libstdc++
fstream.tcc
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1 // File based streams -*- C++ -*-
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
4 // 2007, 2008, 2009, 2010, 2011
5 // Free Software Foundation, Inc.
6 //
7 // This file is part of the GNU ISO C++ Library. This library is free
8 // software; you can redistribute it and/or modify it under the
9 // terms of the GNU General Public License as published by the
10 // Free Software Foundation; either version 3, or (at your option)
11 // any later version.
12 
13 // This library is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
17 
18 // Under Section 7 of GPL version 3, you are granted additional
19 // permissions described in the GCC Runtime Library Exception, version
20 // 3.1, as published by the Free Software Foundation.
21 
22 // You should have received a copy of the GNU General Public License and
23 // a copy of the GCC Runtime Library Exception along with this program;
24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 // <http://www.gnu.org/licenses/>.
26 
27 /** @file bits/fstream.tcc
28  * This is an internal header file, included by other library headers.
29  * Do not attempt to use it directly. @headername{fstream}
30  */
31 
32 //
33 // ISO C++ 14882: 27.8 File-based streams
34 //
35 
36 #ifndef _FSTREAM_TCC
37 #define _FSTREAM_TCC 1
38 
39 #pragma GCC system_header
40 
41 #include <bits/cxxabi_forced.h>
42 
43 namespace std _GLIBCXX_VISIBILITY(default)
44 {
45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46 
47  template<typename _CharT, typename _Traits>
48  void
49  basic_filebuf<_CharT, _Traits>::
50  _M_allocate_internal_buffer()
51  {
52  // Allocate internal buffer only if one doesn't already exist
53  // (either allocated or provided by the user via setbuf).
54  if (!_M_buf_allocated && !_M_buf)
55  {
56  _M_buf = new char_type[_M_buf_size];
57  _M_buf_allocated = true;
58  }
59  }
60 
61  template<typename _CharT, typename _Traits>
62  void
63  basic_filebuf<_CharT, _Traits>::
64  _M_destroy_internal_buffer() throw()
65  {
66  if (_M_buf_allocated)
67  {
68  delete [] _M_buf;
69  _M_buf = 0;
70  _M_buf_allocated = false;
71  }
72  delete [] _M_ext_buf;
73  _M_ext_buf = 0;
74  _M_ext_buf_size = 0;
75  _M_ext_next = 0;
76  _M_ext_end = 0;
77  }
78 
79  template<typename _CharT, typename _Traits>
81  basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
82  _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
83  _M_state_last(), _M_buf(0), _M_buf_size(BUFSIZ),
84  _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(),
85  _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
86  _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
87  _M_ext_end(0)
88  {
89  if (has_facet<__codecvt_type>(this->_M_buf_locale))
90  _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
91  }
92 
93  template<typename _CharT, typename _Traits>
96  open(const char* __s, ios_base::openmode __mode)
97  {
98  __filebuf_type *__ret = 0;
99  if (!this->is_open())
100  {
101  _M_file.open(__s, __mode);
102  if (this->is_open())
103  {
104  _M_allocate_internal_buffer();
105  _M_mode = __mode;
106 
107  // Setup initial buffer to 'uncommitted' mode.
108  _M_reading = false;
109  _M_writing = false;
110  _M_set_buffer(-1);
111 
112  // Reset to initial state.
113  _M_state_last = _M_state_cur = _M_state_beg;
114 
115  // 27.8.1.3,4
116  if ((__mode & ios_base::ate)
117  && this->seekoff(0, ios_base::end, __mode)
118  == pos_type(off_type(-1)))
119  this->close();
120  else
121  __ret = this;
122  }
123  }
124  return __ret;
125  }
126 
127  template<typename _CharT, typename _Traits>
131  {
132  if (!this->is_open())
133  return 0;
134 
135  bool __testfail = false;
136  {
137  // NB: Do this here so that re-opened filebufs will be cool...
138  struct __close_sentry
139  {
140  basic_filebuf *__fb;
141  __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
142  ~__close_sentry ()
143  {
144  __fb->_M_mode = ios_base::openmode(0);
145  __fb->_M_pback_init = false;
146  __fb->_M_destroy_internal_buffer();
147  __fb->_M_reading = false;
148  __fb->_M_writing = false;
149  __fb->_M_set_buffer(-1);
150  __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
151  }
152  } __cs (this);
153 
154  __try
155  {
156  if (!_M_terminate_output())
157  __testfail = true;
158  }
160  {
161  _M_file.close();
162  __throw_exception_again;
163  }
164  __catch(...)
