1/* Copyright libuv contributors. All rights reserved. 2 * 3 * Permission is hereby granted, free of charge, to any person obtaining a copy 4 * of this software and associated documentation files (the "Software"), to 5 * deal in the Software without restriction, including without limitation the 6 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 7 * sell copies of the Software, and to permit persons to whom the Software is 8 * furnished to do so, subject to the following conditions: 9 * 10 * The above copyright notice and this permission notice shall be included in 11 * all copies or substantial portions of the Software. 12 * 13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 16 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 17 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 18 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 19 * IN THE SOFTWARE. 20 */ 21 22#include "uv.h" 23#include "internal.h" 24 25#ifdef __linux__ 26 27#include "linux-syscalls.h" 28 29#define uv__random_getrandom_init() 0 30 31#else /* !__linux__ */ 32 33#include <stddef.h> 34#include <dlfcn.h> 35 36typedef ssize_t (*uv__getrandom_cb)(void *, size_t, unsigned); 37 38static uv__getrandom_cb uv__getrandom; 39static uv_once_t once = UV_ONCE_INIT; 40 41static void uv__random_getrandom_init_once(void) { 42 uv__getrandom = (uv__getrandom_cb) dlsym(RTLD_DEFAULT, "getrandom"); 43} 44 45static int uv__random_getrandom_init(void) { 46 uv_once(&once, uv__random_getrandom_init_once); 47 48 if (uv__getrandom == NULL) 49 return UV_ENOSYS; 50 51 return 0; 52} 53 54#endif /* !__linux__ */ 55 56int uv__random_getrandom(void* buf, size_t buflen) { 57 ssize_t n; 58 size_t pos; 59 int rc; 60 61 rc = uv__random_getrandom_init(); 62 if (rc != 0) 63 return rc; 64 65 for (pos = 0; pos != buflen; pos += n) { 66 do { 67 n = buflen - pos; 68 69 /* Most getrandom() implementations promise that reads <= 256 bytes 70 * will always succeed and won't be interrupted by signals. 71 * It's therefore useful to split it up in smaller reads because 72 * one big read may, in theory, continuously fail with EINTR. 73 */ 74 if (n > 256) 75 n = 256; 76 77 n = uv__getrandom((char *) buf + pos, n, 0); 78 } while (n == -1 && errno == EINTR); 79 80 if (n == -1) 81 return UV__ERR(errno); 82 83 if (n == 0) 84 return UV_EIO; 85 } 86 87 return 0; 88} 89