1 /*
2 * Copyright (c) 2008-2014 Travis Geiselbrecht
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files
6 * (the "Software"), to deal in the Software without restriction,
7 * including without limitation the rights to use, copy, modify, merge,
8 * publish, distribute, sublicense, and/or sell copies of the Software,
9 * and to permit persons to whom the Software is furnished to do so,
10 * subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
19 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
20 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
21 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
22 */
23 #include <rand.h>
24 #include <sys/types.h>
25
26 static unsigned int randseed = KERNEL_LIBC_RANDSEED;
27
srand(unsigned int seed)28 void srand(unsigned int seed)
29 {
30 randseed = seed;
31 }
32
libc_trusty_rand_add_entropy(const void * buf,size_t len)33 void libc_trusty_rand_add_entropy(const void *buf, size_t len)
34 {
35 if (len == 0)
36 return;
37
38 uint32_t enp = 0;
39 for (size_t i = 0; i < len; i++) {
40 enp ^= ((enp << 8) | (enp >> 24)) ^ ((const uint8_t *)buf)[i];
41 }
42
43 randseed ^= enp;
44 }
45
46 /* This is expected to overflow sometimes */
47 __attribute__((no_sanitize("unsigned-integer-overflow")))
rand(void)48 int rand(void)
49 {
50 return (int)(randseed = randseed * 1664525 + 1013904223);
51 }
52