/*

 * Copyright (c) 1996,1997

 * Silicon Graphics Computer Systems, Inc.

 *

 * Copyright (c) 1999

 * Boris Fomitchev

 *

 * This material is provided "as is", with absolutely no warranty expressed

 * or implied. Any use is at your own risk.

 *

 * Permission to use or copy this software for any purpose is hereby granted

 * without fee, provided the above notices are retained on all copies.

 * Permission to modify the code and to distribute modified code is granted,

 * provided the above notices are retained, and a notice that the code was

 * modified is included with the above copyright notice.

 *

 */

#ifndef _STLP_FSTREAM_C

#define _STLP_FSTREAM_C

#ifndef _STLP_INTERNAL_FSTREAM_H

#  include <stl/_fstream.h>

#endif

#ifndef _STLP_INTERNAL_LIMITS

#  include <stl/_limits.h>

#endif

_STLP_BEGIN_NAMESPACE

# if defined ( _STLP_NESTED_TYPE_PARAM_BUG )

// no wchar_t is supported for this mode

# define __BF_int_type__ int

# define __BF_pos_type__ streampos

# define __BF_off_type__ streamoff

# else

# define __BF_int_type__ _STLP_TYPENAME_ON_RETURN_TYPE basic_filebuf<_CharT, _Traits>::int_type

# define __BF_pos_type__ _STLP_TYPENAME_ON_RETURN_TYPE basic_filebuf<_CharT, _Traits>::pos_type

# define __BF_off_type__ _STLP_TYPENAME_ON_RETURN_TYPE basic_filebuf<_CharT, _Traits>::off_type

# endif

//----------------------------------------------------------------------

// Public basic_filebuf<> member functions

template <class _CharT, class _Traits>

basic_filebuf<_CharT, _Traits>::basic_filebuf()

     :  basic_streambuf<_CharT, _Traits>(), _M_base(),

    _M_constant_width(false), _M_always_noconv(false),

    _M_int_buf_dynamic(false),

    _M_in_input_mode(false), _M_in_output_mode(false),

    _M_in_error_mode(false), _M_in_putback_mode(false),

    _M_int_buf(0), _M_int_buf_EOS(0),

    _M_ext_buf(0), _M_ext_buf_EOS(0),

    _M_ext_buf_converted(0), _M_ext_buf_end(0),

    _M_state(_STLP_DEFAULT_CONSTRUCTED(_State_type)),

    _M_end_state(_STLP_DEFAULT_CONSTRUCTED(_State_type)),

    _M_mmap_base(0), _M_mmap_len(0),

    _M_saved_eback(0), _M_saved_gptr(0), _M_saved_egptr(0),

    _M_codecvt(0),

    _M_width(1), _M_max_width(1)

{

  this->_M_setup_codecvt(locale(), false);

}

template <class _CharT, class _Traits>

basic_filebuf<_CharT, _Traits>::~basic_filebuf() {

  this->close();

  _M_deallocate_buffers();

}

template <class _CharT, class _Traits>

_STLP_TYPENAME_ON_RETURN_TYPE basic_filebuf<_CharT, _Traits>::int_type

basic_filebuf<_CharT, _Traits>::underflow() {

  return _Underflow<_CharT, _Traits>::_M_doit(this);

}

template <class _CharT, class _Traits>

basic_filebuf<_CharT, _Traits>*

basic_filebuf<_CharT, _Traits>::close() {

  bool __ok = this->is_open();

  if (_M_in_output_mode) {

    __ok = __ok && !_Traits::eq_int_type(this->overflow(traits_type::eof()),

                                         traits_type::eof());

    __ok == __ok && this->_M_unshift();

  }

  else if (_M_in_input_mode)

      this->_M_exit_input_mode();

  // Note order of arguments.  We close the file even if __ok is false.

  __ok = _M_base._M_close() && __ok;

  // Restore the initial state, except that we don't deallocate the buffer

  // or mess with the cached codecvt information.

