2 * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
32 #include "random_seed.h"
34 #include "intreadwrite.h"
40 static int read_random(uint32_t *dst, const char *file)
43 int fd = open(file, O_RDONLY);
48 err = read(fd, dst, sizeof(*dst));
57 static uint32_t get_generic_seed(void)
60 struct AVSHA *sha = (void*)tmp;
62 static uint64_t i = 0;
63 static uint32_t buffer[512] = {0};
64 unsigned char digest[32];
67 av_assert0(sizeof(tmp) >= av_sha_size);
70 memset(buffer, 0, sizeof(buffer));
74 buffer[13] ^= AV_READ_TIME();
75 buffer[41] ^= AV_READ_TIME()>>32;
85 buffer[++i&511]+= (t-last_t) % 3294638521U;
86 if(last_i && i-last_i > 4 || i-last_i > 64 || TEST && i-last_i > 8)
93 buffer[0] = buffer[1] = 0;
95 av_sha_init(sha, 160);
96 av_sha_update(sha, (uint8_t*)buffer, sizeof(buffer));
97 av_sha_final(sha, digest);
98 return AV_RB32(digest) + AV_RB32(digest+32);
101 uint32_t av_get_random_seed(void)
105 if (read_random(&seed, "/dev/urandom") == sizeof(seed))
107 if (read_random(&seed, "/dev/random") == sizeof(seed))
109 return get_generic_seed();
122 for (retry=0; retry<3; retry++){
124 seeds[i] = av_get_random_seed();
126 if (seeds[j] == seeds[i])
129 printf("seeds OK\n");
133 printf("FAIL at %d with %X\n", j, seeds[j]);