libstdc++-v3/include/bits/fstream.tcc

   1 // File based streams -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
   4 // Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 2, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING.  If not, write to the Free
  19 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  20 // USA.
  21
  22 // As a special exception, you may use this file as part of a free software
  23 // library without restriction.  Specifically, if other files instantiate
  24 // templates or use macros or inline functions from this file, or you compile
  25 // this file and link it with other files to produce an executable, this
  26 // file does not by itself cause the resulting executable to be covered by
  27 // the GNU General Public License.  This exception does not however
  28 // invalidate any other reasons why the executable file might be covered by
  29 // the GNU General Public License.
  30
  31 //
  32 // ISO C++ 14882: 27.8  File-based streams
  33 //
  34
  35 #ifndef _FSTREAM_TCC
  36 #define _FSTREAM_TCC 1
  37
  38 #pragma GCC system_header
  39
  40 namespace std
  41 {
  42   template<typename _CharT, typename _Traits>
  43     void
  44     basic_filebuf<_CharT, _Traits>::
  45     _M_allocate_internal_buffer()
  46     {
  47       // Allocate internal buffer only if one doesn't already exist
  48       // (either allocated or provided by the user via setbuf).
  49       if (!_M_buf_allocated && !this->_M_buf)
  50         {
  51           this->_M_buf = new char_type[this->_M_buf_size];
  52           _M_buf_allocated = true;
  53         }
  54     }
  55
  56   template<typename _CharT, typename _Traits>
  57     void
  58     basic_filebuf<_CharT, _Traits>::
  59     _M_destroy_internal_buffer() throw()
  60     {
  61       if (_M_buf_allocated)
  62         {
  63           delete [] this->_M_buf;
  64           this->_M_buf = NULL;
  65           _M_buf_allocated = false;
  66         }
  67       delete [] _M_ext_buf;
  68       _M_ext_buf = NULL;
  69       _M_ext_buf_size = 0;
  70       _M_ext_next = NULL;
  71       _M_ext_end = NULL;
  72     }
  73
  74   template<typename _CharT, typename _Traits>
  75     basic_filebuf<_CharT, _Traits>::
  76     basic_filebuf() : __streambuf_type(), _M_file(&_M_lock),
  77     _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
  78     _M_state_last(), _M_buf(NULL), _M_buf_size(BUFSIZ),
  79     _M_buf_allocated(false), _M_reading(false), _M_writing(false),
  80     _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
  81     _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
  82     _M_ext_end(0)
  83     {
  84       if (has_facet<__codecvt_type>(this->_M_buf_locale))
  85         _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
  86     }
  87
  88   template<typename _CharT, typename _Traits>
  89     typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
  90     basic_filebuf<_CharT, _Traits>::
  91     open(const char* __s, ios_base::openmode __mode)
  92     {
  93       __filebuf_type *__ret = NULL;
  94       if (!this->is_open())
  95         {
  96           _M_file.open(__s, __mode);
  97           if (this->is_open())
  98             {
  99               _M_allocate_internal_buffer();
 100               this->_M_mode = __mode;
 101
 102               // Setup initial buffer to 'uncommitted' mode.
 103               _M_reading = false;
 104               _M_writing = false;
 105               _M_set_buffer(-1);
 106
 107               // Reset to initial state.
 108               _M_state_last = _M_state_cur = _M_state_beg;
 109
 110               // 27.8.1.3,4
 111               if ((__mode & ios_base::ate)
 112                   && this->seekoff(0, ios_base::end, __mode)
 113                   == pos_type(off_type(-1)))
 114                 this->close();
 115               else
 116                 __ret = this;
 117             }
 118         }
 119       return __ret;
 120     }
 121
 122   template<typename _CharT, typename _Traits>
 123     typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
 124     basic_filebuf<_CharT, _Traits>::
 125     close() throw()
 126     {
 127       __filebuf_type* __ret = NULL;
 128       if (this->is_open())
 129         {
 130           bool __testfail = false;
 131           try
 132             {
 133               if (!_M_terminate_output())
 134                 __testfail = true;
 135             }
 136           catch(...)
