Embedding Julia with dynamic loading

Makefile

test_static_loading: test_static_loading.c
	gcc -Wall test_static_loading.c -ljulia -I ../src -I ../src/support -I../usr/include -L../usr/lib -Wl,-rpath,../usr/lib -o test_static_loading -DJULIA_ENABLE_THREADING=1 -fPIC

test_dynamic_loading: test_dynamic_loading.c
	gcc -Wall test_dynamic_loading.c -ldl -I ../src -I ../src/support -I../usr/include -o test_dynamic_loading -DJULIA_ENABLE_THREADING=1 -fPIC

test_dynamic_loading.c

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

int
main(void)
{
    void *handle;
    void (*p_jl_init)(const char *);
    void (*p_jl_atexit_hook)(int);
    jl_value_t *(*p_jl_eval_string)(const char *);
    jl_sym_t *(*p_jl_symbol)(const char *);
    jl_module_t *p_jl_main_module;
    jl_value_t *(*p_jl_get_global)(jl_module_t *, jl_sym_t *);
    void *(*p_jl_unbox_voidpointer)(jl_value_t *);

    handle = dlopen("../usr/lib/libjulia.so", RTLD_LAZY | RTLD_GLOBAL);
    if (!handle) {
        fprintf(stderr, "%s\n", dlerror());
        exit(EXIT_FAILURE);
    }

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

    p_jl_init = dlsym(handle, "jl_init");
    p_jl_atexit_hook = dlsym(handle, "jl_atexit_hook");
    p_jl_eval_string = dlsym(handle, "jl_eval_string");
    p_jl_symbol = dlsym(handle, "jl_symbol");
    p_jl_main_module = dlsym(handle, "jl_main_module");
    p_jl_get_global = dlsym(handle, "jl_get_global");
    p_jl_unbox_voidpointer = dlsym(handle, "jl_unbox_voidpointer");
    
    char *error = dlerror();
    if (error != NULL) {
        fprintf(stderr, "%s\n", error);
        exit(EXIT_FAILURE);
    }

    (*p_jl_init)("../usr/bin");
    (*p_jl_eval_string)("include(\"test_loading.jl\")");
    jl_sym_t *f_pointer_symbol = (*p_jl_symbol)("f_pointer");
    jl_value_t *f_pointer_value = (*p_jl_get_global)(p_jl_main_module, f_pointer_symbol);
    int (*f_pointer)(int, int) = (*p_jl_unbox_voidpointer)(f_pointer_value);
    printf("%d\n", (*f_pointer)(3.0, 4.0));
    (*p_jl_atexit_hook)(0);
    dlclose(handle);
    exit(EXIT_SUCCESS);
}

test_loading.jl

f(x, y) = x + y * y
const f_pointer = cfunction(f, Cint, (Cint, Cint))

test_static_loading.c

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

int
main(void)
{
    jl_init("../usr/bin");
    jl_eval_string("include(\"test_loading.jl\")");
    jl_sym_t *f_pointer_symbol = jl_symbol("f_pointer");
    jl_value_t *f_pointer_value = jl_get_global(jl_main_module, f_pointer_symbol);
    int (*f_pointer)(int, int) = jl_unbox_voidpointer(f_pointer_value);
    printf("%d\n", (*f_pointer)(3, 4));
    jl_atexit_hook(0);
    exit(EXIT_SUCCESS);
}

Found the mistake. p_jl_main_module should be a jl_module_t **.