fstream.tcc source code [include/c++/7/bits/fstream.tcc]

1	// File based streams -- C++ --
2
3	// Copyright (C) 1997-2017 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
42	namespace std _GLIBCXX_VISIBILITY(default)
43	{
44	_GLIBCXX_BEGIN_NAMESPACE_VERSION
45
46	template<typename _CharT, typename _Traits>
47	void
48	basic_filebuf<_CharT, _Traits>::
49	_M_allocate_internal_buffer()
50	{
51	// Allocate internal buffer only if one doesn't already exist
52	// (either allocated or provided by the user via setbuf).
53	if (!_M_buf_allocated && !_M_buf)
54	{
55	_M_buf = new char_type[_M_buf_size];
56	_M_buf_allocated = true;
57	}
58	}
59
60	template<typename _CharT, typename _Traits>
61	void
62	basic_filebuf<_CharT, _Traits>::
63	_M_destroy_internal_buffer() throw()
64	{
65	if (_M_buf_allocated)
66	{
67	delete [] _M_buf;
68	_M_buf = 0;
69	_M_buf_allocated = false;
70	}
71	delete [] _M_ext_buf;
72	_M_ext_buf = 0;
73	_M_ext_buf_size = 0;
74	_M_ext_next = 0;
75	_M_ext_end = 0;
76	}
77
78	template<typename _CharT, typename _Traits>
79	basic_filebuf<_CharT, _Traits>::
80	basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
81	_M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
82	_M_state_last(), _M_buf(0), _M_buf_size(BUFSIZ),
83	_M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(),
84	_M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
85	_M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
86	_M_ext_end(0)
87	{
88	if (has_facet<__codecvt_type>(this->_M_buf_locale))
89	_M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
90	}
91
92	#if __cplusplus >= 201103L
93	template<typename _CharT, typename _Traits>
94	basic_filebuf<_CharT, _Traits>::
95	basic_filebuf(basic_filebuf&& __rhs)
96	: __streambuf_type(__rhs),
97	_M_lock(), _M_file(std::move(__rhs._M_file), &_M_lock),
98	_M_mode(std::__exchange(__rhs._M_mode, ios_base::openmode(0))),
99	_M_state_beg(std::move(__rhs._M_state_beg)),
100	_M_state_cur(std::move(__rhs._M_state_cur)),
101	_M_state_last(std::move(__rhs._M_state_last)),
102	_M_buf(std::__exchange(__rhs._M_buf, nullptr)),
103	_M_buf_size(std::__exchange(__rhs._M_buf_size, 1)),
104	_M_buf_allocated(std::__exchange(__rhs._M_buf_allocated, false)),
105	_M_reading(std::__exchange(__rhs._M_reading, false)),
106	_M_writing(std::__exchange(__rhs._M_writing, false)),
107	_M_pback(__rhs._M_pback),
108	_M_pback_cur_save(std::__exchange(__rhs._M_pback_cur_save, nullptr)),
109	_M_pback_end_save(std::__exchange(__rhs._M_pback_end_save, nullptr)),
110	_M_pback_init(std::__exchange(__rhs._M_pback_init, false)),
111	_M_codecvt(__rhs._M_codecvt),
112	_M_ext_buf(std::__exchange(__rhs._M_ext_buf, nullptr)),
113	_M_ext_buf_size(std::__exchange(__rhs._M_ext_buf_size, 0)),
114	_M_ext_next(std::__exchange(__rhs._M_ext_next, nullptr)),
115	_M_ext_end(std::__exchange(__rhs._M_ext_end, nullptr))
116	{
117	__rhs._M_set_buffer(-1);
118	__rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg;
119	}
120
121	template<typename _CharT, typename _Traits>
122	basic_filebuf<_CharT, _Traits>&
123	basic_filebuf<_CharT, _Traits>::
124	operator=(basic_filebuf&& __rhs)
125	{
126	this->close();
127	__streambuf_type::operator=(__rhs);
128	_M_file.swap(__rhs._M_file);
129	_M_mode = std::__exchange(__rhs._M_mode, ios_base::openmode(0));
130	_M_state_beg = std::move(__rhs._M_state_beg);
131	_M_state_cur = std::move(__rhs._M_state_cur);
132	_M_state_last = std::move(__rhs._M_state_last);
133	_M_buf = std::__exchange(__rhs._M_buf, nullptr);
134	_M_buf_size = std::__exchange(__rhs._M_buf_size, 1);
