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The C and C++ Include Header Files
/usr/include/c++/13/ext/malloc_allocator.h
$ cat -n /usr/include/c++/13/ext/malloc_allocator.h 1 // Allocator that wraps "C" malloc -*- C++ -*- 2 3 // Copyright (C) 2001-2023 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 <bits/requires_hosted.h> // malloc 33 34 #include <cstdlib> 35 #include <cstddef> 36 #include <new> 37 #include <bits/functexcept.h> 38 #include <bits/move.h> 39 #if __cplusplus >= 201103L 40 #include <type_traits> 41 #endif 42 43 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 44 { 45 _GLIBCXX_BEGIN_NAMESPACE_VERSION 46 47 /** 48 * @brief An allocator that uses malloc. 49 * @ingroup allocators 50 * 51 * This is precisely the allocator defined in the C++ Standard. 52 * - all allocation calls malloc 53 * - all deallocation calls free 54 */ 55 template<typename _Tp> 56 class malloc_allocator 57 { 58 public: 59 typedef _Tp value_type; 60 typedef std::size_t size_type; 61 typedef std::ptrdiff_t difference_type; 62 #if __cplusplus <= 201703L 63 typedef _Tp* pointer; 64 typedef const _Tp* const_pointer; 65 typedef _Tp& reference; 66 typedef const _Tp& const_reference; 67 68 template<typename _Tp1> 69 struct rebind 70 { typedef malloc_allocator<_Tp1> other; }; 71 #endif 72 73 #if __cplusplus >= 201103L 74 // _GLIBCXX_RESOLVE_LIB_DEFECTS 75 // 2103. propagate_on_container_move_assignment 76 typedef std::true_type propagate_on_container_move_assignment; 77 #endif 78 79 _GLIBCXX20_CONSTEXPR 80 malloc_allocator() _GLIBCXX_USE_NOEXCEPT { } 81 82 _GLIBCXX20_CONSTEXPR 83 malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { } 84 85 template<typename _Tp1> 86 _GLIBCXX20_CONSTEXPR 87 malloc_allocator(const malloc_allocator<_Tp1>&) 88 _GLIBCXX_USE_NOEXCEPT { } 89 90 #if __cplusplus <= 201703L 91 ~malloc_allocator() _GLIBCXX_USE_NOEXCEPT { } 92 93 pointer 94 address(reference __x) const _GLIBCXX_NOEXCEPT 95 { return std::__addressof(__x); } 96 97 const_pointer 98 address(const_reference __x) const _GLIBCXX_NOEXCEPT 99 { return std::__addressof(__x); } 100 #endif 101 102 // NB: __n is permitted to be 0. The C++ standard says nothing 103 // about what the return value is when __n == 0. 104 _GLIBCXX_NODISCARD _Tp* 105 allocate(size_type __n, const void* = 0) 106 { 107 #if __cplusplus >= 201103L 108 // _GLIBCXX_RESOLVE_LIB_DEFECTS 109 // 3308. std::allocator<void>().allocate(n) 110 static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types"); 111 #endif 112 113 if (__builtin_expect(__n > this->_M_max_size(), false)) 114 { 115 // _GLIBCXX_RESOLVE_LIB_DEFECTS 116 // 3190. allocator::allocate sometimes returns too little storage 117 if (__n > (std::size_t(-1) / sizeof(_Tp))) 118 std::__throw_bad_array_new_length(); 119 std::__throw_bad_alloc(); 120 } 121 122 _Tp* __ret = 0; 123 #if __cpp_aligned_new 124 #if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC 125 if (alignof(_Tp) > alignof(std::max_align_t)) 126 { 127 __ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp), 128 __n * sizeof(_Tp))); 129 } 130 #else 131 # define _GLIBCXX_CHECK_MALLOC_RESULT 132 #endif 133 #endif 134 if (!__ret) 135 __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp))); 136 if (!__ret) 137 std::__throw_bad_alloc(); 138 #ifdef _GLIBCXX_CHECK_MALLOC_RESULT 139 #undef _GLIBCXX_CHECK_MALLOC_RESULT 140 if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp)) 141 { 142 // Memory returned by malloc is not suitably aligned for _Tp. 143 deallocate(__ret, __n); 144 std::__throw_bad_alloc(); 145 } 146 #endif 147 return __ret; 148 } 149 150 // __p is not permitted to be a null pointer. 151 void 152 deallocate(_Tp* __p, size_type) 153 { std::free(static_cast<void*>(__p)); } 154 155 #if __cplusplus <= 201703L 156 size_type 157 max_size() const _GLIBCXX_USE_NOEXCEPT 158 { return _M_max_size(); } 159 160 #if __cplusplus >= 201103L 161 template<typename _Up, typename... _Args> 162 void 163 construct(_Up* __p, _Args&&... __args) 164 noexcept(std::is_nothrow_constructible<_Up, _Args...>::value) 165 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 166 167 template<typename _Up> 168 void 169 destroy(_Up* __p) 170 noexcept(std::is_nothrow_destructible<_Up>::value) 171 { __p->~_Up(); } 172 #else 173 // _GLIBCXX_RESOLVE_LIB_DEFECTS 174 // 402. wrong new expression in [some_] allocator::construct 175 void 176 construct(pointer __p, const _Tp& __val) 177 { ::new((void *)__p) value_type(__val); } 178 179 void 180 destroy(pointer __p) { __p->~_Tp(); } 181 #endif 182 #endif // ! C++20 183 184 template<typename _Up> 185 friend _GLIBCXX20_CONSTEXPR bool 186 operator==(const malloc_allocator&, const malloc_allocator<_Up>&) 187 _GLIBCXX_NOTHROW 188 { return true; } 189 190 #if __cpp_impl_three_way_comparison < 201907L 191 template<typename _Up> 192 friend _GLIBCXX20_CONSTEXPR bool 193 operator!=(const malloc_allocator&, const malloc_allocator<_Up>&) 194 _GLIBCXX_NOTHROW 195 { return false; } 196 #endif 197 198 private: 199 _GLIBCXX_CONSTEXPR size_type 200 _M_max_size() const _GLIBCXX_USE_NOEXCEPT 201 { 202 #if __PTRDIFF_MAX__ < __SIZE_MAX__ 203 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 204 #else 205 return std::size_t(-1) / sizeof(_Tp); 206 #endif 207 } 208 }; 209 210 _GLIBCXX_END_NAMESPACE_VERSION 211 } // namespace 212 213 #endif
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