fstream.tcc revision 1.1.1.4.4.2
1 // File based streams -*- C++ -*- 2 3 // Copyright (C) 1997-2018 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file bits/fstream.tcc 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{fstream} 28 */ 29 30 // 31 // ISO C++ 14882: 27.8 File-based streams 32 // 33 34 #ifndef _FSTREAM_TCC 35 #define _FSTREAM_TCC 1 36 37 #pragma GCC system_header 38 39 #include <bits/cxxabi_forced.h> 40 #include <bits/move.h> // for swap 41 42 namespace std _GLIBCXX_VISIBILITY(default) 43 { 44 _GLIBCXX_BEGIN_NAMESPACE_VERSION 45 46 template<typename _CharT, typename _Traits> 47 void 48 basic_filebuf<_CharT, _Traits>:: 49 _M_allocate_internal_buffer() 50 { 51 // Allocate internal buffer only if one doesn't already exist 52 // (either allocated or provided by the user via setbuf). 53 if (!_M_buf_allocated && !_M_buf) 54 { 55 _M_buf = new char_type[_M_buf_size]; 56 _M_buf_allocated = true; 57 } 58 } 59 60 template<typename _CharT, typename _Traits> 61 void 62 basic_filebuf<_CharT, _Traits>:: 63 _M_destroy_internal_buffer() throw() 64 { 65 if (_M_buf_allocated) 66 { 67 delete [] _M_buf; 68 _M_buf = 0; 69 _M_buf_allocated = false; 70 } 71 delete [] _M_ext_buf; 72 _M_ext_buf = 0; 73 _M_ext_buf_size = 0; 74 _M_ext_next = 0; 75 _M_ext_end = 0; 76 } 77 78 template<typename _CharT, typename _Traits> 79 basic_filebuf<_CharT, _Traits>:: 80 basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock), 81 _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(), 82 _M_state_last(), _M_buf(0), _M_buf_size(BUFSIZ), 83 _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(), 84 _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false), 85 _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0), 86 _M_ext_end(0) 87 { 88 if (has_facet<__codecvt_type>(this->_M_buf_locale)) 89 _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale); 90 } 91 92 #if __cplusplus >= 201103L 93 template<typename _CharT, typename _Traits> 94 basic_filebuf<_CharT, _Traits>:: 95 basic_filebuf(basic_filebuf&& __rhs) 96 : __streambuf_type(__rhs), 97 _M_lock(), _M_file(std::move(__rhs._M_file), &_M_lock), 98 _M_mode(std::__exchange(__rhs._M_mode, ios_base::openmode(0))), 99 _M_state_beg(std::move(__rhs._M_state_beg)), 100 _M_state_cur(std::move(__rhs._M_state_cur)), 101 _M_state_last(std::move(__rhs._M_state_last)), 102 _M_buf(std::__exchange(__rhs._M_buf, nullptr)), 103 _M_buf_size(std::__exchange(__rhs._M_buf_size, 1)), 104 _M_buf_allocated(std::__exchange(__rhs._M_buf_allocated, false)), 105 _M_reading(std::__exchange(__rhs._M_reading, false)), 106 _M_writing(std::__exchange(__rhs._M_writing, false)), 107 _M_pback(__rhs._M_pback), 108 _M_pback_cur_save(std::__exchange(__rhs._M_pback_cur_save, nullptr)), 109 _M_pback_end_save(std::__exchange(__rhs._M_pback_end_save, nullptr)), 110 _M_pback_init(std::__exchange(__rhs._M_pback_init, false)), 111 _M_codecvt(__rhs._M_codecvt), 112 _M_ext_buf(std::__exchange(__rhs._M_ext_buf, nullptr)), 113 _M_ext_buf_size(std::__exchange(__rhs._M_ext_buf_size, 0)), 114 _M_ext_next(std::__exchange(__rhs._M_ext_next, nullptr)), 115 _M_ext_end(std::__exchange(__rhs._M_ext_end, nullptr)) 116 { 117 __rhs._M_set_buffer(-1); 118 __rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg; 