1 // File based streams -*- C++ -*- 2 3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 4 // 2007, 2008, 2009, 2010, 2011 5 // Free Software Foundation, Inc. 6 // 7 // This file is part of the GNU ISO C++ Library. This library is free 8 // software; you can redistribute it and/or modify it under the 9 // terms of the GNU General Public License as published by the 10 // Free Software Foundation; either version 3, or (at your option) 11 // any later version. 12 13 // This library is distributed in the hope that it will be useful, 14 // but WITHOUT ANY WARRANTY; without even the implied warranty of 15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 // GNU General Public License for more details. 17 18 // Under Section 7 of GPL version 3, you are granted additional 19 // permissions described in the GCC Runtime Library Exception, version 20 // 3.1, as published by the Free Software Foundation. 21 22 // You should have received a copy of the GNU General Public License and 23 // a copy of the GCC Runtime Library Exception along with this program; 24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 25 // <http://www.gnu.org/licenses/>. 26 27 /** @file bits/fstream.tcc 28 * This is an internal header file, included by other library headers. 29 * Do not attempt to use it directly. @headername{fstream} 30 */ 31 32 // 33 // ISO C++ 14882: 27.8 File-based streams 34 // 35 36 #ifndef _FSTREAM_TCC 37 #define _FSTREAM_TCC 1 38 39 #pragma GCC system_header 40 41 #include <bits/cxxabi_forced.h> 42 43 namespace std _GLIBCXX_VISIBILITY(default) 44 { 45 _GLIBCXX_BEGIN_NAMESPACE_VERSION 46 47 template<typename _CharT, typename _Traits> 48 void 49 basic_filebuf<_CharT, _Traits>:: 50 _M_allocate_internal_buffer() 51 { 52 // Allocate internal buffer only if one doesn't already exist 53 // (either allocated or provided by the user via setbuf). 54 if (!_M_buf_allocated && !_M_buf) 55 { 56 _M_buf = new char_type[_M_buf_size]; 57 _M_buf_allocated = true; 58 } 59 } 60 61 template<typename _CharT, typename _Traits> 62 void 63 basic_filebuf<_CharT, _Traits>:: 64 _M_destroy_internal_buffer() throw() 65 { 66 if (_M_buf_allocated) 67 { 68 delete [] _M_buf; 69 _M_buf = 0; 70 _M_buf_allocated = false; 71 } 72 delete [] _M_ext_buf; 73 _M_ext_buf = 0; 74 _M_ext_buf_size = 0; 75 _M_ext_next = 0; 76 _M_ext_end = 0; 77 } 78 79 template<typename _CharT, typename _Traits> 80 basic_filebuf<_CharT, _Traits>:: 81 basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock), 82 _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(), 83 _M_state_last(), _M_buf(0), _M_buf_size(BUFSIZ), 84 _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(), 85 _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false), 86 _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0), 87 _M_ext_end(0) 88 { 89 if (has_facet<__codecvt_type>(this->_M_buf_locale)) 90 _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale); 91 } 92 93 template<typename _CharT, typename _Traits> 94 typename basic_filebuf<_CharT, _Traits>::__filebuf_type* 95 basic_filebuf<_CharT, _Traits>:: 96 open(const char* __s, ios_base::openmode __mode) 97 { 98 __filebuf_type *__ret = 0; 99 if (!this->is_open()) 100 { 101 _M_file.open(__s, __mode); 102 if (this->is_open()) 103 { 104 _M_allocate_internal_buffer(); 105 _M_mode = __mode; 106 107 // Setup initial buffer to 'uncommitted' mode. 108 _M_reading = false; 109 _M_writing = false; 110 _M_set_buffer(-1); 111 112 // Reset to initial state. 