135	_M_buf_allocated = std::__exchange(__rhs._M_buf_allocated, false);
136	_M_ext_buf = std::__exchange(__rhs._M_ext_buf, nullptr);
137	_M_ext_buf_size = std::__exchange(__rhs._M_ext_buf_size, 0);
138	_M_ext_next = std::__exchange(__rhs._M_ext_next, nullptr);
139	_M_ext_end = std::__exchange(__rhs._M_ext_end, nullptr);
140	_M_reading = std::__exchange(__rhs._M_reading, false);
141	_M_writing = std::__exchange(__rhs._M_writing, false);
142	_M_pback_cur_save = std::__exchange(__rhs._M_pback_cur_save, nullptr);
143	_M_pback_end_save = std::__exchange(__rhs._M_pback_end_save, nullptr);
144	_M_pback_init = std::__exchange(__rhs._M_pback_init, false);
145	__rhs._M_set_buffer(-1);
146	__rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg;
147	return *this;
148	}
149
150	template<typename _CharT, typename _Traits>
151	void
152	basic_filebuf<_CharT, _Traits>::
153	swap(basic_filebuf& __rhs)
154	{
155	__streambuf_type::swap(__rhs);
156	_M_file.swap(__rhs._M_file);
157	std::swap(_M_mode, __rhs._M_mode);
158	std::swap(_M_state_beg, __rhs._M_state_beg);
159	std::swap(_M_state_cur, __rhs._M_state_cur);
160	std::swap(_M_state_last, __rhs._M_state_last);
161	std::swap(_M_buf, __rhs._M_buf);
162	std::swap(_M_buf_size, __rhs._M_buf_size);
163	std::swap(_M_buf_allocated, __rhs._M_buf_allocated);
164	std::swap(_M_ext_buf, __rhs._M_ext_buf);
165	std::swap(_M_ext_buf_size, __rhs._M_ext_buf_size);
166	std::swap(_M_ext_next, __rhs._M_ext_next);
167	std::swap(_M_ext_end, __rhs._M_ext_end);
168	std::swap(_M_reading, __rhs._M_reading);
169	std::swap(_M_writing, __rhs._M_writing);
170	std::swap(_M_pback_cur_save, __rhs._M_pback_cur_save);
171	std::swap(_M_pback_end_save, __rhs._M_pback_end_save);
172	std::swap(_M_pback_init, __rhs._M_pback_init);
173	}
174	#endif
175
176	template<typename _CharT, typename _Traits>
177	typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
178	basic_filebuf<_CharT, _Traits>::
179	open(const char* __s, ios_base::openmode __mode)
180	{
181	__filebuf_type *__ret = 0;
182	if (!this->is_open())
183	{
184	_M_file.open(__s, __mode);
185	if (this->is_open())
186	{
187	_M_allocate_internal_buffer();
188	_M_mode = __mode;
189
190	// Setup initial buffer to 'uncommitted' mode.
191	_M_reading = false;
192	_M_writing = false;
193	_M_set_buffer(-1);
194
195	// Reset to initial state.
196	_M_state_last = _M_state_cur = _M_state_beg;
197
198	// 27.8.1.3,4
199	if ((__mode & ios_base::ate)
200	&& this->seekoff(0, ios_base::end, __mode)
201	== pos_type(off_type(-1)))
202	this->close();
203	else
204	__ret = this;
205	}
206	}
207	return __ret;
208	}
209
210	template<typename _CharT, typename _Traits>
211	typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
212	basic_filebuf<_CharT, _Traits>::
213	close()
214	{
215	if (!this->is_open())
216	return 0;
217
218	bool __testfail = false;
219	{
220	// NB: Do this here so that re-opened filebufs will be cool...
221	struct __close_sentry
222	{
223	basic_filebuf *__fb;
224	__close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
225	~__close_sentry ()
226	{
227	__fb->_M_mode = ios_base::openmode(0);
228	__fb->_M_pback_init = false;
229	__fb->_M_destroy_internal_buffer();
230	__fb->_M_reading = false;
231	__fb->_M_writing = false;
232	__fb->_M_set_buffer(-1);
233	__fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
234	}
235	} __cs (this);
236
237	__try
238	{
239	if (!_M_terminate_output())
240	__testfail = true;
241	}
242	__catch(__cxxabiv1::__forced_unwind&)
243	{
244	_M_file.close();
245	__throw_exception_again;
246	}
247	__catch(...)
