1 // File based streams -*- C++ -*- 2 3 // Copyright (C) 1997-2024 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 #include <cerrno> 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(_GLIBCXX_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 _M_codecvt = std::__try_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 #if _GLIBCXX_HAVE__WFOPEN && _GLIBCXX_USE_WCHAR_T 211 template<typename _CharT, typename _Traits> 212 basic_filebuf<_CharT, _Traits>* 213 basic_filebuf<_CharT, _Traits>:: 214 open(const wchar_t* __s, ios_base::openmode __mode) 215 { 216 __filebuf_type *__ret = 0; 217 if (!this->is_open()) 218 { 219 _M_file.open(__s, __mode); 220 if (this->is_open()) 221 { 222 _M_allocate_internal_buffer(); 223 _M_mode = __mode; 224 225 // Setup initial buffer to 'uncommitted' mode. 226 _M_reading = false; 227 _M_writing = false; 228 _M_set_buffer(-1); 229 230 // Reset to initial state. 231 _M_state_last = _M_state_cur = _M_state_beg; 232 233 // 27.8.1.3,4 234 if ((__mode & ios_base::ate) 235 && this->seekoff(0, ios_base::end, __mode) 236 == pos_type(off_type(-1))) 237 this->close(); 238 else 239 __ret = this; 240 } 241 } 242 return __ret; 243 } 244 #endif // HAVE__WFOPEN && USE_WCHAR_T 245 246 template<typename _CharT, typename _Traits> 247 typename basic_filebuf<_CharT, _Traits>::__filebuf_type* 248 basic_filebuf<_CharT, _Traits>:: 249 close() 250 { 251 if (!this->is_open()) 252 return 0; 253 254 bool __testfail = false; 255 { 256 // NB: Do this here so that re-opened filebufs will be cool... 257 struct __close_sentry 258 { 259 basic_filebuf *__fb; 260 __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { } 261 ~__close_sentry () 262 { 263 __fb->_M_mode = ios_base::openmode(0); 264 __fb->_M_pback_init = false; 265 __fb->_M_destroy_internal_buffer(); 266 __fb->_M_reading = false; 267 __fb->_M_writing = false; 268 __fb->_M_set_buffer(-1); 269 __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg; 270 } 271 } __cs (this); 272 273 __try 274 { 275 if (!_M_terminate_output()) 276 __testfail = true; 277 } 278 __catch(...) 279 { 280 _M_file.close(); 281 __throw_exception_again; 282 } 283 } 284 285 if (!_M_file.close()) 286 __testfail = true; 287 288 if (__testfail) 289 return 0; 290 else 291 return this; 292 } 293 294 template<typename _CharT, typename _Traits> 295 streamsize 296 basic_filebuf<_CharT, _Traits>:: 297 showmanyc() 298 { 299 streamsize __ret = -1; 300 const bool __testin = _M_mode & ios_base::in; 301 if (__testin && this->is_open()) 302 { 303 // For a stateful encoding (-1) the pending sequence might be just 304 // shift and unshift prefixes with no actual character. 305 __ret = this->egptr() - this->gptr(); 306 307 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM 308 // About this workaround, see libstdc++/20806. 309 const bool __testbinary = _M_mode & ios_base::binary; 310 if (__check_facet(_M_codecvt).encoding() >= 0 311 && __testbinary) 312 #else 313 if (__check_facet(_M_codecvt).encoding() >= 0) 314 #endif 315 __ret += _M_file.showmanyc() / _M_codecvt->max_length(); 316 } 317 return __ret; 318 } 319 320 template<typename _CharT, typename _Traits> 321 typename basic_filebuf<_CharT, _Traits>::int_type 322 basic_filebuf<_CharT, _Traits>:: 323 underflow() 324 { 325 int_type __ret = traits_type::eof(); 326 const bool __testin = _M_mode & ios_base::in; 327 if (__testin) 328 { 329 if (_M_writing) 330 { 331 if (overflow() == traits_type::eof()) 332 return __ret; 333 _M_set_buffer(-1); 334 _M_writing = false; 335 } 336 // Check for pback madness, and if so switch back to the 337 // normal buffers and jet outta here before expensive 338 // fileops happen... 