libstdc++
fstream.tcc
1 // File based streams -*- C++ -*-
2 
3 // Copyright (C) 1997-2014 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file bits/fstream.tcc
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{fstream}
28  */
29 
30 //
31 // ISO C++ 14882: 27.8 File-based streams
32 //
33 
34 #ifndef _FSTREAM_TCC
35 #define _FSTREAM_TCC 1
36 
37 #pragma GCC system_header
38 
39 #include <bits/cxxabi_forced.h>
40 
41 namespace std _GLIBCXX_VISIBILITY(default)
42 {
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
44 
45  template<typename _CharT, typename _Traits>
46  void
47  basic_filebuf<_CharT, _Traits>::
48  _M_allocate_internal_buffer()
49  {
50  // Allocate internal buffer only if one doesn't already exist
51  // (either allocated or provided by the user via setbuf).
52  if (!_M_buf_allocated && !_M_buf)
53  {
54  _M_buf = new char_type[_M_buf_size];
55  _M_buf_allocated = true;
56  }
57  }
58 
59  template<typename _CharT, typename _Traits>
60  void
61  basic_filebuf<_CharT, _Traits>::
62  _M_destroy_internal_buffer() throw()
63  {
64  if (_M_buf_allocated)
65  {
66  delete [] _M_buf;
67  _M_buf = 0;
68  _M_buf_allocated = false;
69  }
70  delete [] _M_ext_buf;
71  _M_ext_buf = 0;
72  _M_ext_buf_size = 0;
73  _M_ext_next = 0;
74  _M_ext_end = 0;
75  }
76 
77  template<typename _CharT, typename _Traits>
78  basic_filebuf<_CharT, _Traits>::
79  basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
80  _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
81  _M_state_last(), _M_buf(0), _M_buf_size(BUFSIZ),
82  _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(),
83  _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
84  _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
85  _M_ext_end(0)
86  {
87  if (has_facet<__codecvt_type>(this->_M_buf_locale))
88  _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
89  }
90 
91  template<typename _CharT, typename _Traits>
92  typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
93  basic_filebuf<_CharT, _Traits>::
94  open(const char* __s, ios_base::openmode __mode)
95  {
96  __filebuf_type *__ret = 0;
97  if (!this->is_open())
98  {
99  _M_file.open(__s, __mode);
100  if (this->is_open())
101  {
102  _M_allocate_internal_buffer();
103  _M_mode = __mode;
104 
105  // Setup initial buffer to 'uncommitted' mode.
106  _M_reading = false;
107  _M_writing = false;
108  _M_set_buffer(-1);
109 
110  // Reset to initial state.
111  _M_state_last = _M_state_cur = _M_state_beg;
112 
113  // 27.8.1.3,4
114  if ((__mode & ios_base::ate)
115  && this->seekoff(0, ios_base::end, __mode)
116  == pos_type(off_type(-1)))
117  this->close();
118  else
119  __ret = this;
120  }
121  }
122  return __ret;
123  }
124 
125  template<typename _CharT, typename _Traits>
126  typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
127  basic_filebuf<_CharT, _Traits>::
128  close()
129  {
130  if (!this->is_open())
131  return 0;
132 
133  bool __testfail = false;
134  {
135  // NB: Do this here so that re-opened filebufs will be cool...
136  struct __close_sentry
137  {
138  basic_filebuf *__fb;
139  __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
140  ~__close_sentry ()
141  {
142  __fb->_M_mode = ios_base::openmode(0);
143  __fb->_M_pback_init = false;
144  __fb->_M_destroy_internal_buffer();
145  __fb->_M_reading = false;
146  __fb->_M_writing = false;
147  __fb->_M_set_buffer(-1);
148  __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
149  }
150  } __cs (this);
151 
152  __try
153  {
154  if (!_M_terminate_output())
155  __testfail = true;
156  }
157  __catch(__cxxabiv1::__forced_unwind&)
158  {
159  _M_file.close();
160  __throw_exception_again;
161  }
162  __catch(...)
163  { __testfail = true; }
164  }
165 
166  if (!_M_file.close())
167  __testfail = true;
168 
169  if (__testfail)
170  return 0;
171  else
172  return this;
173  }
174 
175  template<typename _CharT, typename _Traits>
176  streamsize
177  basic_filebuf<_CharT, _Traits>::
178  showmanyc()
179  {
180  streamsize __ret = -1;
181  const bool __testin = _M_mode & ios_base::in;
182  if (__testin && this->is_open())
183  {
184  // For a stateful encoding (-1) the pending sequence might be just
185  // shift and unshift prefixes with no actual character.
