libstdc++-v3/include/ext/stdio_sync_filebuf.h

   1 // Iostreams wrapper for stdio FILE* -*- C++ -*-
   2
   3 // Copyright (C) 2003-2014 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*
  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