cdsa/cdsa_utilities/devrandom.cpp

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // devrandom - RNG operations based on /dev/random
  21 //
  22 #include <Security/devrandom.h>
  23
  24 using namespace UnixPlusPlus;
  25
  26
  27 namespace Security {
  28
  29
  30 //
  31 // The common (shared) open file descriptor to /dev/random
  32 //
  33 ModuleNexus<FileDesc> DevRandomGenerator::mDevRandom;
  34
  35
  36 //
  37 // DevRandomGenerator objects immediately open their file descriptors
  38 //
  39 DevRandomGenerator::DevRandomGenerator(bool writable)
  40 {
  41     FileDesc &fd = mDevRandom();
  42     if (!fd) {
  43         fd.open("/dev/random", writable ? O_RDWR : O_RDONLY);
  44     } else if (writable && !fd.isWritable()) {
  45         FileDesc newFd("/dev/random", O_RDWR);
  46         fd.close();
  47         fd = newFd;
  48     }
  49 }
  50
  51
  52 //
  53 // Standard generate (directly from /dev/random)
  54 //
  55 void DevRandomGenerator::random(void *data, size_t length)
  56 {
  57     mDevRandom().read(data, length);
  58 }
  59
  60
  61 //
  62 // If you opened for writing, you add entropy to the global pool here
  63 //
  64 void DevRandomGenerator::addEntropy(const void *data, size_t length)
  65 {
  66     mDevRandom().write(data, length);
  67 }
  68
  69
  70 }       // end namespace Security