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12471842 PL |
1 | /* |
2 | * This file is part of PowerDNS or dnsdist. | |
3 | * Copyright -- PowerDNS.COM B.V. and its contributors | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of version 2 of the GNU General Public License as | |
7 | * published by the Free Software Foundation. | |
8 | * | |
9 | * In addition, for the avoidance of any doubt, permission is granted to | |
10 | * link this program with OpenSSL and to (re)distribute the binaries | |
11 | * produced as the result of such linking. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
21 | */ | |
e8c59f2d | 22 | #pragma once |
5cf909f3 AN |
23 | #include <cstddef> |
24 | #include <utility> | |
25 | #include <type_traits> | |
15880e10 OM |
26 | #include <new> |
27 | #include <sys/mman.h> | |
28 | ||
29 | // On OpenBSD mem used as stack should be marked MAP_STACK | |
30 | #if !defined(MAP_STACK) | |
31 | #define MAP_STACK 0 | |
32 | #endif | |
5cf909f3 AN |
33 | |
34 | template <typename T> | |
35 | struct lazy_allocator { | |
36 | using value_type = T; | |
37 | using pointer = T*; | |
38 | using size_type = std::size_t; | |
39 | static_assert (std::is_trivial<T>::value, | |
40 | "lazy_allocator must only be used with trivial types"); | |
41 | ||
42 | pointer | |
43 | allocate (size_type const n) { | |
584ab041 | 44 | #ifdef __OpenBSD__ |
70a29b7d | 45 | void *p = mmap(nullptr, n * sizeof(value_type), |
15880e10 OM |
46 | PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0); |
47 | if (p == MAP_FAILED) | |
48 | throw std::bad_alloc(); | |
49 | return static_cast<pointer>(p); | |
584ab041 OM |
50 | #else |
51 | return static_cast<pointer>(::operator new (n * sizeof(value_type))); | |
52 | #endif | |
5cf909f3 AN |
53 | } |
54 | ||
55 | void | |
56 | deallocate (pointer const ptr, size_type const n) noexcept { | |
584ab041 | 57 | #ifdef __OpenBSD__ |
15880e10 | 58 | munmap(ptr, n * sizeof(value_type)); |
584ab041 OM |
59 | #else |
60 | #if defined(__cpp_sized_deallocation) && (__cpp_sized_deallocation >= 201309) | |
61 | ::operator delete (ptr, n * sizeof(value_type)); | |
62 | #else | |
63 | (void) n; | |
64 | ::operator delete (ptr); | |
65 | #endif | |
66 | #endif | |
5cf909f3 AN |
67 | } |
68 | ||
69 | void construct (T*) const noexcept {} | |
70 | ||
71 | template <typename X, typename... Args> | |
72 | void | |
73 | construct (X* place, Args&&... args) const noexcept { | |
74 | new (static_cast<void*>(place)) X (std::forward<Args>(args)...); | |
75 | } | |
76 | }; | |
77 | ||
78 | template <typename T> inline | |
79 | bool operator== (lazy_allocator<T> const&, lazy_allocator<T> const&) noexcept { | |
80 | return true; | |
81 | } | |
82 | ||
83 | template <typename T> inline | |
84 | bool operator!= (lazy_allocator<T> const&, lazy_allocator<T> const&) noexcept { | |
85 | return false; | |
86 | } |