119 } 120 121 template<typename _CharT, typename _Traits> 122 basic_filebuf<_CharT, _Traits>& 123 basic_filebuf<_CharT, _Traits>:: 124 operator=(basic_filebuf&& __rhs) 125 { 126 this->close(); 127 __streambuf_type::operator=(__rhs); 128 _M_file.swap(__rhs._M_file); 129 _M_mode = std::__exchange(__rhs._M_mode, ios_base::openmode(0)); 130 _M_state_beg = std::move(__rhs._M_state_beg); 131 _M_state_cur = std::move(__rhs._M_state_cur); 132 _M_state_last = std::move(__rhs._M_state_last); 133 _M_buf = std::__exchange(__rhs._M_buf, nullptr); 134 _M_buf_size = std::__exchange(__rhs._M_buf_size, 1); 135 _M_buf_allocated = std::__exchange(__rhs._M_buf_allocated, false); 136 _M_ext_buf = std::__exchange(__rhs._M_ext_buf, nullptr); 137 _M_ext_buf_size = std::__exchange(__rhs._M_ext_buf_size, 0); 138 _M_ext_next = std::__exchange(__rhs._M_ext_next, nullptr); 139 _M_ext_end = std::__exchange(__rhs._M_ext_end, nullptr); 140 _M_reading = std::__exchange(__rhs._M_reading, false); 141 _M_writing = std::__exchange(__rhs._M_writing, false); 142 _M_pback_cur_save = std::__exchange(__rhs._M_pback_cur_save, nullptr); 143 _M_pback_end_save = std::__exchange(__rhs._M_pback_end_save, nullptr); 144 _M_pback_init = std::__exchange(__rhs._M_pback_init, false); 145 __rhs._M_set_buffer(-1); 146 __rhs._M_state_last = __rhs._M_state_cur = __rhs._M_state_beg; 147 return *this; 148 } 149 150 template<typename _CharT, typename _Traits> 151 void 152 basic_filebuf<_CharT, _Traits>:: 153 swap(basic_filebuf& __rhs) 154 { 155 __streambuf_type::swap(__rhs); 156 _M_file.swap(__rhs._M_file); 157 std::swap(_M_mode, __rhs._M_mode); 158 std::swap(_M_state_beg, __rhs._M_state_beg); 159 std::swap(_M_state_cur, __rhs._M_state_cur); 160 std::swap(_M_state_last, __rhs._M_state_last); 161 std::swap(_M_buf, __rhs._M_buf); 162 std::swap(_M_buf_size, __rhs._M_buf_size); 163 std::swap(_M_buf_allocated, __rhs._M_buf_allocated); 164 std::swap(_M_ext_buf, __rhs._M_ext_buf); 165 std::swap(_M_ext_buf_size, __rhs._M_ext_buf_size); 166 std::swap(_M_ext_next, __rhs._M_ext_next); 167 std::swap(_M_ext_end, __rhs._M_ext_end); 168 std::swap(_M_reading, __rhs._M_reading); 169 std::swap(_M_writing, __rhs._M_writing); 170 std::swap(_M_pback_cur_save, __rhs._M_pback_cur_save); 171 std::swap(_M_pback_end_save, __rhs._M_pback_end_save); 172 std::swap(_M_pback_init, __rhs._M_pback_init); 173 } 174 #endif 175 176 template<typename _CharT, typename _Traits> 177 typename basic_filebuf<_CharT, _Traits>::__filebuf_type* 178 basic_filebuf<_CharT, _Traits>:: 179 open(const char* __s, ios_base::openmode __mode) 180 { 181 __filebuf_type *__ret = 0; 182 if (!this->is_open()) 183 { 184 _M_file.open(__s, __mode); 185 if (this->is_open()) 186 { 187 _M_allocate_internal_buffer(); 188 _M_mode = __mode; 189 190 // Setup initial buffer to 'uncommitted' mode. 191 _M_reading = false; 192 _M_writing = false; 193 _M_set_buffer(-1); 194 195 // Reset to initial state. 