libstdc++
fstream.tcc
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1 // File based streams -*- C++ -*-
2 
3 // Copyright (C) 1997-2021 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 #include <bits/move.h> // for swap
41 #include <cerrno>
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(_GLIBCXX_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 #if __cplusplus >= 201103L
94  template<typename _CharT, typename _Traits>
97  : __streambuf_type(__rhs),
98  _M_lock(), _M_file(std::move(__rhs._M_file), &_M_lock),
99  _M_mode(std::__exchange(__rhs._M_mode, ios_base::openmode(0))),
100  _M_state_beg(std::move(__rhs._M_state_beg)),
101  _M_state_cur(std::move(__rhs._M_state_cur)),
102  _M_state_last(std::move(__rhs._M_state_last)),
103  _M_buf(std::__exchange(__rhs._M_buf, nullptr)),
104  _M_buf_size(std::__exchange(__rhs._M_buf_size, 1)),
105  _M_buf_allocated(std::__exchange(__rhs._M_buf_allocated, false)),
106  _M_reading(std::__exchange(__rhs._M_reading, false)),
107  _M_writing(std::__exchange(__rhs._M_writing, false)),
108  _M_pback(__rhs._M_pback),
109  _M_pback_cur_save(std::__exchange(__rhs._M_pback_cur_save, nullptr)),
110  _M_pback_end_save(std::__exchange(__rhs._M_pback_end_save, nullptr)),
111  _M_pback_init(std::__exchange(__rhs._M_pback_init, false)),
112  _M_codecvt(__rhs._M_codecvt),
113  _M_ext_buf(std::__exchange(__rhs._M_ext_buf, nullptr)),
114  _M_ext_buf_size(std::__exchange(__rhs._M_ext_buf_size, 0)),
115  _M_ext_next(std::__exchange(__rhs._M_ext_next, nullptr)),
116  _M_ext_end(std::__exchange(__rhs._M_ext_end, nullptr))
117  {
118  __rhs._M_set_buffer(-1);
119  __rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg;
120  }
121 
122  template<typename _CharT, typename _Traits>
123  basic_filebuf<_CharT, _Traits>&
124  basic_filebuf<_CharT, _Traits>::
125  operator=(basic_filebuf&& __rhs)
126  {
127  this->close();
128  __streambuf_type::operator=(__rhs);
129  _M_file.swap(__rhs._M_file);
130  _M_mode = std::__exchange(__rhs._M_mode, ios_base::openmode(0));
131  _M_state_beg = std::move(__rhs._M_state_beg);
132  _M_state_cur = std::move(__rhs._M_state_cur);
133  _M_state_last = std::move(__rhs._M_state_last);
134  _M_buf = std::__exchange(__rhs._M_buf, nullptr);
135  _M_buf_size = std::__exchange(__rhs._M_buf_size, 1);
136  _M_buf_allocated = std::__exchange(__rhs._M_buf_allocated, false);
137  _M_ext_buf = std::__exchange(__rhs._M_ext_buf, nullptr);
138  _M_ext_buf_size = std::__exchange(__rhs._M_ext_buf_size, 0);
139  _M_ext_next = std::__exchange(__rhs._M_ext_next, nullptr);
140  _M_ext_end = std::__exchange(__rhs._M_ext_end, nullptr);
141  _M_reading = std::__exchange(__rhs._M_reading, false);
142  _M_writing = std::__exchange(__rhs._M_writing, false);
143  _M_pback_cur_save = std::__exchange(__rhs._M_pback_cur_save, nullptr);
144  _M_pback_end_save = std::__exchange(__rhs._M_pback_end_save, nullptr);
145  _M_pback_init = std::__exchange(__rhs._M_pback_init, false);
146  __rhs._M_set_buffer(-1);
147  __rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg;
148  return *this;
149  }
150 
151  template<typename _CharT, typename _Traits>
152  void
153  basic_filebuf<_CharT, _Traits>::
154  swap(basic_filebuf& __rhs)
155  {
156  __streambuf_type::swap(__rhs);
157  _M_file.swap(__rhs._M_file);
158  std::swap(_M_mode, __rhs._M_mode);
159  std::swap(_M_state_beg, __rhs._M_state_beg);
160  std::swap(_M_state_cur, __rhs._M_state_cur);
161  std::swap(_M_state_last, __rhs._M_state_last);
162  std::swap(_M_buf, __rhs._M_buf);
163  std::swap(_M_buf_size, __rhs._M_buf_size);
