libstdc++

fstream.tcc
Go to the documentation of this file.
1 // File based streams -*- C++ -*-
2
3 // Copyright (C) 1997-2013 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 /** @file bits/fstream.tcc
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{fstream}
28 */
29
30 //
31 // ISO C++ 14882: 27.8 File-based streams
32 //
33
34 #ifndef _FSTREAM_TCC
35 #define _FSTREAM_TCC 1
36
37 #pragma GCC system_header
38
39 #include <bits/cxxabi_forced.h>
40
41 namespace std _GLIBCXX_VISIBILITY(default)
42 {
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
44
45 template<typename _CharT, typename _Traits>
46 void
47 basic_filebuf<_CharT, _Traits>::
48 _M_allocate_internal_buffer()
49 {
50 // Allocate internal buffer only if one doesn't already exist
51 // (either allocated or provided by the user via setbuf).
52 if (!_M_buf_allocated && !_M_buf)
53 {
54 _M_buf = new char_type[_M_buf_size];
55 _M_buf_allocated = true;
56 }
57 }
58
59 template<typename _CharT, typename _Traits>
60 void
61 basic_filebuf<_CharT, _Traits>::
62 _M_destroy_internal_buffer() throw()
63 {
64 if (_M_buf_allocated)
65 {
66 delete [] _M_buf;
67 _M_buf = 0;
68 _M_buf_allocated = false;
69 }
70 delete [] _M_ext_buf;
71 _M_ext_buf = 0;
72 _M_ext_buf_size = 0;
73 _M_ext_next = 0;
74 _M_ext_end = 0;
75 }
76
77 template<typename _CharT, typename _Traits>
78 basic_filebuf<_CharT, _Traits>::
79 basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
80 _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
81 _M_state_last(), _M_buf(0), _M_buf_size(BUFSIZ),
82 _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(),
83 _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
84 _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
85 _M_ext_end(0)
86 {
87 if (has_facet<__codecvt_type>(this->_M_buf_locale))
88 _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
89 }
90
91 template<typename _CharT, typename _Traits>
92 typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
93 basic_filebuf<_CharT, _Traits>::
94 open(const char* __s, ios_base::openmode __mode)
95 {
96 __filebuf_type *__ret = 0;
97 if (!this->is_open())
98 {
99 _M_file.open(__s, __mode);
100 if (this->is_open())
101 {
102 _M_allocate_internal_buffer();
103 _M_mode = __mode;
104
105 // Setup initial buffer to 'uncommitted' mode.
106 _M_reading = false;
107 _M_writing = false;
108 _M_set_buffer(-1);
109
110 // Reset to initial state.
111 _M_state_last = _M_state_cur = _M_state_beg;
112
113 // 27.8.1.3,4
114 if ((__mode & ios_base::ate)
115 && this->seekoff(0, ios_base::end, __mode)
116 == pos_type(off_type(-1)))
117 this->close();
118 else
119 __ret = this;
120 }
121 }
122 return __ret;
123 }
124
125 template<typename _CharT, typename _Traits>
126 typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
127 basic_filebuf<_CharT, _Traits>::
128 close()
129 {
130 if (!this->is_open())
131 return 0;
132
133 bool __testfail = false;
134 {
135 // NB: Do this here so that re-opened filebufs will be cool...
136 struct __close_sentry
137 {
138 basic_filebuf *__fb;
139 __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
140 ~__close_sentry ()
141 {
142 __fb->_M_mode = ios_base::openmode(0);
143 __fb->_M_pback_init = false;
144 __fb->_M_destroy_internal_buffer();
145 __fb->_M_reading = false;
146 __fb->_M_writing = false;
147 __fb->_M_set_buffer(-1);
148 __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
149 }
150 } __cs (this);
151
152 __try
153 {
154 if (!_M_terminate_output())
155 __testfail = true;
156 }
157 __catch(__cxxabiv1::__forced_unwind&)
158 {
159 _M_file.close();
160 __throw_exception_again;
161 }
162 __catch(...)
163 { __testfail = true; }
164 }
165
166 if (!_M_file.close())
167 __testfail = true;
168
169 if (__testfail)
170 return 0;
171 else
172 return this;
173 }
174
175 template<typename _CharT, typename _Traits>
176 streamsize
177 basic_filebuf<_CharT, _Traits>::
178 showmanyc()
179 {
180 streamsize __ret = -1;
181 const bool __testin = _M_mode & ios_base::in;
182 if (__testin && this->is_open())
183 {
184 // For a stateful encoding (-1) the pending sequence might be just
185 // shift and unshift prefixes with no actual character.