 137             { __testfail = true; }
 138
 139           // NB: Do this here so that re-opened filebufs will be cool...
 140           this->_M_mode = ios_base::openmode(0);
 141           this->_M_pback_init = false;
 142           _M_destroy_internal_buffer();
 143           _M_reading = false;
 144           _M_writing = false;
 145           _M_set_buffer(-1);
 146           _M_state_last = _M_state_cur = _M_state_beg;
 147
 148           if (!_M_file.close())
 149             __testfail = true;
 150
 151           if (!__testfail)
 152             __ret = this;
 153         }
 154       return __ret;
 155     }
 156
 157   template<typename _CharT, typename _Traits>
 158     streamsize
 159     basic_filebuf<_CharT, _Traits>::
 160     showmanyc()
 161     {
 162       streamsize __ret = -1;
 163       const bool __testin = this->_M_mode & ios_base::in;
 164       if (__testin && this->is_open())
 165         {
 166           // For a stateful encoding (-1) the pending sequence might be just
 167           // shift and unshift prefixes with no actual character.
 168           __ret = this->egptr() - this->gptr();
 169           if (__check_facet(_M_codecvt).encoding() >= 0)
 170             __ret += _M_file.showmanyc() / _M_codecvt->max_length();
 171         }
 172       return __ret;
 173     }
 174
 175   template<typename _CharT, typename _Traits>
 176     typename basic_filebuf<_CharT, _Traits>::int_type
 177     basic_filebuf<_CharT, _Traits>::
 178     underflow()
 179     {
 180       int_type __ret = traits_type::eof();
 181       const bool __testin = this->_M_mode & ios_base::in;
 182       if (__testin && !_M_writing)
 183         {
 184           // Check for pback madness, and if so swich back to the
 185           // normal buffers and jet outta here before expensive
 186           // fileops happen...
 187           _M_destroy_pback();
 188
 189           if (this->gptr() < this->egptr())
 190             return traits_type::to_int_type(*this->gptr());
 191
 192           // Get and convert input sequence.
 193           const size_t __buflen = this->_M_buf_size > 1
 194                                   ? this->_M_buf_size - 1 : 1;
 195
 196           // Will be set to true if ::read() returns 0 indicating EOF.
 197           bool __got_eof = false;
 198           // Number of internal characters produced.
 199           streamsize __ilen = 0;
 200           codecvt_base::result __r = codecvt_base::ok;
 201           if (__check_facet(_M_codecvt).always_noconv())
 202             {
 203               __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
 204                                       __buflen);
 205               if (__ilen == 0)
 206                 __got_eof = true;
 207             }
 208           else
 209             {
 210               // Worst-case number of external bytes.
 211               // XXX Not done encoding() == -1.
 212               const int __enc = _M_codecvt->encoding();
 213               streamsize __blen; // Minimum buffer size.
 214               streamsize __rlen; // Number of chars to read.
 215               if (__enc > 0)
 216                 __blen = __rlen = __buflen * __enc;
 217               else
 218                 {
 219                   __blen = __buflen + _M_codecvt->max_length() - 1;
 220                   __rlen = __buflen;
 221                 }
 222               const streamsize __remainder = _M_ext_end - _M_ext_next;
 223               __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
 224
 225               // An imbue in 'read' mode implies first converting the external
 226               // chars already present.
 227               if (_M_reading && this->egptr() == this->eback() && __remainder)
 228                 __rlen = 0;
 229
 230               // Allocate buffer if necessary and move unconverted
 231               // bytes to front.
 232               if (_M_ext_buf_size < __blen)
 233                 {
 234                   char* __buf = new char[__blen];
 235                   if (__remainder)
 236                     std::memcpy(__buf, _M_ext_next, __remainder);
 237
 238                   delete [] _M_ext_buf;
 239                   _M_ext_buf = __buf;
 240                   _M_ext_buf_size = __blen;
 241                 }
 242               else if (__remainder)
 243                 std::memmove(_M_ext_buf, _M_ext_next, __remainder);
 244
 245               _M_ext_next = _M_ext_buf;
 246               _M_ext_end = _M_ext_buf + __remainder;
 247               _M_state_last = _M_state_cur;
 248
 249               do
 250                 {
 251                   if (__rlen > 0)
 252                     {
 253                       // Sanity check!
