stdio_sync_filebuf.h

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00001 // Iostreams wrapper for stdio FILE* -*- C++ -*-
00002 
00003 // Copyright (C) 2003, 2004, 2005, 2006, 2007 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 2, 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 // You should have received a copy of the GNU General Public License along
00017 // with this library; see the file COPYING.  If not, write to the Free
00018 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
00019 // USA.
00020 
00021 // As a special exception, you may use this file as part of a free software
00022 // library without restriction.  Specifically, if other files instantiate
00023 // templates or use macros or inline functions from this file, or you compile
00024 // this file and link it with other files to produce an executable, this
00025 // file does not by itself cause the resulting executable to be covered by
00026 // the GNU General Public License.  This exception does not however
00027 // invalidate any other reasons why the executable file might be covered by
00028 // the GNU General Public License.
00029 
00030 /** @file ext/stdio_sync_filebuf.h
00031  *  This file is a GNU extension to the Standard C++ Library.
00032  */
00033 
00034 #ifndef _STDIO_SYNC_FILEBUF_H
00035 #define _STDIO_SYNC_FILEBUF_H 1
00036 
00037 #pragma GCC system_header
00038 
00039 #include <streambuf>
00040 #include <unistd.h>
00041 #include <cstdio>
00042 #include <bits/c++io.h>  // For __c_file
00043 
00044 #ifdef _GLIBCXX_USE_WCHAR_T
00045 #include <cwchar>
00046 #endif
00047 
00048 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00049 
00050   /// class stdio_sync_filebuf.
00051   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
00052     class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
00053     {
00054     public:
00055       // Types:
00056       typedef _CharT                    char_type;
00057       typedef _Traits                   traits_type;
00058       typedef typename traits_type::int_type        int_type;
00059       typedef typename traits_type::pos_type        pos_type;
00060       typedef typename traits_type::off_type        off_type;
00061 
00062     private:
00063       // Underlying stdio FILE
00064       std::__c_file* const _M_file;
00065 
00066       // Last character gotten. This is used when pbackfail is
00067       // called from basic_streambuf::sungetc()
00068       int_type _M_unget_buf;
00069 
00070     public:
00071       explicit
00072       stdio_sync_filebuf(std::__c_file* __f)
00073       : _M_file(__f), _M_unget_buf(traits_type::eof())
00074       { }
00075 
00076       /**
00077        *  @return  The underlying FILE*.
00078        *
00079        *  This function can be used to access the underlying "C" file pointer.
00080        *  Note that there is no way for the library to track what you do
00081        *  with the file, so be careful.
00082        */
00083       std::__c_file* const
00084       file() { return this->_M_file; }
00085 
00086     protected:
00087       int_type
00088       syncgetc();
00089 
00090       int_type
00091       syncungetc(int_type __c);
00092 
00093       int_type
00094       syncputc(int_type __c);
00095 
00096       virtual int_type
00097       underflow()
00098       {
00099     int_type __c = this->syncgetc();
00100     return this->syncungetc(__c);
00101       }
00102 
00103       virtual int_type
00104       uflow()
00105       {
00106     // Store the gotten character in case we need to unget it.
00107     _M_unget_buf = this->syncgetc();
00108     return _M_unget_buf;
00109       }
00110 
00111       virtual int_type
00112       pbackfail(int_type __c = traits_type::eof())
00113       {
00114     int_type __ret;
00115     const int_type __eof = traits_type::eof();
00116 
00117     // Check if the unget or putback was requested
00118     if (traits_type::eq_int_type(__c, __eof)) // unget
00119       {
00120         if (!traits_type::eq_int_type(_M_unget_buf, __eof))
00121           __ret = this->syncungetc(_M_unget_buf);
00122         else // buffer invalid, fail.
00123           __ret = __eof;
00124       }
00125     else // putback
00126       __ret = this->syncungetc(__c);
00127 
00128     // The buffered character is no longer valid, discard it.
