projects/pwm

view rand-getrandom.c @ 26:5bdea77d0c1d

Add pwm-clip utility for setting the X11 CLIPBOARD selection
author Guido Berhoerster <guido+pwm@berhoerster.name>
date Thu Sep 21 09:45:59 2017 +0200 (2017-09-21)
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1 /*
2 * Copyright (C) 2017 Guido Berhoerster <guido+pwm@berhoerster.name>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be included
13 * 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 */
24 #include "compat.h"
26 #include <stdlib.h>
27 /* glibc and Solaris 11 */
28 #include <sys/random.h>
30 #include "rand.h"
32 #define RANDOM_CHUNK 256U
34 void
35 rand_buf(void *buf, size_t buf_size)
36 {
37 unsigned char *p = buf;
38 ssize_t nread;
39 size_t nsize = buf_size;
41 while (nsize > 0) {
42 nread = getrandom(p, nsize, 0);
43 if (nread < 0) {
44 if (errno == EINTR) {
45 continue;
46 }
47 err(1, "read");
48 }
49 nsize -= nread;
50 p += nread;
51 }
52 }
54 uint32_t
55 rand_random(void)
56 {
57 uint32_t r;
59 getrandom(r, sizeof (uint32_t), 0);
61 return (r);
62 }
64 /* random number between 0 and upper_bound - 1 without modulo bias */
65 uint32_t
66 rand_uniform(uint32_t upper_bound)
67 {
68 uint32_t r;
69 /* (2^32 - upper_bound) % upper_bound */
70 uint32_t threshold = -upper_bound % upper_bound;
72 do {
73 r = rand_random();
74 } while (r < threshold);
76 return (r % upper_bound);
77 }