# stdio_sync_filebuf.h

Go to the documentation of this file.

    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