# 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