1// File descriptor layer for filebuf -*- C++ -*-
2
3// Copyright (C) 2002-2022 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
36namespace __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>(_GLIBCXX_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>(_GLIBCXX_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
172