164  std::swap(_M_buf_allocated, __rhs._M_buf_allocated);
165  std::swap(_M_ext_buf, __rhs._M_ext_buf);
166  std::swap(_M_ext_buf_size, __rhs._M_ext_buf_size);
167  std::swap(_M_ext_next, __rhs._M_ext_next);
168  std::swap(_M_ext_end, __rhs._M_ext_end);
169  std::swap(_M_reading, __rhs._M_reading);
170  std::swap(_M_writing, __rhs._M_writing);
171  std::swap(_M_pback_cur_save, __rhs._M_pback_cur_save);
172  std::swap(_M_pback_end_save, __rhs._M_pback_end_save);
173  std::swap(_M_pback_init, __rhs._M_pback_init);
174  }
175 #endif
176 
177  template<typename _CharT, typename _Traits>
178  typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
180  open(const char* __s, ios_base::openmode __mode)
181  {
182  __filebuf_type *__ret = 0;
183  if (!this->is_open())
184  {
185  _M_file.open(__s, __mode);
186  if (this->is_open())
187  {
188  _M_allocate_internal_buffer();
189  _M_mode = __mode;
190 
191  // Setup initial buffer to 'uncommitted' mode.
192  _M_reading = false;
193  _M_writing = false;
194  _M_set_buffer(-1);
195 
196  // Reset to initial state.
197  _M_state_last = _M_state_cur = _M_state_beg;
198 
199  // 27.8.1.3,4
200  if ((__mode & ios_base::ate)
201  && this->seekoff(0, ios_base::end, __mode)
202  == pos_type(off_type(-1)))
203  this->close();
204  else
205  __ret = this;
206  }
207  }
208  return __ret;
209  }
210 
211 #if _GLIBCXX_HAVE__WFOPEN && _GLIBCXX_USE_WCHAR_T
212  template<typename _CharT, typename _Traits>
215  open(const wchar_t* __s, ios_base::openmode __mode)
216  {
217  __filebuf_type *__ret = 0;
218  if (!this->is_open())
219  {
220  _M_file.open(__s, __mode);
221  if (this->is_open())
222  {
223  _M_allocate_internal_buffer();
224  _M_mode = __mode;
225 
226  // Setup initial buffer to 'uncommitted' mode.
227  _M_reading = false;
228  _M_writing = false;
229  _M_set_buffer(-1);
230 
231  // Reset to initial state.
232  _M_state_last = _M_state_cur = _M_state_beg;
233 
234  // 27.8.1.3,4
235  if ((__mode & ios_base::ate)
236  && this->seekoff(0, ios_base::end, __mode)
237  == pos_type(off_type(-1)))
238  this->close();
239  else
240  __ret = this;
241  }
242  }
243  return __ret;
244  }
245 #endif // HAVE__WFOPEN && USE_WCHAR_T
246 
247  template<typename _CharT, typename _Traits>
248  typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
250  close()
251  {
252  if (!this->is_open())
253  return 0;
254 
255  bool __testfail = false;
256  {
257  // NB: Do this here so that re-opened filebufs will be cool...
258  struct __close_sentry
259  {
260  basic_filebuf *__fb;
261  __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
262  ~__close_sentry ()
263  {
264  __fb->_M_mode = ios_base::openmode(0);
265  __fb->_M_pback_init = false;
266  __fb->_M_destroy_internal_buffer();
267  __fb->_M_reading = false;
268  __fb->_M_writing = false;
269  __fb->_M_set_buffer(-1);
270  __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
271  }
272  } __cs (this);
273 
274  __try
275  {
276  if (!_M_terminate_output())
277  __testfail = true;
278  }
279  __catch(...)
280  {
281  _M_file.close();
282  __throw_exception_again;
283  }
284  }
285 
286  if (!_M_file.close())
287  __testfail = true;
288 
289  if (__testfail)
290  return 0;
291  else
292  return this;
293  }
294 
295  template<typename _CharT, typename _Traits>
296  streamsize
298  showmanyc()
299  {
300  streamsize __ret = -1;
301  const bool __testin = _M_mode & ios_base::in;
302  if (__testin && this->is_open())
303  {
304  // For a stateful encoding (-1) the pending sequence might be just
305  // shift and unshift prefixes with no actual character.
