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

   1 // Iostreams wrapper for stdio FILE* -*- C++ -*-
   2
   3 // Copyright (C) 2003, 2004, 2005, 2006, 2007 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  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 #include <bits/c++io.h>  // For __c_file
  43
  44 #ifdef _GLIBCXX_USE_WCHAR_T
  45 #include <cwchar>
  46 #endif
  47
  48 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  49
  50   /// class stdio_sync_filebuf.
  51   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
  52     class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
  53     {
  54     public:
  55       // Types:
  56       typedef _CharT                                    char_type;
  57       typedef _Traits                                   traits_type;
  58       typedef typename traits_type::int_type            int_type;
  59       typedef typename traits_type::pos_type            pos_type;
  60       typedef typename traits_type::off_type            off_type;
  61
  62     private:
  63       // Underlying stdio FILE
  64       std::__c_file* const _M_file;
  65
  66       // Last character gotten. This is used when pbackfail is
  67       // called from basic_streambuf::sungetc()
  68       int_type _M_unget_buf;
  69
  70     public:
  71       explicit
  72       stdio_sync_filebuf(std::__c_file* __f)
  73       : _M_file(__f), _M_unget_buf(traits_type::eof())
  74       { }
  75
  76       /**
  77        *  @return  The underlying FILE*.
  78        *
  79        *  This function can be used to access the underlying "C" file pointer.
  80        *  Note that there is no way for the library to track what you do
  81        *  with the file, so be careful.
  82        */
  83       std::__c_file* const
  84       file() { return this->_M_file; }
  85
  86     protected:
  87       int_type
  88       syncgetc();
  89
  90       int_type
  91       syncungetc(int_type __c);
  92
  93       int_type
  94       syncputc(int_type __c);
  95
  96       virtual int_type
  97       underflow()
  98       {
  99         int_type __c = this->syncgetc();
 100         return this->syncungetc(__c);
 101       }
 102
 103       virtual int_type
 104       uflow()
 105       {
 106         // Store the gotten character in case we need to unget it.
 107         _M_unget_buf = this->syncgetc();
 108         return _M_unget_buf;
 109       }
 110
 111       virtual int_type
 112       pbackfail(int_type __c = traits_type::eof())
 113       {
 114         int_type __ret;
 115         const int_type __eof = traits_type::eof();
 116
 117         // Check if the unget or putback was requested
 118         if (traits_type::eq_int_type(__c, __eof)) // unget
 119           {
 120             if (!traits_type::eq_int_type(_M_unget_buf, __eof))
 121               __ret = this->syncungetc(_M_unget_buf);
 122             else // buffer invalid, fail.
 123               __ret = __eof;
 124           }
 125         else // putback
 126           __ret = this->syncungetc(__c);
 127
 128         // The buffered character is no longer valid, discard it.
 129         _M_unget_buf = __eof;
 130         return __ret;
 131       }
 132
 133       virtual std::streamsize
 134       xsgetn(char_type* __s, std::streamsize __n);
 135
 136       virtual int_type
 137       overflow(int_type __c = traits_type::eof())
 138       {
 139         int_type __ret;
 140         if (traits_type::eq_int_type(__c, traits_type::eof()))
 141           {
 142             if (std::fflush(_M_file))
 143               __ret = traits_type::eof();
 144             else
 145               __ret = traits_type::not_eof(__c);
 146           }
 147         else
 148           __ret = this->syncputc(__c);
 149         return __ret;
 150       }
 151
 152       virtual std::streamsize
 153       xsputn(const char_type* __s, std::streamsize __n);
 154
 155       virtual int
 156       sync()
 157       { return std::fflush(_M_file); }
 158
 159       virtual std::streampos
 160       seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
 161               std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
 162       {
 163         std::streampos __ret(std::streamoff(-1));
 164         int __whence;
 165         if (__dir == std::ios_base::beg)
 166           __whence = SEEK_SET;
 167         else if (__dir == std::ios_base::cur)
 168           __whence = SEEK_CUR;
 169         else
 170           __whence = SEEK_END;
 171 #ifdef _GLIBCXX_USE_LFS
 172         if (!fseeko64(_M_file, __off, __whence))
 173           __ret = std::streampos(ftello64(_M_file));
 174 #else
 175         if (!fseek(_M_file, __off, __whence))
 176           __ret = std::streampos(std::ftell(_M_file));
 177 #endif
 178         return __ret;
 179       }
 180
 181       virtual std::streampos
 182       seekpos(std::streampos __pos,
 183               std::ios_base::openmode __mode =
 184               std::ios_base::in | std::ios_base::out)
 185       { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
 186     };
 187
 188   template<>
 189     inline stdio_sync_filebuf<char>::int_type
 190     stdio_sync_filebuf<char>::syncgetc()
 191     { return std::getc(_M_file); }
 192
 193   template<>
 194     inline stdio_sync_filebuf<char>::int_type
 195     stdio_sync_filebuf<char>::syncungetc(int_type __c)
 196     { return std::ungetc(__c, _M_file); }
 197
 198   template<>
 199     inline stdio_sync_filebuf<char>::int_type
 200     stdio_sync_filebuf<char>::syncputc(int_type __c)
 201     { return std::putc(__c, _M_file); }
 202
 203   template<>
 204     inline std::streamsize
 205     stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
 206     {
 207       std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
 208       if (__ret > 0)
 209         _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
 210       else
 211         _M_unget_buf = traits_type::eof();
 212       return __ret;
 213     }
 214
 215   template<>
 216     inline std::streamsize
 217     stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
 218     { return std::fwrite(__s, 1, __n, _M_file); }
 219
 220 #ifdef _GLIBCXX_USE_WCHAR_T
 221   template<>
 222     inline stdio_sync_filebuf<wchar_t>::int_type
 223     stdio_sync_filebuf<wchar_t>::syncgetc()
 224     { return std::getwc(_M_file); }
 225
 226   template<>
 227     inline stdio_sync_filebuf<wchar_t>::int_type
 228     stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
 229     { return std::ungetwc(__c, _M_file); }
 230
 231   template<>
 232     inline stdio_sync_filebuf<wchar_t>::int_type
 233     stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
 234     { return std::putwc(__c, _M_file); }
 235
 236   template<>
 237     inline std::streamsize
 238     stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
 239     {
 240       std::streamsize __ret = 0;
 241       const int_type __eof = traits_type::eof();
 242       while (__n--)
 243         {
 244           int_type __c = this->syncgetc();
 245           if (traits_type::eq_int_type(__c, __eof))
 246             break;
 247           __s[__ret] = traits_type::to_char_type(__c);
 248           ++__ret;
 249         }
 250
 251       if (__ret > 0)
 252         _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
 253       else
 254         _M_unget_buf = traits_type::eof();
 255       return __ret;
 256     }
 257
 258   template<>
 259     inline std::streamsize
 260     stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
 261                                         std::streamsize __n)
 262     {
 263       std::streamsize __ret = 0;
 264       const int_type __eof = traits_type::eof();
 265       while (__n--)
 266         {
 267           if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
 268             break;
 269           ++__ret;
 270         }
 271       return __ret;
 272     }
 273 #endif
 274
 275 #if _GLIBCXX_EXTERN_TEMPLATE
 276   extern template class stdio_sync_filebuf<char>;
 277 #ifdef _GLIBCXX_USE_WCHAR_T
 278   extern template class stdio_sync_filebuf<wchar_t>;
 279 #endif
 280 #endif
 281
 282 _GLIBCXX_END_NAMESPACE
 283
 284 #endif