186  __ret = this->egptr() - this->gptr();
187 
188 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
189  // About this workaround, see libstdc++/20806.
190  const bool __testbinary = _M_mode & ios_base::binary;
191  if (__check_facet(_M_codecvt).encoding() >= 0
192  && __testbinary)
193 #else
194  if (__check_facet(_M_codecvt).encoding() >= 0)
195 #endif
196  __ret += _M_file.showmanyc() / _M_codecvt->max_length();
197  }
198  return __ret;
199  }
200 
201  template<typename _CharT, typename _Traits>
202  typename basic_filebuf<_CharT, _Traits>::int_type
203  basic_filebuf<_CharT, _Traits>::
204  underflow()
205  {
206  int_type __ret = traits_type::eof();
207  const bool __testin = _M_mode & ios_base::in;
208  if (__testin)
209  {
210  if (_M_writing)
211  {
212  if (overflow() == traits_type::eof())
213  return __ret;
214  _M_set_buffer(-1);
215  _M_writing = false;
216  }
217  // Check for pback madness, and if so switch back to the
218  // normal buffers and jet outta here before expensive
219  // fileops happen...
220  _M_destroy_pback();
221 
222  if (this->gptr() < this->egptr())
223  return traits_type::to_int_type(*this->gptr());
224 
225  // Get and convert input sequence.
226  const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
227 
228  // Will be set to true if ::read() returns 0 indicating EOF.
229  bool __got_eof = false;
230  // Number of internal characters produced.
231  streamsize __ilen = 0;
232  codecvt_base::result __r = codecvt_base::ok;
233  if (__check_facet(_M_codecvt).always_noconv())
234  {
235  __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
236  __buflen);
237  if (__ilen == 0)
238  __got_eof = true;
239  }
240  else
241  {
242  // Worst-case number of external bytes.
243  // XXX Not done encoding() == -1.
244  const int __enc = _M_codecvt->encoding();
245  streamsize __blen; // Minimum buffer size.
246  streamsize __rlen; // Number of chars to read.
247  if (__enc > 0)
248  __blen = __rlen = __buflen * __enc;
249  else
250  {
251  __blen = __buflen + _M_codecvt->max_length() - 1;
252  __rlen = __buflen;
253  }
254  const streamsize __remainder = _M_ext_end - _M_ext_next;
255  __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
256 
257  // An imbue in 'read' mode implies first converting the external
258  // chars already present.
259  if (_M_reading && this->egptr() == this->eback() && __remainder)
260  __rlen = 0;
261 
262  // Allocate buffer if necessary and move unconverted
263  // bytes to front.
264  if (_M_ext_buf_size < __blen)
265  {
266  char* __buf = new char[__blen];
267  if (__remainder)
268  __builtin_memcpy(__buf, _M_ext_next, __remainder);
269 
270  delete [] _M_ext_buf;
271  _M_ext_buf = __buf;
272  _M_ext_buf_size = __blen;
273  }
274  else if (__remainder)
275  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
276 
277  _M_ext_next = _M_ext_buf;
278  _M_ext_end = _M_ext_buf + __remainder;
279  _M_state_last = _M_state_cur;
280 
281  do
282  {
283  if (__rlen > 0)
284  {
285  // Sanity check!
286  // This may fail if the return value of
287  // codecvt::max_length() is bogus.
288  if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
289  {
290  __throw_ios_failure(__N("basic_filebuf::underflow "
291  "codecvt::max_length() "
292  "is not valid"));
293  }
294  streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
295  if (__elen == 0)
296  __got_eof = true;
297  else if (__elen == -1)
298  break;
299  _M_ext_end += __elen;
300  }
301 
302  char_type* __iend = this->eback();
303  if (_M_ext_next < _M_ext_end)
304  __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
305  _M_ext_end, _M_ext_next,
306  this->eback(),
307  this->eback() + __buflen, __iend);
308  if (__r == codecvt_base::noconv)
309  {
310  size_t __avail = _M_ext_end - _M_ext_buf;
311  __ilen = std::min(__avail, __buflen);
312  traits_type::copy(this->eback(),
313  reinterpret_cast<char_type*>
314  (_M_ext_buf), __ilen);
315  _M_ext_next = _M_ext_buf + __ilen;
316  }
317  else
318  __ilen = __iend - this->eback();
319 
320  // _M_codecvt->in may return error while __ilen > 0: this is
321  // ok, and actually occurs in case of mixed encodings (e.g.,
322  // XML files).