 254                       // This may fail if the return value of
 255                       // codecvt::max_length() is bogus.
 256                       if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
 257                         {
 258                           __throw_ios_failure(__N("basic_filebuf::underflow "
 259                                               "codecvt::max_length() "
 260                                               "is not valid"));
 261                         }
 262                       streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
 263                       if (__elen == 0)
 264                         __got_eof = true;
 265                       else if (__elen == -1)
 266                         break;
 267                       _M_ext_end += __elen;
 268                     }
 269
 270                   char_type* __iend;
 271                   __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
 272                                        _M_ext_end, _M_ext_next, this->eback(),
 273                                        this->eback() + __buflen, __iend);
 274                   if (__r == codecvt_base::noconv)
 275                     {
 276                       size_t __avail = _M_ext_end - _M_ext_buf;
 277                       __ilen = std::min(__avail, __buflen);
 278                       traits_type::copy(this->eback(),
 279                                         reinterpret_cast<char_type*>(_M_ext_buf), __ilen);
 280                       _M_ext_next = _M_ext_buf + __ilen;
 281                     }
 282                   else
 283                     __ilen = __iend - this->eback();
 284
 285                   // _M_codecvt->in may return error while __ilen > 0: this is
 286                   // ok, and actually occurs in case of mixed encodings (e.g.,
 287                   // XML files).
 288                   if (__r == codecvt_base::error)
 289                     break;
 290
 291                   __rlen = 1;
 292                 }
 293               while (__ilen == 0 && !__got_eof);
 294             }
 295
 296           if (__ilen > 0)
 297             {
 298               _M_set_buffer(__ilen);
 299               _M_reading = true;
 300               __ret = traits_type::to_int_type(*this->gptr());
 301             }
 302           else if (__got_eof)
 303             {
 304               // If the actual end of file is reached, set 'uncommitted'
 305               // mode, thus allowing an immediate write without an
 306               // intervening seek.
 307               _M_set_buffer(-1);
 308               _M_reading = false;
 309               // However, reaching it while looping on partial means that
 310               // the file has got an incomplete character.
 311               if (__r == codecvt_base::partial)
 312                 __throw_ios_failure(__N("basic_filebuf::underflow "
 313                                     "incomplete character in file"));
 314             }
 315           else if (__r == codecvt_base::error)
 316             __throw_ios_failure(__N("basic_filebuf::underflow "
 317                                 "invalid byte sequence in file"));
 318           else
 319             __throw_ios_failure(__N("basic_filebuf::underflow "
 320                                 "error reading the file"));
 321         }
 322       return __ret;
 323     }
 324
 325   template<typename _CharT, typename _Traits>
 326     typename basic_filebuf<_CharT, _Traits>::int_type
 327     basic_filebuf<_CharT, _Traits>::
 328     pbackfail(int_type __i)
 329     {
 330       int_type __ret = traits_type::eof();
 331       const bool __testin = this->_M_mode & ios_base::in;
 332       if (__testin && !_M_writing)
 333         {
 334           // Remember whether the pback buffer is active, otherwise below
 335           // we may try to store in it a second char (libstdc++/9761).
 336           const bool __testpb = this->_M_pback_init;
 337           const bool __testeof = traits_type::eq_int_type(__i, __ret);
 338           int_type __tmp;
 339           if (this->eback() < this->gptr())
 340             {
 341               this->gbump(-1);
 342               __tmp = traits_type::to_int_type(*this->gptr());
 343             }
 344           else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
 345             {
 346               __tmp = this->underflow();
 347               if (traits_type::eq_int_type(__tmp, __ret))
 348                 return __ret;
 349             }
 350           else
 351             {
 352               // At the beginning of the buffer, need to make a
 353               // putback position available.  But the seek may fail
 354               // (f.i., at the beginning of a file, see
 355               // libstdc++/9439) and in that case we return
 356               // traits_type::eof().
 357               return __ret;
 358             }
 359
 360           // Try to put back __i into input sequence in one of three ways.
 361           // Order these tests done in is unspecified by the standard.
