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

   1 // Iostreams wrapper for stdio FILE* -*- C++ -*-
   2
   3 // Copyright (C) 2003, 2004 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /** @file ext/stdio_sync_filebuf.h
  31  *  This file is a GNU extension to the Standard C++ Library.
  32  */
  33
  34 #ifndef _STDIO_SYNC_FILEBUF_H
  35 #define _STDIO_SYNC_FILEBUF_H 1
  36
  37 #pragma GCC system_header
  38
  39 #include <streambuf>
  40 #include <unistd.h>
  41 #include <cstdio>
  42
  43 #ifdef _GLIBCXX_USE_WCHAR_T
  44 #include <cwchar>
  45 #endif
  46
  47 namespace __gnu_cxx
  48 {
  49   /// @brief  class stdio_sync_filebuf.
  50   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  51     class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
  52     {
  53     public:
  54       // Types:
  55       typedef _CharT                                    char_type;
  56       typedef _Traits                                   traits_type;
  57       typedef typename traits_type::int_type            int_type;
  58       typedef typename traits_type::pos_type            pos_type;
  59       typedef typename traits_type::off_type            off_type;
  60
  61     private:
  62       // Underlying stdio FILE
  63       std::__c_file* const _M_file;
  64
  65       // Last character gotten. This is used when pbackfail is
  66       // called from basic_streambuf::sungetc()
  67       int_type _M_unget_buf;
  68
  69     public:
  70       explicit
  71       stdio_sync_filebuf(std::__c_file* __f)
  72       : _M_file(__f), _M_unget_buf(traits_type::eof())
  73       { }
  74
  75       /**
  76        *  @return  The underlying FILE*.
  77        *
  78        *  This function can be used to access the underlying "C" file pointer.
  79        *  Note that there is no way for the library to track what you do
  80        *  with the file, so be careful.
  81        */
  82       std::__c_file* const
  83       file() { return this->_M_file; }
  84
  85     protected:
  86       int_type
  87       syncgetc();
  88
  89       int_type
  90       syncungetc(int_type __c);
  91
  92       int_type
  93       syncputc(int_type __c);
  94
  95       virtual int_type
  96       underflow()
  97       {
  98         int_type __c = this->syncgetc();
  99         return this->syncungetc(__c);
 100       }
 101
 102       virtual int_type
 103       uflow()
 104       {
 105         // Store the gotten character in case we need to unget it.
 106         _M_unget_buf = this->syncgetc();
 107         return _M_unget_buf;
 108       }
 109
 110       virtual int_type
 111       pbackfail(int_type __c = traits_type::eof())
 112       {
 113         int_type __ret;
 114         const int_type __eof = traits_type::eof();
 115
 116         // Check if the unget or putback was requested
 117         if (traits_type::eq_int_type(__c, __eof)) // unget
 118           {
 119             if (!traits_type::eq_int_type(_M_unget_buf, __eof))
 120               __ret = this->syncungetc(_M_unget_buf);
 121             else // buffer invalid, fail.
 122               __ret = __eof;
 123           }
 124         else // putback
 125           __ret = this->syncungetc(__c);
 126
 127         // The buffered character is no longer valid, discard it.
