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