libstdc++-v3/include/ext/stdio_filebuf.h

   1 // File descriptor layer for filebuf -*- C++ -*-
   2
   3 // Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 2, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /** @file ext/stdio_filebuf.h
  31  *  This file is a GNU extension to the Standard C++ Library.
  32  */
  33
  34 #ifndef _STDIO_FILEBUF_H
  35 #define _STDIO_FILEBUF_H 1
  36
  37 #pragma GCC system_header
  38
  39 #include <fstream>
  40
  41 namespace __gnu_cxx
  42 {
  43   /**
  44    *  @brief Provides a layer of compatibility for C/POSIX.
  45    *
  46    *  This GNU extension provides extensions for working with standard C
  47    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
  48    *  user with the type of character used in the file stream, e.g.,
  49    *  stdio_filebuf<char>.
  50   */
  51   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  52     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
  53     {
  54     public:
  55       // Types:
  56       typedef _CharT                                    char_type;
  57       typedef _Traits                                   traits_type;
  58       typedef typename traits_type::int_type            int_type;
  59       typedef typename traits_type::pos_type            pos_type;
  60       typedef typename traits_type::off_type            off_type;
  61       typedef std::size_t                               size_t;
  62
  63     public:
  64       /**
  65        * deferred initialization
  66       */
  67       stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
  68
  69       /**
  70        *  @param  fd  An open file descriptor.
  71        *  @param  mode  Same meaning as in a standard filebuf.
  72        *  @param  size  Optimal or preferred size of internal buffer, in chars.
  73        *
  74        *  This constructor associates a file stream buffer with an open
  75        *  POSIX file descriptor. The file descriptor will be automatically
  76        *  closed when the stdio_filebuf is closed/destroyed.
  77       */
  78       stdio_filebuf(int __fd, std::ios_base::openmode __mode,
  79                     size_t __size = static_cast<size_t>(BUFSIZ));
  80
  81       /**
  82        *  @param  f  An open @c FILE*.
  83        *  @param  mode  Same meaning as in a standard filebuf.
  84        *  @param  size  Optimal or preferred size of internal buffer, in chars.
  85        *                Defaults to system's @c BUFSIZ.
  86        *
  87        *  This constructor associates a file stream buffer with an open
  88        *  C @c FILE*.  The @c FILE* will not be automatically closed when the
  89        *  stdio_filebuf is closed/destroyed.
  90       */
  91       stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
  92                     size_t __size = static_cast<size_t>(BUFSIZ));
  93
  94       /**
  95        *  Closes the external data stream if the file descriptor constructor
  96        *  was used.
  97       */
  98       virtual
  99       ~stdio_filebuf();
 100
 101       /**
 102        *  @return  The underlying file descriptor.
 103        *
 104        *  Once associated with an external data stream, this function can be
 105        *  used to access the underlying POSIX file descriptor.  Note that
 106        *  there is no way for the library to track what you do with the
 107        *  descriptor, so be careful.
 108       */
 109       int
 110       fd() { return this->_M_file.fd(); }
 111
 112       /**
 113        *  @return  The underlying FILE*.
 114        *
 115        *  This function can be used to access the underlying "C" file pointer.
 116        *  Note that there is no way for the library to track what you do
 117        *  with the file, so be careful.
 118        */
 119       std::__c_file*
 120       file() { return this->_M_file.file(); }
 121     };
 122
 123   template<typename _CharT, typename _Traits>
 124     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
 125     { }
 126
 127   template<typename _CharT, typename _Traits>
 128     stdio_filebuf<_CharT, _Traits>::
 129     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
 130     {
 131       this->_M_file.sys_open(__fd, __mode);
 132       if (this->is_open())
 133         {
 134           this->_M_mode = __mode;
 135           this->_M_buf_size = __size;
 136           this->_M_allocate_internal_buffer();
 137           this->_M_reading = false;
 138           this->_M_writing = false;
 139           this->_M_set_buffer(-1);
 140         }
 141     }
 142
 143   template<typename _CharT, typename _Traits>
 144     stdio_filebuf<_CharT, _Traits>::
 145     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
 146                   size_t __size)
 147     {
 148       this->_M_file.sys_open(__f, __mode);
 149       if (this->is_open())
 150         {
 151           this->_M_mode = __mode;
 152           this->_M_buf_size = __size;
 153           this->_M_allocate_internal_buffer();
 154           this->_M_reading = false;
 155           this->_M_writing = false;
 156           this->_M_set_buffer(-1);
 157         }
 158     }
 159 } // namespace __gnu_cxx
 160
 161 #endif