libstdc++

stdio_sync_filebuf.h
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1 // Iostreams wrapper for stdio FILE* -*- C++ -*-
2
3 // Copyright (C) 2003-2013 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_sync_filebuf.h
26 * This file is a GNU extension to the Standard C++ Library.
27 */
28
29 #ifndef _STDIO_SYNC_FILEBUF_H
30 #define _STDIO_SYNC_FILEBUF_H 1
31
32 #pragma GCC system_header
33
34 #include <streambuf>
35 #include <unistd.h>
36 #include <cstdio>
37 #include <bits/c++io.h> // For __c_file
38
39 #ifdef _GLIBCXX_USE_WCHAR_T
40 #include <cwchar>
41 #endif
42
43 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
44 {
45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46
47 /**
48 * @brief Provides a layer of compatibility for C.
49 * @ingroup io
50 *
51 * This GNU extension provides extensions for working with standard
52 * C FILE*'s. It must be instantiated by the user with the type of
53 * character used in the file stream, e.g., stdio_filebuf<char>.
54 */
55 template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
56 class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
57 {
58 public:
59 // Types:
60 typedef _CharT char_type;
61 typedef _Traits traits_type;
62 typedef typename traits_type::int_type int_type;
63 typedef typename traits_type::pos_type pos_type;
64 typedef typename traits_type::off_type off_type;
65
66 private:
67 // Underlying stdio FILE
68 std::__c_file* const _M_file;
69
70 // Last character gotten. This is used when pbackfail is
71 // called from basic_streambuf::sungetc()
72 int_type _M_unget_buf;
73
74 public:
75 explicit
76 stdio_sync_filebuf(std::__c_file* __f)
77 : _M_file(__f), _M_unget_buf(traits_type::eof())
78 { }
79
80 /**
81 * @return The underlying FILE*.
82 *
83 * This function can be used to access the underlying C file pointer.
84 * Note that there is no way for the library to track what you do
85 * with the file, so be careful.
86 */
87 std::__c_file* const
88 file() { return this->_M_file; }
89
90 protected:
91 int_type
92 syncgetc();
93
94 int_type
95 syncungetc(int_type __c);
96
97 int_type
98 syncputc(int_type __c);
99
100 virtual int_type
101 underflow()
102 {
103 int_type __c = this->syncgetc();
104 return this->syncungetc(__c);
105 }
106
107 virtual int_type
108 uflow()
109 {
110 // Store the gotten character in case we need to unget it.
111 _M_unget_buf = this->syncgetc();
112 return _M_unget_buf;
113 }
114
115 virtual int_type
116 pbackfail(int_type __c = traits_type::eof())
117 {
118 int_type __ret;
119 const int_type __eof = traits_type::eof();
120
121 // Check if the unget or putback was requested
122 if (traits_type::eq_int_type(__c, __eof)) // unget
123 {
124 if (!traits_type::eq_int_type(_M_unget_buf, __eof))
125 __ret = this->syncungetc(_M_unget_buf);
126 else // buffer invalid, fail.
127 __ret = __eof;
128 }
129 else // putback
130 __ret = this->syncungetc(__c);
131
132 // The buffered character is no longer valid, discard it.
133 _M_unget_buf = __eof;
134 return __ret;
135 }
136
137 virtual std::streamsize
138 xsgetn(char_type* __s, std::streamsize __n);
139
140 virtual int_type
141 overflow(int_type __c = traits_type::eof())
142 {
143 int_type __ret;
144 if (traits_type::eq_int_type(__c, traits_type::eof()))
145 {
146 if (std::fflush(_M_file))
147 __ret = traits_type::eof();
148 else
149 __ret = traits_type::not_eof(__c);
150 }
151 else
152 __ret = this->syncputc(__c);
153 return __ret;
154 }
155
156 virtual std::streamsize
157 xsputn(const char_type* __s, std::streamsize __n);
158
159 virtual int
160 sync()
161 { return std::fflush(_M_file); }
162
163 virtual std::streampos
164 seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
165 std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
166 {
167 std::streampos __ret(std::streamoff(-1));
168 int __whence;
169 if (__dir == std::ios_base::beg)
170 __whence = SEEK_SET;
171 else if (__dir == std::ios_base::cur)
172 __whence = SEEK_CUR;
173 else
174 __whence = SEEK_END;
175 #ifdef _GLIBCXX_USE_LFS
176 if (!fseeko64(_M_file, __off, __whence))
177 __ret = std::streampos(ftello64(_M_file));
178 #else
179 if (!fseek(_M_file, __off, __whence))
180 __ret = std::streampos(std::ftell(_M_file));
181 #endif
182 return __ret;
183 }
184
185 virtual std::streampos
186 seekpos(std::streampos __pos,
187 std::ios_base::openmode __mode =
188 std::ios_base::in | std::ios_base::out)
189 { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
190 };
191
192 template<>
193 inline stdio_sync_filebuf<char>::int_type
194 stdio_sync_filebuf<char>::syncgetc()
195 { return std::getc(_M_file); }
196
197 template<>
198 inline stdio_sync_filebuf<char>::int_type
199 stdio_sync_filebuf<char>::syncungetc(int_type __c)
200 { return std::ungetc(__c, _M_file); }
201
202 template<>
203 inline stdio_sync_filebuf<char>::int_type
204 stdio_sync_filebuf<char>::syncputc(int_type __c)
205 { return std::putc(__c, _M_file); }
206
207 template<>
208 inline std::streamsize
209 stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
210 {
211 std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
212 if (__ret > 0)
213 _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
214 else
215 _M_unget_buf = traits_type::eof();
216 return __ret;
217 }
218
219 template<>
220 inline std::streamsize
221 stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
222 { return std::fwrite(__s, 1, __n, _M_file); }
223
224 #ifdef _GLIBCXX_USE_WCHAR_T
225 template<>
226 inline stdio_sync_filebuf<wchar_t>::int_type
227 stdio_sync_filebuf<wchar_t>::syncgetc()
228 { return std::getwc(_M_file); }
229
230 template<>
231 inline stdio_sync_filebuf<wchar_t>::int_type
232 stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
233 { return std::ungetwc(__c, _M_file); }
234
235 template<>
236 inline stdio_sync_filebuf<wchar_t>::int_type
237 stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
238 { return std::putwc(__c, _M_file); }
239
240 template<>
241 inline std::streamsize
242 stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
243 {
244 std::streamsize __ret = 0;
245 const int_type __eof = traits_type::eof();
246 while (__n--)
247 {
248 int_type __c = this->syncgetc();
249 if (traits_type::eq_int_type(__c, __eof))
250 break;
251 __s[__ret] = traits_type::to_char_type(__c);
252 ++__ret;
253 }
254
255 if (__ret > 0)
256 _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
257 else
258 _M_unget_buf = traits_type::eof();
259 return __ret;
260 }
261
262 template<>
263 inline std::streamsize
264 stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
265 std::streamsize __n)
266 {
267 std::streamsize __ret = 0;
268 const int_type __eof = traits_type::eof();
269 while (__n--)
270 {
271 if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
272 break;
273 ++__ret;
274 }
275 return __ret;
276 }
277 #endif
278
279 #if _GLIBCXX_EXTERN_TEMPLATE
280 extern template class stdio_sync_filebuf<char>;
281 #ifdef _GLIBCXX_USE_WCHAR_T
282 extern template class stdio_sync_filebuf<wchar_t>;
283 #endif
284 #endif
285
286 _GLIBCXX_END_NAMESPACE_VERSION
287 } // namespace
288
289 #endif