  _M_state = _M_end_state = _State_type();

  _M_ext_buf_converted = _M_ext_buf_end = 0;

  _M_mmap_base = 0;

  _M_mmap_len = 0;

  this->setg(0, 0, 0);

  this->setp(0, 0);

  _M_saved_eback = _M_saved_gptr = _M_saved_egptr = 0;

  _M_in_input_mode = _M_in_output_mode = _M_in_error_mode = _M_in_putback_mode

    = false;

  return __ok ? this : 0;

}

// This member function is called whenever we exit input mode.

// It unmaps the memory-mapped file, if any, and sets

// _M_in_input_mode to false.

template <class _CharT, class _Traits>

void basic_filebuf<_CharT, _Traits>::_M_exit_input_mode() {

   if (_M_mmap_base != 0)

     _M_base._M_unmap(_M_mmap_base, _M_mmap_len);

   _M_in_input_mode = false;

   _M_mmap_base = 0;

}

//----------------------------------------------------------------------

// basic_filebuf<> overridden protected virtual member functions

template <class _CharT, class _Traits>

streamsize basic_filebuf<_CharT, _Traits>::showmanyc() {

  // Is there any possibility that reads can succeed?

  if (!this->is_open() || _M_in_output_mode || _M_in_error_mode)

    return -1;

  else if (_M_in_putback_mode)

    return this->egptr() - this->gptr();

  else if (_M_constant_width) {

    streamoff __pos  = _M_base._M_seek(0, ios_base::cur);

    streamoff __size = _M_base._M_file_size();

    return __pos >= 0 && __size > __pos ? __size - __pos : 0;

  }

  else

    return 0;

}

// Make a putback position available, if necessary, by switching to a

// special internal buffer used only for putback.  The buffer is

// [_M_pback_buf, _M_pback_buf + _S_pback_buf_size), but the base

// class only sees a piece of it at a time.  (We want to make sure

// that we don't try to read a character that hasn't been initialized.)

// The end of the putback buffer is always _M_pback_buf + _S_pback_buf_size,

// but the beginning is usually not _M_pback_buf.

template <class _CharT, class _Traits>

__BF_int_type__

basic_filebuf<_CharT, _Traits>::pbackfail(int_type __c) {

  const int_type __eof = traits_type::eof();

  // If we aren't already in input mode, pushback is impossible.

  if (!_M_in_input_mode)

    return __eof;

  // We can use the ordinary get buffer if there's enough space, and

  // if it's a buffer that we're allowed to write to.

  if (this->gptr() != this->eback() &&

      (traits_type::eq_int_type(__c, __eof) ||

       traits_type::eq(traits_type::to_char_type(__c), this->gptr()[-1]) ||

       !_M_mmap_base)) {

    this->gbump(-1);

    if (traits_type::eq_int_type(__c, __eof) ||

        traits_type::eq(traits_type::to_char_type(__c), *this->gptr()))

      return traits_type::to_int_type(*this->gptr());

  }

  else if (!traits_type::eq_int_type(__c, __eof)) {

    // Are we in the putback buffer already?

    _CharT* __pback_end = _M_pback_buf + __STATIC_CAST(int,_S_pback_buf_size);

    if (_M_in_putback_mode) {

      // Do we have more room in the putback buffer?

      if (this->eback() != _M_pback_buf)

        this->setg(this->egptr() - 1, this->egptr() - 1, __pback_end);

      else

        return __eof;           // No more room in the buffer, so fail.

    }

    else {                      // We're not yet in the putback buffer.

      _M_saved_eback = this->eback();

      _M_saved_gptr  = this->gptr();

      _M_saved_egptr = this->egptr();

      this->setg(__pback_end - 1, __pback_end - 1, __pback_end);

      _M_in_putback_mode = true;

    }

  }

  else

    return __eof;

  // We have made a putback position available.  Assign to it, and return.

