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

   1 // File descriptor layer for filebuf -*- C++ -*-
   2
   3 // Copyright (C) 2002, 2003, 2004, 2005, 2009, 2010
   4 // Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 /** @file ext/stdio_filebuf.h
  27  *  This file is a GNU extension to the Standard C++ Library.
  28  */
  29
  30 #ifndef _STDIO_FILEBUF_H
  31 #define _STDIO_FILEBUF_H 1
  32
  33 #pragma GCC system_header
  34
  35 #include <fstream>
  36
  37 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  38
  39   /**
  40    *  @brief Provides a layer of compatibility for C/POSIX.
  41    *  @ingroup io
  42    *
  43    *  This GNU extension provides extensions for working with standard C
  44    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
  45    *  user with the type of character used in the file stream, e.g.,
  46    *  stdio_filebuf<char>.
  47   */
  48   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  49     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
  50     {
  51     public:
  52       // Types:
  53       typedef _CharT                                    char_type;
  54       typedef _Traits                                   traits_type;
  55       typedef typename traits_type::int_type            int_type;
  56       typedef typename traits_type::pos_type            pos_type;
  57       typedef typename traits_type::off_type            off_type;
  58       typedef std::size_t                               size_t;
  59
  60     public:
  61       /**
  62        * deferred initialization
  63       */
  64       stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
  65
  66       /**
  67        *  @param  fd  An open file descriptor.
  68        *  @param  mode  Same meaning as in a standard filebuf.
  69        *  @param  size  Optimal or preferred size of internal buffer, in chars.
  70        *
  71        *  This constructor associates a file stream buffer with an open
  72        *  POSIX file descriptor. The file descriptor will be automatically
  73        *  closed when the stdio_filebuf is closed/destroyed.
  74       */
  75       stdio_filebuf(int __fd, std::ios_base::openmode __mode,
  76                     size_t __size = static_cast<size_t>(BUFSIZ));
  77
  78       /**
  79        *  @param  f  An open @c FILE*.
  80        *  @param  mode  Same meaning as in a standard filebuf.
  81        *  @param  size  Optimal or preferred size of internal buffer, in chars.
  82        *                Defaults to system's @c BUFSIZ.
  83        *
  84        *  This constructor associates a file stream buffer with an open
  85        *  C @c FILE*.  The @c FILE* will not be automatically closed when the
  86        *  stdio_filebuf is closed/destroyed.
  87       */
  88       stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
  89                     size_t __size = static_cast<size_t>(BUFSIZ));
  90
  91       /**
  92        *  Closes the external data stream if the file descriptor constructor
  93        *  was used.
  94       */
  95       virtual
  96       ~stdio_filebuf();
  97
  98       /**
  99        *  @return  The underlying file descriptor.
 100        *
 101        *  Once associated with an external data stream, this function can be
 102        *  used to access the underlying POSIX file descriptor.  Note that
 103        *  there is no way for the library to track what you do with the
 104        *  descriptor, so be careful.
 105       */
 106       int
 107       fd() { return this->_M_file.fd(); }
 108
 109       /**
 110        *  @return  The underlying FILE*.
 111        *
 112        *  This function can be used to access the underlying "C" file pointer.
 113        *  Note that there is no way for the library to track what you do
 114        *  with the file, so be careful.
 115        */
 116       std::__c_file*
 117       file() { return this->_M_file.file(); }
 118     };
 119
 120   template<typename _CharT, typename _Traits>
 121     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
 122     { }
 123
 124   template<typename _CharT, typename _Traits>
 125     stdio_filebuf<_CharT, _Traits>::
 126     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
 127     {
 128       this->_M_file.sys_open(__fd, __mode);
 129       if (this->is_open())
 130         {
 131           this->_M_mode = __mode;
 132           this->_M_buf_size = __size;
 133           this->_M_allocate_internal_buffer();
 134           this->_M_reading = false;
 135           this->_M_writing = false;
 136           this->_M_set_buffer(-1);
 137         }
 138     }
 139
 140   template<typename _CharT, typename _Traits>
 141     stdio_filebuf<_CharT, _Traits>::
 142     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
 143                   size_t __size)
 144     {
 145       this->_M_file.sys_open(__f, __mode);
 146       if (this->is_open())
 147         {
 148           this->_M_mode = __mode;
 149           this->_M_buf_size = __size;
 150           this->_M_allocate_internal_buffer();
 151           this->_M_reading = false;
 152           this->_M_writing = false;
 153           this->_M_set_buffer(-1);
 154         }
 155     }
 156
 157 _GLIBCXX_END_NAMESPACE
 158
 159 #endif