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/*
* Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config.h"
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_IO_H
#include <io.h>
#endif
#if HAVE_BCRYPT
#include <windows.h>
#include <bcrypt.h>
#endif
#include <fcntl.h>
#include <math.h>
#include <time.h>
#include <string.h>
#include "avassert.h"
#include "internal.h"
#include "intreadwrite.h"
#include "timer.h"
#include "random_seed.h"
#include "sha.h"
#ifndef TEST
#define TEST 0
#endif
static int read_random(uint32_t *dst, const char *file)
{
#if HAVE_UNISTD_H
int fd = avpriv_open(file, O_RDONLY);
int err = -1;
if (fd == -1)
return -1;
err = read(fd, dst, sizeof(*dst));
close(fd);
return err;
#else
return -1;
#endif
}
static uint32_t get_generic_seed(void)
{
uint64_t tmp[120/8];
struct AVSHA *sha = (void*)tmp;
clock_t last_t = 0;
clock_t last_td = 0;
clock_t init_t = 0;
static uint64_t i = 0;
static uint32_t buffer[512] = { 0 };
unsigned char digest[20];
uint64_t last_i = i;
av_assert0(sizeof(tmp) >= av_sha_size);
if(TEST){
memset(buffer, 0, sizeof(buffer));
last_i = i = 0;
}else{
#ifdef AV_READ_TIME
buffer[13] ^= AV_READ_TIME();
buffer[41] ^= AV_READ_TIME()>>32;
#endif
}
for (;;) {
clock_t t = clock();
if (last_t + 2*last_td + (CLOCKS_PER_SEC > 1000) >= t) {
last_td = t - last_t;
buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U);
} else {
last_td = t - last_t;
buffer[++i & 511] += last_td % 3294638521U;
if ((t - init_t) >= CLOCKS_PER_SEC>>5)
if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8)
break;
}
last_t = t;
if (!init_t)
init_t = t;
}
if(TEST) {
buffer[0] = buffer[1] = 0;
} else {
#ifdef AV_READ_TIME
buffer[111] += AV_READ_TIME();
#endif
}
av_sha_init(sha, 160);
av_sha_update(sha, (const uint8_t *)buffer, sizeof(buffer));
av_sha_final(sha, digest);
return AV_RB32(digest) + AV_RB32(digest + 16);
}
uint32_t av_get_random_seed(void)
{
uint32_t seed;
#if HAVE_BCRYPT
BCRYPT_ALG_HANDLE algo_handle;
NTSTATUS ret = BCryptOpenAlgorithmProvider(&algo_handle, BCRYPT_RNG_ALGORITHM,
MS_PRIMITIVE_PROVIDER, 0);
if (BCRYPT_SUCCESS(ret)) {
NTSTATUS ret = BCryptGenRandom(algo_handle, (UCHAR*)&seed, sizeof(seed), 0);
BCryptCloseAlgorithmProvider(algo_handle, 0);
if (BCRYPT_SUCCESS(ret))
return seed;
}
#endif
#if HAVE_ARC4RANDOM
return arc4random();
#endif
if (read_random(&seed, "/dev/urandom") == sizeof(seed))
return seed;
if (read_random(&seed, "/dev/random") == sizeof(seed))
return seed;
return get_generic_seed();
}
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