fstream.tcc   [plain text]

// 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()
    {
      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();

	      // Set input buffer to something real.
	      // NB: Must open in non-blocking way to do this, or must
	      // set the initial position in a different manner than
	      // using underflow.
 	      if (__mode & ios_base::in && _M_buf_allocated)
 		this->underflow();
	      
	      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()
    {
      __filebuf_type *__ret = NULL;
      if (this->is_open())
	{
	  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))
	    return __ret;

	  // NB: Do this here so that re-opened filebufs will be cool...
	  _M_mode = ios_base::openmode(0);
	  _M_destroy_internal_buffer();
	  _M_pback_destroy();
	  
#if 0
	  // XXX not done
	  if (_M_last_overflowed)
	    {
	      _M_output_unshift();
	      _M_really_overflow(__eof);
	    }
#endif

	  if (_M_file.close())
	    __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;

      if (__testin && this->is_open())
	__ret = _M_in_end - _M_in_cur;
      _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 (__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);
	}

      _M_last_overflowed = false;    // Set in _M_really_overflow, below.
      return __ret;
    }
  
  template<typename _CharT, typename _Traits>
    void
    basic_filebuf<_CharT, _Traits>::
    _M_convert_to_external(_CharT* __ibuf, streamsize __ilen,
			   streamsize& __elen, streamsize& __plen)
    {
      const locale __loc = this->getloc();
      const __codecvt_type& __cvt = use_facet<__codecvt_type>(__loc);
      
      if (__cvt.always_noconv() && __ilen)
	{
	  __elen += _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
	  __plen += __ilen;
	}
      else
	{
	  // Worst-case number of external bytes needed.
	  int __ext_multiplier = __cvt.encoding();
	  if (__ext_multiplier ==  -1 || __ext_multiplier == 0)
	    __ext_multiplier = sizeof(char_type);
	  streamsize __blen = __ilen * __ext_multiplier;
	  char* __buf = static_cast<char*>(__builtin_alloca(__blen));
	  char* __bend;
	  const char_type* __iend;
	  __res_type __r = __cvt.out(_M_state_cur, __ibuf, __ibuf + __ilen, 
		 		     __iend, __buf, __buf + __blen, __bend);

	  if (__r == codecvt_base::ok || __r == codecvt_base::partial)
	    __blen = __bend - __buf;
	  // Similarly to the always_noconv case above.
	  else if (__r == codecvt_base::noconv)
	    {
	      __buf = reinterpret_cast<char*>(__ibuf);
	      __blen = __ilen;
	    }
	  // Result == error
	  else 
	    __blen = 0;
	  
	  if (__blen)
	    {
	      __elen += _M_file.xsputn(__buf, __blen);
	      __plen += __blen;
	    }

	  // Try once more for partial conversions.
	  if (__r == codecvt_base::partial)
	    {
	      const char_type* __iresume = __iend;
	      streamsize __rlen = _M_out_end - __iend;
	      __r = __cvt.out(_M_state_cur, __iresume, __iresume + __rlen, 
			      __iend, __buf, __buf + __blen, __bend);
	      if (__r != codecvt_base::error)
		__rlen = __bend - __buf;
	      else 
		__rlen = 0;
	      if (__rlen)
		{
		  __elen += _M_file.xsputn(__buf, __rlen);
		  __plen += __rlen;
		}
	    }
	}
    }

  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::int_type 
    basic_filebuf<_CharT, _Traits>::
    _M_really_overflow(int_type __c)
    {
      int_type __ret = traits_type::eof();
      bool __testput = _M_out_cur && _M_out_beg < _M_out_end;
      bool __testunbuffered = _M_file.is_open() && !_M_buf_size_opt;

      if (__testput || __testunbuffered)
	{
	  // Sizes of external and pending output.
	  streamsize __elen = 0;
	  streamsize __plen = 0;

	  // Need to restore current position. The position of the external
	  // byte sequence (_M_file) corresponds to _M_filepos, and we need
	  // to move it to _M_out_beg for the write.
	  if (_M_filepos && _M_filepos != _M_out_beg)
	    {
	      off_type __off = _M_out_beg - _M_filepos;
	      _M_file.seekoff(__off, ios_base::cur);
	    }

	  // Convert internal buffer to external representation, output.
	  // NB: In the unbuffered case, no internal buffer exists. 
	  if (!__testunbuffered)
	    _M_convert_to_external(_M_out_beg,  _M_out_end - _M_out_beg, 
				   __elen, __plen);

	  // Convert pending sequence to external representation, output.
	  // If eof, then just attempt sync.
	  if (!traits_type::eq_int_type(__c, traits_type::eof()))
	    {
	      char_type __pending = traits_type::to_char_type(__c);
	      _M_convert_to_external(&__pending, 1, __elen, __plen);

