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 41namespace __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 _GLIBCXX_NODISCARD _Tp* 103 allocate(size_type __n, const void* = 0) 104 { 105#if __cplusplus >= 201103L 106 // _GLIBCXX_RESOLVE_LIB_DEFECTS 107 // 3308. std::allocator<void>().allocate(n) 108 static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types"); 109#endif 110 111 if (__n > this->_M_max_size()) 112 std::__throw_bad_alloc(); 113 114 _Tp* __ret = 0; 115#if __cpp_aligned_new 116#if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC 117 if (alignof(_Tp) > alignof(std::max_align_t)) 118 { 119 __ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp), 120 __n * sizeof(_Tp))); 121 } 122#else 123# define _GLIBCXX_CHECK_MALLOC_RESULT 124#endif 125#endif 126 if (!__ret) 127 __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp))); 128 if (!__ret) 129 std::__throw_bad_alloc(); 130#ifdef _GLIBCXX_CHECK_MALLOC_RESULT 131#undef _GLIBCXX_CHECK_MALLOC_RESULT 132 if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp)) 133 { 134 // Memory returned by malloc is not suitably aligned for _Tp. 135 deallocate(__ret, __n); 136 std::__throw_bad_alloc(); 137 } 138#endif 139 return __ret; 140 } 141 142 // __p is not permitted to be a null pointer. 143 void 144 deallocate(_Tp* __p, size_type) 145 { std::free(static_cast<void*>(__p)); } 146 147#if __cplusplus <= 201703L 148 size_type 149 max_size() const _GLIBCXX_USE_NOEXCEPT 150 { return _M_max_size(); } 151 152#if __cplusplus >= 201103L 153 template<typename _Up, typename... _Args> 154 void 155 construct(_Up* __p, _Args&&... __args) 156 noexcept(std::is_nothrow_constructible<_Up, _Args...>::value) 157 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 158 159 template<typename _Up> 160 void 161 destroy(_Up* __p) 162 noexcept(std::is_nothrow_destructible<_Up>::value) 163 { __p->~_Up(); } 164#else 165 // _GLIBCXX_RESOLVE_LIB_DEFECTS 166 // 402. wrong new expression in [some_] allocator::construct 167 void 168 construct(pointer __p, const _Tp& __val) 169 { ::new((void *)__p) value_type(__val); } 170 171 void 172 destroy(pointer __p) { __p->~_Tp(); } 173#endif 174#endif // ! C++20 175 176 template<typename _Up> 177 friend _GLIBCXX20_CONSTEXPR bool 178 operator==(const malloc_allocator&, const malloc_allocator<_Up>&) 179 _GLIBCXX_NOTHROW 180 { return true; } 181 182#if __cpp_impl_three_way_comparison < 201907L 183 template<typename _Up> 184 friend _GLIBCXX20_CONSTEXPR bool 185 operator!=(const malloc_allocator&, const malloc_allocator<_Up>&) 186 _GLIBCXX_NOTHROW 187 { return false; } 188#endif 189 190 private: 191 _GLIBCXX_CONSTEXPR size_type 192 _M_max_size() const _GLIBCXX_USE_NOEXCEPT 193 { 194#if __PTRDIFF_MAX__ < __SIZE_MAX__ 195 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 196#else 197 return std::size_t(-1) / sizeof(_Tp); 198#endif 199 } 200 }; 201 202_GLIBCXX_END_NAMESPACE_VERSION 203} // namespace 204 205#endif 206