git.itanic.dy.fi Git - sudoku/blob - random.cpp

   1 #include <stdio.h>
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4 #include <fcntl.h>
   5 #include <errno.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8
   9 #include "random.h"
  10
  11 #define RAND_BUF_SIZE   1024
  12 #define RND_DEV         "/dev/urandom"
  13
  14 unsigned int get_random(void)
  15 {
  16         static int rndbuf[RAND_BUF_SIZE];
  17         static int index = RAND_BUF_SIZE;
  18         int fd, error, i = 0, ret;
  19
  20         if (index < RAND_BUF_SIZE)
  21                 return rndbuf[index++];
  22
  23         fd = open(RND_DEV, O_RDONLY);
  24         if (fd < 0) {
  25                 error = errno;
  26                 fprintf(stderr, "Error opening file %s: %s\n",
  27                         RND_DEV, strerror(error));
  28                 return -1;
  29         }
  30
  31         do {
  32                 ret = read(fd, rndbuf + i,
  33                           RAND_BUF_SIZE * (sizeof(rndbuf[0]) - i));
  34
  35                 if (ret <= 0) {
  36                         error = errno;
  37                         fprintf(stderr, "Error reading file %s: %s\n",
  38                                 RND_DEV, strerror(error));
  39                         goto out;
  40                 }
  41
  42                 i += ret;
  43         } while (i < RAND_BUF_SIZE * sizeof(rndbuf[0]));
  44         index = 0;
  45  out:
  46         return get_random();
  47         close(fd);
  48 }