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annotate rand-getrandom.c @ 17:a08ef0674d8e

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author Guido Berhoerster <guido+pwm@berhoerster.name>
date Sat, 12 Aug 2017 10:41:52 +0200
parents 8768fbd09bc5
children
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1 /*
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2 * Copyright (C) 2017 Guido Berhoerster <guido+pwm@berhoerster.name>
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3 *
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4 * Permission is hereby granted, free of charge, to any person obtaining
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5 * a copy of this software and associated documentation files (the
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6 * "Software"), to deal in the Software without restriction, including
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7 * without limitation the rights to use, copy, modify, merge, publish,
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8 * distribute, sublicense, and/or sell copies of the Software, and to
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9 * permit persons to whom the Software is furnished to do so, subject to
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10 * the following conditions:
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11 *
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12 * The above copyright notice and this permission notice shall be included
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13 * in all copies or substantial portions of the Software.
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14 *
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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19 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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20 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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21 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 */
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23
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24 #include "compat.h"
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25
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26 #include <stdlib.h>
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27 /* glibc and Solaris 11 */
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28 #include <sys/random.h>
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29
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30 #include "rand.h"
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31
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32 #define RANDOM_CHUNK 256U
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33
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34 void
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35 rand_buf(void *buf, size_t buf_size)
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36 {
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37 unsigned char *p = buf;
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38 ssize_t nread;
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39 size_t nsize = buf_size;
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40
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41 while (nsize > 0) {
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42 nread = getrandom(p, nsize, 0);
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43 if (nread < 0) {
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44 if (errno == EINTR) {
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45 continue;
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46 }
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47 err(1, "read");
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48 }
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49 nsize -= nread;
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50 p += nread;
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51 }
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52 }
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53
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54 uint32_t
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55 rand_random(void)
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56 {
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57 uint32_t r;
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58
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59 getrandom(r, sizeof (uint32_t), 0);
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60
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61 return (r);
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62 }
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63
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64 /* random number between 0 and upper_bound - 1 without modulo bias */
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65 uint32_t
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66 rand_uniform(uint32_t upper_bound)
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67 {
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68 uint32_t r;
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69 /* (2^32 - upper_bound) % upper_bound */
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70 uint32_t threshold = -upper_bound % upper_bound;
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71
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72 do {
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73 r = rand_random();
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74 } while (r < threshold);
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75
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76 return (r % upper_bound);
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77 }