libstdc++
fstream.tcc
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1 // File based streams -*- C++ -*-
2 
3 // Copyright (C) 1997-2025 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 #ifdef _GLIBCXX_SYSHDR
38 #pragma GCC system_header
39 #endif
40 
41 #pragma GCC diagnostic push
42 #pragma GCC diagnostic ignored "-Wc++11-extensions" // extern template
43 
44 #include <bits/cxxabi_forced.h>
45 #include <bits/move.h> // for swap
46 #include <cerrno>
47 
48 namespace std _GLIBCXX_VISIBILITY(default)
49 {
50 _GLIBCXX_BEGIN_NAMESPACE_VERSION
51 
52  template<typename _CharT, typename _Traits>
53  void
54  basic_filebuf<_CharT, _Traits>::
55  _M_allocate_internal_buffer()
56  {
57  // Allocate internal buffer only if one doesn't already exist
58  // (either allocated or provided by the user via setbuf).
59  if (!_M_buf_allocated && !_M_buf)
60  {
61  _M_buf = new char_type[_M_buf_size];
62  _M_buf_allocated = true;
63  }
64  }
65 
66  template<typename _CharT, typename _Traits>
67  void
68  basic_filebuf<_CharT, _Traits>::
69  _M_destroy_internal_buffer() throw()
70  {
71  if (_M_buf_allocated)
72  {
73  delete [] _M_buf;
74  _M_buf = 0;
75  _M_buf_allocated = false;
76  }
77  delete [] _M_ext_buf;
78  _M_ext_buf = 0;
79  _M_ext_buf_size = 0;
80  _M_ext_next = 0;
81  _M_ext_end = 0;
82  }
83 
84  template<typename _CharT, typename _Traits>
86  basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
87  _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
88  _M_state_last(), _M_buf(0), _M_buf_size(_GLIBCXX_BUFSIZ),
89  _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(),
90  _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
91  _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
92  _M_ext_end(0)
93  {
94  _M_codecvt = std::__try_use_facet<__codecvt_type>(this->_M_buf_locale);
95  }
96 
97 #if __cplusplus >= 201103L
98  template<typename _CharT, typename _Traits>
101  : __streambuf_type(__rhs),
102  _M_lock(), _M_file(std::move(__rhs._M_file), &_M_lock),
103  _M_mode(std::__exchange(__rhs._M_mode, ios_base::openmode(0))),
104  _M_state_beg(std::move(__rhs._M_state_beg)),
105  _M_state_cur(std::move(__rhs._M_state_cur)),
106  _M_state_last(std::move(__rhs._M_state_last)),
107  _M_buf(std::__exchange(__rhs._M_buf, nullptr)),
108  _M_buf_size(std::__exchange(__rhs._M_buf_size, 1)),
109  _M_buf_allocated(std::__exchange(__rhs._M_buf_allocated, false)),
110  _M_reading(std::__exchange(__rhs._M_reading, false)),
111  _M_writing(std::__exchange(__rhs._M_writing, false)),
112  _M_pback(__rhs._M_pback),
113  _M_pback_cur_save(std::__exchange(__rhs._M_pback_cur_save, nullptr)),
114  _M_pback_end_save(std::__exchange(__rhs._M_pback_end_save, nullptr)),
115  _M_pback_init(std::__exchange(__rhs._M_pback_init, false)),
116  _M_codecvt(__rhs._M_codecvt),
117  _M_ext_buf(std::__exchange(__rhs._M_ext_buf, nullptr)),
118  _M_ext_buf_size(std::__exchange(__rhs._M_ext_buf_size, 0)),
119  _M_ext_next(std::__exchange(__rhs._M_ext_next, nullptr)),
120  _M_ext_end(std::__exchange(__rhs._M_ext_end, nullptr))
121  {
122  __rhs._M_set_buffer(-1);
123  __rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg;
124  }
125 
126  template<typename _CharT, typename _Traits>
127  basic_filebuf<_CharT, _Traits>&
128  basic_filebuf<_CharT, _Traits>::
129  operator=(basic_filebuf&& __rhs)
130  {
131  this->close();
132  __streambuf_type::operator=(__rhs);
133  _M_file.swap(__rhs._M_file);
134  _M_mode = std::__exchange(__rhs._M_mode, ios_base::openmode(0));
135  _M_state_beg = std::move(__rhs._M_state_beg);
136  _M_state_cur = std::move(__rhs._M_state_cur);
137  _M_state_last = std::move(__rhs._M_state_last);
138  _M_buf = std::__exchange(__rhs._M_buf, nullptr);
139  _M_buf_size = std::__exchange(__rhs._M_buf_size, 1);
140  _M_buf_allocated = std::__exchange(__rhs._M_buf_allocated, false);
141  _M_ext_buf = std::__exchange(__rhs._M_ext_buf, nullptr);
142  _M_ext_buf_size = std::__exchange(__rhs._M_ext_buf_size, 0);
143  _M_ext_next = std::__exchange(__rhs._M_ext_next, nullptr);
