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/* Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program 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 3 of the License, or
(at your option) any later version.
This program 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. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <time.h>
#include <sys/time.h>
#include "prng.h"
#include "dSFMT.h"
/*! \brief TLS unique key for each thread seed. */
static pthread_key_t tls_prng_key;
static pthread_once_t tls_prng_once = PTHREAD_ONCE_INIT;
static void tls_prng_deinit(void *ptr)
{
free(ptr);
}
static void tls_prng_deinit_main()
{
tls_prng_deinit(pthread_getspecific(tls_prng_key));
}
static void tls_prng_init()
{
(void) pthread_key_create(&tls_prng_key, tls_prng_deinit);
atexit(tls_prng_deinit_main); // Main thread cleanup
}
double tls_rand()
{
/* Setup PRNG state for current thread. */
(void)pthread_once(&tls_prng_once, tls_prng_init);
/* Create PRNG state if not exists. */
dsfmt_t* s = pthread_getspecific(tls_prng_key);
if (!s) {
/* Initialize seed from system PRNG generator. */
uint32_t seed = 0;
FILE *fp = fopen("/dev/urandom", "r");
if (fp == NULL) {
fp = fopen("/dev/random", "r");
}
if (fp != NULL) {
if (fread(&seed, sizeof(uint32_t), 1, fp) != 1) {
fclose(fp);
fp = NULL;
}
}
if (fp == NULL) {
fprintf(stderr, "error: PRNG: cannot seed from "
"/dev/urandom, seeding from local time\n");
struct timeval tv;
if (gettimeofday(&tv, NULL) == 0) {
seed = (uint32_t)(tv.tv_sec ^ tv.tv_usec);
} else {
/* Last resort. */
seed = (uint32_t)time(NULL);
}
} else {
fclose(fp);
}
/* Initialize PRNG state. */
s = malloc(sizeof(dsfmt_t));
if (s == NULL) {
fprintf(stderr, "error: PRNG: not enough memory\n");
return .0;
} else {
dsfmt_init_gen_rand(s, seed);
(void)pthread_setspecific(tls_prng_key, s);
}
}
return dsfmt_genrand_close_open(s);
}
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