323  if (__r == codecvt_base::error)
324  break;
325 
326  __rlen = 1;
327  }
328  while (__ilen == 0 && !__got_eof);
329  }
330 
331  if (__ilen > 0)
332  {
333  _M_set_buffer(__ilen);
334  _M_reading = true;
335  __ret = traits_type::to_int_type(*this->gptr());
336  }
337  else if (__got_eof)
338  {
339  // If the actual end of file is reached, set 'uncommitted'
340  // mode, thus allowing an immediate write without an
341  // intervening seek.
342  _M_set_buffer(-1);
343  _M_reading = false;
344  // However, reaching it while looping on partial means that
345  // the file has got an incomplete character.
346  if (__r == codecvt_base::partial)
347  __throw_ios_failure(__N("basic_filebuf::underflow "
348  "incomplete character in file"));
349  }
350  else if (__r == codecvt_base::error)
351  __throw_ios_failure(__N("basic_filebuf::underflow "
352  "invalid byte sequence in file"));
353  else
354  __throw_ios_failure(__N("basic_filebuf::underflow "
355  "error reading the file"));
356  }
357  return __ret;
358  }
359 
360  template<typename _CharT, typename _Traits>
361  typename basic_filebuf<_CharT, _Traits>::int_type
362  basic_filebuf<_CharT, _Traits>::
363  pbackfail(int_type __i)
364  {
365  int_type __ret = traits_type::eof();
366  const bool __testin = _M_mode & ios_base::in;
367  if (__testin)
368  {
369  if (_M_writing)
370  {
371  if (overflow() == traits_type::eof())
372  return __ret;
373  _M_set_buffer(-1);
374  _M_writing = false;
375  }
376  // Remember whether the pback buffer is active, otherwise below
377  // we may try to store in it a second char (libstdc++/9761).
378  const bool __testpb = _M_pback_init;
379  const bool __testeof = traits_type::eq_int_type(__i, __ret);
380  int_type __tmp;
381  if (this->eback() < this->gptr())
382  {
383  this->gbump(-1);
384  __tmp = traits_type::to_int_type(*this->gptr());
385  }
386  else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
387  {
388  __tmp = this->underflow();
389  if (traits_type::eq_int_type(__tmp, __ret))
390  return __ret;
391  }
392  else
393  {
394  // At the beginning of the buffer, need to make a
395  // putback position available. But the seek may fail
396  // (f.i., at the beginning of a file, see
397  // libstdc++/9439) and in that case we return
398  // traits_type::eof().
399  return __ret;
400  }
401 
402  // Try to put back __i into input sequence in one of three ways.
403  // Order these tests done in is unspecified by the standard.
404  if (!__testeof && traits_type::eq_int_type(__i, __tmp))
405  __ret = __i;
406  else if (__testeof)
407  __ret = traits_type::not_eof(__i);
408  else if (!__testpb)
409  {
410  _M_create_pback();
411  _M_reading = true;
412  *this->gptr() = traits_type::to_char_type(__i);
413  __ret = __i;
414  }
415  }
416  return __ret;
417  }
418 
419  template<typename _CharT, typename _Traits>
420  typename basic_filebuf<_CharT, _Traits>::int_type
421  basic_filebuf<_CharT, _Traits>::
422  overflow(int_type __c)
423  {
424  int_type __ret = traits_type::eof();
425  const bool __testeof = traits_type::eq_int_type(__c, __ret);
426  const bool __testout = (_M_mode & ios_base::out
427  || _M_mode & ios_base::app);
428  if (__testout)
429  {
430  if (_M_reading)
431  {
432  _M_destroy_pback();
433  const int __gptr_off = _M_get_ext_pos(_M_state_last);
434  if (_M_seek(__gptr_off, ios_base::cur, _M_state_last)
435  == pos_type(off_type(-1)))
436  return __ret;
437  }
438  if (this->pbase() < this->pptr())
439  {
440  // If appropriate, append the overflow char.
441  if (!__testeof)
442  {
443  *this->pptr() = traits_type::to_char_type(__c);
444  this->pbump(1);
445  }
446 
447  // Convert pending sequence to external representation,
448  // and output.
