c bidirectional linkage (exe <-> dll)

.gitignore

build

CMakeLists.txt

cmake_minimum_required(VERSION 3.17)
project(bidirectional-link)

add_executable(main main.c)
set_property(TARGET main PROPERTY ENABLE_EXPORTS 1)


add_library(loadable SHARED loadable.c)
target_link_libraries(loadable main)

loadable.c

#include <stdio.h>

#include "main.h"

__declspec(dllexport) void loadable_setup() {
  printf("loadable_main, calling hello_main..\n");
  hello_main();
  printf("done!\n");
}

main.c

#include <windows.h>
#include <stdio.h>

#include "main.h"

typedef void (__cdecl *loadable_setup)();

typedef struct loadable_t {
  loadable_setup setup;
  HINSTANCE hinstLib;
} loadable_t;

void hello_main() {
  printf("main says hello\n");
}

#ifdef _WIN32
  loadable_t load(const char* path) {
    loadable_t ret = {
      .hinstLib = LoadLibrary(TEXT(path)),
      .setup = NULL
    };
    if (ret.hinstLib) {
      ret.setup = (loadable_setup)GetProcAddress(ret.hinstLib, "loadable_setup");
    }
    return ret;
  }

  void unload(loadable_t *loadable) {
    if (loadable->hinstLib) {
      FreeLibrary(loadable->hinstLib);
      loadable->hinstLib = NULL;
      loadable->setup = NULL;
    }
  }
#endif

void main() {
  printf("main::main!\n");
  loadable_t loadable = load("loadable.dll");
  loadable.setup();
  loadable.setup();
  loadable.setup();
  loadable.setup();
  loadable.setup();
  unload(&loadable);
}

main.h

#pragma once

__declspec(dllexport) void hello_main();