144  _M_ext_end = std::__exchange(__rhs._M_ext_end, nullptr);
145  _M_reading = std::__exchange(__rhs._M_reading, false);
146  _M_writing = std::__exchange(__rhs._M_writing, false);
147  _M_pback_cur_save = std::__exchange(__rhs._M_pback_cur_save, nullptr);
148  _M_pback_end_save = std::__exchange(__rhs._M_pback_end_save, nullptr);
149  _M_pback_init = std::__exchange(__rhs._M_pback_init, false);
150  __rhs._M_set_buffer(-1);
151  __rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg;
152  return *this;
153  }
154 
155  template<typename _CharT, typename _Traits>
156  void
157  basic_filebuf<_CharT, _Traits>::
158  swap(basic_filebuf& __rhs)
159  {
160  __streambuf_type::swap(__rhs);
161  _M_file.swap(__rhs._M_file);
162  std::swap(_M_mode, __rhs._M_mode);
163  std::swap(_M_state_beg, __rhs._M_state_beg);
164  std::swap(_M_state_cur, __rhs._M_state_cur);
165  std::swap(_M_state_last, __rhs._M_state_last);
166  std::swap(_M_buf, __rhs._M_buf);
167  std::swap(_M_buf_size, __rhs._M_buf_size);
168  std::swap(_M_buf_allocated, __rhs._M_buf_allocated);
169  std::swap(_M_ext_buf, __rhs._M_ext_buf);
170  std::swap(_M_ext_buf_size, __rhs._M_ext_buf_size);
171  std::swap(_M_ext_next, __rhs._M_ext_next);
172  std::swap(_M_ext_end, __rhs._M_ext_end);
173  std::swap(_M_reading, __rhs._M_reading);
174  std::swap(_M_writing, __rhs._M_writing);
175  std::swap(_M_pback_cur_save, __rhs._M_pback_cur_save);
176  std::swap(_M_pback_end_save, __rhs._M_pback_end_save);
177  std::swap(_M_pback_init, __rhs._M_pback_init);
178  }
179 #endif
180 
181  template<typename _CharT, typename _Traits>
182  typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
184  open(const char* __s, ios_base::openmode __mode)
185  {
186  __filebuf_type *__ret = 0;
187  if (!this->is_open())
188  {
189  _M_file.open(__s, __mode);
190  if (this->is_open())
191  {
192  _M_allocate_internal_buffer();
193  _M_mode = __mode;
194 
195  // Setup initial buffer to 'uncommitted' mode.
196  _M_reading = false;
197  _M_writing = false;
198  _M_set_buffer(-1);
199 
200  // Reset to initial state.
201  _M_state_last = _M_state_cur = _M_state_beg;
202 
203  // 27.8.1.3,4
204  if ((__mode & ios_base::ate)
205  && this->seekoff(0, ios_base::end, __mode)
206  == pos_type(off_type(-1)))
207  this->close();
208  else
209  __ret = this;
210  }
211  }
212  return __ret;
213  }
214 
215 #if _GLIBCXX_HAVE__WFOPEN && _GLIBCXX_USE_WCHAR_T
216  template<typename _CharT, typename _Traits>
219  open(const wchar_t* __s, ios_base::openmode __mode)
220  {
221  __filebuf_type *__ret = 0;
222  if (!this->is_open())
223  {
224  _M_file.open(__s, __mode);
225  if (this->is_open())
226  {
227  _M_allocate_internal_buffer();
228  _M_mode = __mode;
229 
230  // Setup initial buffer to 'uncommitted' mode.
231  _M_reading = false;
232  _M_writing = false;
233  _M_set_buffer(-1);
234 
235  // Reset to initial state.
236  _M_state_last = _M_state_cur = _M_state_beg;
237 
238  // 27.8.1.3,4
239  if ((__mode & ios_base::ate)
240  && this->seekoff(0, ios_base::end, __mode)
241  == pos_type(off_type(-1)))
242  this->close();
243  else
244  __ret = this;
245  }
246  }
247  return __ret;
248  }
249 #endif // HAVE__WFOPEN && USE_WCHAR_T
250 
251  template<typename _CharT, typename _Traits>
254  close()
255  {
256  if (!this->is_open())
257  return 0;
258 
259  bool __testfail = false;
260  {
261  // NB: Do this here so that re-opened filebufs will be cool...
262  struct __close_sentry
263  {
264  basic_filebuf *__fb;
265  __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
266  ~__close_sentry ()
267  {
268  __fb->_M_mode = ios_base::openmode(0);
269  __fb->_M_pback_init = false;
270  __fb->_M_destroy_internal_buffer();
271  __fb->_M_reading = false;
272  __fb->_M_writing = false;
273  __fb->_M_set_buffer(-1);
274  __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
275  }
276  } __cs (this);
277 
278  __try
279  {
280  if (!_M_terminate_output())
281  __testfail = true;
282  }
283  __catch(...)
