1 // File based streams -*- C++ -*- 2 3 // Copyright (C) 1997-2014 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 || _M_mode & ios_base::app); 428 if (__testout) 429 { 430 if (_M_reading) 431 { 432 _M_destroy_pback(); 433 const int __gptr_off = _M_get_ext_pos(_M_state_last); 434 if (_M_seek(__gptr_off, ios_base::cur, _M_state_last) 435 == pos_type(off_type(-1))) 436 return __ret; 437 } 438 if (this->pbase() < this->pptr()) 439 { 440 // If appropriate, append the overflow char. 441 if (!__testeof) 442 { 443 *this->pptr() = traits_type::to_char_type(__c); 444 this->pbump(1); 445 } 446 447 // Convert pending sequence to external representation, 448 // and output. 449 if (_M_convert_to_external(this->pbase(), 450 this->pptr() - this->pbase())) 451 { 452 _M_set_buffer(0); 453 __ret = traits_type::not_eof(__c); 454 } 455 } 456 else if (_M_buf_size > 1) 457 { 458 // Overflow in 'uncommitted' mode: set _M_writing, set 459 // the buffer to the initial 'write' mode, and put __c 460 // into the buffer. 461 _M_set_buffer(0); 462 _M_writing = true; 463 if (!__testeof) 464 { 465 *this->pptr() = traits_type::to_char_type(__c); 466 this->pbump(1); 467 } 468 __ret = traits_type::not_eof(__c); 469 } 470 else 471 { 472 // Unbuffered. 473 char_type __conv = traits_type::to_char_type(__c); 474 if (__testeof || _M_convert_to_external(&__conv, 1)) 475 { 476 _M_writing = true; 477 __ret = traits_type::not_eof(__c); 478 } 479 } 480 } 481 return __ret; 482 } 483 484 template<typename _CharT, typename _Traits> 485 bool 486 basic_filebuf<_CharT, _Traits>:: 487 _M_convert_to_external(_CharT* __ibuf, streamsize __ilen) 488 { 489 // Sizes of external and pending output. 490 streamsize __elen; 491 streamsize __plen; 492 if (__check_facet(_M_codecvt).always_noconv()) 493 { 494 __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen); 495 __plen = __ilen; 496 } 497 else 498 { 499 // Worst-case number of external bytes needed. 500 // XXX Not done encoding() == -1. 501 streamsize __blen = __ilen * _M_codecvt->max_length(); 502 char* __buf = static_cast<char*>(__builtin_alloca(__blen)); 503 504 char* __bend; 505 const char_type* __iend; 506 codecvt_base::result __r; 507 __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen, 508 __iend, __buf, __buf + __blen, __bend); 509 510 if (__r == codecvt_base::ok || __r == codecvt_base::partial) 511 __blen = __bend - __buf; 512 else if (__r == codecvt_base::noconv) 513 { 514 // Same as the always_noconv case above. 515 __buf = reinterpret_cast<char*>(__ibuf); 516 __blen = __ilen; 517 } 518 else 519 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 520 "conversion error")); 521 522 __elen = _M_file.xsputn(__buf, __blen); 523 __plen = __blen; 524 525 // Try once more for partial conversions. 526 if (__r == codecvt_base::partial && __elen == __plen) 527 { 528 const char_type* __iresume = __iend; 529 streamsize __rlen = this->pptr() - __iend; 530 __r = _M_codecvt->out(_M_state_cur, __iresume, 531 __iresume + __rlen, __iend, __buf, 532 __buf + __blen, __bend); 533 if (__r != codecvt_base::error) 534 { 535 __rlen = __bend - __buf; 536 __elen = _M_file.xsputn(__buf, __rlen); 537 __plen = __rlen; 538 } 539 else 540 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 541 "conversion error")); 542 } 543 } 544 return __elen == __plen; 545 } 546 547 template<typename _CharT, typename _Traits> 548 streamsize 549 basic_filebuf<_CharT, _Traits>:: 550 xsgetn(_CharT* __s, streamsize __n) 551 { 552 // Clear out pback buffer before going on to the real deal... 553 streamsize __ret = 0; 554 if (_M_pback_init) 555 { 556 if (__n > 0 && this->gptr() == this->eback()) 557 { 558 *__s++ = *this->gptr(); // emulate non-underflowing sbumpc 559 this->gbump(1); 560 __ret = 1; 561 --__n; 562 } 563 _M_destroy_pback(); 564 } 565 else if (_M_writing) 566 { 567 if (overflow() == traits_type::eof()) 568 return __ret; 569 _M_set_buffer(-1); 570 _M_writing = false; 571 } 572 573 // Optimization in the always_noconv() case, to be generalized in the 574 // future: when __n > __buflen we read directly instead of using the 575 // buffer repeatedly. 