  *this->gptr() = traits_type::to_char_type(__c);

  return __c;

}

// This member function flushes the put area, and also outputs the

// character __c (unless __c is eof).  Invariant: we always leave room

// in the internal buffer for one character more than the base class knows

// about.  We see the internal buffer as [_M_int_buf, _M_int_buf_EOS), but

// the base class only sees [_M_int_buf, _M_int_buf_EOS - 1).

template <class _CharT, class _Traits>

__BF_int_type__

basic_filebuf<_CharT, _Traits>::overflow(int_type __c) {

  // Switch to output mode, if necessary.

  if (!_M_in_output_mode)

    if (!_M_switch_to_output_mode())

      return traits_type::eof();

  _CharT* __ibegin = this->_M_int_buf;

  _CharT* __iend   = this->pptr();

  this->setp(_M_int_buf, _M_int_buf_EOS - 1);

  // Put __c at the end of the internal buffer.

  if (!traits_type::eq_int_type(__c, traits_type::eof()))

    *__iend++ = _Traits::to_char_type(__c);

  // For variable-width encodings, output may take more than one pass.

  while (__ibegin != __iend) {

    const _CharT* __inext = __ibegin;

    char* __enext         = _M_ext_buf;

    typename _Codecvt::result __status

      = _M_codecvt->out(_M_state, __ibegin, __iend, __inext,

                        _M_ext_buf, _M_ext_buf_EOS, __enext);

    if (__status == _Codecvt::noconv) {

      return _Noconv_output<_Traits>::_M_doit(this, __ibegin, __iend)

        ? traits_type::not_eof(__c)

        : _M_output_error();

    }

    // For a constant-width encoding we know that the external buffer

    // is large enough, so failure to consume the entire internal buffer

    // or to produce the correct number of external characters, is an error.

    // For a variable-width encoding, however, we require only that we

    // consume at least one internal character

    else if (__status != _Codecvt::error &&

             (((__inext == __iend) &&

               (__enext - _M_ext_buf == _M_width * (__iend - __ibegin))) ||

              (!_M_constant_width && __inext != __ibegin))) {

        // We successfully converted part or all of the internal buffer.

      ptrdiff_t __n = __enext - _M_ext_buf;

      if (_M_write(_M_ext_buf, __n))

        __ibegin += __inext - __ibegin;

      else

        return _M_output_error();

    }

    else

      return _M_output_error();

  }

  return traits_type::not_eof(__c);

}

// This member function must be called before any I/O has been

// performed on the stream, otherwise it has no effect.

//

// __buf == 0 && __n == 0 means to make this stream unbuffered.

// __buf != 0 && __n > 0 means to use __buf as the stream's internal

// buffer, rather than the buffer that would otherwise be allocated

// automatically.  __buf must be a pointer to an array of _CharT whose

// size is at least __n.

template <class _CharT, class _Traits>

basic_streambuf<_CharT, _Traits>*

basic_filebuf<_CharT, _Traits>::setbuf(_CharT* __buf, streamsize __n) {

  if (!_M_in_input_mode &&! _M_in_output_mode && !_M_in_error_mode &&

      _M_int_buf == 0) {

    if (__buf == 0 && __n == 0)

      _M_allocate_buffers(0, 1);

    else if (__buf != 0 && __n > 0)

      _M_allocate_buffers(__buf, __n);

  }

  return this;

}

template <class _CharT, class _Traits>

__BF_pos_type__

basic_filebuf<_CharT, _Traits>::seekoff(off_type __off,

                                        ios_base::seekdir __whence,

                                        ios_base::openmode /* dummy */) {

  if (this->is_open() &&

      (__off == 0 || (_M_constant_width && this->_M_base._M_in_binary_mode()))) {

    if (!_M_seek_init(__off != 0 || __whence != ios_base::cur))

      return pos_type(-1);

    // Seek to beginning or end, regardless of whether we're in input mode.

    if (__whence == ios_base::beg || __whence == ios_base::end)

      return _M_seek_return(_M_base._M_seek(_M_width * __off, __whence),

                            _State_type());

    // Seek relative to current position. Complicated if we're in input mode.

    else if (__whence == ios_base::cur) {

      if (!_M_in_input_mode)

        return _M_seek_return(_M_base._M_seek(_M_width * __off, __whence),

                              _State_type());

      else if (_M_mmap_base != 0) {

        // __off is relative to gptr().  We need to do a bit of arithmetic

        // to get an offset relative to the external file pointer.

        streamoff __adjust = _M_mmap_len - (this->gptr() - (_CharT*) _M_mmap_base);

        // if __off == 0, we do not need to exit input mode and to shift file pointer

        return __off == 0 ? pos_type(_M_base._M_seek(0, ios_base::cur) - __adjust)

