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   /**
  47    *  @brief Provides a layer of compatibility for C.
  48    *  @ingroup io
  49    *
  50    *  This GNU extension provides extensions for working with standard
  51    *  C FILE*'s.  It must be instantiated by the user with the type of
  52    *  character used in the file stream, e.g., stdio_filebuf<char>.
  53   */
  54   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  55     class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
  56     {
  57     public:
  58       // Types:
  59       typedef _CharT                                    char_type;
  60       typedef _Traits                                   traits_type;
  61       typedef typename traits_type::int_type            int_type;
  62       typedef typename traits_type::pos_type            pos_type;
  63       typedef typename traits_type::off_type            off_type;
  64
  65     private:
  66       // Underlying stdio FILE
  67       std::__c_file* const _M_file;
  68
  69       // Last character gotten. This is used when pbackfail is
  70       // called from basic_streambuf::sungetc()
  71       int_type _M_unget_buf;
  72
  73     public:
  74       explicit
  75       stdio_sync_filebuf(std::__c_file* __f)
  76       : _M_file(__f), _M_unget_buf(traits_type::eof())
  77       { }
  78
  79       /**
  80        *  @return  The underlying FILE*.
  81        *
  82        *  This function can be used to access the underlying C file pointer.
  83        *  Note that there is no way for the library to track what you do
  84        *  with the file, so be careful.
  85        */
  86       std::__c_file* const
  87       file() { return this->_M_file; }
  88
  89     protected:
  90       int_type
  91       syncgetc();
  92
  93       int_type
  94       syncungetc(int_type __c);
  95
  96       int_type
  97       syncputc(int_type __c);
  98
  99       virtual int_type
 100       underflow()
 101       {
 102         int_type __c = this->syncgetc();
 103         return this->syncungetc(__c);
 104       }
 105
 106       virtual int_type
 107       uflow()
 108       {
 109         // Store the gotten character in case we need to unget it.
 110         _M_unget_buf = this->syncgetc();
 111         return _M_unget_buf;
 112       }
 113
 114       virtual int_type
 115       pbackfail(int_type __c = traits_type::eof())
 116       {
 117         int_type __ret;
 118         const int_type __eof = traits_type::eof();
 119
 120         // Check if the unget or putback was requested
 121         if (traits_type::eq_int_type(__c, __eof)) // unget
 122           {
 123             if (!traits_type::eq_int_type(_M_unget_buf, __eof))
 124               __ret = this->syncungetc(_M_unget_buf);
 125             else // buffer invalid, fail.
 126               __ret = __eof;
 127           }
 128         else // putback
 129           __ret = this->syncungetc(__c);
 130
 131         // The buffered character is no longer valid, discard it.
 132         _M_unget_buf = __eof;
 133         return __ret;
 134       }
 135
 136       virtual std::streamsize
 137       xsgetn(char_type* __s, std::streamsize __n);
 138
 139       virtual int_type
 140       overflow(int_type __c = traits_type::eof())
 141       {
 142         int_type __ret;
 143         if (traits_type::eq_int_type(__c, traits_type::eof()))
 144           {
 145             if (std::fflush(_M_file))
 146               __ret = traits_type::eof();
 147             else
 148               __ret = traits_type::not_eof(__c);
 149           }
 150         else
 151           __ret = this->syncputc(__c);
 152         return __ret;
 153       }
 154
 155       virtual std::streamsize
 156       xsputn(const char_type* __s, std::streamsize __n);
 157
 158       virtual int
 159       sync()
 160       { return std::fflush(_M_file); }
 161
 162       virtual std::streampos
 163       seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
 164               std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
 165       {
 166         std::streampos __ret(std::streamoff(-1));
 167         int __whence;
 168         if (__dir == std::ios_base::beg)
 169           __whence = SEEK_SET;
 170         else if (__dir == std::ios_base::cur)
 171           __whence = SEEK_CUR;
 172         else
 173           __whence = SEEK_END;
 174 #ifdef _GLIBCXX_USE_LFS
 175         if (!fseeko64(_M_file, __off, __whence))
 176           __ret = std::streampos(ftello64(_M_file));
 177 #else
 178         if (!fseek(_M_file, __off, __whence))
 179           __ret = std::streampos(std::ftell(_M_file));
 180 #endif
 181         return __ret;
 182       }
 183
 184       virtual std::streampos
 185       seekpos(std::streampos __pos,
 186               std::ios_base::openmode __mode =
 187               std::ios_base::in | std::ios_base::out)
 188       { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
 189     };
 190
 191   template<>
 192     inline stdio_sync_filebuf<char>::int_type
 193     stdio_sync_filebuf<char>::syncgetc()
 194     { return std::getc(_M_file); }
 195
 196   template<>
 197     inline stdio_sync_filebuf<char>::int_type
 198     stdio_sync_filebuf<char>::syncungetc(int_type __c)
 199     { return std::ungetc(__c, _M_file); }
 200
 201   template<>
 202     inline stdio_sync_filebuf<char>::int_type
 203     stdio_sync_filebuf<char>::syncputc(int_type __c)
 204     { return std::putc(__c, _M_file); }
 205
 206   template<>
 207     inline std::streamsize
 208     stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
 209     {
 210       std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
 211       if (__ret > 0)
 212         _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
 213       else
 214         _M_unget_buf = traits_type::eof();
 215       return __ret;
 216     }
 217
 218   template<>
 219     inline std::streamsize
 220     stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
 221     { return std::fwrite(__s, 1, __n, _M_file); }
 222
 223 #ifdef _GLIBCXX_USE_WCHAR_T
 224   template<>
 225     inline stdio_sync_filebuf<wchar_t>::int_type
 226     stdio_sync_filebuf<wchar_t>::syncgetc()
 227     { return std::getwc(_M_file); }
 228
 229   template<>
 230     inline stdio_sync_filebuf<wchar_t>::int_type
 231     stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
 232     { return std::ungetwc(__c, _M_file); }
 233
 234   template<>
 235     inline stdio_sync_filebuf<wchar_t>::int_type
 236     stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
 237     { return std::putwc(__c, _M_file); }
 238
 239   template<>
 240     inline std::streamsize
 241     stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
 242     {
 243       std::streamsize __ret = 0;
 244       const int_type __eof = traits_type::eof();
 245       while (__n--)
 246         {
 247           int_type __c = this->syncgetc();
 248           if (traits_type::eq_int_type(__c, __eof))
 249             break;
 250           __s[__ret] = traits_type::to_char_type(__c);
 251           ++__ret;
 252         }
 253
 254       if (__ret > 0)
 255         _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
 256       else
 257         _M_unget_buf = traits_type::eof();
 258       return __ret;
 259     }
 260
 261   template<>
 262     inline std::streamsize
 263     stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
 264                                         std::streamsize __n)
 265     {
 266       std::streamsize __ret = 0;
 267       const int_type __eof = traits_type::eof();
 268       while (__n--)
 269         {
 270           if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
 271             break;
 272           ++__ret;
 273         }
 274       return __ret;
 275     }
 276 #endif
 277
 278 #if _GLIBCXX_EXTERN_TEMPLATE
 279   extern template class stdio_sync_filebuf<char>;
 280 #ifdef _GLIBCXX_USE_WCHAR_T
 281   extern template class stdio_sync_filebuf<wchar_t>;
 282 #endif
 283 #endif
 284
 285 _GLIBCXX_END_NAMESPACE
 286
 287 #endif