cppmicrohttpd/include/cppmicrohttpd/response/callback_response.h

#pragma once

#include "response.h"

namespace cppmicrohttpd
{

    struct callback_response
        : public response
    {
    public:
        /**
         * @brief Constructor.
         *
         * @param[in] p_request         Request this response belongs to.
         * @param[in] p_chunk_size      Size of the chunk to use for reading data from the callback.
         * @param[in] p_response_size   Total size of the response (-1 for unknown)
         */
        inline callback_response(
            const request_t&    p_request,
            size_t              p_chunk_size,
            ssize_t             p_response_size = -1);

    private:
         /**
         * @brief Handle read requests from MHD.
         *
         * @param[in] p_pos             Total position inside the response data stream.
         * @param[in] p_buf             Buffer to write requested data to.
         * @param[in] p_max             Max number of bytes to write to p_buf.
         *
         * @return                      Number of bytes stored in buf.
         *
         * @retval MHD_CONTENT_READER_END_OF_STREAM     If the stream is finished.
         * @retval MHD_CONTENT_READER_END_WITH_ERROR    If an error occured.
         */
        virtual ssize_t read_content(
            uint64_t p_pos,
            char * p_buf,
            size_t p_max) = 0;

    private:
        /**
         * @brief Handle read requests from MHD.
         *
         * @param[in] cls               User pointer that was passed to the MHD response.
         * @param[in] pos               Total position inside the response data stream.
         * @param[in] buf               Buffer to write requested data to.
         * @param[in] max               Max number of bytes to write to buf.
         *
         * @return Number of bytes stored in buf.
         *
         * @retval MHD_CONTENT_READER_END_OF_STREAM     If the stream is finished.
         * @retval MHD_CONTENT_READER_END_WITH_ERROR    If an error occured.
         */
        static ssize_t mhd_content_reader_callback(
            void * cls,
            uint64_t pos,
            char * buf,
            size_t max);
    };

}