306  __ret = this->egptr() - this->gptr();
307 
308 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
309  // About this workaround, see libstdc++/20806.
310  const bool __testbinary = _M_mode & ios_base::binary;
311  if (__check_facet(_M_codecvt).encoding() >= 0
312  && __testbinary)
313 #else
314  if (__check_facet(_M_codecvt).encoding() >= 0)
315 #endif
316  __ret += _M_file.showmanyc() / _M_codecvt->max_length();
317  }
318  return __ret;
319  }
320 
321  template<typename _CharT, typename _Traits>
322  typename basic_filebuf<_CharT, _Traits>::int_type
324  underflow()
325  {
326  int_type __ret = traits_type::eof();
327  const bool __testin = _M_mode & ios_base::in;
328  if (__testin)
329  {
330  if (_M_writing)
331  {
332  if (overflow() == traits_type::eof())
333  return __ret;
334  _M_set_buffer(-1);
335  _M_writing = false;
336  }
337  // Check for pback madness, and if so switch back to the
338  // normal buffers and jet outta here before expensive
339  // fileops happen...
340  _M_destroy_pback();
341 
342  if (this->gptr() < this->egptr())
343  return traits_type::to_int_type(*this->gptr());
344 
345  // Get and convert input sequence.
346  const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
347 
348  // Will be set to true if ::read() returns 0 indicating EOF.
349  bool __got_eof = false;
350  // Number of internal characters produced.
351  streamsize __ilen = 0;
352  codecvt_base::result __r = codecvt_base::ok;
353  if (__check_facet(_M_codecvt).always_noconv())
354  {
355  __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
356  __buflen);
357  if (__ilen == 0)
358  __got_eof = true;
359  }
360  else
361  {
362  // Worst-case number of external bytes.
363  // XXX Not done encoding() == -1.
364  const int __enc = _M_codecvt->encoding();
365  streamsize __blen; // Minimum buffer size.
366  streamsize __rlen; // Number of chars to read.
367  if (__enc > 0)
368  __blen = __rlen = __buflen * __enc;
369  else
370  {
371  __blen = __buflen + _M_codecvt->max_length() - 1;
372  __rlen = __buflen;
373  }
374  const streamsize __remainder = _M_ext_end - _M_ext_next;
375  __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
376 
377  // An imbue in 'read' mode implies first converting the external
378  // chars already present.
379  if (_M_reading && this->egptr() == this->eback() && __remainder)
380  __rlen = 0;
381 
382  // Allocate buffer if necessary and move unconverted
383  // bytes to front.
384  if (_M_ext_buf_size < __blen)
385  {
386  char* __buf = new char[__blen];
387  if (__remainder)
388  __builtin_memcpy(__buf, _M_ext_next, __remainder);
389 
390  delete [] _M_ext_buf;
391  _M_ext_buf = __buf;
392  _M_ext_buf_size = __blen;
393  }
394  else if (__remainder)
395  __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
396 
397  _M_ext_next = _M_ext_buf;
398  _M_ext_end = _M_ext_buf + __remainder;
399  _M_state_last = _M_state_cur;
400 
401  do
402  {
403  if (__rlen > 0)
404  {
405  // Sanity check!
406  // This may fail if the return value of
407  // codecvt::max_length() is bogus.
408  if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
409  {
410  __throw_ios_failure(__N("basic_filebuf::underflow "
411  "codecvt::max_length() "
412  "is not valid"));
413  }
414  streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
415  if (__elen == 0)
416  __got_eof = true;
417  else if (__elen == -1)
418  break;
419  _M_ext_end += __elen;
420  }
421 
422  char_type* __iend = this->eback();
423  if (_M_ext_next < _M_ext_end)
424  __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
425  _M_ext_end, _M_ext_next,
426  this->eback(),
427  this->eback() + __buflen, __iend);
428  if (__r == codecvt_base::noconv)
429  {
430  size_t __avail = _M_ext_end - _M_ext_buf;
431  __ilen = std::min(__avail, __buflen);
432  traits_type::copy(this->eback(),
433  reinterpret_cast<char_type*>
434  (_M_ext_buf), __ilen);
435  _M_ext_next = _M_ext_buf + __ilen;
436  }
437  else
438  __ilen = __iend - this->eback();
439 
440  // _M_codecvt->in may return error while __ilen > 0: this is
441  // ok, and actually occurs in case of mixed encodings (e.g.,
442  // XML files).