248	{ __testfail = true; }
249	}
250
251	if (!_M_file.close())
252	__testfail = true;
253
254	if (__testfail)
255	return 0;
256	else
257	return this;
258	}
259
260	template<typename _CharT, typename _Traits>
261	streamsize
262	basic_filebuf<_CharT, _Traits>::
263	showmanyc()
264	{
265	streamsize __ret = -1;
266	const bool __testin = _M_mode & ios_base::in;
267	if (__testin && this->is_open())
268	{
269	// For a stateful encoding (-1) the pending sequence might be just
270	// shift and unshift prefixes with no actual character.
271	__ret = this->egptr() - this->gptr();
272
273	#if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
274	// About this workaround, see libstdc++/20806.
275	const bool __testbinary = _M_mode & ios_base::binary;
276	if (__check_facet(_M_codecvt).encoding() >= 0
277	&& __testbinary)
278	#else
279	if (__check_facet(_M_codecvt).encoding() >= 0)
280	#endif
281	__ret += _M_file.showmanyc() / _M_codecvt->max_length();
282	}
283	return __ret;
284	}
285
286	template<typename _CharT, typename _Traits>
287	typename basic_filebuf<_CharT, _Traits>::int_type
288	basic_filebuf<_CharT, _Traits>::
289	underflow()
290	{
291	int_type __ret = traits_type::eof();
292	const bool __testin = _M_mode & ios_base::in;
293	if (__testin)
294	{
295	if (_M_writing)
296	{
297	if (overflow() == traits_type::eof())
298	return __ret;
299	_M_set_buffer(-1);
300	_M_writing = false;
301	}
302	// Check for pback madness, and if so switch back to the
303	// normal buffers and jet outta here before expensive
304	// fileops happen...
305	_M_destroy_pback();
306
307	if (this->gptr() < this->egptr())
308	return traits_type::to_int_type(*this->gptr());
309
310	// Get and convert input sequence.
311	const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
312
313	// Will be set to true if ::read() returns 0 indicating EOF.
314	bool __got_eof = false;
315	// Number of internal characters produced.
316	streamsize __ilen = 0;
317	codecvt_base::result __r = codecvt_base::ok;
318	if (__check_facet(_M_codecvt).always_noconv())
319	{
320	__ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
321	__buflen);
322	if (__ilen == 0)
323	__got_eof = true;
324	}
325	else
326	{
327	// Worst-case number of external bytes.
328	// XXX Not done encoding() == -1.
329	const int __enc = _M_codecvt->encoding();
330	streamsize __blen; // Minimum buffer size.
331	streamsize __rlen; // Number of chars to read.
332	if (__enc > 0)
333	__blen = __rlen = __buflen * __enc;
334	else
335	{
336	__blen = __buflen + _M_codecvt->max_length() - 1;
337	__rlen = __buflen;
338	}
339	const streamsize __remainder = _M_ext_end - _M_ext_next;
340	__rlen = __rlen > __remainder ? __rlen - __remainder : 0;
341
342	// An imbue in 'read' mode implies first converting the external
343	// chars already present.
344	if (_M_reading && this->egptr() == this->eback() && __remainder)
345	__rlen = 0;
346
347	// Allocate buffer if necessary and move unconverted
348	// bytes to front.
349	if (_M_ext_buf_size < __blen)
350	{
351	char* __buf = new char[__blen];
352	if (__remainder)
353	__builtin_memcpy(__buf, _M_ext_next, __remainder);
354
355	delete [] _M_ext_buf;
356	_M_ext_buf = __buf;
357	_M_ext_buf_size = __blen;
358	}
359	else if (__remainder)
360	__builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
361
362	_M_ext_next = _M_ext_buf;
363	_M_ext_end = _M_ext_buf + __remainder;
364	_M_state_last = _M_state_cur;
365
366	do
367	{
368	if (__rlen > 0)
369	{
370	// Sanity check!
371	// This may fail if the return value of
372	// codecvt::max_length() is bogus.
373	if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
374	{
375	__throw_ios_failure(__N("basic_filebuf::underflow "
376	"codecvt::max_length() "
377	"is not valid"));
378	}
379	streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
380	if (__elen == 0)
381	__got_eof = true;
382	else if (__elen == -1)
383	break;
384	_M_ext_end += __elen;
385	}
386
387	char_type* __iend = this->eback();
388	if (_M_ext_next < _M_ext_end)
389	__r = _M_codecvt->in(_M_state_cur, _M_ext_next,
390	_M_ext_end, _M_ext_next,
391	this->eback(),
392	this->eback() + __buflen, __iend);
393	if (__r == codecvt_base::noconv)
394	{
395	size_t __avail = _M_ext_end - _M_ext_buf;
396	__ilen = std::min(__avail, __buflen);
397	traits_type::copy(this->eback(),
398	reinterpret_cast<char_type*>
399	(_M_ext_buf), __ilen);
400	_M_ext_next = _M_ext_buf + __ilen;
401	}
402	else
403	__ilen = __iend - this->eback();
404
405	// _M_codecvt->in may return error while __ilen > 0: this is
406	// ok, and actually occurs in case of mixed encodings (e.g.,
407	// XML files).
