mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-02 03:06:28 +02:00
01d245ef43
The new code is faster and reuses the previous state in case of multiple calls. The previous code could easily end up in near-infinite loops, if the difference between two clock() calls never was larger than 1. This makes fate-parseutils finish in finite time when run in wine, if CryptGenRandom isn't available (which e.g. isn't available if targeting Windows RT/metro). Patch originally by Michael Niedermayer but with some modifications by Martin Storsjö. Signed-off-by: Martin Storsjö <martin@martin.st>
116 lines
3.0 KiB
C
116 lines
3.0 KiB
C
/*
|
|
* Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
|
|
*
|
|
* This file is part of Libav.
|
|
*
|
|
* Libav 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.
|
|
*
|
|
* Libav 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 Libav; 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_CRYPTGENRANDOM
|
|
#include <windows.h>
|
|
#include <wincrypt.h>
|
|
#endif
|
|
#include <fcntl.h>
|
|
#include <math.h>
|
|
#include <time.h>
|
|
#include "internal.h"
|
|
#include "intreadwrite.h"
|
|
#include "mem.h"
|
|
#include "timer.h"
|
|
#include "random_seed.h"
|
|
#include "sha.h"
|
|
|
|
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)
|
|
{
|
|
struct AVSHA *sha = av_sha_alloc();
|
|
clock_t last_t = 0;
|
|
static uint64_t i = 0;
|
|
static uint32_t buffer[512] = { 0 };
|
|
unsigned char digest[20];
|
|
uint64_t last_i = i;
|
|
|
|
for (;;) {
|
|
clock_t t = clock();
|
|
|
|
if (last_t == t) {
|
|
buffer[i & 511]++;
|
|
} else {
|
|
buffer[++i & 511] += (t - last_t) % 3294638521U;
|
|
if (last_i && i - last_i > 4 || i - last_i > 64)
|
|
break;
|
|
}
|
|
last_t = t;
|
|
}
|
|
|
|
if (!sha) {
|
|
uint32_t seed = 0;
|
|
int j;
|
|
// Unable to allocate an sha context, just xor the buffer together
|
|
// to create something hopefully unique.
|
|
for (j = 0; j < 512; j++)
|
|
seed ^= buffer[j];
|
|
return seed;
|
|
}
|
|
av_sha_init(sha, 160);
|
|
av_sha_update(sha, (const uint8_t *) buffer, sizeof(buffer));
|
|
av_sha_final(sha, digest);
|
|
av_free(sha);
|
|
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 (read_random(&seed, "/dev/urandom") == sizeof(seed))
|
|
return seed;
|
|
if (read_random(&seed, "/dev/random") == sizeof(seed))
|
|
return seed;
|
|
return get_generic_seed();
|
|
}
|