# stdio_sync_filebuf.h

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    00001 // Iostreams wrapper for stdio FILE* -*- C++ -*-
    00002
    00003 // Copyright (C) 2003, 2004 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    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
    00043 #ifdef _GLIBCXX_USE_WCHAR_T
    00044 #include <cwchar>
    00045 #endif
    00046
    00047 namespace __gnu_cxx
    00048 {
    00049   /// @brief  class stdio_sync_filebuf.
    00050   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
    00051     class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
    00052     {
    00053     public:
    00054       // Types:
    00055       typedef _CharT                    char_type;
    00056       typedef _Traits                   traits_type;
    00057       typedef typename traits_type::int_type        int_type;
    00058       typedef typename traits_type::pos_type        pos_type;
    00059       typedef typename traits_type::off_type        off_type;
    00060
    00061     private:
    00062       // Underlying stdio FILE
    00063       std::__c_file* const _M_file;
    00064
    00065       // Last character gotten. This is used when pbackfail is
    00066       // called from basic_streambuf::sungetc()
    00067       int_type _M_unget_buf;
    00068
    00069     public:
    00070       explicit
    00071       stdio_sync_filebuf(std::__c_file* __f)
    00072       : _M_file(__f), _M_unget_buf(traits_type::eof())
    00073       { }
    00074
    00075       /**
    00076        *  @return  The underlying FILE*.
    00077        *
    00078        *  This function can be used to access the underlying "C" file pointer.
    00079        *  Note that there is no way for the library to track what you do
    00080        *  with the file, so be careful.
    00081        */
    00082       std::__c_file* const
    00083       file() { return this->_M_file; }
    00084
    00085     protected:
    00086       int_type
    00087       syncgetc();
    00088
    00089       int_type
    00090       syncungetc(int_type __c);
    00091
    00092       int_type
    00093       syncputc(int_type __c);
    00094
    00095       virtual int_type
    00096       underflow()
    00097       {
    00098     int_type __c = this->syncgetc();
    00099     return this->syncungetc(__c);
    00100       }
    00101
    00102       virtual int_type
    00103       uflow()
    00104       {
    00105     // Store the gotten character in case we need to unget it.
    00106     _M_unget_buf = this->syncgetc();
    00107     return _M_unget_buf;
    00108       }
    00109
    00110       virtual int_type
    00111       pbackfail(int_type __c = traits_type::eof())
    00112       {
    00113     int_type __ret;
    00114     const int_type __eof = traits_type::eof();
    00115
    00116     // Check if the unget or putback was requested
    00117     if (traits_type::eq_int_type(__c, __eof)) // unget
    00118       {
    00119         if (!traits_type::eq_int_type(_M_unget_buf, __eof))
    00120           __ret = this->syncungetc(_M_unget_buf);
    00121         else // buffer invalid, fail.
    00122           __ret = __eof;
    00123       }
    00124     else // putback
    00125       __ret = this->syncungetc(__c);
    00126
    00127     // The buffered character is no longer valid, discard it.
