 

[netdrake]

Uff, i not sure that we was understand :) Here is small code example:

/******* MAIN APPLICATION *****/
// main.c
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <dlfcn.h>
#include "main.h"


void logger(const char *message)
{
fprintf(stdout,message);
return;
}


int main(void)
{

char *error;
void *module;
void (*check)(const char*);

// open module.so
module = dlopen("module.so",RTLD_LAZY);
if(!module) { // error check
puts("Cannot open module.so");
exit(1);
}

//get symbol
check = dlsym(module,"check");
if ((error = dlerror()) != NULL) exit(1);

//call function in module ...
(*check)("234xxx3");

// close module.so
dlclose(module);

return 0;
}


//main.h
#ifndef __MAIN_H_
#define __MAIN_H_

void logger(const char *message);

#endif

/**************** MODULE.SO *************/
// module.c
#include "module.h"

void check(const char *string)
{
unsigned int found = 0;
unsigned int i = 0;


if(!string) return;

while(*(string + i)) {
if(*(string + i) < '0' || *(string + i) > '9')
found++;

i++;
}

if(found > 0) {
// I WANT CALL logger func which is in main application
// BUT HOW ? :) IS IT POSIBLE ?
// Here is a big problem with symbols... module.so doesnt known
// about logger func ..
// logger("error fount characters in number");
puts("Module.so: Error found characters in number");
}

return;
}

//module.h
#ifndef __MODULE_H_
#define __MODULE_H_

void check(const char *string);

#endif