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