                          : _M_seek_return(_M_base._M_seek(__off - __adjust, ios_base::cur), _State_type());

      }

      else if (_M_constant_width) { // Get or set the position.

        streamoff __iadj = _M_width * (this->gptr() - this->eback());

        // Compensate for offset relative to gptr versus offset relative

        // to external pointer.  For a text-oriented stream, where the

        // compensation is more than just pointer arithmetic, we may get

        // but not set the current position.

        if (__iadj <= _M_ext_buf_end - _M_ext_buf) {

          streamoff __eadj =  _M_base._M_get_offset(_M_ext_buf + __STATIC_CAST(ptrdiff_t, __iadj), _M_ext_buf_end);

          return __off == 0 ? pos_type(_M_base._M_seek(0, ios_base::cur) - __eadj)

                            : _M_seek_return(_M_base._M_seek(__off - __eadj, ios_base::cur), _State_type());

        }

      } else {                    // Get the position.  Encoding is var width.

        // Get position in internal buffer.

        ptrdiff_t __ipos = this->gptr() - this->eback();

        // Get corresponding position in external buffer.

        _State_type __state = _M_state;

        int __epos = _M_codecvt->length(__state, _M_ext_buf, _M_ext_buf_end,

                                        __ipos);

        if (__epos >= 0) {

          // Sanity check (expensive): make sure __epos is the right answer.

          _State_type __tmp_state = _M_state;

          _Filebuf_Tmp_Buf<_CharT> __buf(__ipos);

          _CharT* __ibegin = __buf._M_ptr;

          _CharT* __inext  = __ibegin;

          const char* __dummy;

          typename _Codecvt::result __status

            = _M_codecvt->in(__tmp_state,

                             _M_ext_buf, _M_ext_buf + __epos, __dummy,

                             __ibegin, __ibegin + __ipos, __inext);

          if (__status != _Codecvt::error &&

              (__status == _Codecvt::noconv ||

               (__inext == __ibegin + __ipos &&

                equal(this->eback(), this->gptr(), __ibegin, _STLP_PRIV _Eq_traits<traits_type>())))) {

            // Get the current position (at the end of the external buffer),

            // then adjust it.  Again, it might be a text-oriented stream.

            streamoff __cur = _M_base._M_seek(0, ios_base::cur);

            streamoff __adj =

              _M_base._M_get_offset(_M_ext_buf, _M_ext_buf + __epos) -

              _M_base._M_get_offset(_M_ext_buf, _M_ext_buf_end);

            if (__cur != -1 && __cur + __adj >= 0)

              return __off == 0 ? pos_type(__cur + __adj)

                                : _M_seek_return(__cur + __adj, __state);

              //return _M_seek_return(__cur + __adj, __state);

          }

          // We failed the sanity check here.

        }

      }

    }

    // Unrecognized value for __whence here.

  }

  return pos_type(-1);

}

template <class _CharT, class _Traits>

__BF_pos_type__

basic_filebuf<_CharT, _Traits>::seekpos(pos_type __pos,

                                        ios_base::openmode /* dummy */) {

  if (this->is_open()) {

    if (!_M_seek_init(true))

      return pos_type(-1);

    streamoff __off = off_type(__pos);

    if (__off != -1 && _M_base._M_seek(__off, ios_base::beg) != -1) {

      _M_state = __pos.state();

      return _M_seek_return(__off, __pos.state());

    }

  }

  return pos_type(-1);

}

template <class _CharT, class _Traits>

int basic_filebuf<_CharT, _Traits>::sync() {

  if (_M_in_output_mode)

    return traits_type::eq_int_type(this->overflow(traits_type::eof()),

                                    traits_type::eof()) ? -1 : 0;

  return 0;

}

// Change the filebuf's locale.  This member function has no effect

// unless it is called before any I/O is performed on the stream.

template <class _CharT, class _Traits>

void basic_filebuf<_CharT, _Traits>::imbue(const locale& __loc) {

  if (!_M_in_input_mode && !_M_in_output_mode && !_M_in_error_mode) {

    this->_M_setup_codecvt(__loc);

  }

}

//----------------------------------------------------------------------

// basic_filebuf<> helper functions.

//----------------------------------------

// Helper functions for switching between modes.

