stdio_sync_filebuf.h

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00001 // Iostreams wrapper for stdio FILE* -*- C++ -*-
00002 
00003 // Copyright (C) 2003, 2004, 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file ext/stdio_sync_filebuf.h
00026  *  This file is a GNU extension to the Standard C++ Library.
00027  */
00028 
00029 #ifndef _STDIO_SYNC_FILEBUF_H
00030 #define _STDIO_SYNC_FILEBUF_H 1
00031 
00032 #pragma GCC system_header
00033 
00034 #include <streambuf>
00035 #include <unistd.h>
00036 #include <cstdio>
00037 #include <bits/c++io.h>  // For __c_file
00038 
00039 #ifdef _GLIBCXX_USE_WCHAR_T
00040 #include <cwchar>
00041 #endif
00042 
00043 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00044 
00045   /// class stdio_sync_filebuf.
00046   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
00047     class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
00048     {
00049     public:
00050       // Types:
00051       typedef _CharT                    char_type;
00052       typedef _Traits                   traits_type;
00053       typedef typename traits_type::int_type        int_type;
00054       typedef typename traits_type::pos_type        pos_type;
00055       typedef typename traits_type::off_type        off_type;
00056 
00057     private:
00058       // Underlying stdio FILE
00059       std::__c_file* const _M_file;
00060 
00061       // Last character gotten. This is used when pbackfail is
00062       // called from basic_streambuf::sungetc()
00063       int_type _M_unget_buf;
00064 
00065     public:
00066       explicit
00067       stdio_sync_filebuf(std::__c_file* __f)
00068       : _M_file(__f), _M_unget_buf(traits_type::eof())
00069       { }
00070 
00071       /**
00072        *  @return  The underlying FILE*.
00073        *
00074        *  This function can be used to access the underlying "C" file pointer.
00075        *  Note that there is no way for the library to track what you do
00076        *  with the file, so be careful.
00077        */
00078       std::__c_file* const
00079       file() { return this->_M_file; }
00080 
00081     protected:
00082       int_type
00083       syncgetc();
00084 
00085       int_type
00086       syncungetc(int_type __c);
00087 
00088       int_type
00089       syncputc(int_type __c);
00090 
00091       virtual int_type
00092       underflow()
00093       {
00094     int_type __c = this->syncgetc();
00095     return this->syncungetc(__c);
00096       }
00097 
00098       virtual int_type
00099       uflow()
00100       {
00101     // Store the gotten character in case we need to unget it.
00102     _M_unget_buf = this->syncgetc();
00103     return _M_unget_buf;
00104       }
00105 
00106       virtual int_type
00107       pbackfail(int_type __c = traits_type::eof())
00108       {
00109     int_type __ret;
00110     const int_type __eof = traits_type::eof();
00111 
00112     // Check if the unget or putback was requested
00113     if (traits_type::eq_int_type(__c, __eof)) // unget
00114       {
00115         if (!traits_type::eq_int_type(_M_unget_buf, __eof))
00116           __ret = this->syncungetc(_M_unget_buf);
00117         else // buffer invalid, fail.
00118           __ret = __eof;
00119       }
00120     else // putback
00121       __ret = this->syncungetc(__c);
00122 
00123     // The buffered character is no longer valid, discard it.