408	if (__r == codecvt_base::error)
409	break;
410
411	__rlen = 1;
412	}
413	while (__ilen == 0 && !__got_eof);
414	}
415
416	if (__ilen > 0)
417	{
418	_M_set_buffer(__ilen);
419	_M_reading = true;
420	__ret = traits_type::to_int_type(*this->gptr());
421	}
422	else if (__got_eof)
423	{
424	// If the actual end of file is reached, set 'uncommitted'
425	// mode, thus allowing an immediate write without an
426	// intervening seek.
427	_M_set_buffer(-1);
428	_M_reading = false;
429	// However, reaching it while looping on partial means that
430	// the file has got an incomplete character.
431	if (__r == codecvt_base::partial)
432	__throw_ios_failure(__N("basic_filebuf::underflow "
433	"incomplete character in file"));
434	}
435	else if (__r == codecvt_base::error)
436	__throw_ios_failure(__N("basic_filebuf::underflow "
437	"invalid byte sequence in file"));
438	else
439	__throw_ios_failure(__N("basic_filebuf::underflow "
440	"error reading the file"));
441	}
442	return __ret;
443	}
444
445	template<typename _CharT, typename _Traits>
446	typename basic_filebuf<_CharT, _Traits>::int_type
447	basic_filebuf<_CharT, _Traits>::
448	pbackfail(int_type __i)
449	{
450	int_type __ret = traits_type::eof();
451	const bool __testin = _M_mode & ios_base::in;
452	if (__testin)
453	{
454	if (_M_writing)
455	{
456	if (overflow() == traits_type::eof())
457	return __ret;
458	_M_set_buffer(-1);
459	_M_writing = false;
460	}
461	// Remember whether the pback buffer is active, otherwise below
462	// we may try to store in it a second char (libstdc++/9761).
463	const bool __testpb = _M_pback_init;
464	const bool __testeof = traits_type::eq_int_type(__i, __ret);
465	int_type __tmp;
466	if (this->eback() < this->gptr())
467	{
468	this->gbump(-1);
469	__tmp = traits_type::to_int_type(*this->gptr());
470	}
471	else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
472	{
473	__tmp = this->underflow();
474	if (traits_type::eq_int_type(__tmp, __ret))
475	return __ret;
476	}
477	else
478	{
479	// At the beginning of the buffer, need to make a
480	// putback position available. But the seek may fail
481	// (f.i., at the beginning of a file, see
482	// libstdc++/9439) and in that case we return
483	// traits_type::eof().
484	return __ret;
485	}
486
487	// Try to put back __i into input sequence in one of three ways.
488	// Order these tests done in is unspecified by the standard.
489	if (!__testeof && traits_type::eq_int_type(__i, __tmp))
490	__ret = __i;
491	else if (__testeof)
492	__ret = traits_type::not_eof(__i);
493	else if (!__testpb)
494	{
495	_M_create_pback();
496	_M_reading = true;
497	*this->gptr() = traits_type::to_char_type(__i);
498	__ret = __i;
499	}
500	}
501	return __ret;
502	}
503
504	template<typename _CharT, typename _Traits>
505	typename basic_filebuf<_CharT, _Traits>::int_type
506	basic_filebuf<_CharT, _Traits>::
507	overflow(int_type __c)
508	{
509	int_type __ret = traits_type::eof();
510	const bool __testeof = traits_type::eq_int_type(__c, __ret);
511	const bool __testout = (_M_mode & ios_base::out
512	\|\| _M_mode & ios_base::app);
513	if (__testout)
514	{
515	if (_M_reading)
516	{
517	_M_destroy_pback();
518	const int __gptr_off = _M_get_ext_pos(_M_state_last);
519	if (_M_seek(__gptr_off, ios_base::cur, _M_state_last)
520	== pos_type(off_type(-1)))
521	return __ret;
522	}
523	if (this->pbase() < this->pptr())
524	{
525	// If appropriate, append the overflow char.