    00128     _M_unget_buf = __eof;
    00129     return __ret;
    00130       }
    00131
    00132       virtual std::streamsize
    00133       xsgetn(char_type* __s, std::streamsize __n);
    00134
    00135       virtual int_type
    00136       overflow(int_type __c = traits_type::eof())
    00137       {
    00138     int_type __ret;
    00139     if (traits_type::eq_int_type(__c, traits_type::eof()))
    00140       {
    00141         if (std::fflush(_M_file))
    00142           __ret = traits_type::eof();
    00143         else
    00144           __ret = traits_type::not_eof(__c);
    00145       }
    00146     else
    00147       __ret = this->syncputc(__c);
    00148     return __ret;
    00149       }
    00150
    00151       virtual std::streamsize
    00152       xsputn(const char_type* __s, std::streamsize __n);
    00153
    00154       virtual int
    00155       sync()
    00156       { return std::fflush(_M_file); }
    00157
    00158       virtual std::streampos
    00159       seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
    00160           std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
    00161       {
    00162     std::streampos __ret(std::streamoff(-1));
    00163     int __whence;
    00164     if (__dir == std::ios_base::beg)
    00165       __whence = SEEK_SET;
    00166     else if (__dir == std::ios_base::cur)
    00167       __whence = SEEK_CUR;
    00168     else
    00169       __whence = SEEK_END;
    00170 #ifdef _GLIBCXX_USE_LFS
    00171     if (!fseeko64(_M_file, __off, __whence))
    00172       __ret = std::streampos(ftello64(_M_file));
    00173 #else
    00174     if (!fseek(_M_file, __off, __whence))
    00175       __ret = std::streampos(std::ftell(_M_file));
    00176 #endif
    00177     return __ret;
    00178       }
    00179
    00180       virtual std::streampos
    00181       seekpos(std::streampos __pos,
    00182           std::ios_base::openmode __mode =
    00183           std::ios_base::in | std::ios_base::out)
    00184       { return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
    00185     };
    00186
    00187   template<>
    00188     inline stdio_sync_filebuf<char>::int_type
    00189     stdio_sync_filebuf<char>::syncgetc()
    00190     { return std::getc(_M_file); }
    00191
    00192   template<>
    00193     inline stdio_sync_filebuf<char>::int_type
    00194     stdio_sync_filebuf<char>::syncungetc(int_type __c)
    00195     { return std::ungetc(__c, _M_file); }
    00196
    00197   template<>
    00198     inline stdio_sync_filebuf<char>::int_type
    00199     stdio_sync_filebuf<char>::syncputc(int_type __c)
    00200     { return std::putc(__c, _M_file); }
    00201
    00202   template<>
    00203     inline std::streamsize
    00204     stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
    00205     {
    00206       std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
    00207       if (__ret > 0)
    00208     _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
    00209       else
    00210     _M_unget_buf = traits_type::eof();
    00211       return __ret;
    00212     }
    00213
    00214   template<>
    00215     inline std::streamsize
    00216     stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
    00217     { return std::fwrite(__s, 1, __n, _M_file); }
    00218
    00219 #ifdef _GLIBCXX_USE_WCHAR_T
    00220   template<>
    00221     inline stdio_sync_filebuf<wchar_t>::int_type
    00222     stdio_sync_filebuf<wchar_t>::syncgetc()
    00223     { return std::getwc(_M_file); }
    00224
    00225   template<>
    00226     inline stdio_sync_filebuf<wchar_t>::int_type
    00227     stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
    00228     { return std::ungetwc(__c, _M_file); }
    00229
    00230   template<>
    00231     inline stdio_sync_filebuf<wchar_t>::int_type
    00232     stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
    00233     { return std::putwc(__c, _M_file); }
    00234
    00235   template<>
    00236     inline std::streamsize
    00237     stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
    00238     {
    00239       std::streamsize __ret = 0;
    00240       const int_type __eof = traits_type::eof();
    00241       while (__n--)
    00242     {
    00243       int_type __c = this->syncgetc();
    00244       if (traits_type::eq_int_type(__c, __eof))
    00245         break;
    00246       __s[__ret] = traits_type::to_char_type(__c);
    00247       ++__ret;
    00248     }
    00249
    00250       if (__ret > 0)
    00251     _M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
    00252       else
    00253     _M_unget_buf = traits_type::eof();
    00254       return __ret;
    00255     }
    00256
    00257   template<>
    00258     inline std::streamsize
    00259     stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
    00260                     std::streamsize __n)
    00261     {
    00262       std::streamsize __ret = 0;
    00263       const int_type __eof = traits_type::eof();
    00264       while (__n--)
    00265     {
    00266       if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
    00267         break;
    00268       ++__ret;
    00269     }
    00270       return __ret;
    00271     }
    00272 #endif
    00273
    00274 #if _GLIBCXX_EXTERN_TEMPLATE
    00275   extern template class stdio_sync_filebuf<char>;
    00276 #ifdef _GLIBCXX_USE_WCHAR_T
    00277   extern template class stdio_sync_filebuf<wchar_t>;
    00278 #endif
    00279 #endif
    00280 } // namespace __gnu_cxx
    00281
    00282 #endif