113 _M_state_last = _M_state_cur = _M_state_beg; 114 115 // 27.8.1.3,4 116 if ((__mode & ios_base::ate) 117 && this->seekoff(0, ios_base::end, __mode) 118 == pos_type(off_type(-1))) 119 this->close(); 120 else 121 __ret = this; 122 } 123 } 124 return __ret; 125 } 126 127 template<typename _CharT, typename _Traits> 128 typename basic_filebuf<_CharT, _Traits>::__filebuf_type* 129 basic_filebuf<_CharT, _Traits>:: 130 close() 131 { 132 if (!this->is_open()) 133 return 0; 134 135 bool __testfail = false; 136 { 137 // NB: Do this here so that re-opened filebufs will be cool... 138 struct __close_sentry 139 { 140 basic_filebuf *__fb; 141 __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { } 142 ~__close_sentry () 143 { 144 __fb->_M_mode = ios_base::openmode(0); 145 __fb->_M_pback_init = false; 146 __fb->_M_destroy_internal_buffer(); 147 __fb->_M_reading = false; 148 __fb->_M_writing = false; 149 __fb->_M_set_buffer(-1); 150 __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg; 151 } 152 } __cs (this); 153 154 __try 155 { 156 if (!_M_terminate_output()) 157 __testfail = true; 158 } 159 __catch(__cxxabiv1::__forced_unwind&) 160 { 161 _M_file.close(); 162 __throw_exception_again; 163 } 164 __catch(...) 165 { __testfail = true; } 166 } 167 168 if (!_M_file.close()) 169 __testfail = true; 170 171 if (__testfail) 172 return 0; 173 else 174 return this; 175 } 176 177 template<typename _CharT, typename _Traits> 178 streamsize 179 basic_filebuf<_CharT, _Traits>:: 180 showmanyc() 181 { 182 streamsize __ret = -1; 183 const bool __testin = _M_mode & ios_base::in; 184 if (__testin && this->is_open()) 185 { 186 // For a stateful encoding (-1) the pending sequence might be just 187 // shift and unshift prefixes with no actual character. 188 __ret = this->egptr() - this->gptr(); 189 190 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM 191 // About this workaround, see libstdc++/20806. 192 const bool __testbinary = _M_mode & ios_base::binary; 193 if (__check_facet(_M_codecvt).encoding() >= 0 194 && __testbinary) 195 #else 196 if (__check_facet(_M_codecvt).encoding() >= 0) 197 #endif 198 __ret += _M_file.showmanyc() / _M_codecvt->max_length(); 199 } 200 return __ret; 201 } 202 203 template<typename _CharT, typename _Traits> 204 typename basic_filebuf<_CharT, _Traits>::int_type 205 basic_filebuf<_CharT, _Traits>:: 206 underflow() 207 { 208 int_type __ret = traits_type::eof(); 209 const bool __testin = _M_mode & ios_base::in; 210 if (__testin) 211 { 212 if (_M_writing) 213 { 214 if (overflow() == traits_type::eof()) 215 return __ret; 216 _M_set_buffer(-1); 217 _M_writing = false; 218 } 219 // Check for pback madness, and if so switch back to the 220 // normal buffers and jet outta here before expensive 221 // fileops happen... 222 _M_destroy_pback(); 223 224 if (this->gptr() < this->egptr()) 225 return traits_type::to_int_type(*this->gptr()); 226 227 // Get and convert input sequence. 228 const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1; 229 230 // Will be set to true if ::read() returns 0 indicating EOF. 231 bool __got_eof = false; 232 // Number of internal characters produced. 233 streamsize __ilen = 0; 234 codecvt_base::result __r = codecvt_base::ok; 235 if (__check_facet(_M_codecvt).always_noconv()) 236 { 237 __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()), 238 __buflen); 239 if (__ilen == 0) 240 __got_eof = true; 241 } 242 else 243 { 244 // Worst-case number of external bytes. 245 // XXX Not done encoding() == -1. 246 const int __enc = _M_codecvt->encoding(); 247 streamsize __blen; // Minimum buffer size. 248 streamsize __rlen; // Number of chars to read. 249 if (__enc > 0) 250 __blen = __rlen = __buflen * __enc; 251 else 252 { 253 __blen = __buflen + _M_codecvt->max_length() - 1; 254 __rlen = __buflen; 255 } 256 const streamsize __remainder = _M_ext_end - _M_ext_next; 257 __rlen = __rlen > __remainder ? __rlen - __remainder : 0; 258 259 // An imbue in 'read' mode implies first converting the external 260 // chars already present. 