339 _M_destroy_pback(); 340 341 if (this->gptr() < this->egptr()) 342 return traits_type::to_int_type(*this->gptr()); 343 344 // Get and convert input sequence. 345 const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1; 346 347 // Will be set to true if ::read() returns 0 indicating EOF. 348 bool __got_eof = false; 349 // Number of internal characters produced. 350 streamsize __ilen = 0; 351 codecvt_base::result __r = codecvt_base::ok; 352 if (__check_facet(_M_codecvt).always_noconv()) 353 { 354 __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()), 355 __buflen); 356 if (__ilen == 0) 357 __got_eof = true; 358 } 359 else 360 { 361 // Worst-case number of external bytes. 362 // XXX Not done encoding() == -1. 363 const int __enc = _M_codecvt->encoding(); 364 streamsize __blen; // Minimum buffer size. 365 streamsize __rlen; // Number of chars to read. 366 if (__enc > 0) 367 __blen = __rlen = __buflen * __enc; 368 else 369 { 370 __blen = __buflen + _M_codecvt->max_length() - 1; 371 __rlen = __buflen; 372 } 373 const streamsize __remainder = _M_ext_end - _M_ext_next; 374 __rlen = __rlen > __remainder ? __rlen - __remainder : 0; 375 376 // An imbue in 'read' mode implies first converting the external 377 // chars already present. 378 if (_M_reading && this->egptr() == this->eback() && __remainder) 379 __rlen = 0; 380 381 // Allocate buffer if necessary and move unconverted 382 // bytes to front. 383 if (_M_ext_buf_size < __blen) 384 { 385 char* __buf = new char[__blen]; 386 if (__remainder) 387 __builtin_memcpy(__buf, _M_ext_next, __remainder); 388 389 delete [] _M_ext_buf; 390 _M_ext_buf = __buf; 391 _M_ext_buf_size = __blen; 392 } 393 else if (__remainder) 394 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder); 395 396 _M_ext_next = _M_ext_buf; 397 _M_ext_end = _M_ext_buf + __remainder; 398 _M_state_last = _M_state_cur; 399 400 do 401 { 402 if (__rlen > 0) 403 { 404 // Sanity check! 405 // This may fail if the return value of 406 // codecvt::max_length() is bogus. 407 if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size) 408 { 409 __throw_ios_failure(__N("basic_filebuf::underflow " 410 "codecvt::max_length() " 411 "is not valid")); 412 } 413 streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen); 414 if (__elen == 0) 415 __got_eof = true; 416 else if (__elen == -1) 417 break; 418 _M_ext_end += __elen; 419 } 420 421 char_type* __iend = this->eback(); 422 if (_M_ext_next < _M_ext_end) 423 __r = _M_codecvt->in(_M_state_cur, _M_ext_next, 424 _M_ext_end, _M_ext_next, 425 this->eback(), 426 this->eback() + __buflen, __iend); 427 if (__r == codecvt_base::noconv) 428 { 429 size_t __avail = _M_ext_end - _M_ext_buf; 430 __ilen = std::min(__avail, __buflen); 431 traits_type::copy(this->eback(), 432 reinterpret_cast<char_type*> 433 (_M_ext_buf), __ilen); 434 _M_ext_next = _M_ext_buf + __ilen; 435 } 436 else 437 __ilen = __iend - this->eback(); 438 439 // _M_codecvt->in may return error while __ilen > 0: this is 440 // ok, and actually occurs in case of mixed encodings (e.g., 441 // XML files). 442 if (__r == codecvt_base::error) 443 break; 444 445 __rlen = 1; 446 } 447 while (__ilen == 0 && !__got_eof); 448 } 449 450 if (__ilen > 0) 451 { 452 _M_set_buffer(__ilen); 453 _M_reading = true; 454 __ret = traits_type::to_int_type(*this->gptr()); 455 } 456 else if (__got_eof) 457 { 458 // If the actual end of file is reached, set 'uncommitted' 459 // mode, thus allowing an immediate write without an 460 // intervening seek. 461 _M_set_buffer(-1); 462 _M_reading = false; 463 // However, reaching it while looping on partial means that 464 // the file has got an incomplete character. 