196 _M_state_last = _M_state_cur = _M_state_beg; 197 198 // 27.8.1.3,4 199 if ((__mode & ios_base::ate) 200 && this->seekoff(0, ios_base::end, __mode) 201 == pos_type(off_type(-1))) 202 this->close(); 203 else 204 __ret = this; 205 } 206 } 207 return __ret; 208 } 209 210 template<typename _CharT, typename _Traits> 211 typename basic_filebuf<_CharT, _Traits>::__filebuf_type* 212 basic_filebuf<_CharT, _Traits>:: 213 close() 214 { 215 if (!this->is_open()) 216 return 0; 217 218 bool __testfail = false; 219 { 220 // NB: Do this here so that re-opened filebufs will be cool... 221 struct __close_sentry 222 { 223 basic_filebuf *__fb; 224 __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { } 225 ~__close_sentry () 226 { 227 __fb->_M_mode = ios_base::openmode(0); 228 __fb->_M_pback_init = false; 229 __fb->_M_destroy_internal_buffer(); 230 __fb->_M_reading = false; 231 __fb->_M_writing = false; 232 __fb->_M_set_buffer(-1); 233 __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg; 234 } 235 } __cs (this); 236 237 __try 238 { 239 if (!_M_terminate_output()) 240 __testfail = true; 241 } 242 __catch(__cxxabiv1::__forced_unwind&) 243 { 244 _M_file.close(); 245 __throw_exception_again; 246 } 247 __catch(...) 248 { __testfail = true; } 249 } 250 251 if (!_M_file.close()) 252 __testfail = true; 253 254 if (__testfail) 255 return 0; 256 else 257 return this; 258 } 259 260 template<typename _CharT, typename _Traits> 261 streamsize 262 basic_filebuf<_CharT, _Traits>:: 263 showmanyc() 264 { 265 streamsize __ret = -1; 266 const bool __testin = _M_mode & ios_base::in; 267 if (__testin && this->is_open()) 268 { 269 // For a stateful encoding (-1) the pending sequence might be just 270 // shift and unshift prefixes with no actual character. 271 __ret = this->egptr() - this->gptr(); 272 273 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM 274 // About this workaround, see libstdc++/20806. 275 const bool __testbinary = _M_mode & ios_base::binary; 276 if (__check_facet(_M_codecvt).encoding() >= 0 277 && __testbinary) 278 #else 279 if (__check_facet(_M_codecvt).encoding() >= 0) 280 #endif 281 __ret += _M_file.showmanyc() / _M_codecvt->max_length(); 282 } 283 return __ret; 284 } 285 286 template<typename _CharT, typename _Traits> 287 typename basic_filebuf<_CharT, _Traits>::int_type 288 basic_filebuf<_CharT, _Traits>:: 289 underflow() 290 { 291 int_type __ret = traits_type::eof(); 292 const bool __testin = _M_mode & ios_base::in; 293 if (__testin) 294 { 295 if (_M_writing) 296 { 297 if (overflow() == traits_type::eof()) 298 return __ret; 299 _M_set_buffer(-1); 300 _M_writing = false; 301 } 302 // Check for pback madness, and if so switch back to the 303 // normal buffers and jet outta here before expensive 304 // fileops happen... 305 _M_destroy_pback(); 306 307 if (this->gptr() < this->egptr()) 308 return traits_type::to_int_type(*this->gptr()); 309 310 // Get and convert input sequence. 311 const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1; 312 313 // Will be set to true if ::read() returns 0 indicating EOF. 314 bool __got_eof = false; 315 // Number of internal characters produced. 316 streamsize __ilen = 0; 317 codecvt_base::result __r = codecvt_base::ok; 318 if (__check_facet(_M_codecvt).always_noconv()) 319 { 320 __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()), 321 __buflen); 322 if (__ilen == 0) 323 __got_eof = true; 324 } 325 else 326 { 327 // Worst-case number of external bytes. 328 // XXX Not done encoding() == -1. 