# stdio_sync_filebuf.h

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