465 if (__r == codecvt_base::partial) 466 __throw_ios_failure(__N("basic_filebuf::underflow " 467 "incomplete character in file")); 468 } 469 else if (__r == codecvt_base::error) 470 __throw_ios_failure(__N("basic_filebuf::underflow " 471 "invalid byte sequence in file")); 472 else 473 __throw_ios_failure(__N("basic_filebuf::underflow " 474 "error reading the file"), errno); 475 } 476 return __ret; 477 } 478 479 template<typename _CharT, typename _Traits> 480 typename basic_filebuf<_CharT, _Traits>::int_type 481 basic_filebuf<_CharT, _Traits>:: 482 pbackfail(int_type __i) 483 { 484 int_type __ret = traits_type::eof(); 485 const bool __testin = _M_mode & ios_base::in; 486 if (__testin) 487 { 488 if (_M_writing) 489 { 490 if (overflow() == traits_type::eof()) 491 return __ret; 492 _M_set_buffer(-1); 493 _M_writing = false; 494 } 495 // Remember whether the pback buffer is active, otherwise below 496 // we may try to store in it a second char (libstdc++/9761). 497 const bool __testpb = _M_pback_init; 498 const bool __testeof = traits_type::eq_int_type(__i, __ret); 499 int_type __tmp; 500 if (this->eback() < this->gptr()) 501 { 502 this->gbump(-1); 503 __tmp = traits_type::to_int_type(*this->gptr()); 504 } 505 else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1))) 506 { 507 __tmp = this->underflow(); 508 if (traits_type::eq_int_type(__tmp, __ret)) 509 return __ret; 510 } 511 else 512 { 513 // At the beginning of the buffer, need to make a 514 // putback position available. But the seek may fail 515 // (f.i., at the beginning of a file, see 516 // libstdc++/9439) and in that case we return 517 // traits_type::eof(). 518 return __ret; 519 } 520 521 // Try to put back __i into input sequence in one of three ways. 522 // Order these tests done in is unspecified by the standard. 523 if (!__testeof && traits_type::eq_int_type(__i, __tmp)) 524 __ret = __i; 525 else if (__testeof) 526 __ret = traits_type::not_eof(__i); 527 else if (!__testpb) 528 { 529 _M_create_pback(); 530 _M_reading = true; 531 *this->gptr() = traits_type::to_char_type(__i); 532 __ret = __i; 533 } 534 } 535 return __ret; 536 } 537 538 template<typename _CharT, typename _Traits> 539 typename basic_filebuf<_CharT, _Traits>::int_type 540 basic_filebuf<_CharT, _Traits>:: 541 overflow(int_type __c) 542 { 543 int_type __ret = traits_type::eof(); 544 const bool __testeof = traits_type::eq_int_type(__c, __ret); 545 const bool __testout = (_M_mode & ios_base::out 546 || _M_mode & ios_base::app); 547 if (__testout) 548 { 549 if (_M_reading) 550 { 551 _M_destroy_pback(); 552 const int __gptr_off = _M_get_ext_pos(_M_state_last); 553 if (_M_seek(__gptr_off, ios_base::cur, _M_state_last) 554 == pos_type(off_type(-1))) 555 return __ret; 556 } 557 if (this->pbase() < this->pptr()) 558 { 559 // If appropriate, append the overflow char. 560 if (!__testeof) 561 { 562 *this->pptr() = traits_type::to_char_type(__c); 563 this->pbump(1); 564 } 565 566 // Convert pending sequence to external representation, 567 // and output. 568 if (_M_convert_to_external(this->pbase(), 569 this->pptr() - this->pbase())) 570 { 571 _M_set_buffer(0); 572 __ret = traits_type::not_eof(__c); 573 } 574 } 575 else if (_M_buf_size > 1) 576 { 577 // Overflow in 'uncommitted' mode: set _M_writing, set 578 // the buffer to the initial 'write' mode, and put __c 579 // into the buffer. 580 _M_set_buffer(0); 581 _M_writing = true; 582 if (!__testeof) 583 { 584 *this->pptr() = traits_type::to_char_type(__c); 585 this->pbump(1); 586 } 587 __ret = traits_type::not_eof(__c); 588 } 589 else 590 { 591 // Unbuffered. 