576 const bool __testin = _M_mode & ios_base::in; 577 const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1; 578 579 if (__n > __buflen && __check_facet(_M_codecvt).always_noconv() 580 && __testin) 581 { 582 // First, copy the chars already present in the buffer. 583 const streamsize __avail = this->egptr() - this->gptr(); 584 if (__avail != 0) 585 { 586 traits_type::copy(__s, this->gptr(), __avail); 587 __s += __avail; 588 this->setg(this->eback(), this->gptr() + __avail, 589 this->egptr()); 590 __ret += __avail; 591 __n -= __avail; 592 } 593 594 // Need to loop in case of short reads (relatively common 595 // with pipes). 596 streamsize __len; 597 for (;;) 598 { 599 __len = _M_file.xsgetn(reinterpret_cast<char*>(__s), 600 __n); 601 if (__len == -1) 602 __throw_ios_failure(__N("basic_filebuf::xsgetn " 603 "error reading the file")); 604 if (__len == 0) 605 break; 606 607 __n -= __len; 608 __ret += __len; 609 if (__n == 0) 610 break; 611 612 __s += __len; 613 } 614 615 if (__n == 0) 616 { 617 _M_set_buffer(0); 618 _M_reading = true; 619 } 620 else if (__len == 0) 621 { 622 // If end of file is reached, set 'uncommitted' 623 // mode, thus allowing an immediate write without 624 // an intervening seek. 625 _M_set_buffer(-1); 626 _M_reading = false; 627 } 628 } 629 else 630 __ret += __streambuf_type::xsgetn(__s, __n); 631 632 return __ret; 633 } 634 635 template<typename _CharT, typename _Traits> 636 streamsize 637 basic_filebuf<_CharT, _Traits>:: 638 xsputn(const _CharT* __s, streamsize __n) 639 { 640 streamsize __ret = 0; 641 // Optimization in the always_noconv() case, to be generalized in the 642 // future: when __n is sufficiently large we write directly instead of 643 // using the buffer. 644 const bool __testout = (_M_mode & ios_base::out 645 || _M_mode & ios_base::app); 646 if (__check_facet(_M_codecvt).always_noconv() 647 && __testout && !_M_reading) 648 { 649 // Measurement would reveal the best choice. 650 const streamsize __chunk = 1ul << 10; 651 streamsize __bufavail = this->epptr() - this->pptr(); 652 653 // Don't mistake 'uncommitted' mode buffered with unbuffered. 654 if (!_M_writing && _M_buf_size > 1) 655 __bufavail = _M_buf_size - 1; 656 657 const streamsize __limit = std::min(__chunk, __bufavail); 658 if (__n >= __limit) 659 { 660 const streamsize __buffill = this->pptr() - this->pbase(); 661 const char* __buf = reinterpret_cast<const char*>(this->pbase()); 662 __ret = _M_file.xsputn_2(__buf, __buffill, 663 reinterpret_cast<const char*>(__s), 664 __n); 665 if (__ret == __buffill + __n) 666 { 667 _M_set_buffer(0); 668 _M_writing = true; 669 } 670 if (__ret > __buffill) 671 __ret -= __buffill; 672 else 673 __ret = 0; 674 } 675 else 676 __ret = __streambuf_type::xsputn(__s, __n); 677 } 678 else 679 __ret = __streambuf_type::xsputn(__s, __n); 680 return __ret; 681 } 682 683 template<typename _CharT, typename _Traits> 684 typename basic_filebuf<_CharT, _Traits>::__streambuf_type* 685 basic_filebuf<_CharT, _Traits>:: 686 setbuf(char_type* __s, streamsize __n) 687 { 688 if (!this->is_open()) 689 { 690 if (__s == 0 && __n == 0) 691 _M_buf_size = 1; 692 else if (__s && __n > 0) 693 { 694 // This is implementation-defined behavior, and assumes that 695 // an external char_type array of length __n exists and has 696 // been pre-allocated. If this is not the case, things will 697 // quickly blow up. When __n > 1, __n - 1 positions will be 698 // used for the get area, __n - 1 for the put area and 1 699 // position to host the overflow char of a full put area. 700 // When __n == 1, 1 position will be used for the get area 701 // and 0 for the put area, as in the unbuffered case above. 702 _M_buf = __s; 703 _M_buf_size = __n; 704 } 705 } 706 return this; 707 } 708 709 710 // According to 27.8.1.4 p11 - 13, seekoff should ignore the last 711 // argument (of type openmode). 