284  {
285  _M_file.close();
286  __throw_exception_again;
287  }
288  }
289 
290  if (!_M_file.close())
291  __testfail = true;
292 
293  if (__testfail)
294  return 0;
295  else
296  return this;
297  }
298 
299  template<typename _CharT, typename _Traits>
300  streamsize
302  showmanyc()
303  {
304  streamsize __ret = -1;
305  const bool __testin = _M_mode & ios_base::in;
306  if (__testin && this->is_open())
307  {
308  // For a stateful encoding (-1) the pending sequence might be just
309  // shift and unshift prefixes with no actual character.
310  __ret = this->egptr() - this->gptr();
311 
312 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
313  // About this workaround, see libstdc++/20806.
314  const bool __testbinary = _M_mode & ios_base::binary;
315  if (__check_facet(_M_codecvt).encoding() >= 0
316  && __testbinary)
317 #else
318  if (__check_facet(_M_codecvt).encoding() >= 0)
319 #endif
320  __ret += _M_file.showmanyc() / _M_codecvt->max_length();
321  }
322  return __ret;
323  }
324 
325  template<typename _CharT, typename _Traits>
326  typename basic_filebuf<_CharT, _Traits>::int_type
328  underflow()
329  {
330  int_type __ret = traits_type::eof();
331  const bool __testin = _M_mode & ios_base::in;
332  if (__testin)
333  {
334  if (_M_writing)
335  {
336  if (overflow() == traits_type::eof())
337  return __ret;
338  _M_set_buffer(-1);
339  _M_writing = false;
340  }
341  // Check for pback madness, and if so switch back to the
342  // normal buffers and jet outta here before expensive
343  // fileops happen...
344  _M_destroy_pback();
345 
346  if (this->gptr() < this->egptr())
347  return traits_type::to_int_type(*this->gptr());
348 
349  // Get and convert input sequence.
350  const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
351 
352  // Will be set to true if ::read() returns 0 indicating EOF.
353  bool __got_eof = false;
354  // Number of internal characters produced.
355  streamsize __ilen = 0;
356  codecvt_base::result __r = codecvt_base::ok;
357  if (__check_facet(_M_codecvt).always_noconv())
358  {
359  __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
360  __buflen);
361  if (__ilen == 0)
362  __got_eof = true;
363  }
364  else
365  {
366  // Worst-case number of external bytes.
367  // XXX Not done encoding() == -1.
368  const int __enc = _M_codecvt->encoding();
369  streamsize __blen; // Minimum buffer size.
370  streamsize __rlen; // Number of chars to read.
371  if (__enc > 0)
372  __blen = __rlen = __buflen * __enc;
373  else
374  {
375  __blen = __buflen + _M_codecvt->max_length() - 1;
376  __rlen = __buflen;
377  }
378  const streamsize __remainder = _M_ext_end - _M_ext_next;
379  __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
380 
381  // An imbue in 'read' mode implies first converting the external
382  // chars already present.
383  if (_M_reading && this->egptr() == this->eback() && __remainder)
384  __rlen = 0;
385 
386  // Allocate buffer if necessary and move unconverted
387  // bytes to front.
388  if (_M_ext_buf_size < __blen)
389  {
390  char* __buf = new char[__blen];
391  if (__remainder)
392  __builtin_memcpy(__buf, _M_ext_next, __remainder);
393 
394  delete [] _M_ext_buf;
395  _M_ext_buf = __buf;
396  _M_ext_buf_size = __blen;
397  }
398  else if (__remainder)
399  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
400 
401  _M_ext_next = _M_ext_buf;
402  _M_ext_end = _M_ext_buf + __remainder;
403  _M_state_last = _M_state_cur;
404 
405  do
406  {
407  if (__rlen > 0)
408  {
409  // Sanity check!
410  // This may fail if the return value of
411  // codecvt::max_length() is bogus.
412  if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
413  {
414  __throw_ios_failure(__N("basic_filebuf::underflow "
415  "codecvt::max_length() "
416  "is not valid"));
417  }
418  streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
419  if (__elen == 0)
420  __got_eof = true;
421  else if (__elen == -1)
422  break;
423  _M_ext_end += __elen;
424  }
425 
426  char_type* __iend = this->eback();
427  if (_M_ext_next < _M_ext_end)
428  __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
429  _M_ext_end, _M_ext_next,
430  this->eback(),
431  this->eback() + __buflen, __iend);
432  if (__r == codecvt_base::noconv)
433  {
434  size_t __avail = _M_ext_end - _M_ext_buf;
435  __ilen = std::min(__avail, __buflen);
436  traits_type::copy(this->eback(),
437  reinterpret_cast<char_type*>
438  (_M_ext_buf), __ilen);
439  _M_ext_next = _M_ext_buf + __ilen;
440  }
441  else
442  __ilen = __iend - this->eback();
443 
444  // _M_codecvt->in may return error while __ilen > 0: this is
445  // ok, and actually occurs in case of mixed encodings (e.g.,
446  // XML files).