329 const int __enc = _M_codecvt->encoding(); 330 streamsize __blen; // Minimum buffer size. 331 streamsize __rlen; // Number of chars to read. 332 if (__enc > 0) 333 __blen = __rlen = __buflen * __enc; 334 else 335 { 336 __blen = __buflen + _M_codecvt->max_length() - 1; 337 __rlen = __buflen; 338 } 339 const streamsize __remainder = _M_ext_end - _M_ext_next; 340 __rlen = __rlen > __remainder ? __rlen - __remainder : 0; 341 342 // An imbue in 'read' mode implies first converting the external 343 // chars already present. 344 if (_M_reading && this->egptr() == this->eback() && __remainder) 345 __rlen = 0; 346 347 // Allocate buffer if necessary and move unconverted 348 // bytes to front. 349 if (_M_ext_buf_size < __blen) 350 { 351 char* __buf = new char[__blen]; 352 if (__remainder) 353 __builtin_memcpy(__buf, _M_ext_next, __remainder); 354 355 delete [] _M_ext_buf; 356 _M_ext_buf = __buf; 357 _M_ext_buf_size = __blen; 358 } 359 else if (__remainder) 360 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder); 361 362 _M_ext_next = _M_ext_buf; 363 _M_ext_end = _M_ext_buf + __remainder; 364 _M_state_last = _M_state_cur; 365 366 do 367 { 368 if (__rlen > 0) 369 { 370 // Sanity check! 371 // This may fail if the return value of 372 // codecvt::max_length() is bogus. 373 if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size) 374 { 375 __throw_ios_failure(__N("basic_filebuf::underflow " 376 "codecvt::max_length() " 377 "is not valid")); 378 } 379 streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen); 380 if (__elen == 0) 381 __got_eof = true; 382 else if (__elen == -1) 383 break; 384 _M_ext_end += __elen; 385 } 386 387 char_type* __iend = this->eback(); 388 if (_M_ext_next < _M_ext_end) 389 __r = _M_codecvt->in(_M_state_cur, _M_ext_next, 390 _M_ext_end, _M_ext_next, 391 this->eback(), 392 this->eback() + __buflen, __iend); 393 if (__r == codecvt_base::noconv) 394 { 395 size_t __avail = _M_ext_end - _M_ext_buf; 396 __ilen = std::min(__avail, __buflen); 397 traits_type::copy(this->eback(), 398 reinterpret_cast<char_type*> 399 (_M_ext_buf), __ilen); 400 _M_ext_next = _M_ext_buf + __ilen; 401 } 402 else 403 __ilen = __iend - this->eback(); 404 405 // _M_codecvt->in may return error while __ilen > 0: this is 406 // ok, and actually occurs in case of mixed encodings (e.g., 407 // XML files). 408 if (__r == codecvt_base::error) 409 break; 410 411 __rlen = 1; 412 } 413 while (__ilen == 0 && !__got_eof); 414 } 415 416 if (__ilen > 0) 417 { 418 _M_set_buffer(__ilen); 419 _M_reading = true; 420 __ret = traits_type::to_int_type(*this->gptr()); 421 } 422 else if (__got_eof) 423 { 424 // If the actual end of file is reached, set 'uncommitted' 425 // mode, thus allowing an immediate write without an 426 // intervening seek. 427 _M_set_buffer(-1); 428 _M_reading = false; 429 // However, reaching it while looping on partial means that 430 // the file has got an incomplete character. 