Unrandomizer for LD_PRELOAD

unrand_count.c

// Created by flarn2006. WTFPL
// Compile with gcc, -fPIC -shared

#include <stdlib.h>

static int n = 0;
static int m = 0;

static int count()
{
	static int chain;
	static int chain_set = 0;
	static int max;
	static int max_set = 0;

	if (!chain_set) {
		const char* var = getenv("UNRAND_CHAIN");
		m = chain = var ? atoi(var) : 1;
		chain_set = 1;
	}
	if (!max_set) {
		const char* var = getenv("UNRAND_MAX");
		max = var ? atoi(var) : RAND_MAX;
	}

	if (m == 0) {
		m = chain;
		++n;
	}
	--m;

	if (max == RAND_MAX)
		return n;
	else
		return n % (max+1);
}

int rand_(void) __asm__("rand");
int rand_()
{
	return count();
}

int rand_r_(unsigned int*) __asm__("rand_r");
int rand_r_(unsigned int* seedp)
{
	return count();
}

int g_rand_int_range_(void*, int, int) __asm__("g_rand_int_range");
int g_rand_int_range_(void *rand_, int begin, int end)
{
	int range = end - begin;
	return begin + count() % range;
}