 362           if (!__testeof && traits_type::eq_int_type(__i, __tmp))
 363             __ret = __i;
 364           else if (__testeof)
 365             __ret = traits_type::not_eof(__i);
 366           else if (!__testpb)
 367             {
 368               _M_create_pback();
 369               _M_reading = true;
 370               *this->gptr() = traits_type::to_char_type(__i);
 371               __ret = __i;
 372             }
 373         }
 374       return __ret;
 375     }
 376
 377   template<typename _CharT, typename _Traits>
 378     typename basic_filebuf<_CharT, _Traits>::int_type
 379     basic_filebuf<_CharT, _Traits>::
 380     overflow(int_type __c)
 381     {
 382       int_type __ret = traits_type::eof();
 383       const bool __testeof = traits_type::eq_int_type(__c, __ret);
 384       const bool __testout = this->_M_mode & ios_base::out;
 385       if (__testout && !_M_reading)
 386         {
 387           if (this->pbase() < this->pptr())
 388             {
 389               // If appropriate, append the overflow char.
 390               if (!__testeof)
 391                 {
 392                   *this->pptr() = traits_type::to_char_type(__c);
 393                   this->pbump(1);
 394                 }
 395
 396               // Convert pending sequence to external representation,
 397               // and output.
 398               if (_M_convert_to_external(this->pbase(),
 399                                          this->pptr() - this->pbase())
 400                   && (!__testeof || !_M_file.sync()))
 401                 {
 402                   _M_set_buffer(0);
 403                   __ret = traits_type::not_eof(__c);
 404                 }
 405             }
 406           else if (this->_M_buf_size > 1)
 407             {
 408               // Overflow in 'uncommitted' mode: set _M_writing, set
 409               // the buffer to the initial 'write' mode, and put __c
 410               // into the buffer.
 411               _M_set_buffer(0);
 412               _M_writing = true;
 413               if (!__testeof)
 414                 {
 415                   *this->pptr() = traits_type::to_char_type(__c);
 416                   this->pbump(1);
 417                 }
 418               __ret = traits_type::not_eof(__c);
 419             }
 420           else
 421             {
 422               // Unbuffered.
 423               char_type __conv = traits_type::to_char_type(__c);
 424               if (__testeof || _M_convert_to_external(&__conv, 1))
 425                 {
 426                   _M_writing = true;
 427                   __ret = traits_type::not_eof(__c);
 428                 }
 429             }
 430         }
 431       return __ret;
 432     }
 433
 434   template<typename _CharT, typename _Traits>
 435     bool
 436     basic_filebuf<_CharT, _Traits>::
 437     _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
 438     {
 439       // Sizes of external and pending output.
 440       streamsize __elen;
 441       streamsize __plen;
 442       if (__check_facet(_M_codecvt).always_noconv())
 443         {
 444           __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
 445           __plen = __ilen;
 446         }
 447       else
 448         {
 449           // Worst-case number of external bytes needed.
 450           // XXX Not done encoding() == -1.
 451           streamsize __blen = __ilen * _M_codecvt->max_length();
 452           char* __buf = static_cast<char*>(__builtin_alloca(__blen));
 453
 454           char* __bend;
 455           const char_type* __iend;
 456           codecvt_base::result __r;
 457           __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
 458                                 __iend, __buf, __buf + __blen, __bend);
 459
 460           if (__r == codecvt_base::ok || __r == codecvt_base::partial)
 461             __blen = __bend - __buf;
 462           else if (__r == codecvt_base::noconv)
 463             {
 464               // Same as the always_noconv case above.
 465               __buf = reinterpret_cast<char*>(__ibuf);
 466               __blen = __ilen;
 467             }
 468           else
 469             __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
 470                                     "conversion error"));
 471
 472           __elen = _M_file.xsputn(__buf, __blen);
 473           __plen = __blen;
 474
 475           // Try once more for partial conversions.