186 __ret = this->egptr() - this->gptr();
187
188 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
189 // About this workaround, see libstdc++/20806.
190 const bool __testbinary = _M_mode & ios_base::binary;
191 if (__check_facet(_M_codecvt).encoding() >= 0
192 && __testbinary)
193 #else
194 if (__check_facet(_M_codecvt).encoding() >= 0)
195 #endif
196 __ret += _M_file.showmanyc() / _M_codecvt->max_length();
197 }
198 return __ret;
199 }
200
201 template<typename _CharT, typename _Traits>
202 typename basic_filebuf<_CharT, _Traits>::int_type
203 basic_filebuf<_CharT, _Traits>::
204 underflow()
205 {
206 int_type __ret = traits_type::eof();
207 const bool __testin = _M_mode & ios_base::in;
208 if (__testin)
209 {
210 if (_M_writing)
211 {
212 if (overflow() == traits_type::eof())
213 return __ret;
214 _M_set_buffer(-1);
215 _M_writing = false;
216 }
217 // Check for pback madness, and if so switch back to the
218 // normal buffers and jet outta here before expensive
219 // fileops happen...
220 _M_destroy_pback();
221
222 if (this->gptr() < this->egptr())
223 return traits_type::to_int_type(*this->gptr());
224
225 // Get and convert input sequence.
226 const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
227
228 // Will be set to true if ::read() returns 0 indicating EOF.
229 bool __got_eof = false;
230 // Number of internal characters produced.
231 streamsize __ilen = 0;
232 codecvt_base::result __r = codecvt_base::ok;
233 if (__check_facet(_M_codecvt).always_noconv())
234 {
235 __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
236 __buflen);
237 if (__ilen == 0)
238 __got_eof = true;
239 }
240 else
241 {
242 // Worst-case number of external bytes.
243 // XXX Not done encoding() == -1.
244 const int __enc = _M_codecvt->encoding();
245 streamsize __blen; // Minimum buffer size.
246 streamsize __rlen; // Number of chars to read.
247 if (__enc > 0)
248 __blen = __rlen = __buflen * __enc;
249 else
250 {
251 __blen = __buflen + _M_codecvt->max_length() - 1;
252 __rlen = __buflen;
253 }
254 const streamsize __remainder = _M_ext_end - _M_ext_next;
255 __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
256
257 // An imbue in 'read' mode implies first converting the external
258 // chars already present.
259 if (_M_reading && this->egptr() == this->eback() && __remainder)
260 __rlen = 0;
261
262 // Allocate buffer if necessary and move unconverted
263 // bytes to front.
264 if (_M_ext_buf_size < __blen)
265 {
266 char* __buf = new char[__blen];
267 if (__remainder)
268 __builtin_memcpy(__buf, _M_ext_next, __remainder);
269
270 delete [] _M_ext_buf;
271 _M_ext_buf = __buf;
272 _M_ext_buf_size = __blen;
273 }
274 else if (__remainder)
275 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
276
277 _M_ext_next = _M_ext_buf;
278 _M_ext_end = _M_ext_buf + __remainder;
279 _M_state_last = _M_state_cur;
280
281 do
282 {
283 if (__rlen > 0)
284 {
285 // Sanity check!
286 // This may fail if the return value of
287 // codecvt::max_length() is bogus.
288 if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
289 {
290 __throw_ios_failure(__N("basic_filebuf::underflow "
291 "codecvt::max_length() "
292 "is not valid"));
293 }
294 streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
295 if (__elen == 0)
296 __got_eof = true;
297 else if (__elen == -1)
298 break;
299 _M_ext_end += __elen;
300 }
301
302 char_type* __iend = this->eback();
303 if (_M_ext_next < _M_ext_end)
304 __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
305 _M_ext_end, _M_ext_next,
306 this->eback(),
307 this->eback() + __buflen, __iend);
308 if (__r == codecvt_base::noconv)
309 {
310 size_t __avail = _M_ext_end - _M_ext_buf;
311 __ilen = std::min(__avail, __buflen);
312 traits_type::copy(this->eback(),
313 reinterpret_cast<char_type*>
314 (_M_ext_buf), __ilen);
315 _M_ext_next = _M_ext_buf + __ilen;
316 }
317 else
318 __ilen = __iend - this->eback();
319
320 // _M_codecvt->in may return error while __ilen > 0: this is
321 // ok, and actually occurs in case of mixed encodings (e.g.,
322 // XML files).
