mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-11-26 19:01:44 +02:00
da73d95bad
Tested-by: Thomas Turner <thomastdt@googlemail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
141 lines
3.4 KiB
C
141 lines
3.4 KiB
C
/*
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* Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "config.h"
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#if HAVE_IO_H
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#include <io.h>
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#endif
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#if HAVE_CRYPTGENRANDOM
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#include <windows.h>
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#include <wincrypt.h>
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#endif
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#include <fcntl.h>
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#include <math.h>
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#include <time.h>
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#include <string.h>
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#include "avassert.h"
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#include "internal.h"
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#include "intreadwrite.h"
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#include "timer.h"
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#include "random_seed.h"
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#include "sha.h"
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#ifndef TEST
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#define TEST 0
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#endif
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static int read_random(uint32_t *dst, const char *file)
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{
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#if HAVE_UNISTD_H
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int fd = avpriv_open(file, O_RDONLY);
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int err = -1;
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if (fd == -1)
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return -1;
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err = read(fd, dst, sizeof(*dst));
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close(fd);
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return err;
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#else
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return -1;
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#endif
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}
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static uint32_t get_generic_seed(void)
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{
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uint64_t tmp[120/8];
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struct AVSHA *sha = (void*)tmp;
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clock_t last_t = 0;
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clock_t last_td = 0;
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static uint64_t i = 0;
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static uint32_t buffer[512] = { 0 };
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unsigned char digest[20];
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uint64_t last_i = i;
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av_assert0(sizeof(tmp) >= av_sha_size);
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if(TEST){
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memset(buffer, 0, sizeof(buffer));
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last_i = i = 0;
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}else{
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#ifdef AV_READ_TIME
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buffer[13] ^= AV_READ_TIME();
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buffer[41] ^= AV_READ_TIME()>>32;
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#endif
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}
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for (;;) {
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clock_t t = clock();
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if (last_t + 2*last_td + 1 >= t) {
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last_td = t - last_t;
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buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U);
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} else {
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last_td = t - last_t;
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buffer[++i & 511] += last_td % 3294638521U;
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if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8)
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break;
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}
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last_t = t;
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}
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if(TEST) {
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buffer[0] = buffer[1] = 0;
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} else {
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#ifdef AV_READ_TIME
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buffer[111] += AV_READ_TIME();
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#endif
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}
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av_sha_init(sha, 160);
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av_sha_update(sha, (const uint8_t *)buffer, sizeof(buffer));
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av_sha_final(sha, digest);
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return AV_RB32(digest) + AV_RB32(digest + 16);
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}
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uint32_t av_get_random_seed(void)
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{
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uint32_t seed;
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#if HAVE_CRYPTGENRANDOM
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HCRYPTPROV provider;
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if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
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CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
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BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed);
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CryptReleaseContext(provider, 0);
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if (ret)
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return seed;
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}
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#endif
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#if HAVE_ARC4RANDOM
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return arc4random();
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#endif
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if (read_random(&seed, "/dev/urandom") == sizeof(seed))
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return seed;
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if (read_random(&seed, "/dev/random") == sizeof(seed))
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return seed;
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return get_generic_seed();
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}
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