 476           if (__r == codecvt_base::partial && __elen == __plen)
 477             {
 478               const char_type* __iresume = __iend;
 479               streamsize __rlen = this->pptr() - __iend;
 480               __r = _M_codecvt->out(_M_state_cur, __iresume,
 481                                     __iresume + __rlen, __iend, __buf,
 482                                     __buf + __blen, __bend);
 483               if (__r != codecvt_base::error)
 484                 {
 485                   __rlen = __bend - __buf;
 486                   __elen = _M_file.xsputn(__buf, __rlen);
 487                   __plen = __rlen;
 488                 }
 489               else
 490                 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
 491                                         "conversion error"));
 492             }
 493         }
 494       return __elen == __plen;
 495     }
 496
 497    template<typename _CharT, typename _Traits>
 498      streamsize
 499      basic_filebuf<_CharT, _Traits>::
 500      xsputn(const _CharT* __s, streamsize __n)
 501      {
 502        // Optimization in the always_noconv() case, to be generalized in the
 503        // future: when __n is sufficiently large we write directly instead of
 504        // using the buffer.
 505        streamsize __ret = 0;
 506        const bool __testout = this->_M_mode & ios_base::out;
 507        if (__testout && !_M_reading
 508            && __check_facet(_M_codecvt).always_noconv())
 509         {
 510           // Measurement would reveal the best choice.
 511           const streamsize __chunk = 1ul << 10;
 512           streamsize __bufavail = this->epptr() - this->pptr();
 513
 514           // Don't mistake 'uncommitted' mode buffered with unbuffered.
 515           if (!_M_writing && this->_M_buf_size > 1)
 516             __bufavail = this->_M_buf_size - 1;
 517
 518           const streamsize __limit = std::min(__chunk, __bufavail);
 519           if (__n >= __limit)
 520             {
 521               const streamsize __buffill = this->pptr() - this->pbase();
 522               const char* __buf = reinterpret_cast<const char*>(this->pbase());
 523               __ret = _M_file.xsputn_2(__buf, __buffill,
 524                                        reinterpret_cast<const char*>(__s),
 525                                        __n);
 526               if (__ret == __buffill + __n)
 527                 {
 528                   _M_set_buffer(0);
 529                   _M_writing = true;
 530                 }
 531               if (__ret > __buffill)
 532                 __ret -= __buffill;
 533               else
 534                 __ret = 0;
 535             }
 536           else
 537             __ret = __streambuf_type::xsputn(__s, __n);
 538         }
 539        else
 540          __ret = __streambuf_type::xsputn(__s, __n);
 541        return __ret;
 542     }
 543
 544   template<typename _CharT, typename _Traits>
 545     typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
 546     basic_filebuf<_CharT, _Traits>::
 547     setbuf(char_type* __s, streamsize __n)
 548     {
 549       if (!this->is_open())
 550         if (__s == 0 && __n == 0)
 551           this->_M_buf_size = 1;
 552         else if (__s && __n > 0)
 553           {
 554             // This is implementation-defined behavior, and assumes that
 555             // an external char_type array of length __n exists and has
 556             // been pre-allocated. If this is not the case, things will
 557             // quickly blow up. When __n > 1, __n - 1 positions will be
 558             // used for the get area, __n - 1 for the put area and 1
 559             // position to host the overflow char of a full put area.
 560             // When __n == 1, 1 position will be used for the get area
 561             // and 0 for the put area, as in the unbuffered case above.
 562             this->_M_buf = __s;
 563             this->_M_buf_size = __n;
 564           }
 565       return this;
 566     }
 567
 568
 569   // According to 27.8.1.4 p11 - 13, seekoff should ignore the last
 570   // argument (of type openmode).
 571   template<typename _CharT, typename _Traits>
 572     typename basic_filebuf<_CharT, _Traits>::pos_type
 573     basic_filebuf<_CharT, _Traits>::
 574     seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
 575     {
 576       int __width = 0;
 577       if (_M_codecvt)
 578         __width = _M_codecvt->encoding();
 579       if (__width < 0)
 580         __width = 0;
 581
 582       pos_type __ret =  pos_type(off_type(-1));
 583       const bool __testfail = __off != 0 && __width <= 0;
 584       if (this->is_open() && !__testfail)
 585         {
 586           // Ditch any pback buffers to avoid confusion.