323 if (__r == codecvt_base::error)
324 break;
325
326 __rlen = 1;
327 }
328 while (__ilen == 0 && !__got_eof);
329 }
330
331 if (__ilen > 0)
332 {
333 _M_set_buffer(__ilen);
334 _M_reading = true;
335 __ret = traits_type::to_int_type(*this->gptr());
336 }
337 else if (__got_eof)
338 {
339 // If the actual end of file is reached, set 'uncommitted'
340 // mode, thus allowing an immediate write without an
341 // intervening seek.
342 _M_set_buffer(-1);
343 _M_reading = false;
344 // However, reaching it while looping on partial means that
345 // the file has got an incomplete character.
346 if (__r == codecvt_base::partial)
347 __throw_ios_failure(__N("basic_filebuf::underflow "
348 "incomplete character in file"));
349 }
350 else if (__r == codecvt_base::error)
351 __throw_ios_failure(__N("basic_filebuf::underflow "
352 "invalid byte sequence in file"));
353 else
354 __throw_ios_failure(__N("basic_filebuf::underflow "
355 "error reading the file"));
356 }
357 return __ret;
358 }
359
360 template<typename _CharT, typename _Traits>
361 typename basic_filebuf<_CharT, _Traits>::int_type
362 basic_filebuf<_CharT, _Traits>::
363 pbackfail(int_type __i)
364 {
365 int_type __ret = traits_type::eof();
366 const bool __testin = _M_mode & ios_base::in;
367 if (__testin)
368 {
369 if (_M_writing)
370 {
371 if (overflow() == traits_type::eof())
372 return __ret;
373 _M_set_buffer(-1);
374 _M_writing = false;
375 }
376 // Remember whether the pback buffer is active, otherwise below
377 // we may try to store in it a second char (libstdc++/9761).
378 const bool __testpb = _M_pback_init;
379 const bool __testeof = traits_type::eq_int_type(__i, __ret);
380 int_type __tmp;
381 if (this->eback() < this->gptr())
382 {
383 this->gbump(-1);
384 __tmp = traits_type::to_int_type(*this->gptr());
385 }
386 else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
387 {
388 __tmp = this->underflow();
389 if (traits_type::eq_int_type(__tmp, __ret))
390 return __ret;
391 }
392 else
393 {
394 // At the beginning of the buffer, need to make a
395 // putback position available. But the seek may fail
396 // (f.i., at the beginning of a file, see
397 // libstdc++/9439) and in that case we return
398 // traits_type::eof().
399 return __ret;
400 }
401
402 // Try to put back __i into input sequence in one of three ways.
403 // Order these tests done in is unspecified by the standard.
404 if (!__testeof && traits_type::eq_int_type(__i, __tmp))
405 __ret = __i;
406 else if (__testeof)
407 __ret = traits_type::not_eof(__i);
408 else if (!__testpb)
409 {
410 _M_create_pback();
411 _M_reading = true;
412 *this->gptr() = traits_type::to_char_type(__i);
413 __ret = __i;
414 }
415 }
416 return __ret;
417 }
418
419 template<typename _CharT, typename _Traits>
420 typename basic_filebuf<_CharT, _Traits>::int_type
421 basic_filebuf<_CharT, _Traits>::
422 overflow(int_type __c)
423 {
424 int_type __ret = traits_type::eof();
425 const bool __testeof = traits_type::eq_int_type(__c, __ret);
426 const bool __testout = _M_mode & ios_base::out;
427 if (__testout)
428 {
429 if (_M_reading)
430 {
431 _M_destroy_pback();
432 const int __gptr_off = _M_get_ext_pos(_M_state_last);
433 if (_M_seek(__gptr_off, ios_base::cur, _M_state_last)
434 == pos_type(off_type(-1)))
435 return __ret;
436 }
437 if (this->pbase() < this->pptr())
438 {
439 // If appropriate, append the overflow char.
440 if (!__testeof)
441 {
442 *this->pptr() = traits_type::to_char_type(__c);
443 this->pbump(1);
444 }
445
446 // Convert pending sequence to external representation,
447 // and output.
