dlreload

CMakeLists.txt

cmake_minimum_required(VERSION 3.10)
project(dlreload)

add_library(inner SHARED inner.c)

add_library(outer SHARED outer.c)

add_executable(test test.c)
target_link_libraries(test PUBLIC outer)

inner.c

#include "inner.h"

void init(int i) {
  g.i = 666 + i;
  g.b = 1;
  another_int = i;
}

inner.h

#ifndef INNER_H
#define INNER_H

#include <stdbool.h>
#include <stdio.h>

typedef struct inner_globals_t {
  int i;
  bool b;
  FILE *f;
} inner_globals;

inner_globals g;

int another_int;

void init(int);

#endif /* INNER_H */

outer.c

#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>

#include "outer.h"

void* handle = NULL;

void load() {
  handle = dlopen("libinner.dylib", RTLD_NOW);
  if (!handle) {
    fprintf(stderr, "%s\n", dlerror());
    exit(EXIT_FAILURE);
  }

  dlerror(); /* Clear any existing error */

  void (*init)(int);
  init = dlsym(handle, "init");

  int* obj = (int*)dlsym(handle, "another_int");

  printf("in load: another_int: %d\n", *obj);

  init(32);

  printf("in load after init: another_int: %d\n", *obj);

  void* handle2 = dlopen("libinner2.dylib", RTLD_NOW);
  init = dlsym(handle2, "init");
  int* obj2 = (int*)dlsym(handle2, "another_int");

  printf("in load, handle2: another_int: %d\n", *obj2);
  init(44);
  printf("in load, handle2: another_int: %d\n", *obj2);
  printf("but handle: another_int: %d\n", *obj);

  dlclose(handle);
  dlclose(handle2);
}

outer.h

#ifndef OUTER_H
#define OUTER_H

void load();

#endif /* OUTER_H */

test.c

#include <stdio.h>

#include "outer.h"

int main(int argc, char **argv) { load(); }