443  if (__r == codecvt_base::error)
444  break;
445 
446  __rlen = 1;
447  }
448  while (__ilen == 0 && !__got_eof);
449  }
450 
451  if (__ilen > 0)
452  {
453  _M_set_buffer(__ilen);
454  _M_reading = true;
455  __ret = traits_type::to_int_type(*this->gptr());
456  }
457  else if (__got_eof)
458  {
459  // If the actual end of file is reached, set 'uncommitted'
460  // mode, thus allowing an immediate write without an
461  // intervening seek.
462  _M_set_buffer(-1);
463  _M_reading = false;
464  // However, reaching it while looping on partial means that
465  // the file has got an incomplete character.
466  if (__r == codecvt_base::partial)
467  __throw_ios_failure(__N("basic_filebuf::underflow "
468  "incomplete character in file"));
469  }
470  else if (__r == codecvt_base::error)
471  __throw_ios_failure(__N("basic_filebuf::underflow "
472  "invalid byte sequence in file"));
473  else
474  __throw_ios_failure(__N("basic_filebuf::underflow "
475  "error reading the file"), errno);
476  }
477  return __ret;
478  }
479 
480  template<typename _CharT, typename _Traits>
481  typename basic_filebuf<_CharT, _Traits>::int_type
483  pbackfail(int_type __i)
484  {
485  int_type __ret = traits_type::eof();
486  const bool __testin = _M_mode & ios_base::in;
487  if (__testin)
488  {
489  if (_M_writing)
490  {
491  if (overflow() == traits_type::eof())
492  return __ret;
493  _M_set_buffer(-1);
494  _M_writing = false;
495  }
496  // Remember whether the pback buffer is active, otherwise below
497  // we may try to store in it a second char (libstdc++/9761).
498  const bool __testpb = _M_pback_init;
499  const bool __testeof = traits_type::eq_int_type(__i, __ret);
500  int_type __tmp;
501  if (this->eback() < this->gptr())
502  {
503  this->gbump(-1);
504  __tmp = traits_type::to_int_type(*this->gptr());
505  }
506  else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
507  {
508  __tmp = this->underflow();
509  if (traits_type::eq_int_type(__tmp, __ret))
510  return __ret;
511  }
512  else
513  {
514  // At the beginning of the buffer, need to make a
515  // putback position available. But the seek may fail
516  // (f.i., at the beginning of a file, see
517  // libstdc++/9439) and in that case we return
518  // traits_type::eof().
519  return __ret;
520  }
521 
522  // Try to put back __i into input sequence in one of three ways.
523  // Order these tests done in is unspecified by the standard.
524  if (!__testeof && traits_type::eq_int_type(__i, __tmp))
525  __ret = __i;
526  else if (__testeof)
527  __ret = traits_type::not_eof(__i);
528  else if (!__testpb)
529  {
530  _M_create_pback();
531  _M_reading = true;
532  *this->gptr() = traits_type::to_char_type(__i);
533  __ret = __i;
534  }
535  }
536  return __ret;
537  }
538 
539  template<typename _CharT, typename _Traits>
540  typename basic_filebuf<_CharT, _Traits>::int_type
542  overflow(int_type __c)
543  {
544  int_type __ret = traits_type::eof();
545  const bool __testeof = traits_type::eq_int_type(__c, __ret);
546  const bool __testout = (_M_mode & ios_base::out
547  || _M_mode & ios_base::app);
548  if (__testout)
549  {
550  if (_M_reading)
551  {
552  _M_destroy_pback();
553  const int __gptr_off = _M_get_ext_pos(_M_state_last);
554  if (_M_seek(__gptr_off, ios_base::cur, _M_state_last)
555  == pos_type(off_type(-1)))
556  return __ret;
557  }
558  if (this->pbase() < this->pptr())
559  {
560  // If appropriate, append the overflow char.
561  if (!__testeof)
562  {
563  *this->pptr() = traits_type::to_char_type(__c);
564  this->pbump(1);
565  }
566 
567  // Convert pending sequence to external representation,
568  // and output.