448 if (_M_convert_to_external(this->pbase(),
449 this->pptr() - this->pbase()))
450 {
451 _M_set_buffer(0);
452 __ret = traits_type::not_eof(__c);
453 }
454 }
455 else if (_M_buf_size > 1)
456 {
457 // Overflow in 'uncommitted' mode: set _M_writing, set
458 // the buffer to the initial 'write' mode, and put __c
459 // into the buffer.
460 _M_set_buffer(0);
461 _M_writing = true;
462 if (!__testeof)
463 {
464 *this->pptr() = traits_type::to_char_type(__c);
465 this->pbump(1);
466 }
467 __ret = traits_type::not_eof(__c);
468 }
469 else
470 {
471 // Unbuffered.
472 char_type __conv = traits_type::to_char_type(__c);
473 if (__testeof || _M_convert_to_external(&__conv, 1))
474 {
475 _M_writing = true;
476 __ret = traits_type::not_eof(__c);
477 }
478 }
479 }
480 return __ret;
481 }
482
483 template<typename _CharT, typename _Traits>
484 bool
485 basic_filebuf<_CharT, _Traits>::
486 _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
487 {
488 // Sizes of external and pending output.
489 streamsize __elen;
490 streamsize __plen;
491 if (__check_facet(_M_codecvt).always_noconv())
492 {
493 __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
494 __plen = __ilen;
495 }
496 else
497 {
498 // Worst-case number of external bytes needed.
499 // XXX Not done encoding() == -1.
500 streamsize __blen = __ilen * _M_codecvt->max_length();
501 char* __buf = static_cast<char*>(__builtin_alloca(__blen));
502
503 char* __bend;
504 const char_type* __iend;
505 codecvt_base::result __r;
506 __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
507 __iend, __buf, __buf + __blen, __bend);
508
509 if (__r == codecvt_base::ok || __r == codecvt_base::partial)
510 __blen = __bend - __buf;
511 else if (__r == codecvt_base::noconv)
512 {
513 // Same as the always_noconv case above.
514 __buf = reinterpret_cast<char*>(__ibuf);
515 __blen = __ilen;
516 }
517 else
518 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
519 "conversion error"));
520
521 __elen = _M_file.xsputn(__buf, __blen);
522 __plen = __blen;
523
524 // Try once more for partial conversions.
525 if (__r == codecvt_base::partial && __elen == __plen)
526 {
527 const char_type* __iresume = __iend;
528 streamsize __rlen = this->pptr() - __iend;
529 __r = _M_codecvt->out(_M_state_cur, __iresume,
530 __iresume + __rlen, __iend, __buf,
531 __buf + __blen, __bend);
532 if (__r != codecvt_base::error)
533 {
534 __rlen = __bend - __buf;
535 __elen = _M_file.xsputn(__buf, __rlen);
536 __plen = __rlen;
537 }
538 else
539 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
540 "conversion error"));
541 }
542 }
543 return __elen == __plen;
544 }
545
546 template<typename _CharT, typename _Traits>
547 streamsize
548 basic_filebuf<_CharT, _Traits>::
549 xsgetn(_CharT* __s, streamsize __n)
550 {
551 // Clear out pback buffer before going on to the real deal...
552 streamsize __ret = 0;
553 if (_M_pback_init)
554 {
555 if (__n > 0 && this->gptr() == this->eback())
556 {
557 *__s++ = *this->gptr(); // emulate non-underflowing sbumpc
558 this->gbump(1);
559 __ret = 1;
560 --__n;
561 }
562 _M_destroy_pback();
563 }
564 else if (_M_writing)
565 {
566 if (overflow() == traits_type::eof())
567 return __ret;
568 _M_set_buffer(-1);
569 _M_writing = false;
570 }
571
572 // Optimization in the always_noconv() case, to be generalized in the
573 // future: when __n > __buflen we read directly instead of using the
574 // buffer repeatedly.
575 const bool __testin = _M_mode & ios_base::in;
576 const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
577
578 if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
579 && __testin)
580 {
581 // First, copy the chars already present in the buffer.
582 const streamsize __avail = this->egptr() - this->gptr();
583 if (__avail != 0)
584 {
585 traits_type::copy(__s, this->gptr(), __avail);
586 __s += __avail;
587 this->setg(this->eback(), this->gptr() + __avail,
588 this->egptr());
589 __ret += __avail;
590 __n -= __avail;
591 }
592
593 // Need to loop in case of short reads (relatively common
594 // with pipes).
