86c60f3838e0c0b02199998fd47da56b02ced904
[libav.git] / 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 #include "avutil.h"
26
27 static int read_random(uint32_t *dst, const char *file)
28 {
29 int fd = open(file, O_RDONLY);
30 int err = -1;
31
32 if (fd == -1)
33 return -1;
34 err = read(fd, dst, sizeof(*dst));
35 close(fd);
36
37 return err;
38 }
39
40 uint32_t av_get_random_seed(void)
41 {
42 uint32_t seed;
43
44 if (read_random(&seed, "/dev/urandom") == sizeof(seed))
45 return seed;
46 if (read_random(&seed, "/dev/random") == sizeof(seed))
47 return seed;
48
49 #ifdef AV_READ_TIME
50 seed = AV_READ_TIME();
51 #endif
52 // XXX what to do ?
53 return seed;
54 }
55
56 #if LIBAVUTIL_VERSION_MAJOR < 51
57 attribute_deprecated uint32_t ff_random_get_seed(void);
58 uint32_t ff_random_get_seed(void)
59 {
60 return av_get_random_seed();
61 }
62 #endif