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  | 
/*
 * Very simple prng to allow for randomized tests with reproducable
 * results.
 *
 * Copyright (C) 2012 by Open Source Routing.
 * Copyright (C) 2012 by Internet Systems Consortium, Inc. ("ISC")
 *
 * This file is part of Quagga
 *
 * Quagga is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * Quagga is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Quagga; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */
#include <zebra.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "prng.h"
struct prng {
	unsigned long long state1;
	unsigned long long state2;
};
static char prng_bit(struct prng *prng)
{
	prng->state1 *= 2416;
	prng->state1 += 374441;
	prng->state1 %= 1771875;
	if (prng->state1 % 2) {
		prng->state2 *= 84589;
		prng->state2 += 45989;
		prng->state2 %= 217728;
	}
	return prng->state2 % 2;
}
struct prng *prng_new(unsigned long long seed)
{
	struct prng *rv = calloc(sizeof(*rv), 1);
	assert(rv);
	rv->state1 = rv->state2 = seed;
	return rv;
}
unsigned int prng_rand(struct prng *prng)
{
	unsigned int i, rv = 0;
	for (i = 0; i < 32; i++) {
		rv |= prng_bit(prng);
		rv <<= 1;
	}
	return rv;
}
const char *prng_fuzz(struct prng *prng, const char *string,
		      const char *charset, unsigned int operations)
{
	static char buf[256];
	unsigned int charset_len;
	unsigned int i;
	unsigned int offset;
	unsigned int op;
	unsigned int character;
	assert(strlen(string) < sizeof(buf));
	strncpy(buf, string, sizeof(buf));
	charset_len = strlen(charset);
	for (i = 0; i < operations; i++) {
		offset = prng_rand(prng) % strlen(buf);
		op = prng_rand(prng) % 3;
		switch (op) {
		case 0:
			/* replace */
			character = prng_rand(prng) % charset_len;
			buf[offset] = charset[character];
			break;
		case 1:
			/* remove */
			memmove(buf + offset, buf + offset + 1,
				strlen(buf) - offset);
			break;
		case 2:
			/* insert */
			assert(strlen(buf) + 1 < sizeof(buf));
			memmove(buf + offset + 1, buf + offset,
				strlen(buf) + 1 - offset);
			character = prng_rand(prng) % charset_len;
			buf[offset] = charset[character];
			break;
		}
	}
	return buf;
}
void prng_free(struct prng *prng)
{
	free(prng);
}
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