526	if (!__testeof)
527	{
528	*this->pptr() = traits_type::to_char_type(__c);
529	this->pbump(1);
530	}
531
532	// Convert pending sequence to external representation,
533	// and output.
534	if (_M_convert_to_external(this->pbase(),
535	this->pptr() - this->pbase()))
536	{
537	_M_set_buffer(0);
538	__ret = traits_type::not_eof(__c);
539	}
540	}
541	else if (_M_buf_size > 1)
542	{
543	// Overflow in 'uncommitted' mode: set _M_writing, set
544	// the buffer to the initial 'write' mode, and put __c
545	// into the buffer.
546	_M_set_buffer(0);
547	_M_writing = true;
548	if (!__testeof)
549	{
550	*this->pptr() = traits_type::to_char_type(__c);
551	this->pbump(1);
552	}
553	__ret = traits_type::not_eof(__c);
554	}
555	else
556	{
557	// Unbuffered.
558	char_type __conv = traits_type::to_char_type(__c);
559	if (__testeof \|\| _M_convert_to_external(&__conv, 1))
560	{
561	_M_writing = true;
562	__ret = traits_type::not_eof(__c);
563	}
564	}
565	}
566	return __ret;
567	}
568
569	template<typename _CharT, typename _Traits>
570	bool
571	basic_filebuf<_CharT, _Traits>::
572	_M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
573	{
574	// Sizes of external and pending output.
575	streamsize __elen;
576	streamsize __plen;
577	if (__check_facet(_M_codecvt).always_noconv())
578	{
579	__elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
580	__plen = __ilen;
581	}
582	else
583	{
584	// Worst-case number of external bytes needed.
585	// XXX Not done encoding() == -1.
586	streamsize __blen = __ilen * _M_codecvt->max_length();
587	char* __buf = static_cast<char*>(__builtin_alloca(__blen));
588
589	char* __bend;
590	const char_type* __iend;
591	codecvt_base::result __r;
592	__r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
593	__iend, __buf, __buf + __blen, __bend);
594
595	if (__r == codecvt_base::ok \|\| __r == codecvt_base::partial)
596	__blen = __bend - __buf;
597	else if (__r == codecvt_base::noconv)
598	{
599	// Same as the always_noconv case above.
600	__buf = reinterpret_cast<char*>(__ibuf);
601	__blen = __ilen;
602	}
603	else
604	__throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
605	"conversion error"));
606
607	__elen = _M_file.xsputn(__buf, __blen);
608	__plen = __blen;
609
610	// Try once more for partial conversions.
611	if (__r == codecvt_base::partial && __elen == __plen)
612	{
613	const char_type* __iresume = __iend;
614	streamsize __rlen = this->pptr() - __iend;
615	__r = _M_codecvt->out(_M_state_cur, __iresume,
616	__iresume + __rlen, __iend, __buf,
617	__buf + __blen, __bend);
618	if (__r != codecvt_base::error)
619	{
620	__rlen = __bend - __buf;
621	__elen = _M_file.xsputn(__buf, __rlen);
622	__plen = __rlen;
623	}
624	else
625	__throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
626	"conversion error"));
627	}
628	}
629	return __elen == __plen;
630	}
631
632	template<typename _CharT, typename _Traits>
633	streamsize
634	basic_filebuf<_CharT, _Traits>::
635	xsgetn(_CharT* __s, streamsize __n)
636	{
637	// Clear out pback buffer before going on to the real deal...
638	streamsize __ret = 0;
639	if (_M_pback_init)
640	{
641	if (__n > 0 && this->gptr() == this->eback())
642	{
643	__s++ = this->gptr(); // emulate non-underflowing sbumpc
644	this->gbump(1);
645	__ret = 1;
646	--__n;
647	}
648	_M_destroy_pback();
649	}
650	else if (_M_writing)
651	{
652	if (overflow() == traits_type::eof())
653	return __ret;
654	_M_set_buffer(-1);
655	_M_writing = false;
656	}
657
658	// Optimization in the always_noconv() case, to be generalized in the
659	// future: when __n > __buflen we read directly instead of using the
660	// buffer repeatedly.
661	const bool __testin = _M_mode & ios_base::in;
662	const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
663
664	if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
665	&& __testin)
666	{
667	// First, copy the chars already present in the buffer.
668	const streamsize __avail = this->egptr() - this->gptr();
669	if (__avail != 0)
670	{
671	traits_type::copy(__s, this->gptr(), __avail);
672	__s += __avail;
673	this->setg(this->eback(), this->gptr() + __avail,
674	this->egptr());
675	__ret += __avail;
676	__n -= __avail;
677	}
678
679	// Need to loop in case of short reads (relatively common
680	// with pipes).