447  if (__r == codecvt_base::error)
448  break;
449 
450  __rlen = 1;
451  }
452  while (__ilen == 0 && !__got_eof);
453  }
454 
455  if (__ilen > 0)
456  {
457  _M_set_buffer(__ilen);
458  _M_reading = true;
459  __ret = traits_type::to_int_type(*this->gptr());
460  }
461  else if (__got_eof)
462  {
463  // If the actual end of file is reached, set 'uncommitted'
464  // mode, thus allowing an immediate write without an
465  // intervening seek.
466  _M_set_buffer(-1);
467  _M_reading = false;
468  // However, reaching it while looping on partial means that
469  // the file has got an incomplete character.
470  if (__r == codecvt_base::partial)
471  __throw_ios_failure(__N("basic_filebuf::underflow "
472  "incomplete character in file"));
473  }
474  else if (__r == codecvt_base::error)
475  __throw_ios_failure(__N("basic_filebuf::underflow "
476  "invalid byte sequence in file"));
477  else
478  __throw_ios_failure(__N("basic_filebuf::underflow "
479  "error reading the file"), errno);
480  }
481  return __ret;
482  }
483 
484  template<typename _CharT, typename _Traits>
485  typename basic_filebuf<_CharT, _Traits>::int_type
487  pbackfail(int_type __i)
488  {
489  int_type __ret = traits_type::eof();
490  const bool __testin = _M_mode & ios_base::in;
491  if (__testin)
492  {
493  if (_M_writing)
494  {
495  if (overflow() == traits_type::eof())
496  return __ret;
497  _M_set_buffer(-1);
498  _M_writing = false;
499  }
500  // Remember whether the pback buffer is active, otherwise below
501  // we may try to store in it a second char (libstdc++/9761).
502  const bool __testpb = _M_pback_init;
503  const bool __testeof = traits_type::eq_int_type(__i, __ret);
504  int_type __tmp;
505  if (this->eback() < this->gptr())
506  {
507  this->gbump(-1);
508  __tmp = traits_type::to_int_type(*this->gptr());
509  }
510  else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
511  {
512  __tmp = this->underflow();
513  if (traits_type::eq_int_type(__tmp, __ret))
514  return __ret;
515  }
516  else
517  {
518  // At the beginning of the buffer, need to make a
519  // putback position available. But the seek may fail
520  // (f.i., at the beginning of a file, see
521  // libstdc++/9439) and in that case we return
522  // traits_type::eof().
523  return __ret;
524  }
525 
526  // Try to put back __i into input sequence in one of three ways.
527  // Order these tests done in is unspecified by the standard.
528  if (!__testeof && traits_type::eq_int_type(__i, __tmp))
529  __ret = __i;
530  else if (__testeof)
531  __ret = traits_type::not_eof(__i);
532  else if (!__testpb)
533  {
534  _M_create_pback();
535  _M_reading = true;
536  *this->gptr() = traits_type::to_char_type(__i);
537  __ret = __i;
538  }
539  }
540  return __ret;
541  }
542 
543  template<typename _CharT, typename _Traits>
544  typename basic_filebuf<_CharT, _Traits>::int_type
546  overflow(int_type __c)
547  {
548  int_type __ret = traits_type::eof();
549  const bool __testeof = traits_type::eq_int_type(__c, __ret);
550  const bool __testout = (_M_mode & ios_base::out
551  || _M_mode & ios_base::app);
552  if (__testout)
553  {
554  if (_M_reading)
555  {
556  _M_destroy_pback();
557  const int __gptr_off = _M_get_ext_pos(_M_state_last);
558  if (_M_seek(__gptr_off, ios_base::cur, _M_state_last)
559  == pos_type(off_type(-1)))
560  return __ret;
561  }
562  if (this->pbase() < this->pptr())
563  {
564  // If appropriate, append the overflow char.
565  if (!__testeof)
566  {
567  *this->pptr() = traits_type::to_char_type(__c);
568  this->pbump(1);
569  }
570 
571  // Convert pending sequence to external representation,
572  // and output.
573  if (_M_convert_to_external(this->pbase(),
574  this->pptr() - this->pbase()))
575  {
576  _M_set_buffer(0);
577  __ret = traits_type::not_eof(__c);
578  }
579  }
580  else if (_M_buf_size > 1)
581  {
582  // Overflow in 'uncommitted' mode: set _M_writing, set
583  // the buffer to the initial 'write' mode, and put __c
584  // into the buffer.
