// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Copyright (c) 2017-2023 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#pragma once

#include <support/cleanse.h>
#include <support/lockedpool.h>

#include <memory>
#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> {
    using base = std::allocator<T>;
    using traits = std::allocator_traits<base>;
    using size_type = typename traits::size_type;
    using difference_type = typename traits::difference_type;
    using pointer = typename traits::pointer;
    using const_pointer = typename traits::const_pointer;
    using value_type = typename traits::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 [[maybe_unused]] = 0) {
        return static_cast<T *>(LockedPoolManager::Instance().alloc(sizeof(T) * n));
    }

    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.
using SecureString = std::basic_string<char, std::char_traits<char>, secure_allocator<char>>;