592 char_type __conv = traits_type::to_char_type(__c); 593 if (__testeof || _M_convert_to_external(&__conv, 1)) 594 { 595 _M_writing = true; 596 __ret = traits_type::not_eof(__c); 597 } 598 } 599 } 600 return __ret; 601 } 602 603 template<typename _CharT, typename _Traits> 604 bool 605 basic_filebuf<_CharT, _Traits>:: 606 _M_convert_to_external(_CharT* __ibuf, streamsize __ilen) 607 { 608 // Sizes of external and pending output. 609 streamsize __elen; 610 streamsize __plen; 611 if (__check_facet(_M_codecvt).always_noconv()) 612 { 613 __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen); 614 __plen = __ilen; 615 } 616 else 617 { 618 // Worst-case number of external bytes needed. 619 // XXX Not done encoding() == -1. 620 streamsize __blen = __ilen * _M_codecvt->max_length(); 621 char* __buf = static_cast<char*>(__builtin_alloca(__blen)); 622 623 char* __bend; 624 const char_type* __iend; 625 codecvt_base::result __r; 626 __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen, 627 __iend, __buf, __buf + __blen, __bend); 628 629 if (__r == codecvt_base::ok || __r == codecvt_base::partial) 630 __blen = __bend - __buf; 631 else if (__r == codecvt_base::noconv) 632 { 633 // Same as the always_noconv case above. 634 __buf = reinterpret_cast<char*>(__ibuf); 635 __blen = __ilen; 636 } 637 else 638 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 639 "conversion error")); 640 641 __elen = _M_file.xsputn(__buf, __blen); 642 __plen = __blen; 643 644 // Try once more for partial conversions. 645 if (__r == codecvt_base::partial && __elen == __plen) 646 { 647 const char_type* __iresume = __iend; 648 streamsize __rlen = this->pptr() - __iend; 649 __r = _M_codecvt->out(_M_state_cur, __iresume, 650 __iresume + __rlen, __iend, __buf, 651 __buf + __blen, __bend); 652 if (__r != codecvt_base::error) 653 { 654 __rlen = __bend - __buf; 655 __elen = _M_file.xsputn(__buf, __rlen); 656 __plen = __rlen; 657 } 658 else 659 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 660 "conversion error")); 661 } 662 } 663 return __elen == __plen; 664 } 665 666 template<typename _CharT, typename _Traits> 667 streamsize 668 basic_filebuf<_CharT, _Traits>:: 669 xsgetn(_CharT* __s, streamsize __n) 670 { 671 // Clear out pback buffer before going on to the real deal... 672 streamsize __ret = 0; 673 if (_M_pback_init) 674 { 675 if (__n > 0 && this->gptr() == this->eback()) 676 { 677 *__s++ = *this->gptr(); // emulate non-underflowing sbumpc 678 this->gbump(1); 679 __ret = 1; 680 --__n; 681 } 682 _M_destroy_pback(); 683 } 684 else if (_M_writing) 685 { 686 if (overflow() == traits_type::eof()) 687 return __ret; 688 _M_set_buffer(-1); 689 _M_writing = false; 690 } 691 692 // Optimization in the always_noconv() case, to be generalized in the 693 // future: when __n > __buflen we read directly instead of using the 694 // buffer repeatedly. 695 const bool __testin = _M_mode & ios_base::in; 696 const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1; 697 698 if (__n > __buflen && __check_facet(_M_codecvt).always_noconv() 699 && __testin) 700 { 701 // First, copy the chars already present in the buffer. 702 const streamsize __avail = this->egptr() - this->gptr(); 703 if (__avail != 0) 704 { 705 traits_type::copy(__s, this->gptr(), __avail); 706 __s += __avail; 707 this->setg(this->eback(), this->gptr() + __avail, this->egptr()); 708 __ret += __avail; 709 __n -= __avail; 710 } 711 712 // Need to loop in case of short reads (relatively common 713 // with pipes). 