165  { __testfail = true; }
166  }
167 
168  if (!_M_file.close())
169  __testfail = true;
170 
171  if (__testfail)
172  return 0;
173  else
174  return this;
175  }
176 
177  template<typename _CharT, typename _Traits>
178  streamsize
181  {
182  streamsize __ret = -1;
183  const bool __testin = _M_mode & ios_base::in;
184  if (__testin && this->is_open())
185  {
186  // For a stateful encoding (-1) the pending sequence might be just
187  // shift and unshift prefixes with no actual character.
188  __ret = this->egptr() - this->gptr();
189 
190 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
191  // About this workaround, see libstdc++/20806.
192  const bool __testbinary = _M_mode & ios_base::binary;
193  if (__check_facet(_M_codecvt).encoding() >= 0
194  && __testbinary)
195 #else
196  if (__check_facet(_M_codecvt).encoding() >= 0)
197 #endif
198  __ret += _M_file.showmanyc() / _M_codecvt->max_length();
199  }
200  return __ret;
201  }
202 
203  template<typename _CharT, typename _Traits>
204  typename basic_filebuf<_CharT, _Traits>::int_type
207  {
208  int_type __ret = traits_type::eof();
209  const bool __testin = _M_mode & ios_base::in;
210  if (__testin)
211  {
212  if (_M_writing)
213  {
214  if (overflow() == traits_type::eof())
215  return __ret;
216  _M_set_buffer(-1);
217  _M_writing = false;
218  }
219  // Check for pback madness, and if so switch back to the
220  // normal buffers and jet outta here before expensive
221  // fileops happen...
222  _M_destroy_pback();
223 
224  if (this->gptr() < this->egptr())
225  return traits_type::to_int_type(*this->gptr());
226 
227  // Get and convert input sequence.
228  const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
229 
230  // Will be set to true if ::read() returns 0 indicating EOF.
231  bool __got_eof = false;
232  // Number of internal characters produced.
233  streamsize __ilen = 0;
234  codecvt_base::result __r = codecvt_base::ok;
235  if (__check_facet(_M_codecvt).always_noconv())
236  {
237  __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
238  __buflen);
239  if (__ilen == 0)
240  __got_eof = true;
241  }
242  else
243  {
244  // Worst-case number of external bytes.
245  // XXX Not done encoding() == -1.
246  const int __enc = _M_codecvt->encoding();
247  streamsize __blen; // Minimum buffer size.
248  streamsize __rlen; // Number of chars to read.
249  if (__enc > 0)
250  __blen = __rlen = __buflen * __enc;
251  else
252  {
253  __blen = __buflen + _M_codecvt->max_length() - 1;
254  __rlen = __buflen;
255  }
256  const streamsize __remainder = _M_ext_end - _M_ext_next;
257  __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
258 
259  // An imbue in 'read' mode implies first converting the external
260  // chars already present.
261  if (_M_reading && this->egptr() == this->eback() && __remainder)
262  __rlen = 0;
263 
264  // Allocate buffer if necessary and move unconverted
265  // bytes to front.
266  if (_M_ext_buf_size < __blen)
267  {
268  char* __buf = new char[__blen];
269  if (__remainder)
270  __builtin_memcpy(__buf, _M_ext_next, __remainder);
271 
272  delete [] _M_ext_buf;
273  _M_ext_buf = __buf;
274  _M_ext_buf_size = __blen;
275  }
276  else if (__remainder)
277  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
278 
279  _M_ext_next = _M_ext_buf;
280  _M_ext_end = _M_ext_buf + __remainder;
281  _M_state_last = _M_state_cur;
282 
283  do
284  {
285  if (__rlen > 0)
286  {
287  // Sanity check!
288  // This may fail if the return value of
289  // codecvt::max_length() is bogus.