449  if (_M_convert_to_external(this->pbase(),
450  this->pptr() - this->pbase()))
451  {
452  _M_set_buffer(0);
453  __ret = traits_type::not_eof(__c);
454  }
455  }
456  else if (_M_buf_size > 1)
457  {
458  // Overflow in 'uncommitted' mode: set _M_writing, set
459  // the buffer to the initial 'write' mode, and put __c
460  // into the buffer.
461  _M_set_buffer(0);
462  _M_writing = true;
463  if (!__testeof)
464  {
465  *this->pptr() = traits_type::to_char_type(__c);
466  this->pbump(1);
467  }
468  __ret = traits_type::not_eof(__c);
469  }
470  else
471  {
472  // Unbuffered.
473  char_type __conv = traits_type::to_char_type(__c);
474  if (__testeof || _M_convert_to_external(&__conv, 1))
475  {
476  _M_writing = true;
477  __ret = traits_type::not_eof(__c);
478  }
479  }
480  }
481  return __ret;
482  }
483 
484  template<typename _CharT, typename _Traits>
485  bool
486  basic_filebuf<_CharT, _Traits>::
487  _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
488  {
489  // Sizes of external and pending output.
490  streamsize __elen;
491  streamsize __plen;
492  if (__check_facet(_M_codecvt).always_noconv())
493  {
494  __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
495  __plen = __ilen;
496  }
497  else
498  {
499  // Worst-case number of external bytes needed.
500  // XXX Not done encoding() == -1.
501  streamsize __blen = __ilen * _M_codecvt->max_length();
502  char* __buf = static_cast<char*>(__builtin_alloca(__blen));
503 
504  char* __bend;
505  const char_type* __iend;
506  codecvt_base::result __r;
507  __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
508  __iend, __buf, __buf + __blen, __bend);
509 
510  if (__r == codecvt_base::ok || __r == codecvt_base::partial)
511  __blen = __bend - __buf;
512  else if (__r == codecvt_base::noconv)
513  {
514  // Same as the always_noconv case above.
515  __buf = reinterpret_cast<char*>(__ibuf);
516  __blen = __ilen;
517  }
518  else
519  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
520  "conversion error"));
521 
522  __elen = _M_file.xsputn(__buf, __blen);
523  __plen = __blen;
524 
525  // Try once more for partial conversions.
526  if (__r == codecvt_base::partial && __elen == __plen)
527  {
528  const char_type* __iresume = __iend;
529  streamsize __rlen = this->pptr() - __iend;
530  __r = _M_codecvt->out(_M_state_cur, __iresume,
531  __iresume + __rlen, __iend, __buf,
532  __buf + __blen, __bend);
533  if (__r != codecvt_base::error)
534  {
535  __rlen = __bend - __buf;
536  __elen = _M_file.xsputn(__buf, __rlen);
537  __plen = __rlen;
538  }
539  else
540  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
541  "conversion error"));
542  }
543  }
544  return __elen == __plen;
545  }
546 
547  template<typename _CharT, typename _Traits>
548  streamsize
549  basic_filebuf<_CharT, _Traits>::
550  xsgetn(_CharT* __s, streamsize __n)
551  {
552  // Clear out pback buffer before going on to the real deal...
553  streamsize __ret = 0;
554  if (_M_pback_init)
555  {
556  if (__n > 0 && this->gptr() == this->eback())
557  {
558  *__s++ = *this->gptr(); // emulate non-underflowing sbumpc
559  this->gbump(1);
560  __ret = 1;
561  --__n;
562  }
563  _M_destroy_pback();
564  }
565  else if (_M_writing)
566  {
567  if (overflow() == traits_type::eof())
568  return __ret;
569  _M_set_buffer(-1);
570  _M_writing = false;
571  }
572 
573  // Optimization in the always_noconv() case, to be generalized in the
574  // future: when __n > __buflen we read directly instead of using the
575  // buffer repeatedly.
576  const bool __testin = _M_mode & ios_base::in;
577  const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
578 
579  if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
580  && __testin)
581  {
582  // First, copy the chars already present in the buffer.
