libstdc++
fstream.tcc
Go to the documentation of this file.
1// File based streams -*- C++ -*-
2
3// Copyright (C) 1997-2022 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
43namespace 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>
80 basic_filebuf<_CharT, _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>
95 basic_filebuf<_CharT, _Traits>::
96 basic_filebuf(basic_filebuf&& __rhs)
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*
179 basic_filebuf<_CharT, _Traits>::
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>
213 basic_filebuf<_CharT, _Traits>*
214 basic_filebuf<_CharT, _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*
249 basic_filebuf<_CharT, _Traits>::
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
297 basic_filebuf<_CharT, _Traits>::
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
323 basic_filebuf<_CharT, _Traits>::
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
482 basic_filebuf<_CharT, _Traits>::
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
541 basic_filebuf<_CharT, _Traits>::
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
606 basic_filebuf<_CharT, _Traits>::
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
669 basic_filebuf<_CharT, _Traits>::
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
755 basic_filebuf<_CharT, _Traits>::
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>
802 typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
803 basic_filebuf<_CharT, _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
832 basic_filebuf<_CharT, _Traits>::
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
892 basic_filebuf<_CharT, _Traits>::
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
907 basic_filebuf<_CharT, _Traits>::
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
1012 basic_filebuf<_CharT, _Traits>::
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
1029 basic_filebuf<_CharT, _Traits>::
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
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
std::swap
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:429
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:230
std
ISO C++ entities toplevel namespace is std.
std::streamsize
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition: postypes.h:68
std::basic_filebuf
The actual work of input and output (for files).
Definition: fstream:86
std::basic_filebuf::seekoff
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
std::basic_filebuf::underflow
virtual int_type underflow()
Fetches more data from the controlled sequence.
Definition: fstream.tcc:324
std::basic_filebuf::showmanyc
virtual streamsize showmanyc()
Investigating the data available.
Definition: fstream.tcc:298
std::basic_filebuf::_M_mode
ios_base::openmode _M_mode
Place to stash in || out || in | out settings for current filebuf.
Definition: fstream:126
std::basic_filebuf::imbue
virtual void imbue(const locale &__loc)
Changes translations.
Definition: fstream.tcc:1030
std::basic_filebuf::xsgetn
virtual streamsize xsgetn(char_type *__s, streamsize __n)
Multiple character extraction.
Definition: fstream.tcc:670
std::basic_filebuf::close
__filebuf_type * close()
Closes the currently associated file.
Definition: fstream.tcc:250
std::basic_filebuf::seekpos
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
std::basic_filebuf::pbackfail
virtual int_type pbackfail(int_type __c=_Traits::eof())
Tries to back up the input sequence.
Definition: fstream.tcc:483
std::basic_filebuf::xsputn
virtual streamsize xsputn(const char_type *__s, streamsize __n)
Multiple character insertion.
Definition: fstream.tcc:756
std::basic_filebuf::_M_pback_init
bool _M_pback_init
Definition: fstream:172
std::basic_filebuf::overflow
virtual int_type overflow(int_type __c=_Traits::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition: fstream.tcc:542
std::basic_filebuf::open
__filebuf_type * open(const char *__s, ios_base::openmode __mode)
Opens an external file.
Definition: fstream.tcc:180
std::basic_filebuf::basic_filebuf
basic_filebuf()
Does not open any files.
Definition: fstream.tcc:81
std::basic_filebuf::_M_set_buffer
void _M_set_buffer(streamsize __off)
Definition: fstream:464
std::basic_filebuf::sync
virtual int sync()
Synchronizes the buffer arrays with the controlled sequences.
Definition: fstream.tcc:1013
std::basic_filebuf::setbuf
virtual __streambuf_type * setbuf(char_type *__s, streamsize __n)
Manipulates the buffer.
Definition: fstream.tcc:804
std::basic_ifstream
Controlling input for files.
Definition: fstream:498
std::basic_ofstream
Controlling output for files.
Definition: fstream:759
std::basic_fstream
Controlling input and output for files.
Definition: fstream:1022
std::basic_streambuf::_M_buf_locale
locale _M_buf_locale
Current locale setting.
Definition: streambuf:197
std::codecvt
Primary class template codecvt.
Definition: codecvt.h:279
std::ios_base
The base of the I/O class hierarchy.
Definition: ios_base.h:234
std::ios_base::cur
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:498
std::ios_base::beg
static const seekdir beg
Request a seek relative to the beginning of the stream.
Definition: ios_base.h:495
std::ios_base::end
static const seekdir end
Request a seek relative to the current end of the sequence.
Definition: ios_base.h:501
std::ios_base::in
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:466
std::ios_base::out
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:469
std::ios_base::binary
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:463
std::ios_base::openmode
_Ios_Openmode openmode
This is a bitmask type.
Definition: ios_base.h:452
std::ios_base::app
static const openmode app
Seek to end before each write.
Definition: ios_base.h:455
std::ios_base::ate
static const openmode ate
Open and seek to end immediately after opening.
Definition: ios_base.h:458
std::locale
Container class for localization functionality.
Definition: locale_classes.h:63