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

static const char* LIB_NAME = "?.so";

int main(int argc, char** argv) {
    void* handle;
    double (*cosine)(double);
    char* error;

    handle = dlopen(LIB_NAME, RTLD_LAZY);
    if (!handle) {
        fprintf(stderr, "%s\n", dlerror());
        return EXIT_FAILURE;
    }

    dlerror();

    cosine = (double(*)(double)) dlsym(handle, "cos");

    *(void**)(&cosine) = dlsym(handle, "cos");

    error = dlerror();
    if (error) {
        fprintf(stderr, "%s\n", error);
        return EXIT_FAILURE;
    }

    printf("%f\n", (*cosine)(2.0));
    dlclose(handle);

    return EXIT_SUCCESS;
}