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

   1 // File descriptor layer for filebuf -*- C++ -*-
   2
   3 // Copyright (C) 2002-2020 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 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  37 {
  38 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  39
  40   /**
  41    *  @brief Provides a layer of compatibility for C/POSIX.
  42    *  @ingroup io
  43    *
  44    *  This GNU extension provides extensions for working with standard C
  45    *  FILE*'s and POSIX file descriptors.  It must be instantiated by the
  46    *  user with the type of character used in the file stream, e.g.,
  47    *  stdio_filebuf<char>.
  48   */
  49   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  50     class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
  51     {
  52     public:
  53       // Types:
  54       typedef _CharT                                    char_type;
  55       typedef _Traits                                   traits_type;
  56       typedef typename traits_type::int_type            int_type;
  57       typedef typename traits_type::pos_type            pos_type;
  58       typedef typename traits_type::off_type            off_type;
  59       typedef std::size_t                               size_t;
  60
  61     public:
  62       /**
  63        * deferred initialization
  64       */
  65       stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
  66
  67       /**
  68        *  @param  __fd  An open file descriptor.
  69        *  @param  __mode  Same meaning as in a standard filebuf.
  70        *  @param  __size Optimal or preferred size of internal buffer,
  71        *                 in chars.
  72        *
  73        *  This constructor associates a file stream buffer with an open
  74        *  POSIX file descriptor. The file descriptor will be automatically
  75        *  closed when the stdio_filebuf is closed/destroyed.
  76       */
  77       stdio_filebuf(int __fd, std::ios_base::openmode __mode,
  78                     size_t __size = static_cast<size_t>(BUFSIZ));
  79
  80       /**
  81        *  @param  __f  An open @c FILE*.
  82        *  @param  __mode  Same meaning as in a standard filebuf.
  83        *  @param  __size Optimal or preferred size of internal buffer,
  84        *                 in chars.  Defaults to system's @c BUFSIZ.
  85        *
  86        *  This constructor associates a file stream buffer with an open
  87        *  C @c FILE*.  The @c FILE* will not be automatically closed when the
  88        *  stdio_filebuf is closed/destroyed.
  89       */
  90       stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
  91                     size_t __size = static_cast<size_t>(BUFSIZ));
  92
  93       /**
  94        *  Closes the external data stream if the file descriptor constructor
  95        *  was used.
  96       */
  97       virtual
  98       ~stdio_filebuf();
  99
 100 #if __cplusplus >= 201103L
 101       stdio_filebuf(stdio_filebuf&&) = default;
 102       stdio_filebuf& operator=(stdio_filebuf&&) = default;
 103
 104       void
 105       swap(stdio_filebuf& __fb)
 106       { std::basic_filebuf<_CharT, _Traits>::swap(__fb); }
 107 #endif
 108
 109       /**
 110        *  @return  The underlying file descriptor.
 111        *
 112        *  Once associated with an external data stream, this function can be
 113        *  used to access the underlying POSIX file descriptor.  Note that
 114        *  there is no way for the library to track what you do with the
 115        *  descriptor, so be careful.
 116       */
 117       int
 118       fd() { return this->_M_file.fd(); }
 119
 120       /**
 121        *  @return  The underlying FILE*.
 122        *
 123        *  This function can be used to access the underlying "C" file pointer.
 124        *  Note that there is no way for the library to track what you do
 125        *  with the file, so be careful.
 126        */
 127       std::__c_file*
 128       file() { return this->_M_file.file(); }
 129     };
 130
 131   template<typename _CharT, typename _Traits>
 132     stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
 133     { }
 134
 135   template<typename _CharT, typename _Traits>
 136     stdio_filebuf<_CharT, _Traits>::
 137     stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
 138     {
 139       this->_M_file.sys_open(__fd, __mode);
 140       if (this->is_open())
 141         {
 142           this->_M_mode = __mode;
 143           this->_M_buf_size = __size;
 144           this->_M_allocate_internal_buffer();
 145           this->_M_reading = false;
 146           this->_M_writing = false;
 147           this->_M_set_buffer(-1);
 148         }
 149     }
 150
 151   template<typename _CharT, typename _Traits>
 152     stdio_filebuf<_CharT, _Traits>::
 153     stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
 154                   size_t __size)
 155     {
 156       this->_M_file.sys_open(__f, __mode);
 157       if (this->is_open())
 158         {
 159           this->_M_mode = __mode;
 160           this->_M_buf_size = __size;
 161           this->_M_allocate_internal_buffer();
 162           this->_M_reading = false;
 163           this->_M_writing = false;
 164           this->_M_set_buffer(-1);
 165         }
 166     }
 167
 168 _GLIBCXX_END_NAMESPACE_VERSION
 169 } // namespace
 170
 171 #endif