583  const streamsize __avail = this->egptr() - this->gptr();
584  if (__avail != 0)
585  {
586  traits_type::copy(__s, this->gptr(), __avail);
587  __s += __avail;
588  this->setg(this->eback(), this->gptr() + __avail,
589  this->egptr());
590  __ret += __avail;
591  __n -= __avail;
592  }
593 
594  // Need to loop in case of short reads (relatively common
595  // with pipes).
596  streamsize __len;
597  for (;;)
598  {
599  __len = _M_file.xsgetn(reinterpret_cast<char*>(__s),
600  __n);
601  if (__len == -1)
602  __throw_ios_failure(__N("basic_filebuf::xsgetn "
603  "error reading the file"));
604  if (__len == 0)
605  break;
606 
607  __n -= __len;
608  __ret += __len;
609  if (__n == 0)
610  break;
611 
612  __s += __len;
613  }
614 
615  if (__n == 0)
616  {
617  _M_set_buffer(0);
618  _M_reading = true;
619  }
620  else if (__len == 0)
621  {
622  // If end of file is reached, set 'uncommitted'
623  // mode, thus allowing an immediate write without
624  // an intervening seek.
625  _M_set_buffer(-1);
626  _M_reading = false;
627  }
628  }
629  else
630  __ret += __streambuf_type::xsgetn(__s, __n);
631 
632  return __ret;
633  }
634 
635  template<typename _CharT, typename _Traits>
636  streamsize
637  basic_filebuf<_CharT, _Traits>::
638  xsputn(const _CharT* __s, streamsize __n)
639  {
640  streamsize __ret = 0;
641  // Optimization in the always_noconv() case, to be generalized in the
642  // future: when __n is sufficiently large we write directly instead of
643  // using the buffer.
644  const bool __testout = (_M_mode & ios_base::out
645  || _M_mode & ios_base::app);
646  if (__check_facet(_M_codecvt).always_noconv()
647  && __testout && !_M_reading)
648  {
649  // Measurement would reveal the best choice.
650  const streamsize __chunk = 1ul << 10;
651  streamsize __bufavail = this->epptr() - this->pptr();
652 
653  // Don't mistake 'uncommitted' mode buffered with unbuffered.
654  if (!_M_writing && _M_buf_size > 1)
655  __bufavail = _M_buf_size - 1;
656 
657  const streamsize __limit = std::min(__chunk, __bufavail);
658  if (__n >= __limit)
659  {
660  const streamsize __buffill = this->pptr() - this->pbase();
661  const char* __buf = reinterpret_cast<const char*>(this->pbase());
662  __ret = _M_file.xsputn_2(__buf, __buffill,
663  reinterpret_cast<const char*>(__s),
664  __n);
665  if (__ret == __buffill + __n)
666  {
667  _M_set_buffer(0);
668  _M_writing = true;
669  }
670  if (__ret > __buffill)
671  __ret -= __buffill;
672  else
673  __ret = 0;
674  }
675  else
676  __ret = __streambuf_type::xsputn(__s, __n);
677  }
678  else
679  __ret = __streambuf_type::xsputn(__s, __n);
680  return __ret;
681  }
682 
683  template<typename _CharT, typename _Traits>
684  typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
685  basic_filebuf<_CharT, _Traits>::
686  setbuf(char_type* __s, streamsize __n)
687  {
688  if (!this->is_open())
689  {
690  if (__s == 0 && __n == 0)
691  _M_buf_size = 1;
692  else if (__s && __n > 0)
693  {
694  // This is implementation-defined behavior, and assumes that
695  // an external char_type array of length __n exists and has
696  // been pre-allocated. If this is not the case, things will
697  // quickly blow up. When __n > 1, __n - 1 positions will be
698  // used for the get area, __n - 1 for the put area and 1
699  // position to host the overflow char of a full put area.
700  // When __n == 1, 1 position will be used for the get area
701  // and 0 for the put area, as in the unbuffered case above.
702  _M_buf = __s;
703  _M_buf_size = __n;
704  }
705  }
706  return this;
707  }
708 
709 
710  // According to 27.8.1.4 p11 - 13, seekoff should ignore the last
711  // argument (of type openmode).
712  template<typename _CharT, typename _Traits>
713  typename basic_filebuf<_CharT, _Traits>::pos_type
714  basic_filebuf<_CharT, _Traits>::
715  seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
716  {
717  int __width = 0;
718  if (_M_codecvt)
719  __width = _M_codecvt->encoding();
720  if (__width < 0)
721  __width = 0;
722 
723  pos_type __ret = pos_type(off_type(-1));
724  const bool __testfail = __off != 0 && __width <= 0;
725  if (this->is_open() && !__testfail)
726  {
727  // tellg and tellp queries do not affect any state, unless
728  // ! always_noconv and the put sequence is not empty.
