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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2020 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 : http://dar.linux.free.fr/email.html
/*********************************************************************/
/// \file tuyau.hpp
/// \brief defines the implementation of pipe under the generic_file interface.
/// \ingroup Private
///
/// mainly used between zapette and slave_zapette, this is a full implementation
/// of the generic_file interface that takes care of dead lock when two pipes needs
/// to be openned between the same two entities, each having one for reading and the
/// other for writing.
#ifndef TUYAU_HPP
#define TUYAU_HPP
#include "../my_config.h"
#include "infinint.hpp"
#include "generic_file.hpp"
#include "thread_cancellation.hpp"
#include "mem_ui.hpp"
namespace libdar
{
/// \addtogroup Private
/// @{
/// pipe implementation under the generic_file interface.
class tuyau : public generic_file, public thread_cancellation, protected mem_ui
{
public:
tuyau(const std::shared_ptr<user_interaction> & dialog, //< for user interaction
int fd); //< fd is the filedescriptor of a pipe extremity already openned
tuyau(const std::shared_ptr<user_interaction> & dialog, //< for user interaction
int fd, //< fd is the filedescriptor of a pipe extremity already openned
gf_mode mode); //< forces the mode if possible
tuyau(const std::shared_ptr<user_interaction> & dialog, //< for user interaction
const std::string &filename, //< named pipe to open
gf_mode mode); //< forces the mode if possible
tuyau(const std::shared_ptr<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(const tuyau & ref) = default;
tuyau(tuyau && ref) noexcept = default;
tuyau & operator = (const tuyau & ref) = default;
tuyau & operator = (tuyau && ref) noexcept = default;
~tuyau();
/// provides the reading end of the anonymous pipe when the current object has created it (no filedesc, no path given to constructor).
/// \note this methid cannot be called more than once.
int get_read_fd() const;
/// closes the read fd of the anonymous pipe (this is to be used by a writer)
/// \note to ensure a proper behavior of the 'eof', the writer must close the read fd
/// this call let this be done, assuming the read has already fetched the fd and forked
/// in a new process
void close_read_fd();
/// ask to not close the read descriptor upon object destruction (the fd survives the object)
void do_not_close_read_fd();
// 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(signed int x) override;
virtual infinint get_position() const override { return position; };
bool has_next_to_read();
protected:
virtual void inherited_read_ahead(const infinint & amount) override {}; // relying on the operating system
virtual U_I inherited_read(char *a, U_I size) override;
virtual void inherited_write(const char *a, U_I size) override;
virtual void inherited_sync_write() override {};
virtual void inherited_flush_read() override {};
virtual void inherited_terminate() override;
private:
enum ///< anonymous structure for pipe_mode field
{
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();
/// skip forward by reading data
/// \param[in] byte is the amount of byte to skip forward
/// \return true if the given amount of byte could be read, false otherwise (reached EOF).
bool read_and_drop(infinint byte);
/// skip to eof by reading data
bool read_to_eof();
};
/// @}
} // end of namespace
#endif
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