595 streamsize __len;
596 for (;;)
597 {
598 __len = _M_file.xsgetn(reinterpret_cast<char*>(__s),
599 __n);
600 if (__len == -1)
601 __throw_ios_failure(__N("basic_filebuf::xsgetn "
602 "error reading the file"));
603 if (__len == 0)
604 break;
605
606 __n -= __len;
607 __ret += __len;
608 if (__n == 0)
609 break;
610
611 __s += __len;
612 }
613
614 if (__n == 0)
615 {
616 _M_set_buffer(0);
617 _M_reading = true;
618 }
619 else if (__len == 0)
620 {
621 // If end of file is reached, set 'uncommitted'
622 // mode, thus allowing an immediate write without
623 // an intervening seek.
624 _M_set_buffer(-1);
625 _M_reading = false;
626 }
627 }
628 else
629 __ret += __streambuf_type::xsgetn(__s, __n);
630
631 return __ret;
632 }
633
634 template<typename _CharT, typename _Traits>
635 streamsize
636 basic_filebuf<_CharT, _Traits>::
637 xsputn(const _CharT* __s, streamsize __n)
638 {
639 streamsize __ret = 0;
640 // Optimization in the always_noconv() case, to be generalized in the
641 // future: when __n is sufficiently large we write directly instead of
642 // using the buffer.
643 const bool __testout = _M_mode & ios_base::out;
644 if (__check_facet(_M_codecvt).always_noconv()
645 && __testout && !_M_reading)
646 {
647 // Measurement would reveal the best choice.
648 const streamsize __chunk = 1ul << 10;
649 streamsize __bufavail = this->epptr() - this->pptr();
650
651 // Don't mistake 'uncommitted' mode buffered with unbuffered.
652 if (!_M_writing && _M_buf_size > 1)
653 __bufavail = _M_buf_size - 1;
654
655 const streamsize __limit = std::min(__chunk, __bufavail);
656 if (__n >= __limit)
657 {
658 const streamsize __buffill = this->pptr() - this->pbase();
659 const char* __buf = reinterpret_cast<const char*>(this->pbase());
660 __ret = _M_file.xsputn_2(__buf, __buffill,
661 reinterpret_cast<const char*>(__s),
662 __n);
663 if (__ret == __buffill + __n)
664 {
665 _M_set_buffer(0);
666 _M_writing = true;
667 }
668 if (__ret > __buffill)
669 __ret -= __buffill;
670 else
671 __ret = 0;
672 }
673 else
674 __ret = __streambuf_type::xsputn(__s, __n);
675 }
676 else
677 __ret = __streambuf_type::xsputn(__s, __n);
678 return __ret;
679 }
680
681 template<typename _CharT, typename _Traits>
682 typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
683 basic_filebuf<_CharT, _Traits>::
684 setbuf(char_type* __s, streamsize __n)
685 {
686 if (!this->is_open())
687 {
688 if (__s == 0 && __n == 0)
689 _M_buf_size = 1;
690 else if (__s && __n > 0)
691 {
692 // This is implementation-defined behavior, and assumes that
693 // an external char_type array of length __n exists and has
694 // been pre-allocated. If this is not the case, things will
695 // quickly blow up. When __n > 1, __n - 1 positions will be
696 // used for the get area, __n - 1 for the put area and 1
697 // position to host the overflow char of a full put area.
698 // When __n == 1, 1 position will be used for the get area
699 // and 0 for the put area, as in the unbuffered case above.
700 _M_buf = __s;
701 _M_buf_size = __n;
702 }
703 }
704 return this;
705 }
706
707
708 // According to 27.8.1.4 p11 - 13, seekoff should ignore the last
709 // argument (of type openmode).
710 template<typename _CharT, typename _Traits>
711 typename basic_filebuf<_CharT, _Traits>::pos_type
712 basic_filebuf<_CharT, _Traits>::
713 seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
714 {
715 int __width = 0;
716 if (_M_codecvt)
717 __width = _M_codecvt->encoding();
718 if (__width < 0)
719 __width = 0;
720
721 pos_type __ret = pos_type(off_type(-1));
722 const bool __testfail = __off != 0 && __width <= 0;
723 if (this->is_open() && !__testfail)
724 {
725 // tellg and tellp queries do not affect any state, unless
726 // ! always_noconv and the put sequence is not empty.