712 template<typename _CharT, typename _Traits> 713 typename basic_filebuf<_CharT, _Traits>::pos_type 714 basic_filebuf<_CharT, _Traits>:: 715 seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode) 716 { 717 int __width = 0; 718 if (_M_codecvt) 719 __width = _M_codecvt->encoding(); 720 if (__width < 0) 721 __width = 0; 722 723 pos_type __ret = pos_type(off_type(-1)); 724 const bool __testfail = __off != 0 && __width <= 0; 725 if (this->is_open() && !__testfail) 726 { 727 // tellg and tellp queries do not affect any state, unless 728 // ! always_noconv and the put sequence is not empty. 729 // In that case, determining the position requires converting the 730 // put sequence. That doesn't use ext_buf, so requires a flush. 731 bool __no_movement = __way == ios_base::cur && __off == 0 732 && (!_M_writing || _M_codecvt->always_noconv()); 733 734 // Ditch any pback buffers to avoid confusion. 735 if (!__no_movement) 736 _M_destroy_pback(); 737 738 // Correct state at destination. Note that this is the correct 739 // state for the current position during output, because 740 // codecvt::unshift() returns the state to the initial state. 741 // This is also the correct state at the end of the file because 742 // an unshift sequence should have been written at the end. 743 __state_type __state = _M_state_beg; 744 off_type __computed_off = __off * __width; 745 if (_M_reading && __way == ios_base::cur) 746 { 747 __state = _M_state_last; 748 __computed_off += _M_get_ext_pos(__state); 749 } 750 if (!__no_movement) 751 __ret = _M_seek(__computed_off, __way, __state); 752 else 753 { 754 if (_M_writing) 755 __computed_off = this->pptr() - this->pbase(); 756 757 off_type __file_off = _M_file.seekoff(0, ios_base::cur); 758 if (__file_off != off_type(-1)) 759 { 760 __ret = __file_off + __computed_off; 761 __ret.state(__state); 762 } 763 } 764 } 765 return __ret; 766 } 767 768 // _GLIBCXX_RESOLVE_LIB_DEFECTS 769 // 171. Strange seekpos() semantics due to joint position 770 // According to the resolution of DR 171, seekpos should ignore the last 771 // argument (of type openmode). 772 template<typename _CharT, typename _Traits> 773 typename basic_filebuf<_CharT, _Traits>::pos_type 774 basic_filebuf<_CharT, _Traits>:: 775 seekpos(pos_type __pos, ios_base::openmode) 776 { 777 pos_type __ret = pos_type(off_type(-1)); 778 if (this->is_open()) 779 { 780 // Ditch any pback buffers to avoid confusion. 781 _M_destroy_pback(); 782 __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state()); 783 } 784 return __ret; 785 } 786 787 template<typename _CharT, typename _Traits> 788 typename basic_filebuf<_CharT, _Traits>::pos_type 789 basic_filebuf<_CharT, _Traits>:: 790 _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state) 791 { 792 pos_type __ret = pos_type(off_type(-1)); 793 if (_M_terminate_output()) 794 { 795 off_type __file_off = _M_file.seekoff(__off, __way); 796 if (__file_off != off_type(-1)) 797 { 798 _M_reading = false; 799 _M_writing = false; 800 _M_ext_next = _M_ext_end = _M_ext_buf; 801 _M_set_buffer(-1); 802 _M_state_cur = __state; 803 __ret = __file_off; 804 __ret.state(_M_state_cur); 805 } 806 } 807 return __ret; 808 } 809 810 // Returns the distance from the end of the ext buffer to the point 811 // corresponding to gptr(). This is a negative value. Updates __state 812 // from eback() correspondence to gptr(). 813 template<typename _CharT, typename _Traits> 814 int basic_filebuf<_CharT, _Traits>:: 815 _M_get_ext_pos(__state_type& __state) 816 { 817 if (_M_codecvt->always_noconv()) 818 return this->gptr() - this->egptr(); 819 else 820 { 821 // Calculate offset from _M_ext_buf that corresponds to 822 // gptr(). Precondition: __state == _M_state_last, which 823 // corresponds to eback(). 824 const int __gptr_off = 825 _M_codecvt->length(__state, _M_ext_buf, _M_ext_next, 826 this->gptr() - this->eback()); 827 return _M_ext_buf + __gptr_off - _M_ext_end; 828 } 829 } 830 831 template<typename _CharT, typename _Traits> 832 bool 833 basic_filebuf<_CharT, _Traits>:: 834 _M_terminate_output() 835 { 836 // Part one: update the output sequence. 837 bool __testvalid = true; 838 if (this->pbase() < this->pptr()) 839 { 840 const int_type __tmp = this->overflow(); 841 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 842 __testvalid = false; 843 } 844 845 // Part two: output unshift sequence. 