libavutil/random_seed.c

   1 /*
   2  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
   3  *
   4  * This file is part of FFmpeg.
   5  *
   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.
  10  *
  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.
  15  *
  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
  19  */
  20
  21 #include <unistd.h>
  22 #include <fcntl.h>
  23 #include "timer.h"
  24 #include "random_seed.h"
  25
  26 uint32_t ff_random_get_seed(void)
  27 {
  28     uint32_t seed;
  29     int fd;
  30
  31     if ((fd = open("/dev/random", O_RDONLY)) == -1)
  32         fd = open("/dev/urandom", O_RDONLY);
  33     if (fd != -1){
  34         read(fd, &seed, 4);
  35         close(fd);
  36         return seed;
  37     }
  38 #ifdef AV_READ_TIME
  39     seed = AV_READ_TIME();
  40 #endif
  41     // XXX what to do ?
  42     return seed;
  43 }