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

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