// This member function is called if we're performing the first I/O

// operation on a filebuf, or if we're performing an input operation

// immediately after a seek.

template <class _CharT, class _Traits>

bool basic_filebuf<_CharT, _Traits>::_M_switch_to_input_mode() {

  if (this->is_open() && (((int)_M_base.__o_mode() & (int)ios_base::in) != 0)

      && (_M_in_output_mode == 0) && (_M_in_error_mode == 0)) {

    if (!_M_int_buf && !_M_allocate_buffers())

      return false;

    _M_ext_buf_converted = _M_ext_buf;

    _M_ext_buf_end       = _M_ext_buf;

    _M_end_state    = _M_state;

    _M_in_input_mode = true;

    return true;

  }

  return false;

}

// This member function is called if we're performing the first I/O

// operation on a filebuf, or if we're performing an output operation

// immediately after a seek.

template <class _CharT, class _Traits>

bool basic_filebuf<_CharT, _Traits>::_M_switch_to_output_mode() {

  if (this->is_open() && (_M_base.__o_mode() & (int)ios_base::out) &&

      _M_in_input_mode == 0 && _M_in_error_mode == 0) {

    if (!_M_int_buf && !_M_allocate_buffers())

      return false;

    // In append mode, every write does an implicit seek to the end

    // of the file.  Whenever leaving output mode, the end of file

    // get put in the initial shift state.

    if (_M_base.__o_mode() & ios_base::app)

      _M_state = _State_type();

    this->setp(_M_int_buf, _M_int_buf_EOS - 1);

    _M_in_output_mode = true;

    return true;

  }

  return false;

}

//----------------------------------------

// Helper functions for input

// This member function is called if there is an error during input.

// It puts the filebuf in error mode, clear the get area buffer, and

// returns eof.

// returns eof.  Error mode is sticky; it is cleared only by close or

// seek.

template <class _CharT, class _Traits>

__BF_int_type__

basic_filebuf<_CharT, _Traits>::_M_input_error() {

   this->_M_exit_input_mode();

  _M_in_output_mode = false;

  _M_in_error_mode = true;

  this->setg(0, 0, 0);

  return traits_type::eof();

}

template <class _CharT, class _Traits>

__BF_int_type__

basic_filebuf<_CharT, _Traits>::_M_underflow_aux() {

  // We have the state and file position from the end of the internal

  // buffer.  This round, they become the beginning of the internal buffer.

  _M_state    = _M_end_state;

  // Fill the external buffer.  Start with any leftover characters that

  // didn't get converted last time.

  if (_M_ext_buf_end > _M_ext_buf_converted)

    _M_ext_buf_end = copy(_M_ext_buf_converted, _M_ext_buf_end, _M_ext_buf);

    // boris : copy_backward did not work

    //_M_ext_buf_end = copy_backward(_M_ext_buf_converted, _M_ext_buf_end,

    //_M_ext_buf+ (_M_ext_buf_end - _M_ext_buf_converted));

  else

    _M_ext_buf_end = _M_ext_buf;

  // Now fill the external buffer with characters from the file.  This is

  // a loop because occasionally we don't get enough external characters

  // to make progress.

  for (;;) {

    ptrdiff_t __n = _M_base._M_read(_M_ext_buf_end, _M_ext_buf_EOS - _M_ext_buf_end);

    // Don't enter error mode for a failed read.  Error mode is sticky,

    // and we might succeed if we try again.

    if (__n <= 0)

      return traits_type::eof();

    // Convert the external buffer to internal characters.

    _M_ext_buf_end += __n;

    const char*   __enext;

    _CharT* __inext;

    typename _Codecvt::result __status

      = _M_codecvt->in(_M_end_state,

                       _M_ext_buf, _M_ext_buf_end, __enext,

                       _M_int_buf, _M_int_buf_EOS, __inext);

    // Error conditions: (1) Return value of error.  (2) Producing internal

    // characters without consuming external characters.  (3) In fixed-width

    // encodings, producing an internal sequence whose length is inconsistent

    // with that of the internal sequence.  (4) Failure to produce any

    // characters if we have enough characters in the external buffer, where

    // "enough" means the largest possible width of a single character.