 128         _M_unget_buf = __eof;
 129         return __ret;
 130       }
 131
 132       virtual std::streamsize
 133       xsgetn(char_type* __s, std::streamsize __n);
 134
 135       virtual int_type
 136       overflow(int_type __c = traits_type::eof())
 137       {
 138         int_type __ret;
 139         if (traits_type::eq_int_type(__c, traits_type::eof()))
 140           {
 141             if (std::fflush(_M_file))
 142               __ret = traits_type::eof();
 143             else
 144               __ret = traits_type::not_eof(__c);
 145           }
 146         else
 147           __ret = this->syncputc(__c);
 148         return __ret;
 149       }
 150
 151       virtual std::streamsize
 152       xsputn(const char_type* __s, std::streamsize __n);
 153
 154       virtual int
 155       sync()
 156       { return std::fflush(_M_file); }
 157
 158       virtual std::streampos
 159       seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
 160               std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
 161       {
 162         std::streampos __ret(std::streamoff(-1));
 163         int __whence;
 164         if (__dir == std::ios_base::beg)
 165           __whence = SEEK_SET;
 166         else if (__dir == std::ios_base::cur)
 167           __whence = SEEK_CUR;
 168         else
 169           __whence = SEEK_END;
 170 #ifdef _GLIBCXX_USE_LFS
 171         if (!fseeko64(_M_file, __off, __whence))
 172           __ret = std::streampos(ftello64(_M_file));
 173 #else
 174         if (!fseek(_M_file, __off, __whence))
 175           __ret = std::streampos(std::ftell(_M_file));
 176 #endif
 177         return __ret;
 178       }
 179
 180       virtual std::streampos
 181       seekpos(std::streampos __pos,
 182               std::ios_base::openmode __mode =
 183               std::ios_base::in | std::ios_base::out)
 184       { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
 185     };
 186
 187   template<>
 188     inline stdio_sync_filebuf<char>::int_type
 189     stdio_sync_filebuf<char>::syncgetc()
 190     { return std::getc(_M_file); }
 191
 192   template<>
 193     inline stdio_sync_filebuf<char>::int_type
 194     stdio_sync_filebuf<char>::syncungetc(int_type __c)
 195     { return std::ungetc(__c, _M_file); }
 196
 197   template<>
 198     inline stdio_sync_filebuf<char>::int_type
 199     stdio_sync_filebuf<char>::syncputc(int_type __c)
 200     { return std::putc(__c, _M_file); }
 201
 202   template<>
 203     inline std::streamsize
 204     stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
 205     {
 206       std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
 207       if (__ret > 0)
 208         _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
 209       else
 210         _M_unget_buf = traits_type::eof();
 211       return __ret;
 212     }
 213
 214   template<>
 215     inline std::streamsize
 216     stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
 217     { return std::fwrite(__s, 1, __n, _M_file); }
 218
 219 #ifdef _GLIBCXX_USE_WCHAR_T
 220   template<>
 221     inline stdio_sync_filebuf<wchar_t>::int_type
 222     stdio_sync_filebuf<wchar_t>::syncgetc()
 223     { return std::getwc(_M_file); }
 224
 225   template<>
 226     inline stdio_sync_filebuf<wchar_t>::int_type
 227     stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
 228     { return std::ungetwc(__c, _M_file); }
 229
 230   template<>
 231     inline stdio_sync_filebuf<wchar_t>::int_type
 232     stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
 233     { return std::putwc(__c, _M_file); }
 234
 235   template<>
 236     inline std::streamsize
 237     stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
 238     {
 239       std::streamsize __ret = 0;
 240       const int_type __eof = traits_type::eof();
 241       while (__n--)
 242         {
 243           int_type __c = this->syncgetc();
 244           if (traits_type::eq_int_type(__c, __eof))
 245             break;
 246           __s[__ret] = traits_type::to_char_type(__c);
 247           ++__ret;
 248         }
 249
 250       if (__ret > 0)
 251         _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
 252       else
 253         _M_unget_buf = traits_type::eof();
 254       return __ret;
 255     }
 256
 257   template<>
 258     inline std::streamsize
 259     stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
 260                                         std::streamsize __n)
 261     {
 262       std::streamsize __ret = 0;
 263       const int_type __eof = traits_type::eof();
 264       while (__n--)
 265         {
 266           if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
 267             break;
 268           ++__ret;
 269         }
 270       return __ret;
 271     }
 272 #endif
 273
 274 #if _GLIBCXX_EXTERN_TEMPLATE
 275   extern template class stdio_sync_filebuf<char>;
 276 #ifdef _GLIBCXX_USE_WCHAR_T
 277   extern template class stdio_sync_filebuf<wchar_t>;
 278 #endif
 279 #endif
 280 } // namespace __gnu_cxx
 281
 282 #endif