 587           _M_destroy_pback();
 588
 589           // Correct state at destination. Note that this is the correct
 590           // state for the current position during output, because
 591           // codecvt::unshift() returns the state to the initial state.
 592           // This is also the correct state at the end of the file because
 593           // an unshift sequence should have been written at the end.
 594           __state_type __state = _M_state_beg;
 595           off_type __computed_off = __off * __width;
 596           if (_M_reading && __way == ios_base::cur)
 597             {
 598               if (_M_codecvt->always_noconv())
 599                 __computed_off += this->gptr() - this->egptr();
 600               else
 601                 {
 602                   // Calculate offset from _M_ext_buf that corresponds
 603                   // to gptr(). Note: uses _M_state_last, which
 604                   // corresponds to eback().
 605                   const int __gptr_off =
 606                     _M_codecvt->length(_M_state_last, _M_ext_buf, _M_ext_next,
 607                                        this->gptr() - this->eback());
 608                   __computed_off += _M_ext_buf + __gptr_off - _M_ext_end;
 609
 610                   // _M_state_last is modified by codecvt::length() so
 611                   // it now corresponds to gptr().
 612                   __state = _M_state_last;
 613                 }
 614             }
 615           __ret = _M_seek(__computed_off, __way, __state);
 616         }
 617       return __ret;
 618     }
 619
 620   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 621   // 171. Strange seekpos() semantics due to joint position
 622   // According to the resolution of DR 171, seekpos should ignore the last
 623   // argument (of type openmode).
 624   template<typename _CharT, typename _Traits>
 625     typename basic_filebuf<_CharT, _Traits>::pos_type
 626     basic_filebuf<_CharT, _Traits>::
 627     seekpos(pos_type __pos, ios_base::openmode)
 628     {
 629       pos_type __ret =  pos_type(off_type(-1));
 630       if (this->is_open())
 631         {
 632           // Ditch any pback buffers to avoid confusion.
 633           _M_destroy_pback();
 634           __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
 635         }
 636       return __ret;
 637     }
 638
 639   template<typename _CharT, typename _Traits>
 640     typename basic_filebuf<_CharT, _Traits>::pos_type
 641     basic_filebuf<_CharT, _Traits>::
 642     _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
 643     {
 644       pos_type __ret = pos_type(off_type(-1));
 645       if (_M_terminate_output())
 646         {
 647           // Returns pos_type(off_type(-1)) in case of failure.
 648           __ret = pos_type(_M_file.seekoff(__off, __way));
 649           _M_reading = false;
 650           _M_writing = false;
 651           _M_ext_next = _M_ext_end = _M_ext_buf;
 652           _M_set_buffer(-1);
 653           _M_state_cur = __state;
 654           __ret.state(_M_state_cur);
 655         }
 656       return __ret;
 657     }
 658
 659   template<typename _CharT, typename _Traits>
 660     bool
 661     basic_filebuf<_CharT, _Traits>::
 662     _M_terminate_output()
 663     {
 664       // Part one: update the output sequence.
 665       bool __testvalid = true;
 666       if (this->pbase() < this->pptr())
 667         {
 668           const int_type __tmp = this->overflow();
 669           if (traits_type::eq_int_type(__tmp, traits_type::eof()))
 670             __testvalid = false;
 671         }
 672
 673       // Part two: output unshift sequence.
 674       if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
 675           && __testvalid)
 676         {
 677           // Note: this value is arbitrary, since there is no way to
 678           // get the length of the unshift sequence from codecvt,
 679           // without calling unshift.
 680           const size_t __blen = 128;
 681           char __buf[__blen];
 682           codecvt_base::result __r;
 683           streamsize __ilen = 0;
 684
 685           do
 686             {
 687               char* __next;
 688               __r = _M_codecvt->unshift(_M_state_cur, __buf,
 689                                         __buf + __blen, __next);
 690               if (__r == codecvt_base::error)
 691                 __testvalid = false;
 692               else if (__r == codecvt_base::ok ||
 693                        __r == codecvt_base::partial)
 694                 {
 695                   __ilen = __next - __buf;
 696                   if (__ilen > 0)
 697                     {
 698                       const streamsize __elen = _M_file.xsputn(__buf, __ilen);
 699                       if (__elen != __ilen)
 700                         __testvalid = false;
 701                     }
 702                 }
 703             }
 704           while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
 705
 706           if (__testvalid)
 707             {
 708               // This second call to overflow() is required by the standard,
 709               // but it's not clear why it's needed, since the output buffer
 710               // should be empty by this point (it should have been emptied
 711               // in the first call to overflow()).