431 if (__r == codecvt_base::partial) 432 __throw_ios_failure(__N("basic_filebuf::underflow " 433 "incomplete character in file")); 434 } 435 else if (__r == codecvt_base::error) 436 __throw_ios_failure(__N("basic_filebuf::underflow " 437 "invalid byte sequence in file")); 438 else 439 __throw_ios_failure(__N("basic_filebuf::underflow " 440 "error reading the file")); 441 } 442 return __ret; 443 } 444 445 template<typename _CharT, typename _Traits> 446 typename basic_filebuf<_CharT, _Traits>::int_type 447 basic_filebuf<_CharT, _Traits>:: 448 pbackfail(int_type __i) 449 { 450 int_type __ret = traits_type::eof(); 451 const bool __testin = _M_mode & ios_base::in; 452 if (__testin) 453 { 454 if (_M_writing) 455 { 456 if (overflow() == traits_type::eof()) 457 return __ret; 458 _M_set_buffer(-1); 459 _M_writing = false; 460 } 461 // Remember whether the pback buffer is active, otherwise below 462 // we may try to store in it a second char (libstdc++/9761). 463 const bool __testpb = _M_pback_init; 464 const bool __testeof = traits_type::eq_int_type(__i, __ret); 465 int_type __tmp; 466 if (this->eback() < this->gptr()) 467 { 468 this->gbump(-1); 469 __tmp = traits_type::to_int_type(*this->gptr()); 470 } 471 else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1))) 472 { 473 __tmp = this->underflow(); 474 if (traits_type::eq_int_type(__tmp, __ret)) 475 return __ret; 476 } 477 else 478 { 479 // At the beginning of the buffer, need to make a 480 // putback position available. But the seek may fail 481 // (f.i., at the beginning of a file, see 482 // libstdc++/9439) and in that case we return 483 // traits_type::eof(). 484 return __ret; 485 } 486 487 // Try to put back __i into input sequence in one of three ways. 488 // Order these tests done in is unspecified by the standard. 489 if (!__testeof && traits_type::eq_int_type(__i, __tmp)) 490 __ret = __i; 491 else if (__testeof) 492 __ret = traits_type::not_eof(__i); 493 else if (!__testpb) 494 { 495 _M_create_pback(); 496 _M_reading = true; 497 *this->gptr() = traits_type::to_char_type(__i); 498 __ret = __i; 499 } 500 } 501 return __ret; 502 } 503 504 template<typename _CharT, typename _Traits> 505 typename basic_filebuf<_CharT, _Traits>::int_type 506 basic_filebuf<_CharT, _Traits>:: 507 overflow(int_type __c) 508 { 509 int_type __ret = traits_type::eof(); 510 const bool __testeof = traits_type::eq_int_type(__c, __ret); 511 const bool __testout = (_M_mode & ios_base::out 512 || _M_mode & ios_base::app); 513 if (__testout) 514 { 515 if (_M_reading) 516 { 517 _M_destroy_pback(); 518 const int __gptr_off = _M_get_ext_pos(_M_state_last); 519 if (_M_seek(__gptr_off, ios_base::cur, _M_state_last) 520 == pos_type(off_type(-1))) 521 return __ret; 522 } 523 if (this->pbase() < this->pptr()) 524 { 525 // If appropriate, append the overflow char. 526 if (!__testeof) 527 { 528 *this->pptr() = traits_type::to_char_type(__c); 529 this->pbump(1); 530 } 531 532 // Convert pending sequence to external representation, 533 // and output. 534 if (_M_convert_to_external(this->pbase(), 535 this->pptr() - this->pbase())) 536 { 537 _M_set_buffer(0); 538 __ret = traits_type::not_eof(__c); 539 } 540 } 541 else if (_M_buf_size > 1) 542 { 543 // Overflow in 'uncommitted' mode: set _M_writing, set 544 // the buffer to the initial 'write' mode, and put __c 545 // into the buffer. 546 _M_set_buffer(0); 547 _M_writing = true; 548 if (!__testeof) 549 { 550 *this->pptr() = traits_type::to_char_type(__c); 551 this->pbump(1); 552 } 553 __ret = traits_type::not_eof(__c); 554 } 555 else 556 { 557 // Unbuffered. 