libstdc++-v3/src/c++11/random.cc

   1 // random -*- C++ -*-
   2
   3 // Copyright (C) 2012-2016 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #define _GLIBCXX_USE_CXX11_ABI 1
  26 #include <random>
  27
  28 #ifdef  _GLIBCXX_USE_C99_STDINT_TR1
  29
  30 #if defined __i386__ || defined __x86_64__
  31 # include <cpuid.h>
  32 #endif
  33
  34 #include <cerrno>
  35 #include <cstdio>
  36
  37 #ifdef _GLIBCXX_HAVE_UNISTD_H
  38 # include <unistd.h>
  39 #endif
  40
  41 namespace std _GLIBCXX_VISIBILITY(default)
  42 {
  43   namespace
  44   {
  45     static unsigned long
  46     _M_strtoul(const std::string& __str)
  47     {
  48       unsigned long __ret = 5489UL;
  49       if (__str != "mt19937")
  50         {
  51           const char* __nptr = __str.c_str();
  52           char* __endptr;
  53           __ret = std::strtoul(__nptr, &__endptr, 0);
  54           if (*__nptr == '\0' || *__endptr != '\0')
  55             std::__throw_runtime_error(__N("random_device::_M_strtoul"
  56                                            "(const std::string&)"));
  57         }
  58       return __ret;
  59     }
  60
  61 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  62     unsigned int
  63     __attribute__ ((target("rdrnd")))
  64     __x86_rdrand(void)
  65     {
  66       unsigned int retries = 100;
  67       unsigned int val;
  68
  69       while (__builtin_ia32_rdrand32_step(&val) == 0)
  70         if (--retries == 0)
  71           std::__throw_runtime_error(__N("random_device::__x86_rdrand(void)"));
  72
  73       return val;
  74     }
  75 #endif
  76   }
  77
  78   void
  79   random_device::_M_init(const std::string& token)
  80   {
  81     const char *fname = token.c_str();
  82
  83     if (token == "default")
  84       {
  85 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  86         unsigned int eax, ebx, ecx, edx;
  87         // Check availability of cpuid and, for now at least, also the
  88         // CPU signature for Intel's
  89         if (__get_cpuid_max(0, &ebx) > 0 && ebx == signature_INTEL_ebx)
  90           {
  91             __cpuid(1, eax, ebx, ecx, edx);
  92             if (ecx & bit_RDRND)
  93               {
  94                 _M_file = nullptr;
  95                 return;
  96               }
  97           }
  98 #endif
  99
 100         fname = "/dev/urandom";
 101       }
 102     else if (token != "/dev/urandom" && token != "/dev/random")
 103     fail:
 104       std::__throw_runtime_error(__N("random_device::"
 105                                      "random_device(const std::string&)"));
 106
 107     _M_file = static_cast<void*>(std::fopen(fname, "rb"));
 108     if (!_M_file)
 109       goto fail;
 110   }
 111
 112   void
 113   random_device::_M_init_pretr1(const std::string& token)
 114   {
 115     _M_mt.seed(_M_strtoul(token));
 116   }
 117
 118   void
 119   random_device::_M_fini()
 120   {
 121     if (_M_file)
 122       std::fclose(static_cast<FILE*>(_M_file));
 123   }
 124
 125   random_device::result_type
 126   random_device::_M_getval()
 127   {
 128 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
 129     if (!_M_file)
 130       return __x86_rdrand();
 131 #endif
 132
 133     result_type __ret;
 134     void* p = &__ret;
 135     size_t n = sizeof(result_type);
 136 #ifdef _GLIBCXX_HAVE_UNISTD_H
 137     do
 138       {
 139         const int e = read(fileno(static_cast<FILE*>(_M_file)), p, n);
 140         if (e > 0)
 141           {
 142             n -= e;
 143             p = static_cast<char*>(p) + e;
 144           }
 145         else if (e != -1 || errno != EINTR)
 146           __throw_runtime_error(__N("random_device could not be read"));
 147       }
 148     while (n > 0);
 149 #else
 150     const size_t e = std::fread(p, n, 1, static_cast<FILE*>(_M_file));
 151     if (e != 1)
 152       __throw_runtime_error(__N("random_device could not be read"));
 153 #endif
 154
 155     return __ret;
 156   }
 157
 158   random_device::result_type
 159   random_device::_M_getval_pretr1()
 160   {
 161     return _M_mt();
 162   }
 163
 164   template class mersenne_twister_engine<
 165     uint_fast32_t,
 166     32, 624, 397, 31,
 167     0x9908b0dfUL, 11,
 168     0xffffffffUL, 7,
 169     0x9d2c5680UL, 15,
 170     0xefc60000UL, 18, 1812433253UL>;
 171 }
 172 #endif