290  if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
291  {
292  __throw_ios_failure(__N("basic_filebuf::underflow "
293  "codecvt::max_length() "
294  "is not valid"));
295  }
296  streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
297  if (__elen == 0)
298  __got_eof = true;
299  else if (__elen == -1)
300  break;
301  _M_ext_end += __elen;
302  }
303 
304  char_type* __iend = this->eback();
305  if (_M_ext_next < _M_ext_end)
306  __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
307  _M_ext_end, _M_ext_next,
308  this->eback(),
309  this->eback() + __buflen, __iend);
310  if (__r == codecvt_base::noconv)
311  {
312  size_t __avail = _M_ext_end - _M_ext_buf;
313  __ilen = std::min(__avail, __buflen);
314  traits_type::copy(this->eback(),
315  reinterpret_cast<char_type*>
316  (_M_ext_buf), __ilen);
317  _M_ext_next = _M_ext_buf + __ilen;
318  }
319  else
320  __ilen = __iend - this->eback();
321 
322  // _M_codecvt->in may return error while __ilen > 0: this is
323  // ok, and actually occurs in case of mixed encodings (e.g.,
324  // XML files).
325  if (__r == codecvt_base::error)
326  break;
327 
328  __rlen = 1;
329  }
330  while (__ilen == 0 && !__got_eof);
331  }
332 
333  if (__ilen > 0)
334  {
335  _M_set_buffer(__ilen);
336  _M_reading = true;
337  __ret = traits_type::to_int_type(*this->gptr());
338  }
339  else if (__got_eof)
340  {
341  // If the actual end of file is reached, set 'uncommitted'
342  // mode, thus allowing an immediate write without an
343  // intervening seek.
344  _M_set_buffer(-1);
345  _M_reading = false;
346  // However, reaching it while looping on partial means that
347  // the file has got an incomplete character.
348  if (__r == codecvt_base::partial)
349  __throw_ios_failure(__N("basic_filebuf::underflow "
350  "incomplete character in file"));
351  }
352  else if (__r == codecvt_base::error)
353  __throw_ios_failure(__N("basic_filebuf::underflow "
354  "invalid byte sequence in file"));
355  else
356  __throw_ios_failure(__N("basic_filebuf::underflow "
357  "error reading the file"));
358  }
359  return __ret;
360  }
361 
362  template<typename _CharT, typename _Traits>
363  typename basic_filebuf<_CharT, _Traits>::int_type
365  pbackfail(int_type __i)
366  {
367  int_type __ret = traits_type::eof();
368  const bool __testin = _M_mode & ios_base::in;
369  if (__testin)
370  {
371  if (_M_writing)
372  {
373  if (overflow() == traits_type::eof())
374  return __ret;
375  _M_set_buffer(-1);
376  _M_writing = false;
377  }
378  // Remember whether the pback buffer is active, otherwise below
379  // we may try to store in it a second char (libstdc++/9761).
380  const bool __testpb = _M_pback_init;
381  const bool __testeof = traits_type::eq_int_type(__i, __ret);
382  int_type __tmp;
383  if (this->eback() < this->gptr())
384  {
385  this->gbump(-1);
386  __tmp = traits_type::to_int_type(*this->gptr());
387  }
388  else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
389  {
390  __tmp = this->underflow();
391  if (traits_type::eq_int_type(__tmp, __ret))
392  return __ret;
393  }
394  else
395  {
396  // At the beginning of the buffer, need to make a
397  // putback position available. But the seek may fail
398  // (f.i., at the beginning of a file, see
399  // libstdc++/9439) and in that case we return
400  // traits_type::eof().
401  return __ret;
402  }
403 
404  // Try to put back __i into input sequence in one of three ways.
405  // Order these tests done in is unspecified by the standard.
406  if (!__testeof && traits_type::eq_int_type(__i, __tmp))
407  __ret = __i;
408  else if (__testeof)
409  __ret = traits_type::not_eof(__i);
410  else if (!__testpb)
411  {
412  _M_create_pback();
413  _M_reading = true;
414  *this->gptr() = traits_type::to_char_type(__i);
415  __ret = __i;
416  }
417  }
418  return __ret;
419  }
420 
421  template<typename _CharT, typename _Traits>
422  typename basic_filebuf<_CharT, _Traits>::int_type
424  overflow(int_type __c)
425  {
426  int_type __ret = traits_type::eof();
427  const bool __testeof = traits_type::eq_int_type(__c, __ret);
428  const bool __testout = _M_mode & ios_base::out;
429  if (__testout)
430  {
431  if (_M_reading)
432  {
433  _M_destroy_pback();
434  const int __gptr_off = _M_get_ext_pos(_M_state_last);
435  if (_M_seek(__gptr_off, ios_base::cur, _M_state_last)
436  == pos_type(off_type(-1)))
437  return __ret;
438  }
439  if (this->pbase() < this->pptr())
440  {
441  // If appropriate, append the overflow char.
