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#include <sys/stat.h> 26#include <unistd.h> 27 28static uv_once_t once = UV_ONCE_INIT; 29static int status; 30 31 32int uv__random_readpath(const char* path, void* buf, size_t buflen) { 33 struct stat s; 34 size_t pos; 35 ssize_t n; 36 int fd; 37 38 fd = uv__open_cloexec(path, O_RDONLY); 39 40 if (fd < 0) 41 return fd; 42 43 if (fstat(fd, &s)) { 44 uv__close(fd); 45 return UV__ERR(errno); 46 } 47 48 if (!S_ISCHR(s.st_mode)) { 49 uv__close(fd); 50 return UV_EIO; 51 } 52 53 for (pos = 0; pos != buflen; pos += n) { 54 do 55 n = read(fd, (char*) buf + pos, buflen - pos); 56 while (n == -1 && errno == EINTR); 57 58 if (n == -1) { 59 uv__close(fd); 60 return UV__ERR(errno); 61 } 62 63 if (n == 0) { 64 uv__close(fd); 65 return UV_EIO; 66 } 67 } 68 69 uv__close(fd); 70 return 0; 71} 72 73 74static void uv__random_devurandom_init(void) { 75 char c; 76 77 /* Linux's random(4) man page suggests applications should read at least 78 * once from /dev/random before switching to /dev/urandom in order to seed 79 * the system RNG. Reads from /dev/random can of course block indefinitely 80 * until entropy is available but that's the point. 81 */ 82 status = uv__random_readpath("/dev/random", &c, 1); 83} 84 85 86int uv__random_devurandom(void* buf, size_t buflen) { 87 uv_once(&once, uv__random_devurandom_init); 88 89 if (status != 0) 90 return status; 91 92 return uv__random_readpath("/dev/urandom", buf, buflen); 93} 94