558 char_type __conv = traits_type::to_char_type(__c); 559 if (__testeof || _M_convert_to_external(&__conv, 1)) 560 { 561 _M_writing = true; 562 __ret = traits_type::not_eof(__c); 563 } 564 } 565 } 566 return __ret; 567 } 568 569 template<typename _CharT, typename _Traits> 570 bool 571 basic_filebuf<_CharT, _Traits>:: 572 _M_convert_to_external(_CharT* __ibuf, streamsize __ilen) 573 { 574 // Sizes of external and pending output. 575 streamsize __elen; 576 streamsize __plen; 577 if (__check_facet(_M_codecvt).always_noconv()) 578 { 579 __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen); 580 __plen = __ilen; 581 } 582 else 583 { 584 // Worst-case number of external bytes needed. 585 // XXX Not done encoding() == -1. 586 streamsize __blen = __ilen * _M_codecvt->max_length(); 587 char* __buf = static_cast<char*>(__builtin_alloca(__blen)); 588 589 char* __bend; 590 const char_type* __iend; 591 codecvt_base::result __r; 592 __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen, 593 __iend, __buf, __buf + __blen, __bend); 594 595 if (__r == codecvt_base::ok || __r == codecvt_base::partial) 596 __blen = __bend - __buf; 597 else if (__r == codecvt_base::noconv) 598 { 599 // Same as the always_noconv case above. 600 __buf = reinterpret_cast<char*>(__ibuf); 601 __blen = __ilen; 602 } 603 else 604 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 605 "conversion error")); 606 607 __elen = _M_file.xsputn(__buf, __blen); 608 __plen = __blen; 609 610 // Try once more for partial conversions. 611 if (__r == codecvt_base::partial && __elen == __plen) 612 { 613 const char_type* __iresume = __iend; 614 streamsize __rlen = this->pptr() - __iend; 615 __r = _M_codecvt->out(_M_state_cur, __iresume, 616 __iresume + __rlen, __iend, __buf, 617 __buf + __blen, __bend); 618 if (__r != codecvt_base::error) 619 { 620 __rlen = __bend - __buf; 621 __elen = _M_file.xsputn(__buf, __rlen); 622 __plen = __rlen; 623 } 624 else 625 __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external " 626 "conversion error")); 627 } 628 } 629 return __elen == __plen; 630 } 631 632 template<typename _CharT, typename _Traits> 633 streamsize 634 basic_filebuf<_CharT, _Traits>:: 635 xsgetn(_CharT* __s, streamsize __n) 636 { 637 // Clear out pback buffer before going on to the real deal... 638 streamsize __ret = 0; 639 if (_M_pback_init) 640 { 641 if (__n > 0 && this->gptr() == this->eback()) 642 { 643 *__s++ = *this->gptr(); // emulate non-underflowing sbumpc 644 this->gbump(1); 645 __ret = 1; 646 --__n; 647 } 648 _M_destroy_pback(); 649 } 650 else if (_M_writing) 651 { 652 if (overflow() == traits_type::eof()) 653 return __ret; 654 _M_set_buffer(-1); 655 _M_writing = false; 656 } 657 658 // Optimization in the always_noconv() case, to be generalized in the 659 // future: when __n > __buflen we read directly instead of using the 660 // buffer repeatedly. 661 const bool __testin = _M_mode & ios_base::in; 662 const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1; 663 664 if (__n > __buflen && __check_facet(_M_codecvt).always_noconv() 665 && __testin) 666 { 667 // First, copy the chars already present in the buffer. 668 const streamsize __avail = this->egptr() - this->gptr(); 669 if (__avail != 0) 670 { 671 traits_type::copy(__s, this->gptr(), __avail); 672 __s += __avail; 673 this->setg(this->eback(), this->gptr() + __avail, this->egptr()); 674 __ret += __avail; 675 __n -= __avail; 676 } 677 678 // Need to loop in case of short reads (relatively common 679 // with pipes). 