585  _M_set_buffer(0);
586  _M_writing = true;
587  if (!__testeof)
588  {
589  *this->pptr() = traits_type::to_char_type(__c);
590  this->pbump(1);
591  }
592  __ret = traits_type::not_eof(__c);
593  }
594  else
595  {
596  // Unbuffered.
597  char_type __conv = traits_type::to_char_type(__c);
598  if (__testeof || _M_convert_to_external(&__conv, 1))
599  {
600  _M_writing = true;
601  __ret = traits_type::not_eof(__c);
602  }
603  }
604  }
605  return __ret;
606  }
607 
608  template<typename _CharT, typename _Traits>
609  bool
611  _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
612  {
613  // Sizes of external and pending output.
614  streamsize __elen;
615  streamsize __plen;
616  if (__check_facet(_M_codecvt).always_noconv())
617  {
618  __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
619  __plen = __ilen;
620  }
621  else
622  {
623  // Worst-case number of external bytes needed.
624  // XXX Not done encoding() == -1.
625  streamsize __blen = __ilen * _M_codecvt->max_length();
626  char* __buf = static_cast<char*>(__builtin_alloca(__blen));
627 
628  char* __bend;
629  const char_type* __iend;
630  codecvt_base::result __r;
631  __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
632  __iend, __buf, __buf + __blen, __bend);
633 
634  if (__r == codecvt_base::ok || __r == codecvt_base::partial)
635  __blen = __bend - __buf;
636  else if (__r == codecvt_base::noconv)
637  {
638  // Same as the always_noconv case above.
639  __buf = reinterpret_cast<char*>(__ibuf);
640  __blen = __ilen;
641  }
642  else
643  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
644  "conversion error"));
645 
646  __elen = _M_file.xsputn(__buf, __blen);
647  __plen = __blen;
648 
649  // Try once more for partial conversions.
650  if (__r == codecvt_base::partial && __elen == __plen)
651  {
652  const char_type* __iresume = __iend;
653  streamsize __rlen = this->pptr() - __iend;
654  __r = _M_codecvt->out(_M_state_cur, __iresume,
655  __iresume + __rlen, __iend, __buf,
656  __buf + __blen, __bend);
657  if (__r != codecvt_base::error)
658  {
659  __rlen = __bend - __buf;
660  __elen = _M_file.xsputn(__buf, __rlen);
661  __plen = __rlen;
662  }
663  else
664  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
665  "conversion error"));
666  }
667  }
668  return __elen == __plen;
669  }
670 
671  template<typename _CharT, typename _Traits>
672  streamsize
674  xsgetn(_CharT* __s, streamsize __n)
675  {
676  // Clear out pback buffer before going on to the real deal...
677  streamsize __ret = 0;
678  if (_M_pback_init)
679  {
680  if (__n > 0 && this->gptr() == this->eback())
681  {
682  *__s++ = *this->gptr(); // emulate non-underflowing sbumpc
683  this->gbump(1);
684  __ret = 1;
685  --__n;
686  }
687  _M_destroy_pback();
688  }
689  else if (_M_writing)
690  {
691  if (overflow() == traits_type::eof())
692  return __ret;
693  _M_set_buffer(-1);
694  _M_writing = false;
695  }
696 
697  // Optimization in the always_noconv() case, to be generalized in the
698  // future: when __n > __buflen we read directly instead of using the
699  // buffer repeatedly.
700  const bool __testin = _M_mode & ios_base::in;
701  const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
702 
703  if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
704  && __testin)
705  {
706  // First, copy the chars already present in the buffer.
707  const streamsize __avail = this->egptr() - this->gptr();
708  if (__avail != 0)
709  {
710  traits_type::copy(__s, this->gptr(), __avail);
711  __s += __avail;
712  this->setg(this->eback(), this->gptr() + __avail, this->egptr());
713  __ret += __avail;
714  __n -= __avail;
715  }
716 
717  // Need to loop in case of short reads (relatively common
718  // with pipes).
719  streamsize __len;
720  for (;;)
721  {
722  __len = _M_file.xsgetn(reinterpret_cast<char*>(__s), __n);
723  if (__len == -1)
724  __throw_ios_failure(__N("basic_filebuf::xsgetn "
725  "error reading the file"), errno);
726  if (__len == 0)
727  break;
728 
729  __n -= __len;
730  __ret += __len;
731  if (__n == 0)
732  break;
733 
734  __s += __len;
735  }
736 
737  if (__n == 0)
738  {
739  // Set _M_reading. Buffer is already in initial 'read' mode.
740  _M_reading = true;
741  }
742  else if (__len == 0)
743  {
744  // If end of file is reached, set 'uncommitted'
745  // mode, thus allowing an immediate write without
746  // an intervening seek.