    if (__status == _Codecvt::noconv)

      return _Noconv_input<_Traits>::_M_doit(this);

    else if (__status == _Codecvt::error ||

             (__inext != _M_int_buf && __enext == _M_ext_buf) ||

             (_M_constant_width &&

              //         __inext - _M_int_buf != _M_width * (__enext - _M_ext_buf)) ||

              (__inext - _M_int_buf) *  _M_width != (__enext - _M_ext_buf)) ||

             (__inext == _M_int_buf && __enext - _M_ext_buf >= _M_max_width))

      return _M_input_error();

    else if (__inext != _M_int_buf) {

      _M_ext_buf_converted = _M_ext_buf + (__enext - _M_ext_buf);

      this->setg(_M_int_buf, _M_int_buf, __inext);

      return traits_type::to_int_type(*_M_int_buf);

    }

    // We need to go around the loop again to get more external characters.

  }

}

//----------------------------------------

// Helper functions for output

// This member function is called if there is an error during output.

// It puts the filebuf in error mode, clear the put area buffer, and

// returns eof.  Error mode is sticky; it is cleared only by close or

// seek.

template <class _CharT, class _Traits>

__BF_int_type__

basic_filebuf<_CharT, _Traits>::_M_output_error() {

  _M_in_output_mode = false;

  _M_in_input_mode = false;

  _M_in_error_mode = true;

  this->setp(0, 0);

  return traits_type::eof();

}

// Write whatever sequence of characters is necessary to get back to

// the initial shift state.  This function overwrites the external

// buffer, changes the external file position, and changes the state.

// Precondition: the internal buffer is empty.

template <class _CharT, class _Traits>

bool basic_filebuf<_CharT, _Traits>::_M_unshift() {

  if (_M_in_output_mode && !_M_constant_width) {

    typename _Codecvt::result __status;

    do {

      char* __enext = _M_ext_buf;

      __status = _M_codecvt->unshift(_M_state,

                                     _M_ext_buf, _M_ext_buf_EOS, __enext);

      if (__status == _Codecvt::noconv ||

          (__enext == _M_ext_buf && __status == _Codecvt::ok))

        return true;

      else if (__status == _Codecvt::error)

        return false;

      else if (!_M_write(_M_ext_buf, __enext - _M_ext_buf))

        return false;

    } while (__status == _Codecvt::partial);

  }

  return true;

}

//----------------------------------------

// Helper functions for buffer allocation and deallocation

// This member function is called when we're initializing a filebuf's

// internal and external buffers.  The argument is the size of the

// internal buffer; the external buffer is sized using the character

// width in the current encoding.  Preconditions: the buffers are currently

// null.  __n >= 1.  __buf is either a null pointer or a pointer to an

// array show size is at least __n.

// We need __n >= 1 for two different reasons.  For input, the base

// class always needs a buffer because of the semantics of underflow().

// For output, we want to have an internal buffer that's larger by one

// element than the buffer that the base class knows about.  (See

// basic_filebuf<>::overflow() for the reason.)

template <class _CharT, class _Traits>

bool basic_filebuf<_CharT, _Traits>::_M_allocate_buffers(_CharT* __buf, streamsize __n) {

  //The major hypothesis in the following implementation is that size_t is unsigned.

  //We also need streamsize byte representation to be larger or equal to the int

  //representation to correctly store the encoding information.

  _STLP_STATIC_ASSERT(!numeric_limits<size_t>::is_signed &&

                      sizeof(streamsize) >= sizeof(int))

  if (__buf == 0) {

    streamsize __bufsize = __n * sizeof(_CharT);

    //We first check that the streamsize representation can't overflow a size_t one.

