1// File descriptor layer for filebuf -*- C++ -*-
2
3// Copyright (C) 2002-2018 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>(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
172