/*
 * print_getenv: 
 * Makes the program calling getenv() print out the environmental variable
 *
 * Based on example here: https://rafalcieslak.wordpress.com/2013/04/02/dynamic-linker-tricks-using-ld_preload-to-cheat-inject-features-and-investigate-programs/
 *
 * Compile: gcc -shared -fPIC print_getenv.c -o print_getenv.so -ldl
 * Use: LD_PRELOAD the .so
 *
*/


#define _GNU_SOURCE

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

typedef char (*orig_getenv)(const char *name);

char getenv(const char *name) {

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

	orig_getenv og_getenv;
	og_getenv = (orig_getenv)dlsym(RTLD_NEXT, "getenv");

	return og_getenv(name);
}