stdio_filebuf.h

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00001 // File descriptor layer for filebuf -*- C++ -*-
00002 
00003 // Copyright (C) 2002, 2003, 2004, 2005, 2009 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file ext/stdio_filebuf.h
00026  *  This file is a GNU extension to the Standard C++ Library.
00027  */
00028 
00029 #ifndef _STDIO_FILEBUF_H
00030 #define _STDIO_FILEBUF_H 1
00031 
00032 #pragma GCC system_header
00033 
00034 #include <fstream>
00035 
00036 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00037 
00038   /**
00039    *  @brief Provides a layer of compatibility for C/POSIX.
00040    *
00041    *  This GNU extension provides extensions for working with standard C
00042    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
00043    *  user with the type of character used in the file stream, e.g.,
00044    *  stdio_filebuf<char>.
00045   */
00046   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
00047     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
00048     {
00049     public:
00050       // Types:
00051       typedef _CharT                        char_type;
00052       typedef _Traits                       traits_type;
00053       typedef typename traits_type::int_type        int_type;
00054       typedef typename traits_type::pos_type        pos_type;
00055       typedef typename traits_type::off_type        off_type;
00056       typedef std::size_t                               size_t;
00057 
00058     public:
00059       /**
00060        * deferred initialization
00061       */
00062       stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
00063 
00064       /**
00065        *  @param  fd  An open file descriptor.
00066        *  @param  mode  Same meaning as in a standard filebuf.
00067        *  @param  size  Optimal or preferred size of internal buffer, in chars.
00068        *
00069        *  This constructor associates a file stream buffer with an open
00070        *  POSIX file descriptor. The file descriptor will be automatically
00071        *  closed when the stdio_filebuf is closed/destroyed.
00072       */
00073       stdio_filebuf(int __fd, std::ios_base::openmode __mode,
00074             size_t __size = static_cast<size_t>(BUFSIZ));
00075 
00076       /**
00077        *  @param  f  An open @c FILE*.
00078        *  @param  mode  Same meaning as in a standard filebuf.
00079        *  @param  size  Optimal or preferred size of internal buffer, in chars.
00080        *                Defaults to system's @c BUFSIZ.
00081        *
00082        *  This constructor associates a file stream buffer with an open
00083        *  C @c FILE*.  The @c FILE* will not be automatically closed when the
00084        *  stdio_filebuf is closed/destroyed.
00085       */
00086       stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
00087             size_t __size = static_cast<size_t>(BUFSIZ));
00088 
00089       /**
00090        *  Closes the external data stream if the file descriptor constructor
00091        *  was used.
00092       */
00093       virtual
00094       ~stdio_filebuf();
00095 
00096       /**
00097        *  @return  The underlying file descriptor.
00098        *
00099        *  Once associated with an external data stream, this function can be
00100        *  used to access the underlying POSIX file descriptor.  Note that
00101        *  there is no way for the library to track what you do with the
00102        *  descriptor, so be careful.
00103       */
00104       int
00105       fd() { return this->_M_file.fd(); }
00106 
00107       /**
00108        *  @return  The underlying FILE*.
00109        *
00110        *  This function can be used to access the underlying "C" file pointer.
00111        *  Note that there is no way for the library to track what you do
00112        *  with the file, so be careful.
00113        */
00114       std::__c_file*
00115       file() { return this->_M_file.file(); }
00116     };
00117 
00118   template<typename _CharT, typename _Traits>
00119     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
00120     { }
00121 
00122   template<typename _CharT, typename _Traits>
00123     stdio_filebuf<_CharT, _Traits>::
00124     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
00125     {
00126       this->_M_file.sys_open(__fd, __mode);
00127       if (this->is_open())
00128     {
00129       this->_M_mode = __mode;
00130       this->_M_buf_size = __size;
00131       this->_M_allocate_internal_buffer();
00132       this->_M_reading = false;
00133       this->_M_writing = false;
00134       this->_M_set_buffer(-1);
00135     }
00136     }
00137 
00138   template<typename _CharT, typename _Traits>
00139     stdio_filebuf<_CharT, _Traits>::
00140     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
00141           size_t __size)
00142     {
00143       this->_M_file.sys_open(__f, __mode);
00144       if (this->is_open())
00145     {
00146       this->_M_mode = __mode;
00147       this->_M_buf_size = __size;
00148       this->_M_allocate_internal_buffer();
00149       this->_M_reading = false;
00150       this->_M_writing = false;
00151       this->_M_set_buffer(-1);
00152     }
00153     }
00154 
00155 _GLIBCXX_END_NAMESPACE
00156 
00157 #endif

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