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1 /* Copyright libuv contributors. All rights reserved.
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2 *
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3 * Permission is hereby granted, free of charge, to any person obtaining a copy
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4 * of this software and associated documentation files (the "Software"), to
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5 * deal in the Software without restriction, including without limitation the
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6 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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7 * sell copies of the Software, and to permit persons to whom the Software is
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8 * furnished to do so, subject to the following conditions:
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9 *
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10 * The above copyright notice and this permission notice shall be included in
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11 * all copies or substantial portions of the Software.
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12 *
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13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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16 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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17 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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18 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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19 * IN THE SOFTWARE.
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20 */
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21
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22 #include "uv.h"
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23 #include "internal.h"
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24
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25 #ifdef __linux__
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26
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27 #define uv__random_getrandom_init() 0
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28
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29 #else /* !__linux__ */
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30
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31 #include <stddef.h>
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32 #include <dlfcn.h>
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33
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34 typedef ssize_t (*uv__getrandom_cb)(void *, size_t, unsigned);
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35
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36 static uv__getrandom_cb uv__getrandom;
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37 static uv_once_t once = UV_ONCE_INIT;
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38
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39 static void uv__random_getrandom_init_once(void) {
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40 uv__getrandom = (uv__getrandom_cb) dlsym(RTLD_DEFAULT, "getrandom");
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41 }
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42
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43 static int uv__random_getrandom_init(void) {
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44 uv_once(&once, uv__random_getrandom_init_once);
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45
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46 if (uv__getrandom == NULL)
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47 return UV_ENOSYS;
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48
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49 return 0;
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50 }
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51
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52 #endif /* !__linux__ */
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53
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54 int uv__random_getrandom(void* buf, size_t buflen) {
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55 ssize_t n;
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56 size_t pos;
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57 int rc;
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58
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59 rc = uv__random_getrandom_init();
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60 if (rc != 0)
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61 return rc;
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62
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63 for (pos = 0; pos != buflen; pos += n) {
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64 do {
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65 n = buflen - pos;
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66
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67 /* Most getrandom() implementations promise that reads <= 256 bytes
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68 * will always succeed and won't be interrupted by signals.
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69 * It's therefore useful to split it up in smaller reads because
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70 * one big read may, in theory, continuously fail with EINTR.
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71 */
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72 if (n > 256)
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73 n = 256;
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74
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75 n = uv__getrandom((char *) buf + pos, n, 0);
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76 } while (n == -1 && errno == EINTR);
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77
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78 if (n == -1)
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79 return UV__ERR(errno);
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80
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81 if (n == 0)
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82 return UV_EIO;
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83 }
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84
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85 return 0;
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86 }
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