libstdc++
stdio_filebuf.h
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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>
120  { }
121 
122  template<typename _CharT, typename _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>
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