Однажды, я написал вот такой код :)

gistfile1.cpp

    apr_pool_t* mem_pool_;  //< local memory pool
    apr_mmap_t *mmap_;
    apr_file_t *fp_;
    apr_finfo_t finfo_;
    static log4cxx::LoggerPtr s_logger_;

    PersistentPageManager(const char* file_name) {
        AprStatusChecker status;  // status.count increments on each assign
        try {
            status = apr_pool_create(&mem_pool_, NULL);
            status = apr_file_open(&fp_, file_name, APR_WRITE|APR_READ, APR_OS_DEFAULT, mem_pool_);
            status = apr_file_info_get(&finfo_, APR_FINFO_SIZE, fp_);
            status = apr_mmap_create(&mmap_, fp_, 0, finfo_.size, APR_MMAP_WRITE|APR_MMAP_READ, mem_pool_);
        }
        catch(AprException const& err) {
            free_resources(status.count);
            LOG4CXX_ERROR(s_logger_, "Can't create PersistentPageManager, error " << err << " on step " << status.count);
            throw;
        }
    }

    void free_resources(int cnt)
    {
        switch(cnt)
        {
        default:
        case 4:
            apr_mmap_delete(mmap_);
        case 3:
        case 2:
            apr_file_close(fp_);
        case 1:
            apr_pool_destroy(mem_pool_);
        };
    }