747  _M_set_buffer(-1);
748  _M_reading = false;
749  }
750  }
751  else
752  __ret += __streambuf_type::xsgetn(__s, __n);
753 
754  return __ret;
755  }
756 
757  template<typename _CharT, typename _Traits>
758  streamsize
760  xsputn(const _CharT* __s, streamsize __n)
761  {
762  streamsize __ret = 0;
763  // Optimization in the always_noconv() case, to be generalized in the
764  // future: when __n is larger than the available capacity we write
765  // directly instead of using the buffer.
766  const bool __testout = (_M_mode & ios_base::out
767  || _M_mode & ios_base::app);
768  if (__check_facet(_M_codecvt).always_noconv()
769  && __testout && !_M_reading)
770  {
771  streamsize __bufavail = this->epptr() - this->pptr();
772 
773  // Don't mistake 'uncommitted' mode buffered with unbuffered.
774  if (!_M_writing && _M_buf_size > 1)
775  __bufavail = _M_buf_size - 1;
776 
777  if (__n >= __bufavail)
778  {
779  const streamsize __buffill = this->pptr() - this->pbase();
780  const char* __buf = reinterpret_cast<const char*>(this->pbase());
781  __ret = _M_file.xsputn_2(__buf, __buffill,
782  reinterpret_cast<const char*>(__s),
783  __n);
784  if (__ret == __buffill + __n)
785  {
786  _M_set_buffer(0);
787  _M_writing = true;
788  }
789  if (__ret > __buffill)
790  __ret -= __buffill;
791  else
792  __ret = 0;
793  }
794  else
795  __ret = __streambuf_type::xsputn(__s, __n);
796  }
797  else
798  __ret = __streambuf_type::xsputn(__s, __n);
799  return __ret;
800  }
801 
802  template<typename _CharT, typename _Traits>
805  setbuf(char_type* __s, streamsize __n)
806  {
807  if (!this->is_open())
808  {
809  if (__s == 0 && __n == 0)
810  _M_buf_size = 1;
811  else if (__s && __n > 0)
812  {
813  // This is implementation-defined behavior, and assumes that
814  // an external char_type array of length __n exists and has
815  // been pre-allocated. If this is not the case, things will
816  // quickly blow up. When __n > 1, __n - 1 positions will be
817  // used for the get area, __n - 1 for the put area and 1
818  // position to host the overflow char of a full put area.
819  // When __n == 1, 1 position will be used for the get area
820  // and 0 for the put area, as in the unbuffered case above.
821  _M_buf = __s;
822  _M_buf_size = __n;
823  }
824  }
825  return this;
826  }
827 
828 
829  // According to 27.8.1.4 p11 - 13, seekoff should ignore the last
830  // argument (of type openmode).
831  template<typename _CharT, typename _Traits>
832  typename basic_filebuf<_CharT, _Traits>::pos_type
834  seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
835  {
836  int __width = 0;
837  if (_M_codecvt)
838  __width = _M_codecvt->encoding();
839  if (__width < 0)
840  __width = 0;
841 
842  pos_type __ret = pos_type(off_type(-1));
843  const bool __testfail = __off != 0 && __width <= 0;
844  if (this->is_open() && !__testfail)
845  {
846  // tellg and tellp queries do not affect any state, unless
847  // ! always_noconv and the put sequence is not empty.
848  // In that case, determining the position requires converting the
849  // put sequence. That doesn't use ext_buf, so requires a flush.
850  bool __no_movement = __way == ios_base::cur && __off == 0
851  && (!_M_writing || _M_codecvt->always_noconv());
852 
853  // Ditch any pback buffers to avoid confusion.
854  if (!__no_movement)
855  _M_destroy_pback();
856 
857  // Correct state at destination. Note that this is the correct
858  // state for the current position during output, because
859  // codecvt::unshift() returns the state to the initial state.
860  // This is also the correct state at the end of the file because
861  // an unshift sequence should have been written at the end.
862  __state_type __state = _M_state_beg;
863  off_type __computed_off = __off * __width;
864  if (_M_reading && __way == ios_base::cur)
865  {
866  __state = _M_state_last;
867  __computed_off += _M_get_ext_pos(__state);
868  }
869  if (!__no_movement)
870  __ret = _M_seek(__computed_off, __way, __state);
871  else
872  {
873  if (_M_writing)
874  __computed_off = this->pptr() - this->pbase();
875 
876  off_type __file_off = _M_file.seekoff(0, ios_base::cur);
877  if (__file_off != off_type(-1))
878  {
879  __ret = __file_off + __computed_off;
880  __ret.state(__state);
881  }
882  }
883  }
884  return __ret;
885  }
886 
887  // _GLIBCXX_RESOLVE_LIB_DEFECTS
888  // 171. Strange seekpos() semantics due to joint position
889  // According to the resolution of DR 171, seekpos should ignore the last
890  // argument (of type openmode).
