1  // Copyright (c) 2009-2010 Satoshi Nakamoto
 2  // Copyright (c) 2009-2022 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  
14  template <typename T>
15  struct 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      template <typename U>
42      friend bool operator!=(const zero_after_free_allocator&, const zero_after_free_allocator<U>&) noexcept
43      {
44          return false;
45      }
46  };
47  
48  /** Byte-vector that clears its contents before deletion. */
49  using SerializeData = std::vector<std::byte, zero_after_free_allocator<std::byte>>;
50  
51  #endif // BITCOIN_SUPPORT_ALLOCATORS_ZEROAFTERFREE_H