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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")
* Copyright (C) 2017 Christian Franke
*
* 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 this program; see the file COPYING; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <zebra.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "prng.h"
struct prng {
uint64_t state;
};
struct prng *prng_new(unsigned long long seed)
{
struct prng *rv = calloc(sizeof(*rv), 1);
assert(rv);
rv->state = seed;
return rv;
}
/*
* This implementation has originally been provided to musl libc by
* Szabolcs Nagy <nsz at port70 dot net> in 2013 under the terms of
* the MIT license.
* It is a simple LCG which D.E. Knuth attributes to C.E. Haynes in
* TAOCP Vol2 3.3.4
*/
int prng_rand(struct prng *prng)
{
prng->state = 6364136223846793005ULL * prng->state + 1;
return prng->state >> 33;
}
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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