15.1.44. tablet_qt/crypto/zallocator.h

/*
    Copyright (C) 2012, University of Cambridge, Department of Psychiatry.
    Created by Rudolf Cardinal (rnc1001@cam.ac.uk).

    This file is part of CamCOPS.

    CamCOPS is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    CamCOPS is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with CamCOPS. If not, see <https://www.gnu.org/licenses/>.
*/

#pragma once
#include <limits>  // for std::numeric_limits
#include <new>  // for std::bad_alloc
#include <QtGlobal>  // for Q_UNUSED

// Currently unused.

template<typename T> struct zallocator
{
public:
    typedef T value_type;
    typedef value_type* pointer;
    typedef const value_type* const_pointer;
    typedef value_type& reference;
    typedef const value_type& const_reference;
    typedef std::size_t size_type;
    typedef std::ptrdiff_t difference_type;

    pointer address(reference v) const
    {
        return &v;
    }

    const_pointer address(const_reference v) const
    {
        return &v;
    }

    pointer allocate(size_type n, const void* hint = nullptr)
    {
        Q_UNUSED(hint)
        if (n > std::numeric_limits<size_type>::max() / sizeof(T)) {
            throw std::bad_alloc();
        }
        return static_cast<pointer>(::operator new(n * sizeof(value_type)));
    }

    void deallocate(pointer p, size_type n)
    {
        OPENSSL_cleanse(p, n * sizeof(T));
        ::operator delete(p);
    }

    size_type max_size() const
    {
        return std::numeric_limits<size_type>::max() / sizeof(T);
    }

    template<typename U> struct rebind
    {
        typedef zallocator<U> other;
    };

    void construct(pointer ptr, const T& val)
    {
        new (static_cast<T*>(ptr)) T(val);
    }

    void destroy(pointer ptr)
    {
        static_cast<T*>(ptr)->~T();
    }

#if __cplusplus >= 201103L
    template<typename U, typename... Args>
    void construct(U* ptr, Args&&... args)
    {
        ::new (static_cast<void*>(ptr)) U(std::forward<Args>(args)...);
    }

    template<typename U> void destroy(U* ptr)
    {
        ptr->~U();
    }
#endif
};