	      // User code must flush when switching modes (thus don't sync).
	      if (__elen == __plen)
		{
		  _M_set_indeterminate();
		  __ret = traits_type::not_eof(__c);
		}
	    }
	  else if (!_M_file.sync())
	    {
	      _M_set_indeterminate();
	      __ret = traits_type::not_eof(__c);
	    }
	}	      
      _M_last_overflowed = true;	
      return __ret;
    }

  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::__streambuf_type* 
    basic_filebuf<_CharT, _Traits>::
    setbuf(char_type* __s, streamsize __n)
    {
      if (!this->is_open() && __s == 0 && __n == 0)
	_M_buf_size_opt = 0;
      else if (__s && __n)
	{
	  // This is implementation-defined behavior, and assumes
	  // that an external char_type array of length (__s + __n)
	  // exists and has been pre-allocated. If this is not the
	  // case, things will quickly blow up.
	  // Step 1: Destroy the current internal array.
	  _M_destroy_internal_buffer();
	  
	  // Step 2: Use the external array.
	  _M_buf = __s;
	  _M_buf_size_opt = _M_buf_size = __n;
	  _M_set_indeterminate();
	}
      _M_last_overflowed = false;	
      return this; 
    }
  
  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::pos_type
    basic_filebuf<_CharT, _Traits>::
    seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __mode)
    {
      pos_type __ret =  pos_type(off_type(-1)); 
      bool __testin = (ios_base::in & _M_mode & __mode) != 0;
      bool __testout = (ios_base::out & _M_mode & __mode) != 0;

      // Should probably do has_facet checks here.
      int __width = use_facet<__codecvt_type>(_M_buf_locale).encoding();
      if (__width < 0)
	__width = 0;
      bool __testfail = __off != 0 && __width <= 0;
      
      if (this->is_open() && !__testfail && (__testin || __testout)) 
	{
	  // Ditch any pback buffers to avoid confusion.
	  _M_pback_destroy();

	  if (__way != ios_base::cur || __off != 0)
	    { 
	      off_type __computed_off = __width * __off;
	      
	      bool __testget = _M_in_cur && _M_in_beg < _M_in_end;
	      bool __testput = _M_out_cur && _M_out_beg < _M_out_end;
	      // Sync the internal and external streams.
	      // out
	      if (__testput || _M_last_overflowed)
		{
		  // Part one: update the output sequence.
		  this->sync();
		  // Part two: output unshift sequence.
		  _M_output_unshift();
		}
	      //in
	      else if (__testget && __way == ios_base::cur)
		__computed_off += _M_in_cur - _M_filepos;

	      // Return pos_type(off_type(-1)) in case of failure.	  
	      __ret = _M_file.seekoff(__computed_off, __way, __mode);
	      _M_set_indeterminate();
	    }
	  // NB: Need to do this in case _M_file in indeterminate
	  // state, ie _M_file._offset == -1
	  else
	    {
 	      pos_type __tmp =
 		_M_file.seekoff(__off, ios_base::cur, __mode);
 	      if (__tmp >= 0)
		{
		  // Seek successful.
		  __ret = __tmp;
		  __ret += max(_M_out_cur, _M_in_cur) - _M_filepos;
		}
	    }
	}
      _M_last_overflowed = false;	
      return __ret;
    }

  template<typename _CharT, typename _Traits>
    typename basic_filebuf<_CharT, _Traits>::pos_type
    basic_filebuf<_CharT, _Traits>::
    seekpos(pos_type __pos, ios_base::openmode __mode)
    {
#ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
// 171. Strange seekpos() semantics due to joint position
      return this->seekoff(off_type(__pos), ios_base::beg, __mode);
#endif
    }

  template<typename _CharT, typename _Traits>
    void 
    basic_filebuf<_CharT, _Traits>::
    _M_output_unshift()
    { }

  template<typename _CharT, typename _Traits>
    void
    basic_filebuf<_CharT, _Traits>::
    imbue(const locale& __loc)
    {
      bool __testbeg = gptr() == eback() && pptr() == pbase();

      if (__testbeg && _M_buf_locale != __loc)
	_M_buf_locale = __loc;

      // NB this may require the reconversion of previously
      // converted chars. This in turn may cause the reconstruction
      // of the original file. YIKES!!
      // XXX The part in the above comment is not done.
      _M_last_overflowed = false;	
    }

  // Inhibit implicit instantiations for required instantiations,
  // which are defined via explicit instantiations elsewhere.  
  // NB:  This syntax is a GNU extension.
#if _GLIBCPP_EXTERN_TEMPLATE
  extern template class basic_filebuf<char>;
  extern template class basic_ifstream<char>;
  extern template class basic_ofstream<char>;
  extern template class basic_fstream<char>;

#ifdef _GLIBCPP_USE_WCHAR_T
  extern template class basic_filebuf<wchar_t>;
  extern template class basic_ifstream<wchar_t>;
  extern template class basic_ofstream<wchar_t>;
  extern template class basic_fstream<wchar_t>;
#endif
#endif
} // namespace std

#endif