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

   1 // random -*- C++ -*-
   2
   3 // Copyright (C) 2012-2018 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 #ifdef _GLIBCXX_HAVE_SYS_IOCTL_H
  42 # include <sys/ioctl.h>
  43 #endif
  44
  45 #ifdef _GLIBCXX_HAVE_LINUX_TYPES_H
  46 # include <linux/types.h>
  47 #endif
  48
  49 #ifdef _GLIBCXX_HAVE_LINUX_RANDOM_H
  50 # include <linux/random.h>
  51 #endif
  52
  53 namespace std _GLIBCXX_VISIBILITY(default)
  54 {
  55   namespace
  56   {
  57     static unsigned long
  58     _M_strtoul(const std::string& __str)
  59     {
  60       unsigned long __ret = 5489UL;
  61       if (__str != "mt19937")
  62         {
  63           const char* __nptr = __str.c_str();
  64           char* __endptr;
  65           __ret = std::strtoul(__nptr, &__endptr, 0);
  66           if (*__nptr == '\0' || *__endptr != '\0')
  67             std::__throw_runtime_error(__N("random_device::_M_strtoul"
  68                                            "(const std::string&)"));
  69         }
  70       return __ret;
  71     }
  72
  73 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  74     unsigned int
  75     __attribute__ ((target("rdrnd")))
  76     __x86_rdrand(void)
  77     {
  78       unsigned int retries = 100;
  79       unsigned int val;
  80
  81       while (__builtin_ia32_rdrand32_step(&val) == 0)
  82         if (--retries == 0)
  83           std::__throw_runtime_error(__N("random_device::__x86_rdrand(void)"));
  84
  85       return val;
  86     }
  87 #endif
  88   }
  89
  90   void
  91   random_device::_M_init(const std::string& token)
  92   {
  93     const char *fname = token.c_str();
  94
  95     if (token == "default")
  96       {
  97 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  98         unsigned int eax, ebx, ecx, edx;
  99         // Check availability of cpuid and, for now at least, also the
 100         // CPU signature for Intel's
 101         if (__get_cpuid_max(0, &ebx) > 0 && ebx == signature_INTEL_ebx)
 102           {
 103             __cpuid(1, eax, ebx, ecx, edx);
 104             if (ecx & bit_RDRND)
 105               {
 106                 _M_file = nullptr;
 107                 return;
 108               }
 109           }
 110 #endif
 111
 112         fname = "/dev/urandom";
 113       }
 114     else if (token != "/dev/urandom" && token != "/dev/random")
 115     fail:
 116       std::__throw_runtime_error(__N("random_device::"
 117                                      "random_device(const std::string&)"));
 118
 119     _M_file = static_cast<void*>(std::fopen(fname, "rb"));
 120     if (!_M_file)
 121       goto fail;
 122   }
 123
 124   void
 125   random_device::_M_init_pretr1(const std::string& token)
 126   {
 127     _M_mt.seed(_M_strtoul(token));
 128   }
 129
 130   void
 131   random_device::_M_fini()
 132   {
 133     if (_M_file)
 134       std::fclose(static_cast<FILE*>(_M_file));
 135   }
 136
 137   random_device::result_type
 138   random_device::_M_getval()
 139   {
 140 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
 141     if (!_M_file)
 142       return __x86_rdrand();
 143 #endif
 144
 145     result_type __ret;
 146     void* p = &__ret;
 147     size_t n = sizeof(result_type);
 148 #ifdef _GLIBCXX_HAVE_UNISTD_H
 149     do
 150       {
 151         const int e = read(fileno(static_cast<FILE*>(_M_file)), p, n);
 152         if (e > 0)
 153           {
 154             n -= e;
 155             p = static_cast<char*>(p) + e;
 156           }
 157         else if (e != -1 || errno != EINTR)
 158           __throw_runtime_error(__N("random_device could not be read"));
 159       }
 160     while (n > 0);
 161 #else
 162     const size_t e = std::fread(p, n, 1, static_cast<FILE*>(_M_file));
 163     if (e != 1)
 164       __throw_runtime_error(__N("random_device could not be read"));
 165 #endif
 166
 167     return __ret;
 168   }
 169
 170   random_device::result_type
 171   random_device::_M_getval_pretr1()
 172   {
 173     return _M_mt();
 174   }
 175
 176   double
 177   random_device::_M_getentropy() const noexcept
 178   {
 179 #if defined _GLIBCXX_HAVE_SYS_IOCTL_H && defined RNDGETENTCNT
 180     if (!_M_file)
 181       return 0.0;
 182
 183     const int fd = fileno(static_cast<FILE*>(_M_file));
 184     if (fd < 0)
 185       return 0.0;
 186
 187     int ent;
 188     if (ioctl(fd, RNDGETENTCNT, &ent) < 0)
 189       return 0.0;
 190
 191     if (ent < 0)
 192       return 0.0;
 193
 194     const int max = sizeof(result_type) * __CHAR_BIT__;
 195     if (ent > max)
 196       ent = max;
 197
 198     return static_cast<double>(ent);
 199 #else
 200     return 0.0;
 201 #endif
 202   }
 203
 204   template class mersenne_twister_engine<
 205     uint_fast32_t,
 206     32, 624, 397, 31,
 207     0x9908b0dfUL, 11,
 208     0xffffffffUL, 7,
 209     0x9d2c5680UL, 15,
 210     0xefc60000UL, 18, 1812433253UL>;
 211 }
 212 #endif