714 streamsize __len; 715 for (;;) 716 { 717 __len = _M_file.xsgetn(reinterpret_cast<char*>(__s), __n); 718 if (__len == -1) 719 __throw_ios_failure(__N("basic_filebuf::xsgetn " 720 "error reading the file"), errno); 721 if (__len == 0) 722 break; 723 724 __n -= __len; 725 __ret += __len; 726 if (__n == 0) 727 break; 728 729 __s += __len; 730 } 731 732 if (__n == 0) 733 { 734 // Set _M_reading. Buffer is already in initial 'read' mode. 735 _M_reading = true; 736 } 737 else if (__len == 0) 738 { 739 // If end of file is reached, set 'uncommitted' 740 // mode, thus allowing an immediate write without 741 // an intervening seek. 742 _M_set_buffer(-1); 743 _M_reading = false; 744 } 745 } 746 else 747 __ret += __streambuf_type::xsgetn(__s, __n); 748 749 return __ret; 750 } 751 752 template<typename _CharT, typename _Traits> 753 streamsize 754 basic_filebuf<_CharT, _Traits>:: 755 xsputn(const _CharT* __s, streamsize __n) 756 { 757 streamsize __ret = 0; 758 // Optimization in the always_noconv() case, to be generalized in the 759 // future: when __n is larger than the available capacity we write 760 // directly instead of using the buffer. 761 const bool __testout = (_M_mode & ios_base::out 762 || _M_mode & ios_base::app); 763 if (__check_facet(_M_codecvt).always_noconv() 764 && __testout && !_M_reading) 765 { 766 streamsize __bufavail = this->epptr() - this->pptr(); 767 768 // Don't mistake 'uncommitted' mode buffered with unbuffered. 769 if (!_M_writing && _M_buf_size > 1) 770 __bufavail = _M_buf_size - 1; 771 772 if (__n >= __bufavail) 773 { 774 const streamsize __buffill = this->pptr() - this->pbase(); 775 const char* __buf = reinterpret_cast<const char*>(this->pbase()); 776 __ret = _M_file.xsputn_2(__buf, __buffill, 777 reinterpret_cast<const char*>(__s), 778 __n); 779 if (__ret == __buffill + __n) 780 { 781 _M_set_buffer(0); 782 _M_writing = true; 783 } 784 if (__ret > __buffill) 785 __ret -= __buffill; 786 else 787 __ret = 0; 788 } 789 else 790 __ret = __streambuf_type::xsputn(__s, __n); 791 } 792 else 793 __ret = __streambuf_type::xsputn(__s, __n); 794 return __ret; 795 } 796 797 template<typename _CharT, typename _Traits> 798 typename basic_filebuf<_CharT, _Traits>::__streambuf_type* 799 basic_filebuf<_CharT, _Traits>:: 800 setbuf(char_type* __s, streamsize __n) 801 { 802 if (!this->is_open()) 803 { 804 if (__s == 0 && __n == 0) 805 _M_buf_size = 1; 806 else if (__s && __n > 0) 807 { 808 // This is implementation-defined behavior, and assumes that 809 // an external char_type array of length __n exists and has 810 // been pre-allocated. If this is not the case, things will 811 // quickly blow up. When __n > 1, __n - 1 positions will be 812 // used for the get area, __n - 1 for the put area and 1 813 // position to host the overflow char of a full put area. 814 // When __n == 1, 1 position will be used for the get area 815 // and 0 for the put area, as in the unbuffered case above. 816 _M_buf = __s; 817 _M_buf_size = __n; 818 } 819 } 820 return this; 821 } 822 823 824 // According to 27.8.1.4 p11 - 13, seekoff should ignore the last 825 // argument (of type openmode). 826 template<typename _CharT, typename _Traits> 827 typename basic_filebuf<_CharT, _Traits>::pos_type 828 basic_filebuf<_CharT, _Traits>:: 829 seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode) 830 { 831 int __width = 0; 832 if (_M_codecvt) 833 __width = _M_codecvt->encoding(); 834 if (__width < 0) 835 __width = 0; 836 837 pos_type __ret = pos_type(off_type(-1)); 838 const bool __testfail = __off != 0 && __width <= 0; 839 if (this->is_open() && !__testfail) 840 { 841 // tellg and tellp queries do not affect any state, unless 842 // ! always_noconv and the put sequence is not empty. 843 // In that case, determining the position requires converting the 844 // put sequence. That doesn't use ext_buf, so requires a flush. 845 bool __no_movement = __way == ios_base::cur && __off == 0 846 && (!_M_writing || _M_codecvt->always_noconv()); 847 848 // Ditch any pback buffers to avoid confusion. 849 if (!