OSX/libsecurity_utilities/lib/devrandom.cpp

   1 /*
   2  * Copyright (c) 2000-2004,2011,2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  18  * Please see the License for the specific language governing rights and
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  22  */
  23
  24
  25 //
  26 // devrandom - RNG operations based on /dev/random
  27 //
  28 #include <security_utilities/devrandom.h>
  29 #include <security_utilities/logging.h>
  30
  31 using namespace UnixPlusPlus;
  32
  33
  34 namespace Security {
  35
  36
  37 //
  38 // The common (shared) open file descriptor to /dev/random
  39 //
  40 ModuleNexus<DevRandomGenerator::Readonly> DevRandomGenerator::mReader;
  41 ModuleNexus<DevRandomGenerator::Writable> DevRandomGenerator::mWriter;
  42
  43
  44 //
  45 // In the current implementation, opening the file descriptor is deferred.
  46 //
  47 DevRandomGenerator::DevRandomGenerator(bool writable)
  48 {
  49 }
  50
  51
  52 //
  53 // Standard generate (directly from /dev/random)
  54 //
  55 void DevRandomGenerator::random(void *data, size_t length)
  56 {
  57     try {
  58                 size_t bytesRead = mReader().read(data, length);
  59                 if (bytesRead != length) {      // short read (shouldn't happen)
  60                         Syslog::error("DevRandomGenerator: wanted %ld got %ld bytes",
  61                                 length, bytesRead);
  62                         UnixError::throwMe(EIO);
  63                 }
  64         } catch(const UnixError &uerr) {
  65                 Syslog::error("DevRandomGenerator: error %d reading /dev/random",
  66                         uerr.error);
  67                 throw;
  68         }
  69 }
  70
  71
  72 //
  73 // If you opened for writing, you add entropy to the global pool here
  74 //
  75 void DevRandomGenerator::addEntropy(const void *data, size_t length)
  76 {
  77     if (mWriter().write(data, length) != length)
  78                 UnixError::throwMe(EIO);        // short write (shouldn't happen)
  79 }
  80
  81
  82 }       // end namespace Security