442  if (!__testeof)
443  {
444  *this->pptr() = traits_type::to_char_type(__c);
445  this->pbump(1);
446  }
447 
448  // Convert pending sequence to external representation,
449  // and output.
450  if (_M_convert_to_external(this->pbase(),
451  this->pptr() - this->pbase()))
452  {
453  _M_set_buffer(0);
454  __ret = traits_type::not_eof(__c);
455  }
456  }
457  else if (_M_buf_size > 1)
458  {
459  // Overflow in 'uncommitted' mode: set _M_writing, set
460  // the buffer to the initial 'write' mode, and put __c
461  // into the buffer.
462  _M_set_buffer(0);
463  _M_writing = true;
464  if (!__testeof)
465  {
466  *this->pptr() = traits_type::to_char_type(__c);
467  this->pbump(1);
468  }
469  __ret = traits_type::not_eof(__c);
470  }
471  else
472  {
473  // Unbuffered.
474  char_type __conv = traits_type::to_char_type(__c);
475  if (__testeof || _M_convert_to_external(&__conv, 1))
476  {
477  _M_writing = true;
478  __ret = traits_type::not_eof(__c);
479  }
480  }
481  }
482  return __ret;
483  }
484 
485  template<typename _CharT, typename _Traits>
486  bool
488  _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
489  {
490  // Sizes of external and pending output.
491  streamsize __elen;
492  streamsize __plen;
493  if (__check_facet(_M_codecvt).always_noconv())
494  {
495  __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
496  __plen = __ilen;
497  }
498  else
499  {
500  // Worst-case number of external bytes needed.
501  // XXX Not done encoding() == -1.
502  streamsize __blen = __ilen * _M_codecvt->max_length();
503  char* __buf = static_cast<char*>(__builtin_alloca(__blen));
504 
505  char* __bend;
506  const char_type* __iend;
507  codecvt_base::result __r;
508  __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
509  __iend, __buf, __buf + __blen, __bend);
510 
511  if (__r == codecvt_base::ok || __r == codecvt_base::partial)
512  __blen = __bend - __buf;
513  else if (__r == codecvt_base::noconv)
514  {
515  // Same as the always_noconv case above.
516  __buf = reinterpret_cast<char*>(__ibuf);
517  __blen = __ilen;
518  }
519  else
520  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
521  "conversion error"));
522 
523  __elen = _M_file.xsputn(__buf, __blen);
524  __plen = __blen;
525 
526  // Try once more for partial conversions.
527  if (__r == codecvt_base::partial && __elen == __plen)
528  {
529  const char_type* __iresume = __iend;
530  streamsize __rlen = this->pptr() - __iend;
531  __r = _M_codecvt->out(_M_state_cur, __iresume,
532  __iresume + __rlen, __iend, __buf,
533  __buf + __blen, __bend);
534  if (__r != codecvt_base::error)
535  {
536  __rlen = __bend - __buf;
537  __elen = _M_file.xsputn(__buf, __rlen);
538  __plen = __rlen;
539  }
540  else
541  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
542  "conversion error"));
543  }
544  }
545  return __elen == __plen;
546  }
547 
548  template<typename _CharT, typename _Traits>
549  streamsize
551  xsgetn(_CharT* __s, streamsize __n)
552  {
553  // Clear out pback buffer before going on to the real deal...
554  streamsize __ret = 0;
555  if (_M_pback_init)
556  {
557  if (__n > 0 && this->gptr() == this->eback())
558  {
559  *__s++ = *this->gptr(); // emulate non-underflowing sbumpc
560  this->gbump(1);
561  __ret = 1;
562  --__n;
563  }
564  _M_destroy_pback();
565  }
566  else if (_M_writing)
567  {
568  if (overflow() == traits_type::eof())
569  return __ret;
570  _M_set_buffer(-1);
571  _M_writing = false;
572  }
573 
574  // Optimization in the always_noconv() case, to be generalized in the
575  // future: when __n > __buflen we read directly instead of using the
576  // buffer repeatedly.
577  const bool __testin = _M_mode & ios_base::in;
578  const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
579 
580  if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
581  && __testin)
582  {
583  // First, copy the chars already present in the buffer.
584  const streamsize __avail = this->egptr() - this->gptr();
585  if (__avail != 0)
586  {
587  traits_type::copy(__s, this->gptr(), __avail);
588  __s += __avail;
589  this->setg(this->eback(), this->gptr() + __avail,
590  this->egptr());
591  __ret += __avail;
592  __n -= __avail;
593  }
594 
595  // Need to loop in case of short reads (relatively common
596  // with pipes).