569  if (_M_convert_to_external(this->pbase(),
570  this->pptr() - this->pbase()))
571  {
572  _M_set_buffer(0);
573  __ret = traits_type::not_eof(__c);
574  }
575  }
576  else if (_M_buf_size > 1)
577  {
578  // Overflow in 'uncommitted' mode: set _M_writing, set
579  // the buffer to the initial 'write' mode, and put __c
580  // into the buffer.
581  _M_set_buffer(0);
582  _M_writing = true;
583  if (!__testeof)
584  {
585  *this->pptr() = traits_type::to_char_type(__c);
586  this->pbump(1);
587  }
588  __ret = traits_type::not_eof(__c);
589  }
590  else
591  {
592  // Unbuffered.
593  char_type __conv = traits_type::to_char_type(__c);
594  if (__testeof || _M_convert_to_external(&__conv, 1))
595  {
596  _M_writing = true;
597  __ret = traits_type::not_eof(__c);
598  }
599  }
600  }
601  return __ret;
602  }
603 
604  template<typename _CharT, typename _Traits>
605  bool
607  _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
608  {
609  // Sizes of external and pending output.
610  streamsize __elen;
611  streamsize __plen;
612  if (__check_facet(_M_codecvt).always_noconv())
613  {
614  __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
615  __plen = __ilen;
616  }
617  else
618  {
619  // Worst-case number of external bytes needed.
620  // XXX Not done encoding() == -1.
621  streamsize __blen = __ilen * _M_codecvt->max_length();
622  char* __buf = static_cast<char*>(__builtin_alloca(__blen));
623 
624  char* __bend;
625  const char_type* __iend;
626  codecvt_base::result __r;
627  __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
628  __iend, __buf, __buf + __blen, __bend);
629 
630  if (__r == codecvt_base::ok || __r == codecvt_base::partial)
631  __blen = __bend - __buf;
632  else if (__r == codecvt_base::noconv)
633  {
634  // Same as the always_noconv case above.
635  __buf = reinterpret_cast<char*>(__ibuf);
636  __blen = __ilen;
637  }
638  else
639  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
640  "conversion error"));
641 
642  __elen = _M_file.xsputn(__buf, __blen);
643  __plen = __blen;
644 
645  // Try once more for partial conversions.
646  if (__r == codecvt_base::partial && __elen == __plen)
647  {
648  const char_type* __iresume = __iend;
649  streamsize __rlen = this->pptr() - __iend;
650  __r = _M_codecvt->out(_M_state_cur, __iresume,
651  __iresume + __rlen, __iend, __buf,
652  __buf + __blen, __bend);
653  if (__r != codecvt_base::error)
654  {
655  __rlen = __bend - __buf;
656  __elen = _M_file.xsputn(__buf, __rlen);
657  __plen = __rlen;
658  }
659  else
660  __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
661  "conversion error"));
662  }
663  }
664  return __elen == __plen;
665  }
666 
667  template<typename _CharT, typename _Traits>
668  streamsize
670  xsgetn(_CharT* __s, streamsize __n)
671  {
672  // Clear out pback buffer before going on to the real deal...
673  streamsize __ret = 0;
674  if (_M_pback_init)
675  {
676  if (__n > 0 && this->gptr() == this->eback())
677  {
678  *__s++ = *this->gptr(); // emulate non-underflowing sbumpc
679  this->gbump(1);
680  __ret = 1;
681  --__n;
682  }
683  _M_destroy_pback();
684  }
685  else if (_M_writing)
686  {
687  if (overflow() == traits_type::eof())
688  return __ret;
689  _M_set_buffer(-1);
690  _M_writing = false;
691  }
692 
693  // Optimization in the always_noconv() case, to be generalized in the
694  // future: when __n > __buflen we read directly instead of using the
695  // buffer repeatedly.
696  const bool __testin = _M_mode & ios_base::in;
697  const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
698 
699  if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
700  && __testin)
701  {
702  // First, copy the chars already present in the buffer.
703  const streamsize __avail = this->egptr() - this->gptr();
704  if (__avail != 0)
705  {
706  traits_type::copy(__s, this->gptr(), __avail);
707  __s += __avail;
708  this->setg(this->eback(), this->gptr() + __avail, this->egptr());
709  __ret += __avail;
710  __n -= __avail;
711  }
712 
713  // Need to loop in case of short reads (relatively common
714  // with pipes).
