1 // Iostreams wrapper for stdio FILE* -*- C++ -*- 2 3 // Copyright (C) 2003-2018 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_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 #include <bits/move.h> // For __exchange 39 40 #ifdef _GLIBCXX_USE_WCHAR_T 41 #include <cwchar> 42 #endif 43 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 typedef std::basic_streambuf<_CharT, _Traits> __streambuf_type; 69 70 // Underlying stdio FILE 71 std::__c_file* _M_file; 72 73 // Last character gotten. This is used when pbackfail is 74 // called from basic_streambuf::sungetc() 75 int_type _M_unget_buf; 76 77 public: 78 explicit 79 stdio_sync_filebuf(std::__c_file* __f) 80 : _M_file(__f), _M_unget_buf(traits_type::eof()) 81 { } 82 83 #if __cplusplus >= 201103L 84 stdio_sync_filebuf(stdio_sync_filebuf&& __fb) noexcept 85 : __streambuf_type(std::move(__fb)), 86 _M_file(__fb._M_file), _M_unget_buf(__fb._M_unget_buf) 87 { 88 __fb._M_file = nullptr; 89 __fb._M_unget_buf = traits_type::eof(); 90 } 91 92 stdio_sync_filebuf& 93 operator=(stdio_sync_filebuf&& __fb) noexcept 94 { 95 __streambuf_type::operator=(__fb); 96 _M_file = std::__exchange(__fb._M_file, nullptr); 97 _M_unget_buf = std::__exchange(__fb._M_unget_buf, traits_type::eof()); 98 return *this; 99 } 100 101 void 102 swap(stdio_sync_filebuf& __fb) 103 { 104 __streambuf_type::swap(__fb); 105 std::swap(_M_file, __fb._M_file); 106 std::swap(_M_unget_buf, __fb._M_unget_buf); 107 } 108 #endif 109 110 /** 111 * @return The underlying FILE*. 112 * 113 * This function can be used to access the underlying C file pointer. 114 * Note that there is no way for the library to track what you do 115 * with the file, so be careful. 116 */ 117 std::__c_file* 118 file() { return this->_M_file; } 119 120 protected: 121 int_type 122 syncgetc(); 123 124 int_type 125 syncungetc(int_type __c); 126 127 int_type 128 syncputc(int_type __c); 129 130 virtual int_type 131 underflow() 132 { 133 int_type __c = this->syncgetc(); 134 return this->syncungetc(__c); 135 } 136 137 virtual int_type 138 uflow() 139 { 140 // Store the gotten character in case we need to unget it. 141 _M_unget_buf = this->syncgetc(); 142 return _M_unget_buf; 143 } 144 145 virtual int_type 146 pbackfail(int_type __c = traits_type::eof()) 147 { 148 int_type __ret; 149 const int_type __eof = traits_type::eof(); 150 151 // Check if the unget or putback was requested 152 if (traits_type::eq_int_type(__c, __eof)) // unget 153 { 154 if (!traits_type::eq_int_type(_M_unget_buf, __eof)) 155 __ret = this->syncungetc(_M_unget_buf); 156 else // buffer invalid, fail. 157 __ret = __eof; 158 } 159 else // putback 160 __ret = this->syncungetc(__c); 161 162 // The buffered character is no longer valid, discard it. 163 _M_unget_buf = __eof; 164 return __ret; 165 } 166 167 virtual std::streamsize 168 xsgetn(char_type* __s, std::streamsize __n); 169 170 virtual int_type 171 overflow(int_type __c = traits_type::eof()) 172 { 173 int_type __ret; 174 if (traits_type::eq_int_type(__c, traits_type::eof())) 175 { 176 if (std::fflush(_M_file)) 177 __ret = traits_type::eof(); 178 else 179 __ret = traits_type::not_eof(__c); 180 } 181 else 182 __ret = this->syncputc(__c); 183 return __ret; 184 } 185 186 virtual std::streamsize 187 xsputn(const char_type* __s, std::streamsize __n); 188 189 virtual int 190 sync() 191 { return std::fflush(_M_file); } 192 193 virtual std::streampos 194 seekoff(std::streamoff __off, std::ios_base::seekdir __dir, 195 std::ios_base::openmode = std::ios_base::in | std::ios_base::out) 196 { 197 std::streampos __ret(std::streamoff(-1)); 198 int __whence; 199 if (__dir == std::ios_base::beg) 200 __whence = SEEK_SET; 201 else if (__dir == std::ios_base::cur) 202 __whence = SEEK_CUR; 203 else 204 __whence = SEEK_END; 205 #ifdef _GLIBCXX_USE_LFS 206 if (!fseeko64(_M_file, __off, __whence)) 207 __ret = std::streampos(ftello64(_M_file)); 208 #else 209 if (!fseek(_M_file, __off, __whence)) 210 __ret = std::streampos(std::ftell(_M_file)); 211 #endif 212 return __ret; 213 } 214 215 virtual std::streampos 216 seekpos(std::streampos __pos, 217 std::ios_base::openmode __mode = 218 std::ios_base::in | std::ios_base::out) 219 { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); } 220 }; 221 222 template<> 223 inline stdio_sync_filebuf<char>::int_type 224 stdio_sync_filebuf<char>::syncgetc() 225 { return std::getc(_M_file); } 226 227 template<> 228 inline stdio_sync_filebuf<char>::int_type 229 stdio_sync_filebuf<char>::syncungetc(int_type __c) 230 { return std::ungetc(__c, _M_file); } 231 232 template<> 233 inline stdio_sync_filebuf<char>::int_type 234 stdio_sync_filebuf<char>::syncputc(int_type __c) 235 { return std::putc(__c, _M_file); } 236 237 template<> 238 inline std::streamsize 239 stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n) 240 { 241 std::streamsize __ret = std::fread(__s, 1, __n, _M_file); 242 if (__ret > 0) 243 _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]); 244 else 245 _M_unget_buf = traits_type::eof(); 246 return __ret; 247 } 248 249 template<> 250 inline std::streamsize 251 stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n) 252 { return std::fwrite(__s, 1, __n, _M_file); } 253 254 #ifdef _GLIBCXX_USE_WCHAR_T 255 template<> 256 inline stdio_sync_filebuf<wchar_t>::int_type 257 stdio_sync_filebuf<wchar_t>::syncgetc() 258 { return std::getwc(_M_file); } 259 260 template<> 261 inline stdio_sync_filebuf<wchar_t>::int_type 262 stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c) 263 { return std::ungetwc(__c, _M_file); } 264 265 template<> 266 inline stdio_sync_filebuf<wchar_t>::int_type 267 stdio_sync_filebuf<wchar_t>::syncputc(int_type __c) 268 { return std::putwc(__c, _M_file); } 269 270 template<> 271 inline std::streamsize 272 stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n) 273 { 274 std::streamsize __ret = 0; 275 const int_type __eof = traits_type::eof(); 276 while (__n--) 277 { 278 int_type __c = this->syncgetc(); 279 if (traits_type::eq_int_type(__c, __eof)) 280 break; 281 __s[__ret] = traits_type::to_char_type(__c); 282 ++__ret; 283 } 284 285 if (__ret > 0) 286 _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]); 287 else 288 _M_unget_buf = traits_type::eof(); 289 return __ret; 290 } 291 292 template<> 293 inline std::streamsize 294 stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s, 295 std::streamsize __n) 296 { 297 std::streamsize __ret = 0; 298 const int_type __eof = traits_type::eof(); 299 while (__n--) 300 { 301 if (traits_type::eq_int_type(this->syncputc(*__s++), __eof)) 302 break; 303 ++__ret; 304 } 305 return __ret; 306 } 307 #endif 308 309 #if _GLIBCXX_EXTERN_TEMPLATE 310 extern template class stdio_sync_filebuf<char>; 311 #ifdef _GLIBCXX_USE_WCHAR_T 312 extern template class stdio_sync_filebuf<wchar_t>; 313 #endif 314 #endif 315 316 _GLIBCXX_END_NAMESPACE_VERSION 317 } // namespace 318 319 #endif 320