Clearing serialized buffers before deallocation

1// Copyright (c) 2009-2010 Satoshi Nakamoto
2// Copyright (c) 2009-present The Bitcoin Core developers
3// Distributed under the MIT software license, see the accompanying
4// file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6#ifndef BITCOIN_SUPPORT_ALLOCATORS_ZEROAFTERFREE_H
7#define BITCOIN_SUPPORT_ALLOCATORS_ZEROAFTERFREE_H
8
9#include <support/cleanse.h>
10
11#include <memory>
12#include <vector>
13
14template <typename T>
15struct zero_after_free_allocator {
16    using value_type = T;
17
18    zero_after_free_allocator() noexcept = default;
19    template <typename U>
20    zero_after_free_allocator(const zero_after_free_allocator<U>&) noexcept
21    {
22    }
23
24    T* allocate(std::size_t n)
25    {
26        return std::allocator<T>{}.allocate(n);
27    }
28
29    void deallocate(T* p, std::size_t n)
30    {
31        if (p != nullptr)
32            memory_cleanse(p, sizeof(T) * n);
33        std::allocator<T>{}.deallocate(p, n);
34    }
35
36    template <typename U>
37    friend bool operator==(const zero_after_free_allocator&, const zero_after_free_allocator<U>&) noexcept
38    {
39        return true;
40    }
41};
42
43/** Byte-vector that clears its contents before deletion. */
44using SerializeData = std::vector<std::byte, zero_after_free_allocator<std::byte>>;
45
46#endif // BITCOIN_SUPPORT_ALLOCATORS_ZEROAFTERFREE_H
47