261 if (_M_reading && this->egptr() == this->eback() && __remainder) 262 __rlen = 0; 263 264 // Allocate buffer if necessary and move unconverted 265 // bytes to front. 266 if (_M_ext_buf_size < __blen) 267 { 268 char* __buf = new char[__blen]; 269 if (__remainder) 270 __builtin_memcpy(__buf, _M_ext_next, __remainder); 271 272 delete [] _M_ext_buf; 273 _M_ext_buf = __buf; 274 _M_ext_buf_size = __blen; 275 } 276 else if (__remainder) 277 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder); 278 279 _M_ext_next = _M_ext_buf; 280 _M_ext_end = _M_ext_buf + __remainder; 281 _M_state_last = _M_state_cur; 282 283 do 284 { 285 if (__rlen > 0) 286 { 287 // Sanity check! 288 // This may fail if the return value of 289 // codecvt::max_length() is bogus. 290 if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size) 291 { 292 __throw_ios_failure(__N("basic_filebuf::underflow " 293 "codecvt::max_length() " 294 "is not valid")); 295 } 296 streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen); 297 if (__elen == 0) 298 __got_eof = true; 299 else if (__elen == -1) 300 break; 301 _M_ext_end += __elen; 302 } 303 304 char_type* __iend = this->eback(); 305 if (_M_ext_next < _M_ext_end) 306 __r = _M_codecvt->in(_M_state_cur, _M_ext_next, 307 _M_ext_end, _M_ext_next, 308 this->eback(), 309 this->eback() + __buflen, __iend); 310 if (__r == codecvt_base::noconv) 311 { 312 size_t __avail = _M_ext_end - _M_ext_buf; 313 __ilen = std::min(__avail, __buflen); 314 traits_type::copy(this->eback(), 315 reinterpret_cast<char_type*> 316 (_M_ext_buf), __ilen); 317 _M_ext_next = _M_ext_buf + __ilen; 318 } 319 else 320 __ilen = __iend - this->eback(); 321 322 // _M_codecvt->in may return error while __ilen > 0: this is 323 // ok, and actually occurs in case of mixed encodings (e.g., 324 // XML files). 325 if (__r == codecvt_base::error) 326 break; 327 328 __rlen = 1; 329 } 330 while (__ilen == 0 && !__got_eof); 331 } 332 333 if (__ilen > 0) 334 { 335 _M_set_buffer(__ilen); 336 _M_reading = true; 337 __ret = traits_type::to_int_type(*this->gptr()); 338 } 339 else if (__got_eof) 340 { 341 // If the actual end of file is reached, set 'uncommitted' 342 // mode, thus allowing an immediate write without an 343 // intervening seek. 344 _M_set_buffer(-1); 345 _M_reading = false; 346 // However, reaching it while looping on partial means that 347 // the file has got an incomplete character. 348 if (__r == codecvt_base::partial) 349 __throw_ios_failure(__N("basic_filebuf::underflow " 350 "incomplete character in file")); 351 } 352 else if (__r == codecvt_base::error) 353 __throw_ios_failure(__N("basic_filebuf::underflow " 354 "invalid byte sequence in file")); 355 else 356 __throw_ios_failure(__N("basic_filebuf::underflow " 357 "error reading the file")); 358 } 359 return __ret; 360 } 361 362 template<typename _CharT, typename _Traits> 363 typename basic_filebuf<_CharT, _Traits>::int_type 364 basic_filebuf<_CharT, _Traits>:: 365 pbackfail(int_type __i) 366 { 367 int_type __ret = traits_type::eof(); 368 const bool __testin = _M_mode & ios_base::in; 369 if (__testin) 370 { 371 if (_M_writing) 372 { 373 if (overflow() == traits_type::eof()) 374 return __ret; 375 _M_set_buffer(-1); 376 _M_writing = false; 377 } 378 // Remember whether the pback buffer is active, otherwise below 379 // we may try to store in it a second char (libstdc++/9761). 