fichier_libcurl.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2024 Denis Corbin
//
// This program 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 2
// of the License, or (at your option) any later version.
//
// This program 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 this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author, see the AUTHOR file
/*********************************************************************/
 
 
#ifndef FICHIER_LIBCURL_HPP
#define FICHIER_LIBCURL_HPP
 
 
#include "../my_config.h"
 
extern "C"
{
#if LIBCURL_AVAILABLE
#if HAVE_CURL_CURL_H
#include <curl/curl.h>
#endif
#endif
} // end extern "C"
 
#include <string>
#ifdef LIBTHREADAR_AVAILABLE
#include <libthreadar/libthreadar.hpp>
#endif
#include "integers.hpp"
#include "user_interaction.hpp"
#include "fichier_global.hpp"
#include "mycurl_protocol.hpp"
#include "mycurl_easyhandle_node.hpp"
 
namespace libdar
{
 
 
#if defined ( LIBCURL_AVAILABLE ) && defined ( LIBTHREADAR_AVAILABLE )
 
 
    class fichier_libcurl : public fichier_global, protected libthreadar::thread
    {
    public:
 
    fichier_libcurl(const std::shared_ptr<user_interaction> & dialog,      //< for user interaction requested by fichier_global
            const std::string & chemin,     //< full path of the file to open
            mycurl_protocol proto,          //< to workaround some libcurl strange behavior for some protocols
            const std::shared_ptr<mycurl_easyhandle_node> & handle, //< the easy handle wrapper object
            gf_mode m,                      //< open mode
            U_I waiting,                    //< retry timeout in case of network error
            bool force_permission,          //< whether file permission should be modified
            U_I permission,                 //< file permission to enforce if force_permission is set
            bool erase);                    //< whether to erase the file before writing to it
 
 
    fichier_libcurl(const fichier_libcurl & ref) = delete;
 
    fichier_libcurl(fichier_libcurl && ref) = delete;
 
    fichier_libcurl & operator = (const fichier_libcurl & ref) = delete;
 
    fichier_libcurl & operator = (fichier_libcurl && ref) = delete;
 
    ~fichier_libcurl() noexcept { kill(); join(); detruit(); };
 
    virtual void change_permission(U_I perm) override;
 
    virtual void change_ownership(const std::string & user, const std::string & group) override
    { throw Efeature(gettext("user/group ownership not supported for this repository")); }; // not supported
 
        virtual infinint get_size() const override;
 
    virtual void fadvise(advise adv) const override {}; // not supported and ignored
 
            // inherited from generic_file
    virtual bool skippable(skippability direction, const infinint & amount) override;
        virtual bool skip(const infinint & pos) override;
        virtual bool skip_to_eof() override;
        virtual bool skip_relative(S_I x) override;
    virtual bool truncatable(const infinint & pos) const override { return pos == get_position(); };
        virtual infinint get_position() const override { return current_offset; };
 
    protected:
        // inherited from generic_file grand-parent class
    virtual void inherited_read_ahead(const infinint & amount) override;
    virtual void inherited_truncate(const infinint & pos) override;
    virtual void inherited_sync_write() override;
    virtual void inherited_flush_read() override;
    virtual void inherited_terminate() override;
 
        // inherited from fichier_global parent class
    virtual U_I fichier_global_inherited_write(const char *a, U_I size) override;
        virtual bool fichier_global_inherited_read(char *a, U_I size, U_I & read, std::string & message) override;
 
        // inherited from thread
    virtual void inherited_run() override;
 
    private:
    static const U_I tampon_size = CURL_MAX_WRITE_SIZE;
 
        //
        // implementation internals
        //
        // the object has two modes:
        // - meta data mode (skip, get_position() and other non read/write operations)
        // - data mode (read or write operations)
        //
        // in metadata mode each method is a simple code execution (no subthread, no callback)
        //
        // in data mode, a subthread is used to interact with libcurl. It sends or receives
        // data through the interthread pipe. A callback is occasionally run by libcurl in this
        // subthread.
        // in read mode, the subthread is run only if the interthread is empty. the subthread may
        // survive the inherited_read call and may suspend on writing data to interthread being full
        // - "subthread_net_offset" is updated by the callback and read by the subthread when
        //   libcurl has returned it keeps trace of the amount of data sent to interthread.
        // - "network_block" is set by the main thread to define the amount of data to be fetched. It
        //   it used to setup libcurl and is read by the subthread for control/validation purposes
 
    bool end_data_mode;               
    bool sub_is_dying;                
    bool sync_write_asked;            
    bool weof;                        
    std::shared_ptr<mycurl_easyhandle_node> ehandle; 
    bool metadatamode;                
    infinint current_offset;          
    bool has_maxpos;                  
    infinint maxpos;                  
    bool append_write;                
    U_I meta_inbuf;                   
    U_I wait_delay;                   
    infinint network_block;           
    infinint subthread_net_offset;    
    infinint subthread_cur_offset;    
    libthreadar::fast_tampon<char> interthread; 
    libthreadar::barrier synchronize; 
    mycurl_protocol x_proto;          
 
    void set_range(const infinint & begin, const infinint & range_size); 
    void unset_range();  
    void switch_to_metadata(bool mode);
    void detruit();     
    void run_thread();  
    void stop_thread(); 
    void relaunch_thread(const infinint & block_size); 
    void initialize_subthread(); 
    void finalize_subthread();   
    void set_subthread(U_I & needed_bytes); 
    bool still_data_to_write(); 
 
    static size_t write_data_callback(char *buffer, size_t size, size_t nmemb, void *userp);
    static size_t read_data_callback(char *bufptr, size_t size, size_t nitems, void *userp);
        static size_t write_meta_callback(char *buffer, size_t size, size_t nmemb, void *userp);
    static size_t read_meta_callback(char *bufptr, size_t size, size_t nitems, void *userp);
    };
 
 
#endif
 
} // end of namespace
 
#endif