contrib/libjeffpc/rand.c

   1 /*
   2  * Copyright (c) 2015-2016 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
   3  * Copyright (c) 2015 Holly Sipek
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy
   6  * of this software and associated documentation files (the "Software"), to deal
   7  * in the Software without restriction, including without limitation the rights
   8  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9  * copies of the Software, and to permit persons to whom the Software is
  10  * furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 #include <inttypes.h>
  25
  26 #include <jeffpc/rand.h>
  27 #include <jeffpc/config.h>
  28 #include <jeffpc/error.h>
  29 #include <jeffpc/io.h>
  30
  31 uint32_t rand32(void)
  32 {
  33 #ifdef HAVE_ARC4RANDOM
  34         return arc4random();
  35 #else
  36         uint32_t val;
  37         int ret;
  38         int fd;
  39
  40         fd = xopen("/dev/urandom", O_RDONLY, 0);
  41         if (fd < 0)
  42                 panic("Failed to get random number: %s", xstrerror(fd));
  43
  44         ret = xread(fd, &val, sizeof(val));
  45         if (ret)
  46                 panic("Failed to get random number: %s", xstrerror(ret));
  47
  48         xclose(fd);
  49
  50         return val;
  51 #endif
  52 }
  53
  54 uint64_t rand64(void)
  55 {
  56         uint64_t tmp;
  57
  58         tmp   = rand32();
  59         tmp <<= 32;
  60         tmp  |= rand32();
  61
  62         return tmp;
  63 }