00129     _M_unget_buf = __eof;
00130     return __ret;
00131       }
00132 
00133       virtual std::streamsize
00134       xsgetn(char_type* __s, std::streamsize __n);
00135 
00136       virtual int_type
00137       overflow(int_type __c = traits_type::eof())
00138       {
00139     int_type __ret;
00140     if (traits_type::eq_int_type(__c, traits_type::eof()))
00141       {
00142         if (std::fflush(_M_file))
00143           __ret = traits_type::eof();
00144         else
00145           __ret = traits_type::not_eof(__c);
00146       }
00147     else
00148       __ret = this->syncputc(__c);
00149     return __ret;
00150       }
00151 
00152       virtual std::streamsize
00153       xsputn(const char_type* __s, std::streamsize __n);
00154 
00155       virtual int
00156       sync()
00157       { return std::fflush(_M_file); }
00158 
00159       virtual std::streampos
00160       seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
00161           std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
00162       {
00163     std::streampos __ret(std::streamoff(-1));
00164     int __whence;
00165     if (__dir == std::ios_base::beg)
00166       __whence = SEEK_SET;
00167     else if (__dir == std::ios_base::cur)
00168       __whence = SEEK_CUR;
00169     else
00170       __whence = SEEK_END;
00171 #ifdef _GLIBCXX_USE_LFS
00172     if (!fseeko64(_M_file, __off, __whence))
00173       __ret = std::streampos(ftello64(_M_file));
00174 #else
00175     if (!fseek(_M_file, __off, __whence))
00176       __ret = std::streampos(std::ftell(_M_file));
00177 #endif
00178     return __ret;
00179       }
00180 
00181       virtual std::streampos
00182       seekpos(std::streampos __pos,
00183           std::ios_base::openmode __mode =
00184           std::ios_base::in | std::ios_base::out)
00185       { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
00186     };
00187 
00188   template<>
00189     inline stdio_sync_filebuf<char>::int_type
00190     stdio_sync_filebuf<char>::syncgetc()
00191     { return std::getc(_M_file); }
00192 
00193   template<>
00194     inline stdio_sync_filebuf<char>::int_type
00195     stdio_sync_filebuf<char>::syncungetc(int_type __c)
00196     { return std::ungetc(__c, _M_file); }
00197 
00198   template<>
00199     inline stdio_sync_filebuf<char>::int_type
00200     stdio_sync_filebuf<char>::syncputc(int_type __c)
00201     { return std::putc(__c, _M_file); }
00202 
00203   template<>
00204     inline std::streamsize
00205     stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
00206     {
00207       std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
00208       if (__ret > 0)
00209     _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
00210       else
00211     _M_unget_buf = traits_type::eof();
00212       return __ret;
00213     }
00214 
00215   template<>
00216     inline std::streamsize
00217     stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
00218     { return std::fwrite(__s, 1, __n, _M_file); }
00219 
00220 #ifdef _GLIBCXX_USE_WCHAR_T
00221   template<>
00222     inline stdio_sync_filebuf<wchar_t>::int_type
00223     stdio_sync_filebuf<wchar_t>::syncgetc()
00224     { return std::getwc(_M_file); }
00225 
00226   template<>
00227     inline stdio_sync_filebuf<wchar_t>::int_type
00228     stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
00229     { return std::ungetwc(__c, _M_file); }
00230 
00231   template<>
00232     inline stdio_sync_filebuf<wchar_t>::int_type
00233     stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
00234     { return std::putwc(__c, _M_file); }
00235 
00236   template<>
00237     inline std::streamsize
00238     stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
00239     {
00240       std::streamsize __ret = 0;
00241       const int_type __eof = traits_type::eof();
00242       while (__n--)
00243     {
00244       int_type __c = this->syncgetc();
00245       if (traits_type::eq_int_type(__c, __eof))
00246         break;
00247       __s[__ret] = traits_type::to_char_type(__c);
00248       ++__ret;
00249     }
00250 
00251       if (__ret > 0)
00252     _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
00253       else
00254     _M_unget_buf = traits_type::eof();
00255       return __ret;
00256     }
00257 
00258   template<>
00259     inline std::streamsize
00260     stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
00261                     std::streamsize __n)
00262     {
00263       std::streamsize __ret = 0;
00264       const int_type __eof = traits_type::eof();
00265       while (__n--)
00266     {
00267       if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
00268         break;
00269       ++__ret;
00270     }
00271       return __ret;
00272     }
00273 #endif
00274 
00275 #if _GLIBCXX_EXTERN_TEMPLATE
00276   extern template class stdio_sync_filebuf<char>;
00277 #ifdef _GLIBCXX_USE_WCHAR_T
00278   extern template class stdio_sync_filebuf<wchar_t>;
00279 #endif
00280 #endif
00281 
00282 _GLIBCXX_END_NAMESPACE
00283 
00284 #endif

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