    //If it can, we check that __bufsize is not higher than the size_t max value.

    if ((sizeof(streamsize) > sizeof(size_t)) &&

        (__bufsize > __STATIC_CAST(streamsize, (numeric_limits<size_t>::max)())))

      return false;

    _M_int_buf = __STATIC_CAST(_CharT*, malloc(__STATIC_CAST(size_t, __bufsize)));

    if (!_M_int_buf)

      return false;

    _M_int_buf_dynamic = true;

  }

  else {

    _M_int_buf = __buf;

    _M_int_buf_dynamic = false;

  }

  streamsize __ebufsiz = (max)(__n * __STATIC_CAST(streamsize, _M_width),

                               __STATIC_CAST(streamsize, _M_codecvt->max_length()));

  _M_ext_buf = 0;

  if ((sizeof(streamsize) < sizeof(size_t)) ||

      ((sizeof(streamsize) == sizeof(size_t)) && numeric_limits<streamsize>::is_signed) ||

      (__ebufsiz <= __STATIC_CAST(streamsize, (numeric_limits<size_t>::max)()))) {

    _M_ext_buf = __STATIC_CAST(char*, malloc(__STATIC_CAST(size_t, __ebufsiz)));

  }

  if (!_M_ext_buf) {

    _M_deallocate_buffers();

    return false;

  }

  _M_int_buf_EOS = _M_int_buf + __STATIC_CAST(ptrdiff_t, __n);

  _M_ext_buf_EOS = _M_ext_buf + __STATIC_CAST(ptrdiff_t, __ebufsiz);

  return true;

}

// Abbreviation for the most common case.

template <class _CharT, class _Traits>

bool basic_filebuf<_CharT, _Traits>::_M_allocate_buffers() {

  // Choose a buffer that's at least 4096 characters long and that's a

  // multiple of the page size.

  streamsize __default_bufsiz =

    ((_M_base.__page_size() + 4095UL) / _M_base.__page_size()) * _M_base.__page_size();

  return _M_allocate_buffers(0, __default_bufsiz);

}

template <class _CharT, class _Traits>

void basic_filebuf<_CharT, _Traits>::_M_deallocate_buffers() {

  if (_M_int_buf_dynamic)

    free(_M_int_buf);

  free(_M_ext_buf);

  _M_int_buf     = 0;

  _M_int_buf_EOS = 0;

  _M_ext_buf     = 0;

  _M_ext_buf_EOS = 0;

}

//----------------------------------------

// Helper functiosn for seek and imbue

template <class _CharT, class _Traits>

bool basic_filebuf<_CharT, _Traits>::_M_seek_init(bool __do_unshift) {

  // If we're in error mode, leave it.

   _M_in_error_mode = false;

  // Flush the output buffer if we're in output mode, and (conditionally)

  // emit an unshift sequence.

  if (_M_in_output_mode) {

    bool __ok = !traits_type::eq_int_type(this->overflow(traits_type::eof()),

                                          traits_type::eof());

    if (__do_unshift)

      __ok = __ok && this->_M_unshift();

    if (!__ok) {

      _M_in_output_mode = false;

      _M_in_error_mode = true;

      this->setp(0, 0);

      return false;

    }

  }

  // Discard putback characters, if any.

  if (_M_in_input_mode && _M_in_putback_mode)

    _M_exit_putback_mode();

  return true;

}

/* Change the filebuf's locale.  This member function has no effect

 * unless it is called before any I/O is performed on the stream.

 * This function is called on construction and on an imbue call. In the

 * case of the construction the codecvt facet might be a custom one if

 * the basic_filebuf user has instanciate it with a custom char_traits.

 * The user will have to call imbue before any I/O operation.

 */

template <class _CharT, class _Traits>

void basic_filebuf<_CharT, _Traits>::_M_setup_codecvt(const locale& __loc, bool __on_imbue) {

  if (has_facet<_Codecvt>(__loc)) {

    _M_codecvt = &use_facet<_Codecvt>(__loc) ;

    int __encoding    = _M_codecvt->encoding();

    _M_width          = (max)(__encoding, 1);

    _M_max_width      = _M_codecvt->max_length();

    _M_constant_width = __encoding > 0;

    _M_always_noconv  = _M_codecvt->always_noconv();

  }

  else {

    _M_codecvt = 0;

    _M_width = _M_max_width = 1;

    _M_constant_width = _M_always_noconv  = false;

    if (__on_imbue) {

      //This call will generate an exception reporting the problem.

      use_facet<_Codecvt>(__loc);

    }

  }

}

_STLP_END_NAMESPACE

# undef __BF_int_type__

# undef __BF_pos_type__

# undef __BF_off_type__

#endif /* _STLP_FSTREAM_C */

// Local Variables:

// mode:C++

// End: