--- Makefile
all: main foobar.so

main: main.c
        gcc main.c -export-dynamic -ldl -o main

foobar.so: foobar.c
        gcc foobar.c -shared -o foobar.so
--- foobar.c
#include <stdio.h>

void foobar_run()
{
    puts("foobar_run");
    exported();
}   
--- main.c
#include <stdio.h>
#include <dlfcn.h>

void exported()
{
    puts("expoted");
}   

typedef void (*foonction)(void);

int main(int argc, char **argv)
{
    puts("main");
    void *lib = dlopen("./foobar.so", RTLD_LOCAL | RTLD_NOW);
    printf("lib: %p, error: %s\n", lib, dlerror());
    foonction run = dlsym(lib, "foobar_run");
    printf("run: %p\n", run);
    run();
    return 0;
}