715  streamsize __len;
716  for (;;)
717  {
718  __len = _M_file.xsgetn(reinterpret_cast<char*>(__s), __n);
719  if (__len == -1)
720  __throw_ios_failure(__N("basic_filebuf::xsgetn "
721  "error reading the file"), errno);
722  if (__len == 0)
723  break;
724 
725  __n -= __len;
726  __ret += __len;
727  if (__n == 0)
728  break;
729 
730  __s += __len;
731  }
732 
733  if (__n == 0)
734  {
735  // Set _M_reading. Buffer is already in initial 'read' mode.
736  _M_reading = true;
737  }
738  else if (__len == 0)
739  {
740  // If end of file is reached, set 'uncommitted'
741  // mode, thus allowing an immediate write without
742  // an intervening seek.
743  _M_set_buffer(-1);
744  _M_reading = false;
745  }
746  }
747  else
748  __ret += __streambuf_type::xsgetn(__s, __n);
749 
750  return __ret;
751  }
752 
753  template<typename _CharT, typename _Traits>
754  streamsize
756  xsputn(const _CharT* __s, streamsize __n)
757  {
758  streamsize __ret = 0;
759  // Optimization in the always_noconv() case, to be generalized in the
760  // future: when __n is sufficiently large we write directly instead of
761  // using the buffer.
762  const bool __testout = (_M_mode & ios_base::out
763  || _M_mode & ios_base::app);
764  if (__check_facet(_M_codecvt).always_noconv()
765  && __testout && !_M_reading)
766  {
767  // Measurement would reveal the best choice.
768  const streamsize __chunk = 1ul << 10;
769  streamsize __bufavail = this->epptr() - this->pptr();
770 
771  // Don't mistake 'uncommitted' mode buffered with unbuffered.
772  if (!_M_writing && _M_buf_size > 1)
773  __bufavail = _M_buf_size - 1;
774 
775  const streamsize __limit = std::min(__chunk, __bufavail);
776  if (__n >= __limit)
777  {
778  const streamsize __buffill = this->pptr() - this->pbase();
779  const char* __buf = reinterpret_cast<const char*>(this->pbase());
780  __ret = _M_file.xsputn_2(__buf, __buffill,
781  reinterpret_cast<const char*>(__s),
782  __n);
783  if (__ret == __buffill + __n)
784  {
785  _M_set_buffer(0);
786  _M_writing = true;
787  }
788  if (__ret > __buffill)
789  __ret -= __buffill;
790  else
791  __ret = 0;
792  }
793  else
794  __ret = __streambuf_type::xsputn(__s, __n);
795  }
796  else
797  __ret = __streambuf_type::xsputn(__s, __n);
798  return __ret;
799  }
800 
801  template<typename _CharT, typename _Traits>
804  setbuf(char_type* __s, streamsize __n)
805  {
806  if (!this->is_open())
807  {
808  if (__s == 0 && __n == 0)
809  _M_buf_size = 1;
810  else if (__s && __n > 0)
811  {
812  // This is implementation-defined behavior, and assumes that
813  // an external char_type array of length __n exists and has
814  // been pre-allocated. If this is not the case, things will
815  // quickly blow up. When __n > 1, __n - 1 positions will be
816  // used for the get area, __n - 1 for the put area and 1
817  // position to host the overflow char of a full put area.
818  // When __n == 1, 1 position will be used for the get area
819  // and 0 for the put area, as in the unbuffered case above.
820  _M_buf = __s;
821  _M_buf_size = __n;
822  }
823  }
824  return this;
825  }
826 
827 
828  // According to 27.8.1.4 p11 - 13, seekoff should ignore the last
829  // argument (of type openmode).
830  template<typename _CharT, typename _Traits>
831  typename basic_filebuf<_CharT, _Traits>::pos_type
833  seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
834  {
835  int __width = 0;
836  if (_M_codecvt)
837  __width = _M_codecvt->encoding();
838  if (__width < 0)
839  __width = 0;
840 
841  pos_type __ret = pos_type(off_type(-1));
842  const bool __testfail = __off != 0 && __width <= 0;
843  if (this->is_open() && !__testfail)
844  {
845  // tellg and tellp queries do not affect any state, unless
846  // ! always_noconv and the put sequence is not empty.
847  // In that case, determining the position requires converting the
848  // put sequence. That doesn't use ext_buf, so requires a flush.
