File: fdbuf.h

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/*
**      PJL C++ Library
**      fdbuf.h
**
**      Copyright (C) 2001  Paul J. Lucas
**
**      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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef fdbuf_H
#define fdbuf_H

// local
#include "platform.h"

// standard
#include <iostream>
#include <streambuf>

namespace PJL {

//*****************************************************************************
//
// SYNOPSIS
//
        class fdbuf : public std::streambuf
//
// DESCRIPTION
//
//      An fdbuf is-a streambuf that is used to be attached to a Unix file
//      descriptor.
//
// SEE ALSO
//
//      Nicolai M. Josuttis.  "The C++ Starndard Library: A Tutorial and
//      Reference," Addison-Wesley, 1999, pp. 672-676.
//
//      Angelika Langer and Klaus Kreft.  "Standard C++ IOStreams and Locales:
//      Advanced Programmer's Guide and Reference," Addison-Wesley, 2000, pp.
//      225-244.
//
//*****************************************************************************
{
    enum { buf_size = 1024 };
public:
    explicit fdbuf( int fd = -1 )               { init( fd ); }
    ~fdbuf()                                    { if ( fd_ > -1 ) sync(); }

    // default copy constructor is fine
    // default assignment is fine

    void    attach( int fd );
    //      In the case where an fdbuf object was constructed using the default
    //      constructor, and therefore not attached to any file descriptor,
    //      this function is used to attach an fdbuf to one at some later time.
protected:
    typedef int int_type;

    virtual int_type        overflow( int_type c );
    virtual int             sync();
    virtual int_type        underflow();
    std::streamsize         write_buf( char const*, std::streamsize );
    virtual std::streamsize xsputn( char const *buf, std::streamsize len );
private:
    int     fd_;
    char    rbuf_[ buf_size ];
    char    wbuf_[ buf_size ];

    void    init( int fd );
};

/////////// Inlines ///////////////////////////////////////////////////////////

inline void fdbuf::attach( int fd ) {
    if ( fd_ > -1 ) sync();
    init( fd );
}

} // namespace PJL

#endif  /* fdbuf_H */
/* vim:set et sw=4 ts=4: */