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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_CRYPTGENRANDOM
- #include <windows.h>
- #include <wincrypt.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)
- {
- uint8_t tmp[120];
- struct AVSHA *sha = (void*)tmp;
- clock_t last_t = 0;
- clock_t last_td = 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 (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8)
- break;
- }
- last_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_CRYPTGENRANDOM
- HCRYPTPROV provider;
- if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
- CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
- BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed);
- CryptReleaseContext(provider, 0);
- if (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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