380 const bool __testpb = _M_pback_init; 381 const bool __testeof = traits_type::eq_int_type(__i, __ret); 382 int_type __tmp; 383 if (this->eback() < this->gptr()) 384 { 385 this->gbump(-1); 386 __tmp = traits_type::to_int_type(*this->gptr()); 387 } 388 else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1))) 389 { 390 __tmp = this->underflow(); 391 if (traits_type::eq_int_type(__tmp, __ret)) 392 return __ret; 393 } 394 else 395 { 396 // At the beginning of the buffer, need to make a 397 // putback position available. But the seek may fail 398 // (f.i., at the beginning of a file, see 399 // libstdc++/9439) and in that case we return 400 // traits_type::eof(). 401 return __ret; 402 } 403 404 // Try to put back __i into input sequence in one of three ways. 405 // Order these tests done in is unspecified by the standard. 406 if (!__testeof && traits_type::eq_int_type(__i, __tmp)) 407 __ret = __i; 408 else if (__testeof) 409 __ret = traits_type::not_eof(__i); 410 else if (!__testpb) 411 { 412 _M_create_pback(); 413 _M_reading = true; 414 *this->gptr() = traits_type::to_char_type(__i); 415 __ret = __i; 416 } 417 } 418 return __ret; 419 } 420 421 template<typename _CharT, typename _Traits> 422 typename basic_filebuf<_CharT, _Traits>::int_type 423 basic_filebuf<_CharT, _Traits>:: 424 overflow(int_type __c) 425 { 426 int_type __ret = traits_type::eof(); 427 const bool __testeof = traits_type::eq_int_type(__c, __ret); 428 const bool __testout = _M_mode & ios_base::out; 429 if (__testout) 430 { 431 if (_M_reading) 432 { 433 _M_destroy_pback(); 434 const int __gptr_off = _M_get_ext_pos(_M_state_last); 435 if (_M_seek(__gptr_off, ios_base::cur, _M_state_last) 436 == pos_type(off_type(-1))) 437 return __ret; 438 } 439 if (this->pbase() < this->pptr()) 440 { 441 // If appropriate, append the overflow char. 442 if (!__testeof) 443 { 444 *this->pptr() = traits_type::to_char_type(__c); 445 this->pbump(1); 446 } 447 448 // Convert pending sequence to external representation, 449 // and output. 450 if (_M_convert_to_external(this->pbase(), 451 this->pptr() - this->pbase())) 452 { 453 _M_set_buffer(0); 454 __ret = traits_type::not_eof(__c); 455 } 456 } 457 else if (_M_buf_size > 1) 458 { 459 // Overflow in 'uncommitted' mode: set _M_writing, set 460 // the buffer to the initial 'write' mode, and put __c 461 // into the buffer. 462 _M_set_buffer(0); 463 _M_writing = true; 464 if (!__testeof) 465 { 466 *this->pptr() = traits_type::to_char_type(__c); 467 this->pbump(1); 468 } 469 __ret = traits_type::not_eof(__c); 470 } 471 else 472 { 473 // Unbuffered. 474 char_type __conv = traits_type::to_char_type(__c); 475 if (__testeof || _M_convert_to_external(&__conv, 1)) 476 { 477 _M_writing = true; 478 __ret = traits_type::not_eof(__c); 479 } 480 } 481 } 482 return __ret; 483 } 484 485 template<typename _CharT, typename _Traits> 486 bool 487 basic_filebuf<_CharT, _Traits>:: 488 _M_convert_to_external(_CharT* __ibuf, streamsize __ilen) 489 { 490 // Sizes of external and pending output. 491 streamsize __elen; 492 streamsize __plen; 493 if (__check_facet(_M_codecvt).always_noconv()) 494 { 495 __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen); 496 __plen = __ilen; 497 } 498 else 499 { 500 // Worst-case number of external bytes needed. 501 // XXX Not done encoding() == -1. 502 streamsize __blen = __ilen * _M_codecvt->max_length(); 503 char* __buf = static_cast<char*>(__builtin_alloca(__blen)); 504 505 char* __bend; 506 const char_type* __iend; 507 codecvt_base::result __r; 508 __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen, 509 __iend, __buf, __buf + __blen, __bend); 510 511 if (__r == codecvt_base::ok || __r == codecvt_base::partial) 512 __blen = __bend - __buf; 513 else if (__r == codecvt_base::noconv) 514 { 515 // Same as the always_noconv case above. 