727 // In that case, determining the position requires converting the
728 // put sequence. That doesn't use ext_buf, so requires a flush.
729 bool __no_movement = __way == ios_base::cur && __off == 0
730 && (!_M_writing || _M_codecvt->always_noconv());
731
732 // Ditch any pback buffers to avoid confusion.
733 if (!__no_movement)
734 _M_destroy_pback();
735
736 // Correct state at destination. Note that this is the correct
737 // state for the current position during output, because
738 // codecvt::unshift() returns the state to the initial state.
739 // This is also the correct state at the end of the file because
740 // an unshift sequence should have been written at the end.
741 __state_type __state = _M_state_beg;
742 off_type __computed_off = __off * __width;
743 if (_M_reading && __way == ios_base::cur)
744 {
745 __state = _M_state_last;
746 __computed_off += _M_get_ext_pos(__state);
747 }
748 if (!__no_movement)
749 __ret = _M_seek(__computed_off, __way, __state);
750 else
751 {
752 if (_M_writing)
753 __computed_off = this->pptr() - this->pbase();
754
755 off_type __file_off = _M_file.seekoff(0, ios_base::cur);
756 if (__file_off != off_type(-1))
757 {
758 __ret = __file_off + __computed_off;
759 __ret.state(__state);
760 }
761 }
762 }
763 return __ret;
764 }
765
766 // _GLIBCXX_RESOLVE_LIB_DEFECTS
767 // 171. Strange seekpos() semantics due to joint position
768 // According to the resolution of DR 171, seekpos should ignore the last
769 // argument (of type openmode).
770 template<typename _CharT, typename _Traits>
771 typename basic_filebuf<_CharT, _Traits>::pos_type
772 basic_filebuf<_CharT, _Traits>::
773 seekpos(pos_type __pos, ios_base::openmode)
774 {
775 pos_type __ret = pos_type(off_type(-1));
776 if (this->is_open())
777 {
778 // Ditch any pback buffers to avoid confusion.
779 _M_destroy_pback();
780 __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
781 }
782 return __ret;
783 }
784
785 template<typename _CharT, typename _Traits>
786 typename basic_filebuf<_CharT, _Traits>::pos_type
787 basic_filebuf<_CharT, _Traits>::
788 _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
789 {
790 pos_type __ret = pos_type(off_type(-1));
791 if (_M_terminate_output())
792 {
793 off_type __file_off = _M_file.seekoff(__off, __way);
794 if (__file_off != off_type(-1))
795 {
796 _M_reading = false;
797 _M_writing = false;
798 _M_ext_next = _M_ext_end = _M_ext_buf;
799 _M_set_buffer(-1);
800 _M_state_cur = __state;
801 __ret = __file_off;
802 __ret.state(_M_state_cur);
803 }
804 }
805 return __ret;
806 }
807
808 // Returns the distance from the end of the ext buffer to the point
809 // corresponding to gptr(). This is a negative value. Updates __state
810 // from eback() correspondence to gptr().
811 template<typename _CharT, typename _Traits>
812 int basic_filebuf<_CharT, _Traits>::
813 _M_get_ext_pos(__state_type& __state)
814 {
815 if (_M_codecvt->always_noconv())
816 return this->gptr() - this->egptr();
817 else
818 {
819 // Calculate offset from _M_ext_buf that corresponds to
820 // gptr(). Precondition: __state == _M_state_last, which
821 // corresponds to eback().
822 const int __gptr_off =
823 _M_codecvt->length(__state, _M_ext_buf, _M_ext_next,
824 this->gptr() - this->eback());
825 return _M_ext_buf + __gptr_off - _M_ext_end;
826 }
827 }
828
829 template<typename _CharT, typename _Traits>
830 bool
831 basic_filebuf<_CharT, _Traits>::
832 _M_terminate_output()
833 {
834 // Part one: update the output sequence.
835 bool __testvalid = true;
836 if (this->pbase() < this->pptr())
837 {
838 const int_type __tmp = this->overflow();
839 if (traits_type::eq_int_type(__tmp, traits_type::eof()))
840 __testvalid = false;
841 }
842
843 // Part two: output unshift sequence.
844 if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
845 && __testvalid)
846 {
847 // Note: this value is arbitrary, since there is no way to
848 // get the length of the unshift sequence from codecvt,
849 // without calling unshift.
