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136 lines
3.1 KiB
136 lines
3.1 KiB
/* |
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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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#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 "timer.h" |
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#include "random_seed.h" |
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#include "sha.h" |
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#include "intreadwrite.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 = 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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uint8_t tmp[120]; |
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struct AVSHA *sha = (void*)tmp; |
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clock_t last_t = 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[32]; |
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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 == t){ |
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buffer[i&511]++; |
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}else{ |
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buffer[++i&511]+= (t-last_t) % 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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av_sha_init(sha, 160); |
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av_sha_update(sha, (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+32); |
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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 (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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#if TEST |
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#undef printf |
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#define N 256 |
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#include <stdio.h> |
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int main(void) |
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{ |
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int i, j, retry; |
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uint32_t seeds[N]; |
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for (retry=0; retry<3; retry++){ |
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for (i=0; i<N; i++){ |
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seeds[i] = av_get_random_seed(); |
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for (j=0; j<i; j++) |
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if (seeds[j] == seeds[i]) |
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goto retry; |
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} |
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printf("seeds OK\n"); |
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return 0; |
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retry:; |
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} |
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printf("FAIL at %d with %X\n", j, seeds[j]); |
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return 1; |
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} |
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#endif
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