516 __buf = reinterpret_cast<char*>(__ibuf); 517 __blen = __ilen; 518 } 519 else 520 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 521 "conversion error")); 522 523 __elen = _M_file.xsputn(__buf, __blen); 524 __plen = __blen; 525 526 // Try once more for partial conversions. 527 if (__r == codecvt_base::partial && __elen == __plen) 528 { 529 const char_type* __iresume = __iend; 530 streamsize __rlen = this->pptr() - __iend; 531 __r = _M_codecvt->out(_M_state_cur, __iresume, 532 __iresume + __rlen, __iend, __buf, 533 __buf + __blen, __bend); 534 if (__r != codecvt_base::error) 535 { 536 __rlen = __bend - __buf; 537 __elen = _M_file.xsputn(__buf, __rlen); 538 __plen = __rlen; 539 } 540 else 541 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 542 "conversion error")); 543 } 544 } 545 return __elen == __plen; 546 } 547 548 template<typename _CharT, typename _Traits> 549 streamsize 550 basic_filebuf<_CharT, _Traits>:: 551 xsgetn(_CharT* __s, streamsize __n) 552 { 553 // Clear out pback buffer before going on to the real deal... 554 streamsize __ret = 0; 555 if (_M_pback_init) 556 { 557 if (__n > 0 && this->gptr() == this->eback()) 558 { 559 *__s++ = *this->gptr(); // emulate non-underflowing sbumpc 560 this->gbump(1); 561 __ret = 1; 562 --__n; 563 } 564 _M_destroy_pback(); 565 } 566 else if (_M_writing) 567 { 568 if (overflow() == traits_type::eof()) 569 return __ret; 570 _M_set_buffer(-1); 571 _M_writing = false; 572 } 573 574 // Optimization in the always_noconv() case, to be generalized in the 575 // future: when __n > __buflen we read directly instead of using the 576 // buffer repeatedly. 577 const bool __testin = _M_mode & ios_base::in; 578 const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1; 579 580 if (__n > __buflen && __check_facet(_M_codecvt).always_noconv() 581 && __testin) 582 { 583 // First, copy the chars already present in the buffer. 584 const streamsize __avail = this->egptr() - this->gptr(); 585 if (__avail != 0) 586 { 587 traits_type::copy(__s, this->gptr(), __avail); 588 __s += __avail; 589 this->setg(this->eback(), this->gptr() + __avail, 590 this->egptr()); 591 __ret += __avail; 592 __n -= __avail; 593 } 594 595 // Need to loop in case of short reads (relatively common 596 // with pipes). 597 streamsize __len; 598 for (;;) 599 { 600 __len = _M_file.xsgetn(reinterpret_cast<char*>(__s), 601 __n); 602 if (__len == -1) 603 __throw_ios_failure(__N("basic_filebuf::xsgetn " 604 "error reading the file")); 605 if (__len == 0) 606 break; 607 608 __n -= __len; 609 __ret += __len; 610 if (__n == 0) 611 break; 612 613 __s += __len; 614 } 615 616 if (__n == 0) 617 { 618 _M_set_buffer(0); 619 _M_reading = true; 620 } 621 else if (__len == 0) 622 { 623 // If end of file is reached, set 'uncommitted' 624 // mode, thus allowing an immediate write without 625 // an intervening seek. 626 _M_set_buffer(-1); 627 _M_reading = false; 628 } 629 } 630 else 631 __ret += __streambuf_type::xsgetn(__s, __n); 632 633 return __ret; 634 } 635 636 template<typename _CharT, typename _Traits> 637 streamsize 638 basic_filebuf<_CharT, _Traits>:: 639 xsputn(const _CharT* __s, streamsize __n) 640 { 641 streamsize __ret = 0; 642 // Optimization in the always_noconv() case, to be generalized in the 643 // future: when __n is sufficiently large we write directly instead of 644 // using the buffer. 645 const bool __testout = _M_mode & ios_base::out; 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