681	streamsize __len;
682	for (;;)
683	{
684	__len = _M_file.xsgetn(reinterpret_cast<char*>(__s),
685	__n);
686	if (__len == -1)
687	__throw_ios_failure(__N("basic_filebuf::xsgetn "
688	"error reading the file"));
689	if (__len == 0)
690	break;
691
692	__n -= __len;
693	__ret += __len;
694	if (__n == 0)
695	break;
696
697	__s += __len;
698	}
699
700	if (__n == 0)
701	{
702	// Set _M_reading. Buffer is already in initial 'read' mode.
703	_M_reading = true;
704	}
705	else if (__len == 0)
706	{
707	// If end of file is reached, set 'uncommitted'
708	// mode, thus allowing an immediate write without
709	// an intervening seek.
710	_M_set_buffer(-1);
711	_M_reading = false;
712	}
713	}
714	else
715	__ret += __streambuf_type::xsgetn(__s, __n);
716
717	return __ret;
718	}
719
720	template<typename _CharT, typename _Traits>
721	streamsize
722	basic_filebuf<_CharT, _Traits>::
723	xsputn(const _CharT* __s, streamsize __n)
724	{
725	streamsize __ret = 0;
726	// Optimization in the always_noconv() case, to be generalized in the
727	// future: when __n is sufficiently large we write directly instead of
728	// using the buffer.
729	const bool __testout = (_M_mode & ios_base::out
730	\|\| _M_mode & ios_base::app);
731	if (__check_facet(_M_codecvt).always_noconv()
732	&& __testout && !_M_reading)
733	{
734	// Measurement would reveal the best choice.
735	const streamsize __chunk = 1ul << 10;
736	streamsize __bufavail = this->epptr() - this->pptr();
737
738	// Don't mistake 'uncommitted' mode buffered with unbuffered.
739	if (!_M_writing && _M_buf_size > 1)
740	__bufavail = _M_buf_size - 1;
741
742	const streamsize __limit = std::min(__chunk, __bufavail);
743	if (__n >= __limit)
744	{
745	const streamsize __buffill = this->pptr() - this->pbase();
746	const char* __buf = reinterpret_cast<const char*>(this->pbase());
747	__ret = _M_file.xsputn_2(__buf, __buffill,
748	reinterpret_cast<const char*>(__s),
749	__n);
750	if (__ret == __buffill + __n)
751	{
752	_M_set_buffer(0);
753	_M_writing = true;
754	}
755	if (__ret > __buffill)
756	__ret -= __buffill;
757	else
758	__ret = 0;
759	}
760	else
761	__ret = __streambuf_type::xsputn(__s, __n);
762	}
763	else
764	__ret = __streambuf_type::xsputn(__s, __n);
765	return __ret;
766	}
767
768	template<typename _CharT, typename _Traits>
769	typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
770	basic_filebuf<_CharT, _Traits>::
771	setbuf(char_type* __s, streamsize __n)
772	{
773	if (!this->is_open())
774	{
775	if (__s == 0 && __n == 0)
776	_M_buf_size = 1;
777	else if (__s && __n > 0)
778	{
779	// This is implementation-defined behavior, and assumes that
780	// an external char_type array of length __n exists and has
781	// been pre-allocated. If this is not the case, things will
782	// quickly blow up. When __n > 1, __n - 1 positions will be
783	// used for the get area, __n - 1 for the put area and 1
784	// position to host the overflow char of a full put area.
785	// When __n == 1, 1 position will be used for the get area
786	// and 0 for the put area, as in the unbuffered case above.
787	_M_buf = __s;
788	_M_buf_size = __n;
789	}
790	}
791	return this;
792	}
793
794
795	// According to 27.8.1.4 p11 - 13, seekoff should ignore the last
796	// argument (of type openmode).
797	template<typename _CharT, typename _Traits>
798	typename basic_filebuf<_CharT, _Traits>::pos_type
799	basic_filebuf<_CharT, _Traits>::
800	seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
801	{
802	int __width = 0;
803	if (_M_codecvt)
804	__width = _M_codecvt->encoding();
805	if (__width < 0)
806	__width = 0;
807
808	pos_type __ret = pos_type(off_type(-1));
809	const bool __testfail = __off != 0 && __width <= 0;
810	if (this->is_open() && !__testfail)
811	{
812	// tellg and tellp queries do not affect any state, unless
813	// ! always_noconv and the put sequence is not empty.
