libstdc++
stdio_filebuf.h
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00001 // File descriptor layer for filebuf -*- C++ -*-
00002 
00003 // Copyright (C) 2002, 2003, 2004, 2005, 2009, 2010
00004 // Free Software Foundation, Inc.
00005 //
00006 // This file is part of the GNU ISO C++ Library.  This library is free
00007 // software; you can redistribute it and/or modify it under the
00008 // terms of the GNU General Public License as published by the
00009 // Free Software Foundation; either version 3, or (at your option)
00010 // any later version.
00011 
00012 // This library is distributed in the hope that it will be useful,
00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015 // GNU General Public License for more details.
00016 
00017 // Under Section 7 of GPL version 3, you are granted additional
00018 // permissions described in the GCC Runtime Library Exception, version
00019 // 3.1, as published by the Free Software Foundation.
00020 
00021 // You should have received a copy of the GNU General Public License and
00022 // a copy of the GCC Runtime Library Exception along with this program;
00023 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00024 // <http://www.gnu.org/licenses/>.
00025 
00026 /** @file ext/stdio_filebuf.h
00027  *  This file is a GNU extension to the Standard C++ Library.
00028  */
00029 
00030 #ifndef _STDIO_FILEBUF_H
00031 #define _STDIO_FILEBUF_H 1
00032 
00033 #pragma GCC system_header
00034 
00035 #include <fstream>
00036 
00037 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
00038 {
00039 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00040 
00041   /**
00042    *  @brief Provides a layer of compatibility for C/POSIX.
00043    *  @ingroup io
00044    *
00045    *  This GNU extension provides extensions for working with standard C
00046    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
00047    *  user with the type of character used in the file stream, e.g.,
00048    *  stdio_filebuf<char>.
00049   */
00050   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
00051     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
00052     {
00053     public:
00054       // Types:
00055       typedef _CharT                        char_type;
00056       typedef _Traits                       traits_type;
00057       typedef typename traits_type::int_type        int_type;
00058       typedef typename traits_type::pos_type        pos_type;
00059       typedef typename traits_type::off_type        off_type;
00060       typedef std::size_t                               size_t;
00061 
00062     public:
00063       /**
00064        * deferred initialization
00065       */
00066       stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
00067 
00068       /**
00069        *  @param  fd  An open file descriptor.
00070        *  @param  mode  Same meaning as in a standard filebuf.
00071        *  @param  size  Optimal or preferred size of internal buffer, in chars.
00072        *
00073        *  This constructor associates a file stream buffer with an open
00074        *  POSIX file descriptor. The file descriptor will be automatically
00075        *  closed when the stdio_filebuf is closed/destroyed.
00076       */
00077       stdio_filebuf(int __fd, std::ios_base::openmode __mode,
00078             size_t __size = static_cast<size_t>(BUFSIZ));
00079 
00080       /**
00081        *  @param  f  An open @c FILE*.
00082        *  @param  mode  Same meaning as in a standard filebuf.
00083        *  @param  size  Optimal or preferred size of internal buffer, in chars.
00084        *                Defaults to system's @c BUFSIZ.
00085        *
00086        *  This constructor associates a file stream buffer with an open
00087        *  C @c FILE*.  The @c FILE* will not be automatically closed when the
00088        *  stdio_filebuf is closed/destroyed.
00089       */
00090       stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
00091             size_t __size = static_cast<size_t>(BUFSIZ));
00092 
00093       /**
00094        *  Closes the external data stream if the file descriptor constructor
00095        *  was used.
00096       */
00097       virtual
00098       ~stdio_filebuf();
00099 
00100       /**
00101        *  @return  The underlying file descriptor.
00102        *
00103        *  Once associated with an external data stream, this function can be
00104        *  used to access the underlying POSIX file descriptor.  Note that
00105        *  there is no way for the library to track what you do with the
00106        *  descriptor, so be careful.
00107       */
00108       int
00109       fd() { return this->_M_file.fd(); }
00110 
00111       /**
00112        *  @return  The underlying FILE*.
00113        *
00114        *  This function can be used to access the underlying "C" file pointer.
00115        *  Note that there is no way for the library to track what you do
00116        *  with the file, so be careful.
00117        */
00118       std::__c_file*
00119       file() { return this->_M_file.file(); }
00120     };
00121 
00122   template<typename _CharT, typename _Traits>
00123     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
00124     { }
00125 
00126   template<typename _CharT, typename _Traits>
00127     stdio_filebuf<_CharT, _Traits>::
00128     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
00129     {
00130       this->_M_file.sys_open(__fd, __mode);
00131       if (this->is_open())
00132     {
00133       this->_M_mode = __mode;
00134       this->_M_buf_size = __size;
00135       this->_M_allocate_internal_buffer();
00136       this->_M_reading = false;
00137       this->_M_writing = false;
00138       this->_M_set_buffer(-1);
00139     }
00140     }
00141 
00142   template<typename _CharT, typename _Traits>
00143     stdio_filebuf<_CharT, _Traits>::
00144     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
00145           size_t __size)
00146     {
00147       this->_M_file.sys_open(__f, __mode);
00148       if (this->is_open())
00149     {
00150       this->_M_mode = __mode;
00151       this->_M_buf_size = __size;
00152       this->_M_allocate_internal_buffer();
00153       this->_M_reading = false;
00154       this->_M_writing = false;
00155       this->_M_set_buffer(-1);
00156     }
00157     }
00158 
00159 _GLIBCXX_END_NAMESPACE_VERSION
00160 } // namespace
00161 
00162 #endif