1 // Iostreams wrapper for stdio FILE* -*- C++ -*-
2
3 // Copyright (C) 2003, 2004, 2005, 2006, 2007, 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_sync_filebuf.h
27 * This file is a GNU extension to the Standard C++ Library.
28 */
29
30 #ifndef _STDIO_SYNC_FILEBUF_H
31 #define _STDIO_SYNC_FILEBUF_H 1
32
33 #pragma GCC system_header
34
35 #include <streambuf>
36 #include <unistd.h>
37 #include <cstdio>
38 #include <bits/c++io.h> // For __c_file
39
40 #ifdef _GLIBCXX_USE_WCHAR_T
41 #include <cwchar>
42 #endif
43
_GLIBCXX_VISIBILITY(default)44 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
45 {
46 _GLIBCXX_BEGIN_NAMESPACE_VERSION
47
48 /**
49 * @brief Provides a layer of compatibility for C.
50 * @ingroup io
51 *
52 * This GNU extension provides extensions for working with standard
53 * C FILE*'s. It must be instantiated by the user with the type of
54 * character used in the file stream, e.g., stdio_filebuf<char>.
55 */
56 template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
57 class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
58 {
59 public:
60 // Types:
61 typedef _CharT char_type;
62 typedef _Traits traits_type;
63 typedef typename traits_type::int_type int_type;
64 typedef typename traits_type::pos_type pos_type;
65 typedef typename traits_type::off_type off_type;
66
67 private:
68 // Underlying stdio FILE
69 std::__c_file* const _M_file;
70
71 // Last character gotten. This is used when pbackfail is
72 // called from basic_streambuf::sungetc()
73 int_type _M_unget_buf;
74
75 public:
76 explicit
77 stdio_sync_filebuf(std::__c_file* __f)
78 : _M_file(__f), _M_unget_buf(traits_type::eof())
79 { }
80
81 /**
82 * @return The underlying FILE*.
83 *
84 * This function can be used to access the underlying C file pointer.
85 * Note that there is no way for the library to track what you do
86 * with the file, so be careful.
87 */
88 std::__c_file* const
89 file() { return this->_M_file; }
90
91 protected:
92 int_type
93 syncgetc();
94
95 int_type
96 syncungetc(int_type __c);
97
98 int_type
99 syncputc(int_type __c);
100
101 virtual int_type
102 underflow()
103 {
104 int_type __c = this->syncgetc();
105 return this->syncungetc(__c);
106 }
107
108 virtual int_type
109 uflow()
110 {
111 // Store the gotten character in case we need to unget it.
112 _M_unget_buf = this->syncgetc();
113 return _M_unget_buf;
114 }
115
116 virtual int_type
117 pbackfail(int_type __c = traits_type::eof())
118 {
119 int_type __ret;
120 const int_type __eof = traits_type::eof();
121
122 // Check if the unget or putback was requested
123 if (traits_type::eq_int_type(__c, __eof)) // unget
124 {
125 if (!traits_type::eq_int_type(_M_unget_buf, __eof))
126 __ret = this->syncungetc(_M_unget_buf);
127 else // buffer invalid, fail.
128 __ret = __eof;
129 }
130 else // putback
131 __ret = this->syncungetc(__c);
132
133 // The buffered character is no longer valid, discard it.
