dlopen'ing a program's own self.

huh.c

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

double worker(double x) {
	return x * 2;
}

int main(int argc, char* argv[]) {
	void* self = dlopen(NULL, RTLD_NOW | RTLD_LOCAL);
	if(!self || dlerror() != NULL) {
		perror("dlopen");
		return 1;
	} else
	{
		printf("Loaded library: %p\n", self);
	}

	// Clear global load errors.
	dlerror();

	double (*thing)(double);
	*(void **) (&thing) = dlsym(self, "worker");
	if(!thing || dlerror() != NULL) {
		perror("loading thing");
		return 1;
	} else {
		printf("Run: %f\n", thing(12.1));
	}

	return 0;
}

Makefile

huh: huh.c
  gcc -Wall -pedantic -rdynamic huh.c -o huh -ldl -export-dynamic