814	// In that case, determining the position requires converting the
815	// put sequence. That doesn't use ext_buf, so requires a flush.
816	bool __no_movement = __way == ios_base::cur && __off == 0
817	&& (!_M_writing \|\| _M_codecvt->always_noconv());
818
819	// Ditch any pback buffers to avoid confusion.
820	if (!__no_movement)
821	_M_destroy_pback();
822
823	// Correct state at destination. Note that this is the correct
824	// state for the current position during output, because
825	// codecvt::unshift() returns the state to the initial state.
826	// This is also the correct state at the end of the file because
827	// an unshift sequence should have been written at the end.
828	__state_type __state = _M_state_beg;
829	off_type __computed_off = __off * __width;
830	if (_M_reading && __way == ios_base::cur)
831	{
832	__state = _M_state_last;
833	__computed_off += _M_get_ext_pos(__state);
834	}
835	if (!__no_movement)
836	__ret = _M_seek(__computed_off, __way, __state);
837	else
838	{
839	if (_M_writing)
840	__computed_off = this->pptr() - this->pbase();
841
842	off_type __file_off = _M_file.seekoff(0, ios_base::cur);
843	if (__file_off != off_type(-1))
844	{
845	__ret = __file_off + __computed_off;
846	__ret.state(__state);
847	}
848	}
849	}
850	return __ret;
851	}
852
853	// _GLIBCXX_RESOLVE_LIB_DEFECTS
854	// 171. Strange seekpos() semantics due to joint position
855	// According to the resolution of DR 171, seekpos should ignore the last
856	// argument (of type openmode).
857	template<typename _CharT, typename _Traits>
858	typename basic_filebuf<_CharT, _Traits>::pos_type
859	basic_filebuf<_CharT, _Traits>::
860	seekpos(pos_type __pos, ios_base::openmode)
861	{
862	pos_type __ret = pos_type(off_type(-1));
863	if (this->is_open())
864	{
865	// Ditch any pback buffers to avoid confusion.
866	_M_destroy_pback();
867	__ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
868	}
869	return __ret;
870	}
871
872	template<typename _CharT, typename _Traits>
873	typename basic_filebuf<_CharT, _Traits>::pos_type
874	basic_filebuf<_CharT, _Traits>::
875	_M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
876	{
877	pos_type __ret = pos_type(off_type(-1));
878	if (_M_terminate_output())
879	{
880	off_type __file_off = _M_file.seekoff(__off, __way);
881	if (__file_off != off_type(-1))
882	{
883	_M_reading = false;
884	_M_writing = false;
885	_M_ext_next = _M_ext_end = _M_ext_buf;
886	_M_set_buffer(-1);
887	_M_state_cur = __state;
888	__ret = __file_off;
889	__ret.state(_M_state_cur);
890	}
891	}
892	return __ret;
893	}
894
895	// Returns the distance from the end of the ext buffer to the point
896	// corresponding to gptr(). This is a negative value. Updates __state
897	// from eback() correspondence to gptr().
898	template<typename _CharT, typename _Traits>
899	int basic_filebuf<_CharT, _Traits>::
900	_M_get_ext_pos(__state_type& __state)
901	{
902	if (_M_codecvt->always_noconv())
903	return this->gptr() - this->egptr();
904	else
905	{
906	// Calculate offset from _M_ext_buf that corresponds to
907	// gptr(). Precondition: __state == _M_state_last, which
908	// corresponds to eback().
909	const int __gptr_off =
910	_M_codecvt->length(__state, _M_ext_buf, _M_ext_next,
911	this->gptr() - this->eback());
912	return _M_ext_buf + __gptr_off - _M_ext_end;
913	}
914	}
915
916	template<typename _CharT, typename _Traits>
917	bool
918	basic_filebuf<_CharT, _Traits>::
919	_M_terminate_output()
920	{
921	// Part one: update the output sequence.
922	bool __testvalid = true;
923	if (this->pbase() < this->pptr())
924	{
925	const int_type __tmp = this->overflow();
926	if (traits_type::eq_int_type(__tmp, traits_type::eof()))
927	__testvalid = false;
928	}
929
930	// Part two: output unshift sequence.
931	if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
932	&& __testvalid)
933	{
934	// Note: this value is arbitrary, since there is no way to
935	// get the length of the unshift sequence from codecvt,
936	// without calling unshift.