850 const size_t __blen = 128;
851 char __buf[__blen];
852 codecvt_base::result __r;
853 streamsize __ilen = 0;
854
855 do
856 {
857 char* __next;
858 __r = _M_codecvt->unshift(_M_state_cur, __buf,
859 __buf + __blen, __next);
860 if (__r == codecvt_base::error)
861 __testvalid = false;
862 else if (__r == codecvt_base::ok ||
863 __r == codecvt_base::partial)
864 {
865 __ilen = __next - __buf;
866 if (__ilen > 0)
867 {
868 const streamsize __elen = _M_file.xsputn(__buf, __ilen);
869 if (__elen != __ilen)
870 __testvalid = false;
871 }
872 }
873 }
874 while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
875
876 if (__testvalid)
877 {
878 // This second call to overflow() is required by the standard,
879 // but it's not clear why it's needed, since the output buffer
880 // should be empty by this point (it should have been emptied
881 // in the first call to overflow()).
882 const int_type __tmp = this->overflow();
883 if (traits_type::eq_int_type(__tmp, traits_type::eof()))
884 __testvalid = false;
885 }
886 }
887 return __testvalid;
888 }
889
890 template<typename _CharT, typename _Traits>
891 int
892 basic_filebuf<_CharT, _Traits>::
893 sync()
894 {
895 // Make sure that the internal buffer resyncs its idea of
896 // the file position with the external file.
897 int __ret = 0;
898 if (this->pbase() < this->pptr())
899 {
900 const int_type __tmp = this->overflow();
901 if (traits_type::eq_int_type(__tmp, traits_type::eof()))
902 __ret = -1;
903 }
904 return __ret;
905 }
906
907 template<typename _CharT, typename _Traits>
908 void
909 basic_filebuf<_CharT, _Traits>::
910 imbue(const locale& __loc)
911 {
912 bool __testvalid = true;
913
914 const __codecvt_type* _M_codecvt_tmp = 0;
915 if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
916 _M_codecvt_tmp = &use_facet<__codecvt_type>(__loc);
917
918 if (this->is_open())
919 {
920 // encoding() == -1 is ok only at the beginning.
921 if ((_M_reading || _M_writing)
922 && __check_facet(_M_codecvt).encoding() == -1)
923 __testvalid = false;
924 else
925 {
926 if (_M_reading)
927 {
928 if (__check_facet(_M_codecvt).always_noconv())
929 {
930 if (_M_codecvt_tmp
931 && !__check_facet(_M_codecvt_tmp).always_noconv())
932 __testvalid = this->seekoff(0, ios_base::cur, _M_mode)
933 != pos_type(off_type(-1));
934 }
935 else
936 {
937 // External position corresponding to gptr().
938 _M_ext_next = _M_ext_buf
939 + _M_codecvt->length(_M_state_last, _M_ext_buf,
940 _M_ext_next,
941 this->gptr() - this->eback());
942 const streamsize __remainder = _M_ext_end - _M_ext_next;
943 if (__remainder)
944 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
945
946 _M_ext_next = _M_ext_buf;
947 _M_ext_end = _M_ext_buf + __remainder;
948 _M_set_buffer(-1);
949 _M_state_last = _M_state_cur = _M_state_beg;
950 }
951 }
952 else if (_M_writing && (__testvalid = _M_terminate_output()))
953 _M_set_buffer(-1);
954 }
955 }
956
957 if (__testvalid)
958 _M_codecvt = _M_codecvt_tmp;
959 else
960 _M_codecvt = 0;
961 }
962
963 // Inhibit implicit instantiations for required instantiations,
964 // which are defined via explicit instantiations elsewhere.
965 #if _GLIBCXX_EXTERN_TEMPLATE
966 extern template class basic_filebuf<char>;
967 extern template class basic_ifstream<char>;
968 extern template class basic_ofstream<char>;
969 extern template class basic_fstream<char>;
970
971 #ifdef _GLIBCXX_USE_WCHAR_T
972 extern template class basic_filebuf<wchar_t>;
973 extern template class basic_ifstream<wchar_t>;
974 extern template class basic_ofstream<wchar_t>;
975 extern template class basic_fstream<wchar_t>;
976 #endif
977 #endif
978
979 _GLIBCXX_END_NAMESPACE_VERSION
980 } // namespace std
981
982 #endif