code.delx.au - pulseaudio/blob - polyp/random.c

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of polypaudio.
   5
   6   polypaudio is free software; you can redistribute it and/or modify
   7   it under the terms of the GNU Lesser General Public License as
   8   published by the Free Software Foundation; either version 2.1 of the
   9   License, or (at your option) any later version.
  10
  11   polypaudio is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public
  17   License along with polypaudio; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #include <fcntl.h>
  23 #include <unistd.h>
  24 #include <errno.h>
  25 #include <string.h>
  26 #include <stdlib.h>
  27 #include <assert.h>
  28 #include <time.h>
  29
  30 #include "random.h"
  31 #include "util.h"
  32 #include "log.h"
  33
  34 #define RANDOM_DEVICE "/dev/urandom"
  35
  36 void pa_random(void *ret_data, size_t length) {
  37     int fd;
  38     ssize_t r = 0;
  39     assert(ret_data && length);
  40
  41     if ((fd = open(RANDOM_DEVICE, O_RDONLY)) >= 0) {
  42
  43         if ((r = pa_loop_read(fd, ret_data, length)) < 0 || (size_t) r != length)
  44             pa_log_error(__FILE__": failed to read entropy from '%s'\n", RANDOM_DEVICE);
  45
  46         close(fd);
  47     }
  48
  49     if ((size_t) r != length) {
  50         uint8_t *p;
  51         size_t l;
  52
  53         pa_log_warn(__FILE__": WARNING: Failed to open entropy device '"RANDOM_DEVICE"': %s"
  54                     ", falling back to unsecure pseudo RNG.\n", strerror(errno));
  55
  56         srandom(time(NULL));
  57
  58         for (p = ret_data, l = length; l > 0; p++, l--)
  59             *p = (uint8_t) random();
  60     }
  61 }