1 // Allocator that wraps "C" malloc -*- C++ -*-
2
3 // Copyright (C) 2001-2019 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
_GLIBCXX_VISIBILITY(default)41 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
42 {
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
44
45 using std::size_t;
46 using std::ptrdiff_t;
47
48 /**
49 * @brief An allocator that uses malloc.
50 * @ingroup allocators
51 *
52 * This is precisely the allocator defined in the C++ Standard.
53 * - all allocation calls malloc
54 * - all deallocation calls free
55 */
56 template<typename _Tp>
57 class malloc_allocator
58 {
59 public:
60 typedef size_t size_type;
61 typedef ptrdiff_t difference_type;
62 typedef _Tp* pointer;
63 typedef const _Tp* const_pointer;
64 typedef _Tp& reference;
65 typedef const _Tp& const_reference;
66 typedef _Tp value_type;
67
68 template<typename _Tp1>
69 struct rebind
70 { typedef malloc_allocator<_Tp1> other; };
71
72 #if __cplusplus >= 201103L
73 // _GLIBCXX_RESOLVE_LIB_DEFECTS
74 // 2103. propagate_on_container_move_assignment
75 typedef std::true_type propagate_on_container_move_assignment;
76 #endif
77
78 _GLIBCXX20_CONSTEXPR
79 malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
80
81 _GLIBCXX20_CONSTEXPR
82 malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { }
83
84 template<typename _Tp1>
85 _GLIBCXX20_CONSTEXPR
86 malloc_allocator(const malloc_allocator<_Tp1>&)
87 _GLIBCXX_USE_NOEXCEPT { }
88
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
99 // NB: __n is permitted to be 0. The C++ standard says nothing
100 // about what the return value is when __n == 0.
101 pointer
102 allocate(size_type __n, const void* = 0)
103 {
104 if (__n > this->max_size())
105 std::__throw_bad_alloc();
106
107 pointer __ret = 0;
108 #if __cpp_aligned_new
109 #if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC
110 if (alignof(_Tp) > alignof(std::max_align_t))
111 {
112 __ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp),
113 __n * sizeof(_Tp)));
114 }
115 #else
116 # define _GLIBCXX_CHECK_MALLOC_RESULT
117 #endif
118 #endif
119 if (!__ret)
120 __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp)));
121 if (!__ret)
122 std::__throw_bad_alloc();
123 #ifdef _GLIBCXX_CHECK_MALLOC_RESULT
124 #undef _GLIBCXX_CHECK_MALLOC_RESULT
125 if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp))
126 {
127 // Memory returned by malloc is not suitably aligned for _Tp.
128 deallocate(__ret, __n);
129 std::__throw_bad_alloc();
130 }
131 #endif
132 return __ret;
133 }
134
135 // __p is not permitted to be a null pointer.
136 void
137 deallocate(pointer __p, size_type)
138 { std::free(static_cast<void*>(__p)); }
139
140 size_type
141 max_size() const _GLIBCXX_USE_NOEXCEPT
142 {
143 #if __PTRDIFF_MAX__ < __SIZE_MAX__
144 return size_t(__PTRDIFF_MAX__) / sizeof(_Tp);
145 #else
146 return size_t(-1) / sizeof(_Tp);
147 #endif
148 }
149
150 #if __cplusplus >= 201103L
151 template<typename _Up, typename... _Args>
152 void
153 construct(_Up* __p, _Args&&... __args)
154 noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
155 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
156
157 template<typename _Up>
158 void
159 destroy(_Up* __p)
160 noexcept(std::is_nothrow_destructible<_Up>::value)
161 { __p->~_Up(); }
162 #else
163 // _GLIBCXX_RESOLVE_LIB_DEFECTS
164 // 402. wrong new expression in [some_] allocator::construct
165 void
166 construct(pointer __p, const _Tp& __val)
167 { ::new((void *)__p) value_type(__val); }
168
169 void
170 destroy(pointer __p) { __p->~_Tp(); }
171 #endif
172
173 template<typename _Up>
174 friend bool
175 operator==(const malloc_allocator&, const malloc_allocator<_Up>&)
176 _GLIBCXX_NOTHROW
177 { return true; }
178
179 template<typename _Up>
180 friend bool
181 operator!=(const malloc_allocator&, const malloc_allocator<_Up>&)
182 _GLIBCXX_NOTHROW
183 { return false; }
184 };
185
186 _GLIBCXX_END_NAMESPACE_VERSION
187 } // namespace
188
189 #endif
190