/*
 * simple program illustrating dynamic loading of library functions.
 */
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>

void foo(void);
void bar(void);

void dynamic_call(void * lib_handle, char * name);

int main(void) {
    void *lib_handle;

    lib_handle = dlopen("libtest_s.so", RTLD_LAZY);
    if (!lib_handle) {
        fprintf(stderr, "%s\n", dlerror());
        return 1;
    }

    dynamic_call(lib_handle, "foo");
    dynamic_call(lib_handle, "bar");
    dynamic_call(lib_handle, "foobar");
    dynamic_call(lib_handle, "foo");
    dynamic_call(lib_handle, "bar");

    printf("that's all, folks!\n");

    return 0;
}


void dynamic_call(void * lib_handle, char * name) {
    void (*fcn)(void);
    char *error;

    printf("calling %s\n", name);

    /* 
     * strictly speaking, this is not good C -- dlsym returns a "void *", and
     * C doesn't guarantee that that can be converted to a function pointer --
     * but the POSIX standard says it can, so live with the warning, I guess.
     */
    fcn = dlsym(lib_handle, name);
    if ((error = dlerror()) != NULL) {
        fprintf(stderr, "%s\n", error);
    }
    else {
        (*fcn)();
    }
}