/*

Copyright (c) 2017-2019, Arvid Norberg

All rights reserved.

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions

are met:

    * Redistributions of source code must retain the above copyright

      notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright

      notice, this list of conditions and the following disclaimer in

      the documentation and/or other materials provided with the distribution.

    * Neither the name of the author nor the names of its

      contributors may be used to endorse or promote products derived

      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

*/

#include "libtorrent/stack_allocator.hpp"

#include <cstdarg> // for va_list, va_copy, va_end

namespace libtorrent {

namespace aux {

  allocation_slot stack_allocator::copy_string(string_view str)

  {

    auto const ret = m_storage.size();

    if (std::numeric_limits<int>::max() - str.size() <= ret)

      return {};

    m_storage.resize(ret + str.size() + 1);

    std::memcpy(&m_storage[ret], str.data(), str.size());

    m_storage[ret + str.length()] = '\0';

    return allocation_slot(ret);

  }

  allocation_slot stack_allocator::copy_string(char const* str)

  {

    auto const ret = m_storage.size();

    auto const len = std::strlen(str);

    if (std::numeric_limits<int>::max() - len <= ret)

      return {};

    m_storage.resize(ret + len + 1);

    std::memcpy(&m_storage[ret], str, len);

    m_storage[ret + len] = '\0';

    return allocation_slot(ret);

  }

  allocation_slot stack_allocator::format_string(char const* fmt, va_list v)

  {

    auto const pos = m_storage.size();

    std::size_t len = 512;

    for(;;)

    {

      if (std::numeric_limits<int>::max() - len <= pos)

        return {};

      m_storage.resize(pos + len + 1);

      va_list args;

      va_copy(args, v);

#ifdef __clang__

#pragma clang diagnostic push

#pragma clang diagnostic ignored "-Wformat-nonliteral"

#endif

      int const ret = std::vsnprintf(m_storage.data() + pos, len + 1, fmt, args);

#ifdef __clang__

#pragma clang diagnostic pop

#endif

      va_end(args);

      if (ret < 0)

      {

        m_storage.resize(pos);

        return copy_string("(format error)");

      }

      if (static_cast<std::size_t>(ret) > len)

      {

        // try again

        len = numeric_cast<std::size_t>(ret);

        continue;

      }

      break;

    }

    // +1 is to include the 0-terminator

    m_storage.resize(pos + len + 1);

    return allocation_slot(pos);

  }

  allocation_slot stack_allocator::copy_buffer(span<char const> buf)

  {

    auto const ret = m_storage.size();

    auto const size = numeric_cast<std::size_t>(buf.size());

    if (size < 1) return {};

    if (std::numeric_limits<int>::max() - size <= ret)

      return {};

    m_storage.resize(ret + size);

    std::memcpy(&m_storage[ret], buf.data(), numeric_cast<std::size_t>(size));

    return allocation_slot(ret);

  }

  allocation_slot stack_allocator::allocate(int const bytes)

  {

    if (bytes < 1) return {};

    auto const ret = m_storage.size();

    if (std::numeric_limits<int>::max() - static_cast<std::size_t>(bytes) <= ret)

      return {};

    m_storage.resize(ret + numeric_cast<std::size_t>(bytes));

    return allocation_slot(ret);

  }

  char* stack_allocator::ptr(allocation_slot const idx)

  {

    static char tmp = 0;

    if(!idx.is_valid()) return &tmp;

    TORRENT_ASSERT(idx.val() < m_storage.size());

    return &m_storage[idx.val()];

  }

  char const* stack_allocator::ptr(allocation_slot const idx) const

  {

    if(!idx.is_valid()) return "";

    TORRENT_ASSERT(idx.val() < m_storage.size());

    return &m_storage[idx.val()];

  }

  void stack_allocator::swap(stack_allocator& rhs)

  {

    m_storage.swap(rhs.m_storage);

    std::swap(m_generation, rhs.m_generation);

  }

  void stack_allocator::reset(std::uint32_t const generation)

  {

    m_storage.clear();

    m_generation = generation;

  }

}

}