846 if (_M_writing && !__check_facet(_M_codecvt).always_noconv() 847 && __testvalid) 848 { 849 // Note: this value is arbitrary, since there is no way to 850 // get the length of the unshift sequence from codecvt, 851 // without calling unshift. 852 const size_t __blen = 128; 853 char __buf[__blen]; 854 codecvt_base::result __r; 855 streamsize __ilen = 0; 856 857 do 858 { 859 char* __next; 860 __r = _M_codecvt->unshift(_M_state_cur, __buf, 861 __buf + __blen, __next); 862 if (__r == codecvt_base::error) 863 __testvalid = false; 864 else if (__r == codecvt_base::ok || 865 __r == codecvt_base::partial) 866 { 867 __ilen = __next - __buf; 868 if (__ilen > 0) 869 { 870 const streamsize __elen = _M_file.xsputn(__buf, __ilen); 871 if (__elen != __ilen) 872 __testvalid = false; 873 } 874 } 875 } 876 while (__r == codecvt_base::partial && __ilen > 0 && __testvalid); 877 878 if (__testvalid) 879 { 880 // This second call to overflow() is required by the standard, 881 // but it's not clear why it's needed, since the output buffer 882 // should be empty by this point (it should have been emptied 883 // in the first call to overflow()). 884 const int_type __tmp = this->overflow(); 885 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 886 __testvalid = false; 887 } 888 } 889 return __testvalid; 890 } 891 892 template<typename _CharT, typename _Traits> 893 int 894 basic_filebuf<_CharT, _Traits>:: 895 sync() 896 { 897 // Make sure that the internal buffer resyncs its idea of 898 // the file position with the external file. 899 int __ret = 0; 900 if (this->pbase() < this->pptr()) 901 { 902 const int_type __tmp = this->overflow(); 903 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 904 __ret = -1; 905 } 906 return __ret; 907 } 908 909 template<typename _CharT, typename _Traits> 910 void 911 basic_filebuf<_CharT, _Traits>:: 912 imbue(const locale& __loc) 913 { 914 bool __testvalid = true; 915 916 const __codecvt_type* _M_codecvt_tmp = 0; 917 if (__builtin_expect(has_facet<__codecvt_type>(__loc), true)) 918 _M_codecvt_tmp = &use_facet<__codecvt_type>(__loc); 919 920 if (this->is_open()) 921 { 922 // encoding() == -1 is ok only at the beginning. 923 if ((_M_reading || _M_writing) 924 && __check_facet(_M_codecvt).encoding() == -1) 925 __testvalid = false; 926 else 927 { 928 if (_M_reading) 929 { 930 if (__check_facet(_M_codecvt).always_noconv()) 931 { 932 if (_M_codecvt_tmp 933 && !__check_facet(_M_codecvt_tmp).always_noconv()) 934 __testvalid = this->seekoff(0, ios_base::cur, _M_mode) 935 != pos_type(off_type(-1)); 936 } 937 else 938 { 939 // External position corresponding to gptr(). 940 _M_ext_next = _M_ext_buf 941 + _M_codecvt->length(_M_state_last, _M_ext_buf, 942 _M_ext_next, 943 this->gptr() - this->eback()); 944 const streamsize __remainder = _M_ext_end - _M_ext_next; 945 if (__remainder) 946 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder); 947 948 _M_ext_next = _M_ext_buf; 949 _M_ext_end = _M_ext_buf + __remainder; 950 _M_set_buffer(-1); 951 _M_state_last = _M_state_cur = _M_state_beg; 952 } 953 } 954 else if (_M_writing && (__testvalid = _M_terminate_output())) 955 _M_set_buffer(-1); 956 } 957 } 958 959 if (__testvalid) 960 _M_codecvt = _M_codecvt_tmp; 961 else 962 _M_codecvt = 0; 963 } 964 965 // Inhibit implicit instantiations for required instantiations, 966 // which are defined via explicit instantiations elsewhere. 967 #if _GLIBCXX_EXTERN_TEMPLATE 968 extern template class basic_filebuf<char>; 969 extern template class basic_ifstream<char>; 970 extern template class basic_ofstream<char>; 971 extern template class basic_fstream<char>; 972 973 #ifdef _GLIBCXX_USE_WCHAR_T 974 extern template class basic_filebuf<wchar_t>; 975 extern template class basic_ifstream<wchar_t>; 976 extern template class basic_ofstream<wchar_t>; 977 extern template class basic_fstream<wchar_t>; 978 #endif 979 #endif 980 981 _GLIBCXX_END_NAMESPACE_VERSION 982 } // namespace std 983 984 #endif 985
