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 983
