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

   1 // File descriptor layer for filebuf -*- C++ -*-
   2
   3 // Copyright (C) 2002, 2003 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    *  @class stdio_filebuf ext/stdio_filebuf.h <ext/stdio_filebuf.h>
  45    *  @brief Provides a layer of compatibility for C/POSIX.
  46    *
  47    *  This GNU extension provides extensions for working with standard C
  48    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
  49    *  user with the type of character used in the file stream, e.g.,
  50    *  stdio_filebuf<char>.
  51   */
  52   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  53     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
  54     {
  55     public:
  56       // Types:
  57       typedef _CharT                                    char_type;
  58       typedef _Traits                                   traits_type;
  59       typedef typename traits_type::int_type            int_type;
  60       typedef typename traits_type::pos_type            pos_type;
  61       typedef typename traits_type::off_type            off_type;
  62       typedef std::size_t                               size_t;
  63
  64     public:
  65       /**
  66        *  @param  fd  An open file descriptor.
  67        *  @param  mode  Same meaning as in a standard filebuf.
  68        *  @param  size  Optimal or preferred size of internal buffer, in chars.
  69        *
  70        *  This constructor associates a file stream buffer with an open
  71        *  POSIX file descriptor.
  72       */
  73       stdio_filebuf(int __fd, std::ios_base::openmode __mode,
  74                     size_t __size = static_cast<size_t>(BUFSIZ));
  75
  76       /**
  77        *  @param  f  An open @c FILE*.
  78        *  @param  mode  Same meaning as in a standard filebuf.
  79        *  @param  size  Optimal or preferred size of internal buffer, in chars.
  80        *                Defaults to system's @c BUFSIZ.
  81        *
  82        *  This constructor associates a file stream buffer with an open
  83        *  C @c FILE*.  The @c FILE* will not be automatically closed when the
  84        *  stdio_filebuf is closed/destroyed.
  85       */
  86       stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
  87                     size_t __size = static_cast<size_t>(BUFSIZ));
  88
  89       /**
  90        *  Possibly closes the external data stream, in the case of the file
  91        *  descriptor constructor and @c del @c == @c true.
  92       */
  93       virtual
  94       ~stdio_filebuf();
  95
  96       /**
  97        *  @return  The underlying file descriptor.
  98        *
  99        *  Once associated with an external data stream, this function can be
 100        *  used to access the underlying POSIX file descriptor.  Note that
 101        *  there is no way for the library to track what you do with the
 102        *  descriptor, so be careful.
 103       */
 104       int
 105       fd()
 106       { return this->_M_file.fd(); }
 107     };
 108
 109   template<typename _CharT, typename _Traits>
 110     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
 111     { }
 112
 113   template<typename _CharT, typename _Traits>
 114     stdio_filebuf<_CharT, _Traits>::
 115     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
 116     {
 117       this->_M_file.sys_open(__fd, __mode);
 118       if (this->is_open())
 119         {
 120           this->_M_mode = __mode;
 121           this->_M_buf_size = __size;
 122           this->_M_allocate_internal_buffer();
 123           this->_M_reading = false;
 124           this->_M_writing = false;
 125           this->_M_set_buffer(-1);
 126         }
 127     }
 128
 129   template<typename _CharT, typename _Traits>
 130     stdio_filebuf<_CharT, _Traits>::
 131     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
 132                   size_t __size)
 133     {
 134       this->_M_file.sys_open(__f, __mode);
 135       if (this->is_open())
 136         {
 137           this->_M_mode = __mode;
 138           this->_M_buf_size = __size;
 139           this->_M_allocate_internal_buffer();
 140           this->_M_reading = false;
 141           this->_M_writing = false;
 142           this->_M_set_buffer(-1);
 143         }
 144     }
 145 } // namespace __gnu_cxx
 146
 147 #endif