849  bool __no_movement = __way == ios_base::cur && __off == 0
850  && (!_M_writing || _M_codecvt->always_noconv());
851 
852  // Ditch any pback buffers to avoid confusion.
853  if (!__no_movement)
854  _M_destroy_pback();
855 
856  // Correct state at destination. Note that this is the correct
857  // state for the current position during output, because
858  // codecvt::unshift() returns the state to the initial state.
859  // This is also the correct state at the end of the file because
860  // an unshift sequence should have been written at the end.
861  __state_type __state = _M_state_beg;
862  off_type __computed_off = __off * __width;
863  if (_M_reading && __way == ios_base::cur)
864  {
865  __state = _M_state_last;
866  __computed_off += _M_get_ext_pos(__state);
867  }
868  if (!__no_movement)
869  __ret = _M_seek(__computed_off, __way, __state);
870  else
871  {
872  if (_M_writing)
873  __computed_off = this->pptr() - this->pbase();
874 
875  off_type __file_off = _M_file.seekoff(0, ios_base::cur);
876  if (__file_off != off_type(-1))
877  {
878  __ret = __file_off + __computed_off;
879  __ret.state(__state);
880  }
881  }
882  }
883  return __ret;
884  }
885 
886  // _GLIBCXX_RESOLVE_LIB_DEFECTS
887  // 171. Strange seekpos() semantics due to joint position
888  // According to the resolution of DR 171, seekpos should ignore the last
889  // argument (of type openmode).
890  template<typename _CharT, typename _Traits>
891  typename basic_filebuf<_CharT, _Traits>::pos_type
893  seekpos(pos_type __pos, ios_base::openmode)
894  {
895  pos_type __ret = pos_type(off_type(-1));
896  if (this->is_open())
897  {
898  // Ditch any pback buffers to avoid confusion.
899  _M_destroy_pback();
900  __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
901  }
902  return __ret;
903  }
904 
905  template<typename _CharT, typename _Traits>
906  typename basic_filebuf<_CharT, _Traits>::pos_type
908  _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
909  {
910  pos_type __ret = pos_type(off_type(-1));
911  if (_M_terminate_output())
912  {
913  off_type __file_off = _M_file.seekoff(__off, __way);
914  if (__file_off != off_type(-1))
915  {
916  _M_reading = false;
917  _M_writing = false;
918  _M_ext_next = _M_ext_end = _M_ext_buf;
919  _M_set_buffer(-1);
920  _M_state_cur = __state;
921  __ret = __file_off;
922  __ret.state(_M_state_cur);
923  }
924  }
925  return __ret;
926  }
927 
928  // Returns the distance from the end of the ext buffer to the point
929  // corresponding to gptr(). This is a negative value. Updates __state
930  // from eback() correspondence to gptr().
931  template<typename _CharT, typename _Traits>
932  int basic_filebuf<_CharT, _Traits>::
933  _M_get_ext_pos(__state_type& __state)
934  {
935  if (_M_codecvt->always_noconv())
936  return this->gptr() - this->egptr();
937  else
938  {
939  // Calculate offset from _M_ext_buf that corresponds to
940  // gptr(). Precondition: __state == _M_state_last, which
941  // corresponds to eback().
942  const int __gptr_off =
943  _M_codecvt->length(__state, _M_ext_buf, _M_ext_next,
944  this->gptr() - this->eback());
945  return _M_ext_buf + __gptr_off - _M_ext_end;
946  }
947  }
948 
949  template<typename _CharT, typename _Traits>
950  bool
951  basic_filebuf<_CharT, _Traits>::
952  _M_terminate_output()
953  {
954  // Part one: update the output sequence.
955  bool __testvalid = true;
956  if (this->pbase() < this->pptr())
957  {
958  const int_type __tmp = this->overflow();
959  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
960  __testvalid = false;
961  }
962 
963  // Part two: output unshift sequence.
964  if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
965  && __testvalid)
966  {
967  // Note: this value is arbitrary, since there is no way to
968  // get the length of the unshift sequence from codecvt,
969  // without calling unshift.