134 _M_unget_buf = __eof;
135 return __ret;
136 }
137
138 virtual std::streamsize
139 xsgetn(char_type* __s, std::streamsize __n);
140
141 virtual int_type
142 overflow(int_type __c = traits_type::eof())
143 {
144 int_type __ret;
145 if (traits_type::eq_int_type(__c, traits_type::eof()))
146 {
147 if (std::fflush(_M_file))
148 __ret = traits_type::eof();
149 else
150 __ret = traits_type::not_eof(__c);
151 }
152 else
153 __ret = this->syncputc(__c);
154 return __ret;
155 }
156
157 virtual std::streamsize
158 xsputn(const char_type* __s, std::streamsize __n);
159
160 virtual int
161 sync()
162 { return std::fflush(_M_file); }
163
164 virtual std::streampos
165 seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
166 std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
167 {
168 std::streampos __ret(std::streamoff(-1));
169 int __whence;
170 if (__dir == std::ios_base::beg)
171 __whence = SEEK_SET;
172 else if (__dir == std::ios_base::cur)
173 __whence = SEEK_CUR;
174 else
175 __whence = SEEK_END;
176 #ifdef _GLIBCXX_USE_LFS
177 if (!fseeko64(_M_file, __off, __whence))
178 __ret = std::streampos(ftello64(_M_file));
179 #else
180 if (!fseek(_M_file, __off, __whence))
181 __ret = std::streampos(std::ftell(_M_file));
182 #endif
183 return __ret;
184 }
185
186 virtual std::streampos
187 seekpos(std::streampos __pos,
188 std::ios_base::openmode __mode =
189 std::ios_base::in | std::ios_base::out)
190 { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
191 };
192
193 template<>
194 inline stdio_sync_filebuf<char>::int_type
195 stdio_sync_filebuf<char>::syncgetc()
196 { return std::getc(_M_file); }
197
198 template<>
199 inline stdio_sync_filebuf<char>::int_type
200 stdio_sync_filebuf<char>::syncungetc(int_type __c)
201 { return std::ungetc(__c, _M_file); }
202
203 template<>
204 inline stdio_sync_filebuf<char>::int_type
205 stdio_sync_filebuf<char>::syncputc(int_type __c)
206 { return std::putc(__c, _M_file); }
207
208 template<>
209 inline std::streamsize
210 stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
211 {
212 std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
213 if (__ret > 0)
214 _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
215 else
216 _M_unget_buf = traits_type::eof();
217 return __ret;
218 }
219
220 template<>
221 inline std::streamsize
222 stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
223 { return std::fwrite(__s, 1, __n, _M_file); }
224
225 #ifdef _GLIBCXX_USE_WCHAR_T
226 template<>
227 inline stdio_sync_filebuf<wchar_t>::int_type
228 stdio_sync_filebuf<wchar_t>::syncgetc()
229 { return std::getwc(_M_file); }
230
231 template<>
232 inline stdio_sync_filebuf<wchar_t>::int_type
233 stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
234 { return std::ungetwc(__c, _M_file); }
235
236 template<>
237 inline stdio_sync_filebuf<wchar_t>::int_type
238 stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
239 { return std::putwc(__c, _M_file); }
240
241 template<>
242 inline std::streamsize
243 stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
244 {
245 std::streamsize __ret = 0;
246 const int_type __eof = traits_type::eof();
247 while (__n--)
248 {
249 int_type __c = this->syncgetc();
250 if (traits_type::eq_int_type(__c, __eof))
251 break;
252 __s[__ret] = traits_type::to_char_type(__c);
253 ++__ret;
254 }
255
256 if (__ret > 0)
257 _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
258 else
259 _M_unget_buf = traits_type::eof();
260 return __ret;
261 }
262
263 template<>
264 inline std::streamsize
265 stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
266 std::streamsize __n)
267 {
268 std::streamsize __ret = 0;
269 const int_type __eof = traits_type::eof();
270 while (__n--)
271 {
272 if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
273 break;
274 ++__ret;
275 }
276 return __ret;
277 }
278 #endif
279
280 #if _GLIBCXX_EXTERN_TEMPLATE
281 extern template class stdio_sync_filebuf<char>;
282 #ifdef _GLIBCXX_USE_WCHAR_T
283 extern template class stdio_sync_filebuf<wchar_t>;
284 #endif
285 #endif
286
287 _GLIBCXX_END_NAMESPACE_VERSION
288 } // namespace
289
290 #endif
291