libcxx/include/__cxx03/__random/random_device.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___RANDOM_RANDOM_DEVICE_H
  10 #define _LIBCPP___RANDOM_RANDOM_DEVICE_H
  11
  12 #include <__cxx03/__config>
  13 #include <__cxx03/string>
  14
  15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  16 #  pragma GCC system_header
  17 #endif
  18
  19 _LIBCPP_PUSH_MACROS
  20 #include <__cxx03/__undef_macros>
  21
  22 _LIBCPP_BEGIN_NAMESPACE_STD
  23
  24 #if !defined(_LIBCPP_HAS_NO_RANDOM_DEVICE)
  25
  26 class _LIBCPP_EXPORTED_FROM_ABI random_device {
  27 #  ifdef _LIBCPP_USING_DEV_RANDOM
  28   int __f_;
  29 #  elif !defined(_LIBCPP_ABI_NO_RANDOM_DEVICE_COMPATIBILITY_LAYOUT)
  30   _LIBCPP_DIAGNOSTIC_PUSH
  31   _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wunused-private-field")
  32
  33   // Apple platforms used to use the `_LIBCPP_USING_DEV_RANDOM` code path, and now
  34   // use `arc4random()` as of this comment. In order to avoid breaking the ABI, we
  35   // retain the same layout as before.
  36 #    if defined(__APPLE__)
  37   int __padding_; // padding to fake the `__f_` field above
  38 #    endif
  39
  40   // ... vendors can add workarounds here if they switch to a different representation ...
  41
  42   _LIBCPP_DIAGNOSTIC_POP
  43 #  endif
  44
  45 public:
  46   // types
  47   typedef unsigned result_type;
  48
  49   // generator characteristics
  50   static _LIBCPP_CONSTEXPR const result_type _Min = 0;
  51   static _LIBCPP_CONSTEXPR const result_type _Max = 0xFFFFFFFFu;
  52
  53   _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type min() { return _Min; }
  54   _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type max() { return _Max; }
  55
  56   // constructors
  57 #  ifndef _LIBCPP_CXX03_LANG
  58   _LIBCPP_HIDE_FROM_ABI random_device() : random_device("/dev/urandom") {}
  59   explicit random_device(const string& __token);
  60 #  else
  61   explicit random_device(const string& __token = "/dev/urandom");
  62 #  endif
  63   ~random_device();
  64
  65   // generating functions
  66   result_type operator()();
  67
  68   // property functions
  69   double entropy() const _NOEXCEPT;
  70
  71   random_device(const random_device&)  = delete;
  72   void operator=(const random_device&) = delete;
  73 };
  74
  75 #endif // !_LIBCPP_HAS_NO_RANDOM_DEVICE
  76
  77 _LIBCPP_END_NAMESPACE_STD
  78
  79 _LIBCPP_POP_MACROS
  80
  81 #endif // _LIBCPP___RANDOM_RANDOM_DEVICE_H