contrib/cryptsetup/luks/random.c

   1 /*
   2  *      Random supply helper
   3  * Copyright 2004, Clemens Fruhwirth <clemens@endorphin.org>
   4  *
   5  */
   6
   7 #include <sys/types.h>
   8 #include <sys/stat.h>
   9 #include <fcntl.h>
  10 #include <errno.h>
  11 #include <stdio.h>
  12 #include <unistd.h>
  13
  14 static int randomfd = -1;
  15
  16 int openRandom() {
  17     if(randomfd == -1)
  18         randomfd = open("/dev/urandom", O_RDONLY);
  19     return randomfd;
  20 }
  21
  22 /* This method leaks a file descriptor that can be obtained by calling
  23    closeRandom */
  24 int getRandom(char *buf, size_t len)
  25 {
  26     if(openRandom() == -1) {
  27         perror("getRandom:");
  28         return -EINVAL;
  29     }
  30     while(len) {
  31         int r;
  32         r = read(randomfd,buf,len);
  33         if (-1 == r && errno != -EINTR) {
  34             perror("read: "); return -EINVAL;
  35         }
  36         len-= r; buf += r;
  37     }
  38     return 0;
  39 }
  40
  41 void closeRandom() {
  42     if(randomfd != -1) {
  43         close(randomfd);
  44         randomfd = -1;
  45     }
  46 }