FFmpeg: libavutil/random_seed.c Source File

00001 /*
00002  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
00003  *
00004  * This file is part of FFmpeg.
00005  *
00006  * FFmpeg is free software; you can redistribute it and/or
00007  * modify it under the terms of the GNU Lesser General Public
00008  * License as published by the Free Software Foundation; either
00009  * version 2.1 of the License, or (at your option) any later version.
00010  *
00011  * FFmpeg is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014  * Lesser General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU Lesser General Public
00017  * License along with FFmpeg; if not, write to the Free Software
00018  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00019  */
00020 
00021 #include <unistd.h>
00022 #include <fcntl.h>
00023 #include "timer.h"
00024 #include "random_seed.h"
00025 
00026 uint32_t ff_random_get_seed(void)
00027 {
00028     uint32_t seed;
00029     int fd;
00030 
00031     if ((fd = open("/dev/random", O_RDONLY)) == -1)
00032         fd = open("/dev/urandom", O_RDONLY);
00033     if (fd != -1){
00034         int err = read(fd, &seed, 4);
00035         close(fd);
00036         if (err == 4)
00037             return seed;
00038     }
00039 #ifdef AV_READ_TIME
00040     seed = AV_READ_TIME();
00041 #endif
00042     // XXX what to do ?
00043     return seed;
00044 }