00124     _M_unget_buf = __eof;
00125     return __ret;
00126       }
00127 
00128       virtual std::streamsize
00129       xsgetn(char_type* __s, std::streamsize __n);
00130 
00131       virtual int_type
00132       overflow(int_type __c = traits_type::eof())
00133       {
00134     int_type __ret;
00135     if (traits_type::eq_int_type(__c, traits_type::eof()))
00136       {
00137         if (std::fflush(_M_file))
00138           __ret = traits_type::eof();
00139         else
00140           __ret = traits_type::not_eof(__c);
00141       }
00142     else
00143       __ret = this->syncputc(__c);
00144     return __ret;
00145       }
00146 
00147       virtual std::streamsize
00148       xsputn(const char_type* __s, std::streamsize __n);
00149 
00150       virtual int
00151       sync()
00152       { return std::fflush(_M_file); }
00153 
00154       virtual std::streampos
00155       seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
00156           std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
00157       {
00158     std::streampos __ret(std::streamoff(-1));
00159     int __whence;
00160     if (__dir == std::ios_base::beg)
00161       __whence = SEEK_SET;
00162     else if (__dir == std::ios_base::cur)
00163       __whence = SEEK_CUR;
00164     else
00165       __whence = SEEK_END;
00166 #ifdef _GLIBCXX_USE_LFS
00167     if (!fseeko64(_M_file, __off, __whence))
00168       __ret = std::streampos(ftello64(_M_file));
00169 #else
00170     if (!fseek(_M_file, __off, __whence))
00171       __ret = std::streampos(std::ftell(_M_file));
00172 #endif
00173     return __ret;
00174       }
00175 
00176       virtual std::streampos
00177       seekpos(std::streampos __pos,
00178           std::ios_base::openmode __mode =
00179           std::ios_base::in | std::ios_base::out)
00180       { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
00181     };
00182 
00183   template<>
00184     inline stdio_sync_filebuf<char>::int_type
00185     stdio_sync_filebuf<char>::syncgetc()
00186     { return std::getc(_M_file); }
00187 
00188   template<>
00189     inline stdio_sync_filebuf<char>::int_type
00190     stdio_sync_filebuf<char>::syncungetc(int_type __c)
00191     { return std::ungetc(__c, _M_file); }
00192 
00193   template<>
00194     inline stdio_sync_filebuf<char>::int_type
00195     stdio_sync_filebuf<char>::syncputc(int_type __c)
00196     { return std::putc(__c, _M_file); }
00197 
00198   template<>
00199     inline std::streamsize
00200     stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
00201     {
00202       std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
00203       if (__ret > 0)
00204     _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
00205       else
00206     _M_unget_buf = traits_type::eof();
00207       return __ret;
00208     }
00209 
00210   template<>
00211     inline std::streamsize
00212     stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
00213     { return std::fwrite(__s, 1, __n, _M_file); }
00214 
00215 #ifdef _GLIBCXX_USE_WCHAR_T
00216   template<>
00217     inline stdio_sync_filebuf<wchar_t>::int_type
00218     stdio_sync_filebuf<wchar_t>::syncgetc()
00219     { return std::getwc(_M_file); }
00220 
00221   template<>
00222     inline stdio_sync_filebuf<wchar_t>::int_type
00223     stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
00224     { return std::ungetwc(__c, _M_file); }
00225 
00226   template<>
00227     inline stdio_sync_filebuf<wchar_t>::int_type
00228     stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
00229     { return std::putwc(__c, _M_file); }
00230 
00231   template<>
00232     inline std::streamsize
00233     stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
00234     {
00235       std::streamsize __ret = 0;
00236       const int_type __eof = traits_type::eof();
00237       while (__n--)
00238     {
00239       int_type __c = this->syncgetc();
00240       if (traits_type::eq_int_type(__c, __eof))
00241         break;
00242       __s[__ret] = traits_type::to_char_type(__c);
00243       ++__ret;
00244     }
00245 
00246       if (__ret > 0)
00247     _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
00248       else
00249     _M_unget_buf = traits_type::eof();
00250       return __ret;
00251     }
00252 
00253   template<>
00254     inline std::streamsize
00255     stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
00256                     std::streamsize __n)
00257     {
00258       std::streamsize __ret = 0;
00259       const int_type __eof = traits_type::eof();
00260       while (__n--)
00261     {
00262       if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
00263         break;
00264       ++__ret;
00265     }
00266       return __ret;
00267     }
00268 #endif
00269 
00270 #if _GLIBCXX_EXTERN_TEMPLATE
00271   extern template class stdio_sync_filebuf<char>;
00272 #ifdef _GLIBCXX_USE_WCHAR_T
00273   extern template class stdio_sync_filebuf<wchar_t>;
00274 #endif
00275 #endif
00276 
00277 _GLIBCXX_END_NAMESPACE
00278 
00279 #endif

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