729  // In that case, determining the position requires converting the
730  // put sequence. That doesn't use ext_buf, so requires a flush.
731  bool __no_movement = __way == ios_base::cur && __off == 0
732  && (!_M_writing || _M_codecvt->always_noconv());
733 
734  // Ditch any pback buffers to avoid confusion.
735  if (!__no_movement)
736  _M_destroy_pback();
737 
738  // Correct state at destination. Note that this is the correct
739  // state for the current position during output, because
740  // codecvt::unshift() returns the state to the initial state.
741  // This is also the correct state at the end of the file because
742  // an unshift sequence should have been written at the end.
743  __state_type __state = _M_state_beg;
744  off_type __computed_off = __off * __width;
745  if (_M_reading && __way == ios_base::cur)
746  {
747  __state = _M_state_last;
748  __computed_off += _M_get_ext_pos(__state);
749  }
750  if (!__no_movement)
751  __ret = _M_seek(__computed_off, __way, __state);
752  else
753  {
754  if (_M_writing)
755  __computed_off = this->pptr() - this->pbase();
756 
757  off_type __file_off = _M_file.seekoff(0, ios_base::cur);
758  if (__file_off != off_type(-1))
759  {
760  __ret = __file_off + __computed_off;
761  __ret.state(__state);
762  }
763  }
764  }
765  return __ret;
766  }
767 
768  // _GLIBCXX_RESOLVE_LIB_DEFECTS
769  // 171. Strange seekpos() semantics due to joint position
770  // According to the resolution of DR 171, seekpos should ignore the last
771  // argument (of type openmode).
772  template<typename _CharT, typename _Traits>
773  typename basic_filebuf<_CharT, _Traits>::pos_type
774  basic_filebuf<_CharT, _Traits>::
775  seekpos(pos_type __pos, ios_base::openmode)
776  {
777  pos_type __ret = pos_type(off_type(-1));
778  if (this->is_open())
779  {
780  // Ditch any pback buffers to avoid confusion.
781  _M_destroy_pback();
782  __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
783  }
784  return __ret;
785  }
786 
787  template<typename _CharT, typename _Traits>
788  typename basic_filebuf<_CharT, _Traits>::pos_type
789  basic_filebuf<_CharT, _Traits>::
790  _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
791  {
792  pos_type __ret = pos_type(off_type(-1));
793  if (_M_terminate_output())
794  {
795  off_type __file_off = _M_file.seekoff(__off, __way);
796  if (__file_off != off_type(-1))
797  {
798  _M_reading = false;
799  _M_writing = false;
800  _M_ext_next = _M_ext_end = _M_ext_buf;
801  _M_set_buffer(-1);
802  _M_state_cur = __state;
803  __ret = __file_off;
804  __ret.state(_M_state_cur);
805  }
806  }
807  return __ret;
808  }
809 
810  // Returns the distance from the end of the ext buffer to the point
811  // corresponding to gptr(). This is a negative value. Updates __state
812  // from eback() correspondence to gptr().
813  template<typename _CharT, typename _Traits>
814  int basic_filebuf<_CharT, _Traits>::
815  _M_get_ext_pos(__state_type& __state)
816  {
817  if (_M_codecvt->always_noconv())
818  return this->gptr() - this->egptr();
819  else
820  {
821  // Calculate offset from _M_ext_buf that corresponds to
822  // gptr(). Precondition: __state == _M_state_last, which
823  // corresponds to eback().
824  const int __gptr_off =
825  _M_codecvt->length(__state, _M_ext_buf, _M_ext_next,
826  this->gptr() - this->eback());
827  return _M_ext_buf + __gptr_off - _M_ext_end;
828  }
829  }
830 
831  template<typename _CharT, typename _Traits>
832  bool
833  basic_filebuf<_CharT, _Traits>::
834  _M_terminate_output()
835  {
836  // Part one: update the output sequence.
837  bool __testvalid = true;
838  if (this->pbase() < this->pptr())
839  {
840  const int_type __tmp = this->overflow();
841  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
842  __testvalid = false;
843  }
844 
845  // Part two: output unshift sequence.
