tuyau.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2052 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// to contact the author : http://dar.linux.free.fr/email.html
/*********************************************************************/


#ifndef TUYAU_HPP
#define TUYAU_HPP

#include "../my_config.h"
#include "infinint.hpp"
#include "generic_file.hpp"
#include "thread_cancellation.hpp"

namespace libdar
{



    class tuyau : public generic_file, public thread_cancellation, protected mem_ui
    {
    public:
        tuyau(user_interaction & dialog,    //< for user interaction
              int fd);                      //< fd is the filedescriptor of a pipe extremity already openned
        tuyau(user_interaction & dialog,
              int fd,                       //< fd is the filedescriptor of a pipe extremity already openned
              gf_mode mode);                //< forces the mode if possible
        tuyau(user_interaction & dialog,    //< for user interaction
              const std::string &filename,  //< named pipe to open
              gf_mode mode);                //< forces the mode if possible
        tuyau(user_interaction & dialog);   //< creates a anonymous pipe and bind itself to the writing end. The reading end can be obtained by get_read_side() method
        ~tuyau();

            // provides the reading end of the anonymous pipe when the current object has created it (no filedesc, no path given to constructor).
            // it cannot be called more than once.
        int get_read_fd() const;


        void close_read_fd();

        void do_not_close_read_fd();

            // inherited from generic_file
        bool skip(const infinint & pos);
        bool skip_to_eof();
        bool skip_relative(signed int x);
        infinint get_position() { return position; };

        bool has_next_to_read();

    protected:
        virtual U_I inherited_read(char *a, U_I size);
        virtual void inherited_write(const char *a, U_I size);
        void inherited_sync_write() {};
        void inherited_terminate();

    private:
        enum
        {
            pipe_fd,        //< holds a single file descriptor for the pipe
            pipe_path,      //< holds a filename to be openned (named pipe)
            pipe_both       //< holds a pair of file descriptors
        }
        pipe_mode;          //< defines how the object's status (which possible values defined by the anonymous enum above)
        infinint position;  //< recorded position in the stream
        int filedesc;       //< file descriptors of the pipe
        int other_end_fd;   //< in pipe_both mode, this holds the reading side of the anonymous pipe
        std::string chemin; //< in pipe_path mode only, this holds the named pipe to be open
        bool has_one_to_read; //< if true, the next char to read is placed in "next_to_read"
        char next_to_read;  //< when has_one_to_read is true, contains the next to read byte

        void ouverture();


        bool read_and_drop(infinint byte);

        bool read_to_eof();
    };

} // end of namespace

#endif