891  template<typename _CharT, typename _Traits>
892  typename basic_filebuf<_CharT, _Traits>::pos_type
894  seekpos(pos_type __pos, ios_base::openmode)
895  {
896  pos_type __ret = pos_type(off_type(-1));
897  if (this->is_open())
898  {
899  // Ditch any pback buffers to avoid confusion.
900  _M_destroy_pback();
901  __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
902  }
903  return __ret;
904  }
905 
906  template<typename _CharT, typename _Traits>
907  typename basic_filebuf<_CharT, _Traits>::pos_type
909  _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
910  {
911  pos_type __ret = pos_type(off_type(-1));
912  if (_M_terminate_output())
913  {
914  off_type __file_off = _M_file.seekoff(__off, __way);
915  if (__file_off != off_type(-1))
916  {
917  _M_reading = false;
918  _M_writing = false;
919  _M_ext_next = _M_ext_end = _M_ext_buf;
920  _M_set_buffer(-1);
921  _M_state_cur = __state;
922  __ret = __file_off;
923  __ret.state(_M_state_cur);
924  }
925  }
926  return __ret;
927  }
928 
929  // Returns the distance from the end of the ext buffer to the point
930  // corresponding to gptr(). This is a negative value. Updates __state
931  // from eback() correspondence to gptr().
932  template<typename _CharT, typename _Traits>
933  int basic_filebuf<_CharT, _Traits>::
934  _M_get_ext_pos(__state_type& __state)
935  {
936  if (_M_codecvt->always_noconv())
937  return this->gptr() - this->egptr();
938  else
939  {
940  // Calculate offset from _M_ext_buf that corresponds to
941  // gptr(). Precondition: __state == _M_state_last, which
942  // corresponds to eback().
943  const int __gptr_off =
944  _M_codecvt->length(__state, _M_ext_buf, _M_ext_next,
945  this->gptr() - this->eback());
946  return _M_ext_buf + __gptr_off - _M_ext_end;
947  }
948  }
949 
950  template<typename _CharT, typename _Traits>
951  bool
952  basic_filebuf<_CharT, _Traits>::
953  _M_terminate_output()
954  {
955  // Part one: update the output sequence.
956  bool __testvalid = true;
957  if (this->pbase() < this->pptr())
958  {
959  const int_type __tmp = this->overflow();
960  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
961  __testvalid = false;
962  }
963 
964  // Part two: output unshift sequence.
965  if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
966  && __testvalid)
967  {
968  // Note: this value is arbitrary, since there is no way to
969  // get the length of the unshift sequence from codecvt,
970  // without calling unshift.
971  const size_t __blen = 128;
972  char __buf[__blen];
973  codecvt_base::result __r;
974  streamsize __ilen = 0;
975 
976  do
977  {
978  char* __next;
979  __r = _M_codecvt->unshift(_M_state_cur, __buf,
980  __buf + __blen, __next);
981  if (__r == codecvt_base::error)
982  __testvalid = false;
983  else if (__r == codecvt_base::ok ||
984  __r == codecvt_base::partial)
985  {
986  __ilen = __next - __buf;
987  if (__ilen > 0)
988  {
989  const streamsize __elen = _M_file.xsputn(__buf, __ilen);
990  if (__elen != __ilen)
991  __testvalid = false;
992  }
993  }
994  }
995  while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
996 
997  if (__testvalid)
998  {
999  // This second call to overflow() is required by the standard,
1000  // but it's not clear why it's needed, since the output buffer
1001  // should be empty by this point (it should have been emptied
1002  // in the first call to overflow()).
1003  const int_type __tmp = this->overflow();
1004  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
1005  __testvalid = false;
1006  }
1007  }
1008  return __testvalid;
1009  }
1010 
1011  template<typename _CharT, typename _Traits>
1012  int
1014  sync()
1015  {
1016  // Make sure that the internal buffer resyncs its idea of
1017  // the file position with the external file.
1018  int __ret = 0;
1019  if (this->pbase() < this->pptr())
1020  {
1021  const int_type __tmp = this->overflow();
1022  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
1023  __ret = -1;
1024  }
1025  return __ret;
1026  }
1027 
1028  template<typename _CharT, typename _Traits>
1029  void
1031  imbue(const locale& __loc)
1032  {
1033  bool __testvalid = true;
1034 
1035  const __codecvt_type* const _M_codecvt_tmp
1036  = __try_use_facet<__codecvt_type>(__loc);
1037 
1038  if (this->is_open())
1039  {
1040  // encoding() == -1 is ok only at the beginning.
1041  if ((_M_reading || _M_writing)
1042  && __check_facet(_M_codecvt).encoding() == -1)
1043  __testvalid = false;
1044  else
1045  {
1046  if (_M_reading)
1047  {
1048  if (__check_facet(_M_codecvt).always_noconv())
1049  {
1050  if (_M_codecvt_tmp
1051  && !__check_facet(_M_codecvt_tmp).always_noconv())
1052  __testvalid = this->seekoff(0, ios_base::cur, _M_mode)
1053  != pos_type(off_type(-1));
1054  }
1055  else
1056  {
1057  // External position corresponding to gptr().
