1 // Allocator that wraps "C" malloc -*- C++ -*- 2 3 // Copyright (C) 2001-2020 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 /** @file ext/malloc_allocator.h 26 * This file is a GNU extension to the Standard C++ Library. 27 */ 28 29 #ifndef _MALLOC_ALLOCATOR_H 30 #define _MALLOC_ALLOCATOR_H 1 31 32 #include <cstdlib> 33 #include <cstddef> 34 #include <new> 35 #include <bits/functexcept.h> 36 #include <bits/move.h> 37 #if __cplusplus >= 201103L 38 #include <type_traits> 39 #endif 40 41 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 42 { 43 _GLIBCXX_BEGIN_NAMESPACE_VERSION 44 45 /** 46 * @brief An allocator that uses malloc. 47 * @ingroup allocators 48 * 49 * This is precisely the allocator defined in the C++ Standard. 50 * - all allocation calls malloc 51 * - all deallocation calls free 52 */ 53 template<typename _Tp> 54 class malloc_allocator 55 { 56 public: 57 typedef _Tp value_type; 58 typedef std::size_t size_type; 59 typedef std::ptrdiff_t difference_type; 60 #if __cplusplus <= 201703L 61 typedef _Tp* pointer; 62 typedef const _Tp* const_pointer; 63 typedef _Tp& reference; 64 typedef const _Tp& const_reference; 65 66 template<typename _Tp1> 67 struct rebind 68 { typedef malloc_allocator<_Tp1> other; }; 69 #endif 70 71 #if __cplusplus >= 201103L 72 // _GLIBCXX_RESOLVE_LIB_DEFECTS 73 // 2103. propagate_on_container_move_assignment 74 typedef std::true_type propagate_on_container_move_assignment; 75 #endif 76 77 _GLIBCXX20_CONSTEXPR 78 malloc_allocator() _GLIBCXX_USE_NOEXCEPT { } 79 80 _GLIBCXX20_CONSTEXPR 81 malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { } 82 83 template<typename _Tp1> 84 _GLIBCXX20_CONSTEXPR 85 malloc_allocator(const malloc_allocator<_Tp1>&) 86 _GLIBCXX_USE_NOEXCEPT { } 87 88 #if __cplusplus <= 201703L 89 ~malloc_allocator() _GLIBCXX_USE_NOEXCEPT { } 90 91 pointer 92 address(reference __x) const _GLIBCXX_NOEXCEPT 93 { return std::__addressof(__x); } 94 95 const_pointer 96 address(const_reference __x) const _GLIBCXX_NOEXCEPT 97 { return std::__addressof(__x); } 98 #endif 99 100 // NB: __n is permitted to be 0. The C++ standard says nothing 101 // about what the return value is when __n == 0. 102 _Tp* 103 allocate(size_type __n, const void* = 0) 104 { 105 if (__n > this->_M_max_size()) 106 std::__throw_bad_alloc(); 107 108 _Tp* __ret = 0; 109 #if __cpp_aligned_new 110 #if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC 111 if (alignof(_Tp) > alignof(std::max_align_t)) 112 { 113 __ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp), 114 __n * sizeof(_Tp))); 115 } 116 #else 117 # define _GLIBCXX_CHECK_MALLOC_RESULT 118 #endif 119 #endif 120 if (!__ret) 121 __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp))); 122 if (!__ret) 123 std::__throw_bad_alloc(); 124 #ifdef _GLIBCXX_CHECK_MALLOC_RESULT 125 #undef _GLIBCXX_CHECK_MALLOC_RESULT 126 if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp)) 127 { 128 // Memory returned by malloc is not suitably aligned for _Tp. 129 deallocate(__ret, __n); 130 std::__throw_bad_alloc(); 131 } 132 #endif 133 return __ret; 134 } 135 136 // __p is not permitted to be a null pointer. 137 void 138 deallocate(_Tp* __p, size_type) 139 { std::free(static_cast<void*>(__p)); } 140 141 #if __cplusplus <= 201703L 142 size_type 143 max_size() const _GLIBCXX_USE_NOEXCEPT 144 { return _M_max_size(); } 145 146 #if __cplusplus >= 201103L 147 template<typename _Up, typename... _Args> 148 void 149 construct(_Up* __p, _Args&&... __args) 150 noexcept(std::is_nothrow_constructible<_Up, _Args...>::value) 151 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 152 153 template<typename _Up> 154 void 155 destroy(_Up* __p) 156 noexcept(std::is_nothrow_destructible<_Up>::value) 157 { __p->~_Up(); } 158 #else 159 // _GLIBCXX_RESOLVE_LIB_DEFECTS 160 // 402. wrong new expression in [some_] allocator::construct 161 void 162 construct(pointer __p, const _Tp& __val) 163 { ::new((void *)__p) value_type(__val); } 164 165 void 166 destroy(pointer __p) { __p->~_Tp(); } 167 #endif 168 #endif // ! C++20 169 170 template<typename _Up> 171 friend _GLIBCXX20_CONSTEXPR bool 172 operator==(const malloc_allocator&, const malloc_allocator<_Up>&) 173 _GLIBCXX_NOTHROW 174 { return true; } 175 176 #if __cpp_impl_three_way_comparison < 201907L 177 template<typename _Up> 178 friend _GLIBCXX20_CONSTEXPR bool 179 operator!=(const malloc_allocator&, const malloc_allocator<_Up>&) 180 _GLIBCXX_NOTHROW 181 { return false; } 182 #endif 183 184 private: 185 _GLIBCXX_CONSTEXPR size_type 186 _M_max_size() const _GLIBCXX_USE_NOEXCEPT 187 { 188 #if __PTRDIFF_MAX__ < __SIZE_MAX__ 189 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 190 #else 191 return std::size_t(-1) / sizeof(_Tp); 192 #endif 193 } 194 }; 195 196 _GLIBCXX_END_NAMESPACE_VERSION 197 } // namespace 198 199 #endif 200