#include <unistd.h>
#include <sys/types.h>
#include <cstdint>
#include <cstddef>
#include <fstream>
#include <boost/interprocess/offset_ptr.hpp>
#include <boost/interprocess/file_mapping.hpp>
#include <boost/interprocess/mapped_region.hpp>
#include <boost/interprocess/managed_external_buffer.hpp>

const char file_name[] = "mapped_file";

const std::size_t header_size = 16;
const std::size_t storage_size = 4096;

// Unsigned offset type doesn't work because of incorrect casts in offset_ptr
// typedef boost::interprocess::offset_ptr< void, std::ptrdiff_t, std::uint32_t > void_pointer;
typedef boost::interprocess::offset_ptr< void, std::ptrdiff_t, std::int32_t > void_pointer;

typedef boost::interprocess::basic_managed_external_buffer<
    char,
    boost::interprocess::rbtree_best_fit< boost::interprocess::null_mutex_family, void_pointer >,
    boost::interprocess::iset_index
> managed_external_buffer;

int main()
{
    {
        std::ofstream file(file_name, std::ios::out | std::ios::trunc | std::ios::binary);
    }
    truncate(file_name, header_size + storage_size);

    boost::interprocess::file_mapping file_mapping(file_name, boost::interprocess::read_write);
    boost::interprocess::mapped_region file_region(file_mapping, boost::interprocess::read_write, header_size, storage_size);

    managed_external_buffer buffer(boost::interprocess::create_only, file_region.get_address(), file_region.get_size());

    return 0;
}