1058  _M_ext_next = _M_ext_buf
1059  + _M_codecvt->length(_M_state_last, _M_ext_buf,
1060  _M_ext_next,
1061  this->gptr() - this->eback());
1062  const streamsize __remainder = _M_ext_end - _M_ext_next;
1063  if (__remainder)
1064  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
1065 
1066  _M_ext_next = _M_ext_buf;
1067  _M_ext_end = _M_ext_buf + __remainder;
1068  _M_set_buffer(-1);
1069  _M_state_last = _M_state_cur = _M_state_beg;
1070  }
1071  }
1072  else if (_M_writing && (__testvalid = _M_terminate_output()))
1073  _M_set_buffer(-1);
1074  }
1075  }
1076 
1077  if (__testvalid)
1078  _M_codecvt = _M_codecvt_tmp;
1079  else
1080  _M_codecvt = 0;
1081  }
1082 
1083  // Inhibit implicit instantiations for required instantiations,
1084  // which are defined via explicit instantiations elsewhere.
1085 #if _GLIBCXX_EXTERN_TEMPLATE
1086  extern template class basic_filebuf<char>;
1087  extern template class basic_ifstream<char>;
1088  extern template class basic_ofstream<char>;
1089  extern template class basic_fstream<char>;
1090 
1091 #ifdef _GLIBCXX_USE_WCHAR_T
1092  extern template class basic_filebuf<wchar_t>;
1093  extern template class basic_ifstream<wchar_t>;
1094  extern template class basic_ofstream<wchar_t>;
1095  extern template class basic_fstream<wchar_t>;
1096 #endif
1097 #endif
1098 
1099 _GLIBCXX_END_NAMESPACE_VERSION
1100 } // namespace std
1101 
1102 #pragma GCC diagnostic pop
1103 #endif
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:138
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:234
ISO C++ entities toplevel namespace is std.
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition: postypes.h:73
The actual work of input and output (for files).
Definition: fstream:93
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:834
virtual int_type underflow()
Fetches more data from the controlled sequence.
Definition: fstream.tcc:328
virtual streamsize showmanyc()
Investigating the data available.
Definition: fstream.tcc:302
ios_base::openmode _M_mode
Place to stash in || out || in | out settings for current filebuf.
Definition: fstream:133
virtual void imbue(const locale &__loc)
Changes translations.
Definition: fstream.tcc:1031
virtual streamsize xsgetn(char_type *__s, streamsize __n)
Multiple character extraction.
Definition: fstream.tcc:674
__filebuf_type * close()
Closes the currently associated file.
Definition: fstream.tcc:254
virtual pos_type seekpos(pos_type __pos, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions.
Definition: fstream.tcc:894
virtual int_type pbackfail(int_type __c=_Traits::eof())
Tries to back up the input sequence.
Definition: fstream.tcc:487
virtual streamsize xsputn(const char_type *__s, streamsize __n)
Multiple character insertion.
Definition: fstream.tcc:760
bool _M_pback_init
Definition: fstream:179
virtual int_type overflow(int_type __c=_Traits::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition: fstream.tcc:546
__filebuf_type * open(const char *__s, ios_base::openmode __mode)
Opens an external file.
Definition: fstream.tcc:184
basic_filebuf()
Does not open any files.
Definition: fstream.tcc:86
void _M_set_buffer(streamsize __off)
Definition: fstream:502
virtual int sync()
Synchronizes the buffer arrays with the controlled sequences.
Definition: fstream.tcc:1014
virtual __streambuf_type * setbuf(char_type *__s, streamsize __n)
Manipulates the buffer.
Definition: fstream.tcc:805
Controlling input for files.
Definition: fstream:536
Controlling output for files.
Definition: fstream:809
Controlling input and output for files.
Definition: fstream:1084
The actual work of input and output (interface).
Definition: streambuf:127
locale _M_buf_locale
Current locale setting.
Definition: streambuf:201
Primary class template codecvt.
Definition: codecvt.h:284
The base of the I/O class hierarchy.
Definition: ios_base.h:266
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:529
static const seekdir beg
Request a seek relative to the beginning of the stream.
Definition: ios_base.h:526
static const seekdir end
Request a seek relative to the current end of the sequence.
Definition: ios_base.h:532
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:498
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:501
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:495
_Ios_Openmode openmode
This is a bitmask type.
Definition: ios_base.h:484
static const openmode app
Seek to end before each write.
Definition: ios_base.h:487
static const openmode ate
Open and seek to end immediately after opening.
Definition: ios_base.h:490
Container class for localization functionality.