__no_movement) 850 _M_destroy_pback(); 851 852 // Correct state at destination. Note that this is the correct 853 // state for the current position during output, because 854 // codecvt::unshift() returns the state to the initial state. 855 // This is also the correct state at the end of the file because 856 // an unshift sequence should have been written at the end. 857 __state_type __state = _M_state_beg; 858 off_type __computed_off = __off * __width; 859 if (_M_reading && __way == ios_base::cur) 860 { 861 __state = _M_state_last; 862 __computed_off += _M_get_ext_pos(__state); 863 } 864 if (!__no_movement) 865 __ret = _M_seek(__computed_off, __way, __state); 866 else 867 { 868 if (_M_writing) 869 __computed_off = this->pptr() - this->pbase(); 870 871 off_type __file_off = _M_file.seekoff(0, ios_base::cur); 872 if (__file_off != off_type(-1)) 873 { 874 __ret = __file_off + __computed_off; 875 __ret.state(__state); 876 } 877 } 878 } 879 return __ret; 880 } 881 882 // _GLIBCXX_RESOLVE_LIB_DEFECTS 883 // 171. Strange seekpos() semantics due to joint position 884 // According to the resolution of DR 171, seekpos should ignore the last 885 // argument (of type openmode). 886 template<typename _CharT, typename _Traits> 887 typename basic_filebuf<_CharT, _Traits>::pos_type 888 basic_filebuf<_CharT, _Traits>:: 889 seekpos(pos_type __pos, ios_base::openmode) 890 { 891 pos_type __ret = pos_type(off_type(-1)); 892 if (this->is_open()) 893 { 894 // Ditch any pback buffers to avoid confusion. 895 _M_destroy_pback(); 896 __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state()); 897 } 898 return __ret; 899 } 900 901 template<typename _CharT, typename _Traits> 902 typename basic_filebuf<_CharT, _Traits>::pos_type 903 basic_filebuf<_CharT, _Traits>:: 904 _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state) 905 { 906 pos_type __ret = pos_type(off_type(-1)); 907 if (_M_terminate_output()) 908 { 909 off_type __file_off = _M_file.seekoff(__off, __way); 910 if (__file_off != off_type(-1)) 911 { 912 _M_reading = false; 913 _M_writing = false; 914 _M_ext_next = _M_ext_end = _M_ext_buf; 915 _M_set_buffer(-1); 916 _M_state_cur = __state; 917 __ret = __file_off; 918 __ret.state(_M_state_cur); 919 } 920 } 921 return __ret; 922 } 923 924 // Returns the distance from the end of the ext buffer to the point 925 // corresponding to gptr(). This is a negative value. Updates __state 926 // from eback() correspondence to gptr(). 927 template<typename _CharT, typename _Traits> 928 int basic_filebuf<_CharT, _Traits>:: 929 _M_get_ext_pos(__state_type& __state) 930 { 931 if (_M_codecvt->always_noconv()) 932 return this->gptr() - this->egptr(); 933 else 934 { 935 // Calculate offset from _M_ext_buf that corresponds to 936 // gptr(). Precondition: __state == _M_state_last, which 937 // corresponds to eback(). 938 const int __gptr_off = 939 _M_codecvt->length(__state, _M_ext_buf, _M_ext_next, 940 this->gptr() - this->eback()); 941 return _M_ext_buf + __gptr_off - _M_ext_end; 942 } 943 } 944 945 template<typename _CharT, typename _Traits> 946 bool 947 basic_filebuf<_CharT, _Traits>:: 948 _M_terminate_output() 949 { 950 // Part one: update the output sequence. 951 bool __testvalid = true; 952 if (this->pbase() < this->pptr()) 953 { 954 const int_type __tmp = this->overflow(); 955 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 956 __testvalid = false; 957 } 958 959 // Part two: output unshift sequence. 960 if (_M_writing && !__check_facet(_M_codecvt).always_noconv() 961 && __testvalid) 962 { 963 // Note: this value is arbitrary, since there is no way to 964 // get the length of the unshift sequence from codecvt, 965 // without calling unshift. 