597  streamsize __len;
598  for (;;)
599  {
600  __len = _M_file.xsgetn(reinterpret_cast<char*>(__s),
601  __n);
602  if (__len == -1)
603  __throw_ios_failure(__N("basic_filebuf::xsgetn "
604  "error reading the file"));
605  if (__len == 0)
606  break;
607 
608  __n -= __len;
609  __ret += __len;
610  if (__n == 0)
611  break;
612 
613  __s += __len;
614  }
615 
616  if (__n == 0)
617  {
618  _M_set_buffer(0);
619  _M_reading = true;
620  }
621  else if (__len == 0)
622  {
623  // If end of file is reached, set 'uncommitted'
624  // mode, thus allowing an immediate write without
625  // an intervening seek.
626  _M_set_buffer(-1);
627  _M_reading = false;
628  }
629  }
630  else
631  __ret += __streambuf_type::xsgetn(__s, __n);
632 
633  return __ret;
634  }
635 
636  template<typename _CharT, typename _Traits>
637  streamsize
639  xsputn(const _CharT* __s, streamsize __n)
640  {
641  streamsize __ret = 0;
642  // Optimization in the always_noconv() case, to be generalized in the
643  // future: when __n is sufficiently large we write directly instead of
644  // using the buffer.
645  const bool __testout = _M_mode & ios_base::out;
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>
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
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
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
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
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
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
The base of the I/O class hierarchy.This class defines everything that can be defined about I/O that ...
Definition: ios_base.h:201
virtual pos_type seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions.
Definition: fstream.tcc:715
static const seekdir beg
Request a seek relative to the beginning of the stream.
Definition: ios_base.h:398
static const openmode binary
Perform input and output in binary mode (as opposed to text mode). This is probably not what you thin...
Definition: ios_base.h:374
Controlling input for files.This class supports reading from named files, using the inherited functio...
Definition: fstream:420
static const seekdir end
Request a seek relative to the current end of the sequence.
Definition: ios_base.h:404
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition: postypes.h:100
basic_filebuf()
Does not open any files.
Definition: fstream.tcc:81
static const openmode ate
Open and seek to end immediately after opening.
Definition: ios_base.h:369
virtual int sync()
Synchronizes the buffer arrays with the controlled sequences.
Definition: fstream.tcc:895
Controlling output for files.This class supports reading from named files, using the inherited functi...
Definition: fstream:588
virtual int_type underflow()
Fetches more data from the controlled sequence.
Definition: fstream.tcc:206
virtual __streambuf_type * setbuf(char_type *__s, streamsize __n)
Manipulates the buffer.
Definition: fstream.tcc:686
virtual streamsize xsgetn(char_type *__s, streamsize __n)
Multiple character extraction.
Definition: fstream.tcc:551
__filebuf_type * open(const char *__s, ios_base::openmode __mode)
Opens an external file.
Definition: fstream.tcc:96
Container class for localization functionality.The locale class is first a class wrapper for C librar...
virtual pos_type seekpos(pos_type __pos, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions.
Definition: fstream.tcc:775
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:377
virtual void imbue(const locale &__loc)
Changes translations.
Definition: fstream.tcc:912
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:401
virtual int_type pbackfail(int_type __c=_Traits::eof())
Tries to back up the input sequence.
Definition: fstream.tcc:365
virtual streamsize showmanyc()
Investigating the data available.
Definition: fstream.tcc:180
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:380
The actual work of input and output (interface).This is a base class. Derived stream buffers each con...
Definition: iosfwd:82
__filebuf_type * close()
Closes the currently associated file.
Definition: fstream.tcc:130
Primary class template codecvt.NB: Generic, mostly useless implementation.
Definition: codecvt.h:277
const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:187
locale _M_buf_locale
Current locale setting.
Definition: streambuf:189
virtual int_type overflow(int_type __c=_Traits::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition: fstream.tcc:424
Thrown as part of forced unwinding.A magic placeholder class that can be caught by reference to recog...
Definition: cxxabi_forced.h:48
Controlling input and output for files.This class supports reading from and writing to named files...
Definition: fstream:761
virtual streamsize xsputn(const char_type *__s, streamsize __n)
Multiple character insertion.
Definition: fstream.tcc:639
_Ios_Openmode openmode
This is a bitmask type.
Definition: ios_base.h:363