970  const size_t __blen = 128;
971  char __buf[__blen];
972  codecvt_base::result __r;
973  streamsize __ilen = 0;
974 
975  do
976  {
977  char* __next;
978  __r = _M_codecvt->unshift(_M_state_cur, __buf,
979  __buf + __blen, __next);
980  if (__r == codecvt_base::error)
981  __testvalid = false;
982  else if (__r == codecvt_base::ok ||
983  __r == codecvt_base::partial)
984  {
985  __ilen = __next - __buf;
986  if (__ilen > 0)
987  {
988  const streamsize __elen = _M_file.xsputn(__buf, __ilen);
989  if (__elen != __ilen)
990  __testvalid = false;
991  }
992  }
993  }
994  while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
995 
996  if (__testvalid)
997  {
998  // This second call to overflow() is required by the standard,
999  // but it's not clear why it's needed, since the output buffer
1000  // should be empty by this point (it should have been emptied
1001  // in the first call to overflow()).
1002  const int_type __tmp = this->overflow();
1003  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
1004  __testvalid = false;
1005  }
1006  }
1007  return __testvalid;
1008  }
1009 
1010  template<typename _CharT, typename _Traits>
1011  int
1013  sync()
1014  {
1015  // Make sure that the internal buffer resyncs its idea of
1016  // the file position with the external file.
1017  int __ret = 0;
1018  if (this->pbase() < this->pptr())
1019  {
1020  const int_type __tmp = this->overflow();
1021  if (traits_type::eq_int_type(__tmp, traits_type::eof()))
1022  __ret = -1;
1023  }
1024  return __ret;
1025  }
1026 
1027  template<typename _CharT, typename _Traits>
1028  void
1030  imbue(const locale& __loc)
1031  {
1032  bool __testvalid = true;
1033 
1034  const __codecvt_type* _M_codecvt_tmp = 0;
1035  if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
1036  _M_codecvt_tmp = &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 #endif
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:422
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:230
ISO C++ entities toplevel namespace is std.
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition: postypes.h:68
The actual work of input and output (for files).
Definition: fstream:86
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:833
virtual int_type underflow()
Fetches more data from the controlled sequence.
Definition: fstream.tcc:324
virtual streamsize showmanyc()
Investigating the data available.
Definition: fstream.tcc:298
ios_base::openmode _M_mode
Place to stash in || out || in | out settings for current filebuf.
Definition: fstream:126
virtual void imbue(const locale &__loc)
Changes translations.
Definition: fstream.tcc:1030
virtual streamsize xsgetn(char_type *__s, streamsize __n)
Multiple character extraction.
Definition: fstream.tcc:670
__filebuf_type * close()
Closes the currently associated file.
Definition: fstream.tcc:250
virtual pos_type seekpos(pos_type __pos, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions.
Definition: fstream.tcc:893
virtual int_type pbackfail(int_type __c=_Traits::eof())
Tries to back up the input sequence.
Definition: fstream.tcc:483
virtual streamsize xsputn(const char_type *__s, streamsize __n)
Multiple character insertion.
Definition: fstream.tcc:756
bool _M_pback_init
Definition: fstream:172
virtual int_type overflow(int_type __c=_Traits::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition: fstream.tcc:542
__filebuf_type * open(const char *__s, ios_base::openmode __mode)
Opens an external file.
Definition: fstream.tcc:180
basic_filebuf()
Does not open any files.
Definition: fstream.tcc:81
void _M_set_buffer(streamsize __off)
Definition: fstream:464
virtual int sync()
Synchronizes the buffer arrays with the controlled sequences.
Definition: fstream.tcc:1013
virtual __streambuf_type * setbuf(char_type *__s, streamsize __n)
Manipulates the buffer.
Definition: fstream.tcc:804
Controlling input for files.
Definition: fstream:498
Controlling output for files.
Definition: fstream:759
Controlling input and output for files.
Definition: fstream:1022
The actual work of input and output (interface).
Definition: streambuf:123
locale _M_buf_locale
Current locale setting.
Definition: streambuf:197
Primary class template codecvt.
Definition: codecvt.h:279
The base of the I/O class hierarchy.
Definition: ios_base.h:229
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:485
static const seekdir beg
Request a seek relative to the beginning of the stream.
Definition: ios_base.h:482
static const seekdir end
Request a seek relative to the current end of the sequence.
Definition: ios_base.h:488
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:461
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:464
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:458
_Ios_Openmode openmode
This is a bitmask type.
Definition: ios_base.h:447
static const openmode app
Seek to end before each write.
Definition: ios_base.h:450
static const openmode ate
Open and seek to end immediately after opening.
Definition: ios_base.h:453
Container class for localization functionality.