 712               const int_type __tmp = this->overflow();
 713               if (traits_type::eq_int_type(__tmp, traits_type::eof()))
 714                 __testvalid = false;
 715             }
 716         }
 717       return __testvalid;
 718     }
 719
 720   template<typename _CharT, typename _Traits>
 721     int
 722     basic_filebuf<_CharT, _Traits>::
 723     sync()
 724     {
 725       // Make sure that the internal buffer resyncs its idea of
 726       // the file position with the external file.
 727       // NB: _M_file.sync() will be called within.
 728       int __ret = 0;
 729       if (this->pbase() < this->pptr())
 730         {
 731           const int_type __tmp = this->overflow();
 732           if (traits_type::eq_int_type(__tmp, traits_type::eof()))
 733             __ret = -1;
 734         }
 735       return __ret;
 736     }
 737
 738   template<typename _CharT, typename _Traits>
 739     void
 740     basic_filebuf<_CharT, _Traits>::
 741     imbue(const locale& __loc)
 742     {
 743       bool __testvalid = true;
 744
 745       const __codecvt_type* _M_codecvt_tmp = 0;
 746       if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
 747         _M_codecvt_tmp = &use_facet<__codecvt_type>(__loc);
 748
 749       if (this->is_open())
 750         {
 751           // encoding() == -1 is ok only at the beginning.
 752           if ((_M_reading || _M_writing)
 753               && __check_facet(_M_codecvt).encoding() == -1)
 754             __testvalid = false;
 755           else
 756             {
 757               if (_M_reading)
 758                 {
 759                   if (__check_facet(_M_codecvt).always_noconv())
 760                     {
 761                       if (_M_codecvt_tmp
 762                           && !__check_facet(_M_codecvt_tmp).always_noconv())
 763                         __testvalid = this->seekoff(0, ios_base::cur, this->_M_mode)
 764                                       != pos_type(off_type(-1));
 765                     }
 766                   else
 767                     {
 768                       // External position corresponding to gptr().
 769                       _M_ext_next = _M_ext_buf
 770                         + _M_codecvt->length(_M_state_last, _M_ext_buf, _M_ext_next,
 771                                              this->gptr() - this->eback());
 772                       const streamsize __remainder = _M_ext_end - _M_ext_next;
 773                       if (__remainder)
 774                         std::memmove(_M_ext_buf, _M_ext_next, __remainder);
 775
 776                       _M_ext_next = _M_ext_buf;
 777                       _M_ext_end = _M_ext_buf + __remainder;
 778                       _M_set_buffer(-1);
 779                       _M_state_last = _M_state_cur = _M_state_beg;
 780                     }
 781                 }
 782               else if (_M_writing && (__testvalid = _M_terminate_output()))
 783                 _M_set_buffer(-1);
 784             }
 785         }
 786
 787       if (__testvalid)
 788         _M_codecvt = _M_codecvt_tmp;
 789     }
 790
 791   // Inhibit implicit instantiations for required instantiations,
 792   // which are defined via explicit instantiations elsewhere.
 793   // NB:  This syntax is a GNU extension.
 794 #if _GLIBCXX_EXTERN_TEMPLATE
 795   extern template class basic_filebuf<char>;
 796   extern template class basic_ifstream<char>;
 797   extern template class basic_ofstream<char>;
 798   extern template class basic_fstream<char>;
 799
 800 #ifdef _GLIBCXX_USE_WCHAR_T
 801   extern template class basic_filebuf<wchar_t>;
 802   extern template class basic_ifstream<wchar_t>;
 803   extern template class basic_ofstream<wchar_t>;
 804   extern template class basic_fstream<wchar_t>;
 805 #endif
 806 #endif
 807 } // namespace std
 808
 809 #endif