fstream.tcc

gcc-you can use this code to learn something about gcc, and inquire further into linux,

// File based streams -*- C++ -*-

// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

//
// ISO C++ 14882: 27.8  File-based streams
//

#ifndef _CPP_BITS_FSTREAM_TCC
#define _CPP_BITS_FSTREAM_TCC 1

#pragma GCC system_header

namespace std
{
  template<typename _CharT, typename _Traits>
    void
    basic_filebuf<_CharT, _Traits>::
    _M_allocate_internal_buffer()
    {
      if (!_M_buf && _M_buf_size_opt)
	{
	  _M_buf_size = _M_buf_size_opt;

	  // Allocate internal buffer.
	  _M_buf = new char_type[_M_buf_size]; 
	  _M_buf_allocated = true;
	}
    }

  // Both close and setbuf need to deallocate internal buffers, if it exists.
  template<typename _CharT, typename _Traits>
    void
    basic_filebuf<_CharT, _Traits>::
    _M_destroy_internal_buffer() throw()
    {
      if (_M_buf_allocated)
	{
	  delete [] _M_buf;
	  _M_buf = NULL;
	  _M_buf_allocated = false;
	  this->setg(NULL, NULL, NULL);
	  this->setp(NULL, NULL);
	}
    }

  template<typename _CharT, typename _Traits>
    basic_filebuf<_CharT, _Traits>::
    basic_filebuf() : __streambuf_type(), _M_file(&_M_lock), 
    _M_state_cur(__state_type()), _M_state_beg(__state_type()), 
    _M_buf_allocated(false), _M_last_overflowed(false)
    { _M_buf_unified = true; }

  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::__filebuf_type* 
    basic_filebuf<_CharT, _Traits>::
    open(const char* __s, ios_base::openmode __mode)
    {
      __filebuf_type *__ret = NULL;
      if (!this->is_open())
	{
	  _M_file.open(__s, __mode);
	  if (this->is_open())
	    {
	      _M_allocate_internal_buffer();
	      _M_mode = __mode;

	      // Setup initial position of buffer.
	      _M_set_indeterminate();

	      if ((__mode & ios_base::ate)
		  && this->seekoff(0, ios_base::end, __mode) < 0)
		{
		  // 27.8.1.3,4
		  this->close();
		  return __ret;
		}

	      __ret = this;
	    }
	}
      return __ret;
    }

  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::__filebuf_type* 
    basic_filebuf<_CharT, _Traits>::
    close() throw()
    {
      __filebuf_type* __ret = NULL;
      if (this->is_open())
	{
	  bool __testfail = false;
	  try
	    {
	      const int_type __eof = traits_type::eof();
	      bool __testput = _M_out_cur && _M_out_beg < _M_out_end;
	      if (__testput 
		  && traits_type::eq_int_type(_M_really_overflow(__eof), 
					      __eof))
		__testfail = true;
	      
#if 0
	      // XXX not done
	      if (_M_last_overflowed)
		{
		  _M_output_unshift();
		  _M_really_overflow(__eof);
		}
#endif
	    }
	  catch(...)
	    {
	      __testfail = true;
	    }

	  // NB: Do this here so that re-opened filebufs will be cool...
	  this->_M_mode = ios_base::openmode(0);
	  _M_destroy_internal_buffer();
	  _M_pback_destroy();

	  if (!_M_file.close())
	    __testfail = true;

	  if (!__testfail)
	    __ret = this;
	}
      _M_last_overflowed = false;	
      return __ret;
    }

  template<typename _CharT, typename _Traits>
    streamsize 
    basic_filebuf<_CharT, _Traits>::
    showmanyc()
    {
      streamsize __ret = -1;
      bool __testin = _M_mode & ios_base::in;
      const locale __loc = this->getloc();
      const __codecvt_type& __cvt = use_facet<__codecvt_type>(__loc);

      if (__testin && this->is_open())
	{
	  __ret = _M_in_end - _M_in_cur;
	  if (__cvt.always_noconv())
	    __ret += _M_file.showmanyc_helper();
	}

      _M_last_overflowed = false;	
      return __ret;
    }
  
  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::int_type 
    basic_filebuf<_CharT, _Traits>::
    pbackfail(int_type __i)
    {
      int_type __ret = traits_type::eof();
      bool __testin = _M_mode & ios_base::in;

      if (__testin)
	{
	  bool __testpb = _M_in_beg < _M_in_cur;
	  char_type __c = traits_type::to_char_type(__i);
	  bool __testeof = traits_type::eq_int_type(__i, __ret);

	  if (__testpb)
	    {
	      bool __testout = _M_mode & ios_base::out;
	      bool __testeq = traits_type::eq(__c, this->gptr()[-1]);

	      // Try to put back __c into input sequence in one of three ways.
	      // Order these tests done in is unspecified by the standard.
	      if (!__testeof && __testeq)
		{
		  --_M_in_cur;
		  if (__testout)
		    --_M_out_cur;
		  __ret = __i;
		}
	      else if (__testeof)
		{
		  --_M_in_cur;
		  if (__testout)
		    --_M_out_cur;
		  __ret = traits_type::not_eof(__i);
		}
	      else if (!__testeof)
		{
		  --_M_in_cur;
		  if (__testout)
		    --_M_out_cur;
		  _M_pback_create();
		  *_M_in_cur = __c; 
		  __ret = __i;
		}
	    }
	  else
	    {	 
   	      // At the beginning of the buffer, need to make a
  	      // putback position available.
 	      // But the seek may fail (f.i., at the beginning of
 	      // a file, see libstdc++/9439) and in that case
 	      // we return traits_type::eof()
 	      if (this->seekoff(-1, ios_base::cur) >= 0)
 		{
 		  this->underflow();
 		  if (!__testeof)
  		    {
 		      if (!traits_type::eq(__c, *_M_in_cur))
 			{
 			  _M_pback_create();
 			  *_M_in_cur = __c;
 			}
 		      __ret = __i;
  		    }
 		  else
 		    __ret = traits_type::not_eof(__i);
 		}
 	    }
	}
      _M_last_overflowed = false;	
      return __ret;
    }

  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::int_type 
    basic_filebuf<_CharT, _Traits>::
    overflow(int_type __c)
    {
      int_type __ret = traits_type::eof();
      bool __testput = _M_out_cur && _M_out_cur < _M_buf + _M_buf_size;
      bool __testout = _M_mode & ios_base::out;
      
      if (__testout)
	{
	  if (traits_type::eq_int_type(__c, traits_type::eof()))
	    __ret = traits_type::not_eof(__c);
	  else if (__testput)
	    {
	      *_M_out_cur = traits_type::to_char_type(__c);
	      _M_out_cur_move(1);
	      __ret = traits_type::not_eof(__c);
	    }
	  else 
	    __ret = this->_M_really_overflow(__c);