846  if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
847  && __testvalid)
848  {
849  // Note: this value is arbitrary, since there is no way to
850  // get the length of the unshift sequence from codecvt,
851  // without calling unshift.
852  const size_t __blen = 128;
853  char __buf[__blen];
854  codecvt_base::result __r;
855  streamsize __ilen = 0;
856 
857  do
858  {
859  char* __next;
860  __r = _M_codecvt->unshift(_M_state_cur, __buf,
861  __buf + __blen, __next);
862  if (__r == codecvt_base::error)
863  __testvalid = false;
864  else if (__r == codecvt_base::ok ||
865  __r == codecvt_base::partial)
866  {
867  __ilen = __next - __buf;
868  if (__ilen > 0)
869  {
870  const streamsize __elen = _M_file.xsputn(__buf, __ilen);
871  if (__elen != __ilen)
872  __testvalid = false;
873  }
874  }
875  }
876  while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
877 
878  if (__testvalid)
879  {
880  // This second call to overflow() is required by the standard,
881  // but it's not clear why it's needed, since the output buffer
882  // should be empty by this point (it should have been emptied
883  // in the first call to overflow()).
884  const int_type __tmp = this->overflow();
885  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
886  __testvalid = false;
887  }
888  }
889  return __testvalid;
890  }
891 
892  template<typename _CharT, typename _Traits>
893  int
894  basic_filebuf<_CharT, _Traits>::
895  sync()
896  {
897  // Make sure that the internal buffer resyncs its idea of
898  // the file position with the external file.
899  int __ret = 0;
900  if (this->pbase() < this->pptr())
901  {
902  const int_type __tmp = this->overflow();
903  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
904  __ret = -1;
905  }
906  return __ret;
907  }
908 
909  template<typename _CharT, typename _Traits>
910  void
911  basic_filebuf<_CharT, _Traits>::
912  imbue(const locale& __loc)
913  {
914  bool __testvalid = true;
915 
916  const __codecvt_type* _M_codecvt_tmp = 0;
917  if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
918  _M_codecvt_tmp = &use_facet<__codecvt_type>(__loc);
919 
920  if (this->is_open())
921  {
922  // encoding() == -1 is ok only at the beginning.
923  if ((_M_reading || _M_writing)
924  && __check_facet(_M_codecvt).encoding() == -1)
925  __testvalid = false;
926  else
927  {
928  if (_M_reading)
929  {
930  if (__check_facet(_M_codecvt).always_noconv())
931  {
932  if (_M_codecvt_tmp
933  && !__check_facet(_M_codecvt_tmp).always_noconv())
934  __testvalid = this->seekoff(0, ios_base::cur, _M_mode)
935  != pos_type(off_type(-1));
936  }
937  else
938  {
939  // External position corresponding to gptr().
940  _M_ext_next = _M_ext_buf
941  + _M_codecvt->length(_M_state_last, _M_ext_buf,
942  _M_ext_next,
943  this->gptr() - this->eback());
944  const streamsize __remainder = _M_ext_end - _M_ext_next;
945  if (__remainder)
946  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
947 
948  _M_ext_next = _M_ext_buf;
949  _M_ext_end = _M_ext_buf + __remainder;
950  _M_set_buffer(-1);
951  _M_state_last = _M_state_cur = _M_state_beg;
952  }
953  }
954  else if (_M_writing && (__testvalid = _M_terminate_output()))
955  _M_set_buffer(-1);
956  }
957  }
958 
959  if (__testvalid)
960  _M_codecvt = _M_codecvt_tmp;
961  else
962  _M_codecvt = 0;
963  }
964 
965  // Inhibit implicit instantiations for required instantiations,
966  // which are defined via explicit instantiations elsewhere.
967 #if _GLIBCXX_EXTERN_TEMPLATE
968  extern template class basic_filebuf<char>;
969  extern template class basic_ifstream<char>;
970  extern template class basic_ofstream<char>;
971  extern template class basic_fstream<char>;
972 
973 #ifdef _GLIBCXX_USE_WCHAR_T
974  extern template class basic_filebuf<wchar_t>;
975  extern template class basic_ifstream<wchar_t>;
976  extern template class basic_ofstream<wchar_t>;
977  extern template class basic_fstream<wchar_t>;
978 #endif
979 #endif
980 
981 _GLIBCXX_END_NAMESPACE_VERSION
982 } // namespace std
983 
984 #endif