stdio_filebuf.h

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00001 // File descriptor layer for filebuf -*- C++ -*-
00002 
00003 // Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 2, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // You should have received a copy of the GNU General Public License along
00017 // with this library; see the file COPYING.  If not, write to the Free
00018 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
00019 // USA.
00020 
00021 // As a special exception, you may use this file as part of a free software
00022 // library without restriction.  Specifically, if other files instantiate
00023 // templates or use macros or inline functions from this file, or you compile
00024 // this file and link it with other files to produce an executable, this
00025 // file does not by itself cause the resulting executable to be covered by
00026 // the GNU General Public License.  This exception does not however
00027 // invalidate any other reasons why the executable file might be covered by
00028 // the GNU General Public License.
00029 
00030 /** @file ext/stdio_filebuf.h
00031  *  This file is a GNU extension to the Standard C++ Library.
00032  */
00033 
00034 #ifndef _STDIO_FILEBUF_H
00035 #define _STDIO_FILEBUF_H 1
00036 
00037 #pragma GCC system_header
00038 
00039 #include <fstream>
00040 
00041 namespace __gnu_cxx
00042 {
00043   /**
00044    *  @brief Provides a layer of compatibility for C/POSIX.
00045    *
00046    *  This GNU extension provides extensions for working with standard C
00047    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
00048    *  user with the type of character used in the file stream, e.g.,
00049    *  stdio_filebuf<char>.
00050   */
00051   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
00052     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
00053     {
00054     public:
00055       // Types:
00056       typedef _CharT                        char_type;
00057       typedef _Traits                       traits_type;
00058       typedef typename traits_type::int_type        int_type;
00059       typedef typename traits_type::pos_type        pos_type;
00060       typedef typename traits_type::off_type        off_type;
00061       typedef std::size_t                               size_t;
00062 
00063     public:
00064       /**
00065        * deferred initialization
00066       */
00067       stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
00068 
00069       /**
00070        *  @param  fd  An open file descriptor.
00071        *  @param  mode  Same meaning as in a standard filebuf.
00072        *  @param  size  Optimal or preferred size of internal buffer, in chars.
00073        *
00074        *  This constructor associates a file stream buffer with an open
00075        *  POSIX file descriptor. The file descriptor will be automatically
00076        *  closed when the stdio_filebuf is closed/destroyed.
00077       */
00078       stdio_filebuf(int __fd, std::ios_base::openmode __mode,
00079             size_t __size = static_cast<size_t>(BUFSIZ));
00080 
00081       /**
00082        *  @param  f  An open @c FILE*.
00083        *  @param  mode  Same meaning as in a standard filebuf.
00084        *  @param  size  Optimal or preferred size of internal buffer, in chars.
00085        *                Defaults to system's @c BUFSIZ.
00086        *
00087        *  This constructor associates a file stream buffer with an open
00088        *  C @c FILE*.  The @c FILE* will not be automatically closed when the
00089        *  stdio_filebuf is closed/destroyed.
00090       */
00091       stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
00092             size_t __size = static_cast<size_t>(BUFSIZ));
00093 
00094       /**
00095        *  Closes the external data stream if the file descriptor constructor
00096        *  was used.
00097       */
00098       virtual
00099       ~stdio_filebuf();
00100 
00101       /**
00102        *  @return  The underlying file descriptor.
00103        *
00104        *  Once associated with an external data stream, this function can be
00105        *  used to access the underlying POSIX file descriptor.  Note that
00106        *  there is no way for the library to track what you do with the
00107        *  descriptor, so be careful.
00108       */
00109       int
00110       fd() { return this->_M_file.fd(); }
00111 
00112       /**
00113        *  @return  The underlying FILE*.
00114        *
00115        *  This function can be used to access the underlying "C" file pointer.
00116        *  Note that there is no way for the library to track what you do
00117        *  with the file, so be careful.
00118        */
00119       std::__c_file*
00120       file() { return this->_M_file.file(); }
00121     };
00122 
00123   template<typename _CharT, typename _Traits>
00124     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
00125     { }
00126 
00127   template<typename _CharT, typename _Traits>
00128     stdio_filebuf<_CharT, _Traits>::
00129     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
00130     {
00131       this->_M_file.sys_open(__fd, __mode);
00132       if (this->is_open())
00133     {
00134       this->_M_mode = __mode;
00135       this->_M_buf_size = __size;
00136       this->_M_allocate_internal_buffer();
00137       this->_M_reading = false;
00138       this->_M_writing = false;
00139       this->_M_set_buffer(-1);
00140     }
00141     }
00142 
00143   template<typename _CharT, typename _Traits>
00144     stdio_filebuf<_CharT, _Traits>::
00145     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
00146           size_t __size)
00147     {
00148       this->_M_file.sys_open(__f, __mode);
00149       if (this->is_open())
00150     {
00151       this->_M_mode = __mode;
00152       this->_M_buf_size = __size;
00153       this->_M_allocate_internal_buffer();
00154       this->_M_reading = false;
00155       this->_M_writing = false;
00156       this->_M_set_buffer(-1);
00157     }
00158     }
00159 } // namespace __gnu_cxx
00160 
00161 #endif

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