966 const size_t __blen = 128; 967 char __buf[__blen]; 968 codecvt_base::result __r; 969 streamsize __ilen = 0; 970 971 do 972 { 973 char* __next; 974 __r = _M_codecvt->unshift(_M_state_cur, __buf, 975 __buf + __blen, __next); 976 if (__r == codecvt_base::error) 977 __testvalid = false; 978 else if (__r == codecvt_base::ok || 979 __r == codecvt_base::partial) 980 { 981 __ilen = __next - __buf; 982 if (__ilen > 0) 983 { 984 const streamsize __elen = _M_file.xsputn(__buf, __ilen); 985 if (__elen != __ilen) 986 __testvalid = false; 987 } 988 } 989 } 990 while (__r == codecvt_base::partial && __ilen > 0 && __testvalid); 991 992 if (__testvalid) 993 { 994 // This second call to overflow() is required by the standard, 995 // but it's not clear why it's needed, since the output buffer 996 // should be empty by this point (it should have been emptied 997 // in the first call to overflow()). 998 const int_type __tmp = this->overflow(); 999 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 1000 __testvalid = false; 1001 } 1002 } 1003 return __testvalid; 1004 } 1005 1006 template<typename _CharT, typename _Traits> 1007 int 1008 basic_filebuf<_CharT, _Traits>:: 1009 sync() 1010 { 1011 // Make sure that the internal buffer resyncs its idea of 1012 // the file position with the external file. 1013 int __ret = 0; 1014 if (this->pbase() < this->pptr()) 1015 { 1016 const int_type __tmp = this->overflow(); 1017 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 1018 __ret = -1; 1019 } 1020 return __ret; 1021 } 1022 1023 template<typename _CharT, typename _Traits> 1024 void 1025 basic_filebuf<_CharT, _Traits>:: 1026 imbue(const locale& __loc) 1027 { 1028 bool __testvalid = true; 1029 1030 const __codecvt_type* const _M_codecvt_tmp 1031 = __try_use_facet<__codecvt_type>(__loc); 1032 1033 if (this->is_open()) 1034 { 1035 // encoding() == -1 is ok only at the beginning. 1036 if ((_M_reading || _M_writing) 1037 && __check_facet(_M_codecvt).encoding() == -1) 1038 __testvalid = false; 1039 else 1040 { 1041 if (_M_reading) 1042 { 1043 if (__check_facet(_M_codecvt).always_noconv()) 1044 { 1045 if (_M_codecvt_tmp 1046 && !__check_facet(_M_codecvt_tmp).always_noconv()) 1047 __testvalid = this->seekoff(0, ios_base::cur, _M_mode) 1048 != pos_type(off_type(-1)); 1049 } 1050 else 1051 { 1052 // External position corresponding to gptr(). 1053 _M_ext_next = _M_ext_buf 1054 + _M_codecvt->length(_M_state_last, _M_ext_buf, 1055 _M_ext_next, 1056 this->gptr() - this->eback()); 1057 const streamsize __remainder = _M_ext_end - _M_ext_next; 1058 if (__remainder) 1059 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder); 1060 1061 _M_ext_next = _M_ext_buf; 1062 _M_ext_end = _M_ext_buf + __remainder; 1063 _M_set_buffer(-1); 1064 _M_state_last = _M_state_cur = _M_state_beg; 1065 } 1066 } 1067 else if (_M_writing && (__testvalid = _M_terminate_output())) 1068 _M_set_buffer(-1); 1069 } 1070 } 1071 1072 if (__testvalid) 1073 _M_codecvt = _M_codecvt_tmp; 1074 else 1075 _M_codecvt = 0; 1076 } 1077 1078 // Inhibit implicit instantiations for required instantiations, 1079 // which are defined via explicit instantiations elsewhere. 1080 #if _GLIBCXX_EXTERN_TEMPLATE 1081 extern template class basic_filebuf<char>; 1082 extern template class basic_ifstream<char>; 1083 extern template class basic_ofstream<char>; 1084 extern template class basic_fstream<char>; 1085 1086 #ifdef _GLIBCXX_USE_WCHAR_T 1087 extern template class basic_filebuf<wchar_t>; 1088 extern template class basic_ifstream<wchar_t>; 1089 extern template class basic_ofstream<wchar_t>; 1090 extern template class basic_fstream<wchar_t>; 1091 #endif 1092 #endif 1093 1094 _GLIBCXX_END_NAMESPACE_VERSION 1095 } // namespace std 1096 1097 #endif 1098
Indexes created Sat Feb 28 05:31:39 UTC 2026