text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2019 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
  #define BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
  
  #include "support/lockedpool.h"
  #include "support/cleanse.h"
  
  #include <string>
  
  //
  // Allocator that locks its contents from being paged
  // out of memory and clears its contents before deletion.
  //
  template <typename T>
  struct secure_allocator : public std::allocator<T> {
      // MSVC8 default copy constructor is broken
      typedef std::allocator<T> base;
      typedef typename base::size_type size_type;
      typedef typename base::difference_type difference_type;
      typedef typename base::pointer pointer;
      typedef typename base::const_pointer const_pointer;
      typedef typename base::reference reference;
      typedef typename base::const_reference const_reference;
      typedef typename base::value_type value_type;
      secure_allocator() noexcept {}
      secure_allocator(const secure_allocator& a) noexcept : base(a) {}
      template <typename U>
      secure_allocator(const secure_allocator<U>& a) noexcept : base(a)
      {
      }
      ~secure_allocator() noexcept {}
      template <typename _Other>
      struct rebind {
          typedef secure_allocator<_Other> other;
      };
  
      T* allocate(std::size_t n, const void* hint = 0)
      {
          T* allocation = static_cast<T*>(LockedPoolManager::Instance().alloc(sizeof(T) * n));
          if (!allocation) {
              throw std::bad_alloc();
          }
          return allocation;
      }
  
      void deallocate(T* p, std::size_t n)
      {
          if (p != nullptr) {
              memory_cleanse(p, sizeof(T) * n);
          }
          LockedPoolManager::Instance().free(p);
      }
  };
  
  // This is exactly like std::string, but with a custom allocator.
  typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;
  
  #endif // BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
  