937	const size_t __blen = 128;
938	char __buf[__blen];
939	codecvt_base::result __r;
940	streamsize __ilen = 0;
941
942	do
943	{
944	char* __next;
945	__r = _M_codecvt->unshift(_M_state_cur, __buf,
946	__buf + __blen, __next);
947	if (__r == codecvt_base::error)
948	__testvalid = false;
949	else if (__r == codecvt_base::ok \|\|
950	__r == codecvt_base::partial)
951	{
952	__ilen = __next - __buf;
953	if (__ilen > 0)
954	{
955	const streamsize __elen = _M_file.xsputn(__buf, __ilen);
956	if (__elen != __ilen)
957	__testvalid = false;
958	}
959	}
960	}
961	while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
962
963	if (__testvalid)
964	{
965	// This second call to overflow() is required by the standard,
966	// but it's not clear why it's needed, since the output buffer
967	// should be empty by this point (it should have been emptied
968	// in the first call to overflow()).
969	const int_type __tmp = this->overflow();
970	if (traits_type::eq_int_type(__tmp, traits_type::eof()))
971	__testvalid = false;
972	}
973	}
974	return __testvalid;
975	}
976
977	template<typename _CharT, typename _Traits>
978	int
979	basic_filebuf<_CharT, _Traits>::
980	sync()
981	{
982	// Make sure that the internal buffer resyncs its idea of
983	// the file position with the external file.
984	int __ret = 0;
985	if (this->pbase() < this->pptr())
986	{
987	const int_type __tmp = this->overflow();
988	if (traits_type::eq_int_type(__tmp, traits_type::eof()))
989	__ret = -1;
990	}
991	return __ret;
992	}
993
994	template<typename _CharT, typename _Traits>
995	void
996	basic_filebuf<_CharT, _Traits>::
997	imbue(const locale& __loc)
998	{
999	bool __testvalid = true;
1000
1001	const __codecvt_type* _M_codecvt_tmp = 0;
1002	if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
1003	_M_codecvt_tmp = &use_facet<__codecvt_type>(__loc);
1004
1005	if (this->is_open())
1006	{
1007	// encoding() == -1 is ok only at the beginning.
1008	if ((_M_reading \|\| _M_writing)
1009	&& __check_facet(_M_codecvt).encoding() == -1)
1010	__testvalid = false;
1011	else
1012	{
1013	if (_M_reading)
1014	{
1015	if (__check_facet(_M_codecvt).always_noconv())
1016	{
1017	if (_M_codecvt_tmp
1018	&& !__check_facet(_M_codecvt_tmp).always_noconv())
1019	__testvalid = this->seekoff(0, ios_base::cur, _M_mode)
1020	!= pos_type(off_type(-1));
1021	}
1022	else
1023	{
1024	// External position corresponding to gptr().
1025	_M_ext_next = _M_ext_buf
1026	+ _M_codecvt->length(_M_state_last, _M_ext_buf,
1027	_M_ext_next,
1028	this->gptr() - this->eback());
1029	const streamsize __remainder = _M_ext_end - _M_ext_next;
1030	if (__remainder)
1031	__builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
1032
1033	_M_ext_next = _M_ext_buf;
1034	_M_ext_end = _M_ext_buf + __remainder;
1035	_M_set_buffer(-1);
1036	_M_state_last = _M_state_cur = _M_state_beg;
1037	}
1038	}
1039	else if (_M_writing && (__testvalid = _M_terminate_output()))
1040	_M_set_buffer(-1);
1041	}
1042	}
1043
1044	if (__testvalid)
1045	_M_codecvt = _M_codecvt_tmp;
1046	else
1047	_M_codecvt = 0;
1048	}
1049
1050	// Inhibit implicit instantiations for required instantiations,
1051	// which are defined via explicit instantiations elsewhere.
1052	#if _GLIBCXX_EXTERN_TEMPLATE
1053	extern template class basic_filebuf<char>;
1054	extern template class basic_ifstream<char>;
1055	extern template class basic_ofstream<char>;
1056	extern template class basic_fstream<char>;
1057
1058	#ifdef _GLIBCXX_USE_WCHAR_T
1059	extern template class basic_filebuf<wchar_t>;
1060	extern template class basic_ifstream<wchar_t>;
1061	extern template class basic_ofstream<wchar_t>;
1062	extern template class basic_fstream<wchar_t>;
1063	#endif
1064	#endif
1065
1066	_GLIBCXX_END_NAMESPACE_VERSION
1067	} // namespace std
1068
1069	#endif
1070

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