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

   1 // File descriptor layer for filebuf -*- C++ -*-
   2
   3 // Copyright (C) 2002, 2003, 2004, 2005, 2009 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file ext/stdio_filebuf.h
  26  *  This file is a GNU extension to the Standard C++ Library.
  27  */
  28
  29 #ifndef _STDIO_FILEBUF_H
  30 #define _STDIO_FILEBUF_H 1
  31
  32 #pragma GCC system_header
  33
  34 #include <fstream>
  35
  36 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  37
  38   /**
  39    *  @brief Provides a layer of compatibility for C/POSIX.
  40    *
  41    *  This GNU extension provides extensions for working with standard C
  42    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
  43    *  user with the type of character used in the file stream, e.g.,
  44    *  stdio_filebuf<char>.
  45   */
  46   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  47     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
  48     {
  49     public:
  50       // Types:
  51       typedef _CharT                                    char_type;
  52       typedef _Traits                                   traits_type;
  53       typedef typename traits_type::int_type            int_type;
  54       typedef typename traits_type::pos_type            pos_type;
  55       typedef typename traits_type::off_type            off_type;
  56       typedef std::size_t                               size_t;
  57
  58     public:
  59       /**
  60        * deferred initialization
  61       */
  62       stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
  63
  64       /**
  65        *  @param  fd  An open file descriptor.
  66        *  @param  mode  Same meaning as in a standard filebuf.
  67        *  @param  size  Optimal or preferred size of internal buffer, in chars.
  68        *
  69        *  This constructor associates a file stream buffer with an open
  70        *  POSIX file descriptor. The file descriptor will be automatically
  71        *  closed when the stdio_filebuf is closed/destroyed.
  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        *  Closes the external data stream if the file descriptor constructor
  91        *  was used.
  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() { return this->_M_file.fd(); }
 106
 107       /**
 108        *  @return  The underlying FILE*.
 109        *
 110        *  This function can be used to access the underlying "C" file pointer.
 111        *  Note that there is no way for the library to track what you do
 112        *  with the file, so be careful.
 113        */
 114       std::__c_file*
 115       file() { return this->_M_file.file(); }
 116     };
 117
 118   template<typename _CharT, typename _Traits>
 119     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
 120     { }
 121
 122   template<typename _CharT, typename _Traits>
 123     stdio_filebuf<_CharT, _Traits>::
 124     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
 125     {
 126       this->_M_file.sys_open(__fd, __mode);
 127       if (this->is_open())
 128         {
 129           this->_M_mode = __mode;
 130           this->_M_buf_size = __size;
 131           this->_M_allocate_internal_buffer();
 132           this->_M_reading = false;
 133           this->_M_writing = false;
 134           this->_M_set_buffer(-1);
 135         }
 136     }
 137
 138   template<typename _CharT, typename _Traits>
 139     stdio_filebuf<_CharT, _Traits>::
 140     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
 141                   size_t __size)
 142     {
 143       this->_M_file.sys_open(__f, __mode);
 144       if (this->is_open())
 145         {
 146           this->_M_mode = __mode;
 147           this->_M_buf_size = __size;
 148           this->_M_allocate_internal_buffer();
 149           this->_M_reading = false;
 150           this->_M_writing = false;
 151           this->_M_set_buffer(-1);
 152         }
 153     }
 154
 155 _GLIBCXX_END_NAMESPACE
 156
 157 #endif