680 streamsize __len; 681 for (;;) 682 { 683 __len = _M_file.xsgetn(reinterpret_cast<char*>(__s), __n); 684 if (__len == -1) 685 __throw_ios_failure(__N("basic_filebuf::xsgetn " 686 "error reading the file")); 687 if (__len == 0) 688 break; 689 690 __n -= __len; 691 __ret += __len; 692 if (__n == 0) 693 break; 694 695 __s += __len; 696 } 697 698 if (__n == 0) 699 { 700 // Set _M_reading. Buffer is already in initial 'read' mode. 701 _M_reading = true; 702 } 703 else if (__len == 0) 704 { 705 // If end of file is reached, set 'uncommitted' 706 // mode, thus allowing an immediate write without 707 // an intervening seek. 708 _M_set_buffer(-1); 709 _M_reading = false; 710 } 711 } 712 else 713 __ret += __streambuf_type::xsgetn(__s, __n); 714 715 return __ret; 716 } 717 718 template<typename _CharT, typename _Traits> 719 streamsize 720 basic_filebuf<_CharT, _Traits>:: 721 xsputn(const _CharT* __s, streamsize __n) 722 { 723 streamsize __ret = 0; 724 // Optimization in the always_noconv() case, to be generalized in the 725 // future: when __n is sufficiently large we write directly instead of 726 // using the buffer. 727 const bool __testout = (_M_mode & ios_base::out 728 || _M_mode & ios_base::app); 729 if (__check_facet(_M_codecvt).always_noconv() 730 && __testout && !_M_reading) 731 { 732 // Measurement would reveal the best choice. 733 const streamsize __chunk = 1ul << 10; 734 streamsize __bufavail = this->epptr() - this->pptr(); 735 736 // Don't mistake 'uncommitted' mode buffered with unbuffered. 737 if (!_M_writing && _M_buf_size > 1) 738 __bufavail = _M_buf_size - 1; 739 740 const streamsize __limit = std::min(__chunk, __bufavail); 741 if (__n >= __limit) 742 { 743 const streamsize __buffill = this->pptr() - this->pbase(); 744 const char* __buf = reinterpret_cast<const char*>(this->pbase()); 745 __ret = _M_file.xsputn_2(__buf, __buffill, 746 reinterpret_cast<const char*>(__s), 747 __n); 748 if (__ret == __buffill + __n) 749 { 750 _M_set_buffer(0); 751 _M_writing = true; 752 } 753 if (__ret > __buffill) 754 __ret -= __buffill; 755 else 756 __ret = 0; 757 } 758 else 759 __ret = __streambuf_type::xsputn(__s, __n); 760 } 761 else 762 __ret = __streambuf_type::xsputn(__s, __n); 763 return __ret; 764 } 765 766 template<typename _CharT, typename _Traits> 767 typename basic_filebuf<_CharT, _Traits>::__streambuf_type* 768 basic_filebuf<_CharT, _Traits>:: 769 setbuf(char_type* __s, streamsize __n) 770 { 771 if (!this->is_open()) 772 { 773 if (__s == 0 && __n == 0) 774 _M_buf_size = 1; 775 else if (__s && __n > 0) 776 { 777 // This is implementation-defined behavior, and assumes that 778 // an external char_type array of length __n exists and has 779 // been pre-allocated. If this is not the case, things will 780 // quickly blow up. When __n > 1, __n - 1 positions will be 781 // used for the get area, __n - 1 for the put area and 1 782 // position to host the overflow char of a full put area. 783 // When __n == 1, 1 position will be used for the get area 784 // and 0 for the put area, as in the unbuffered case above. 785 _M_buf = __s; 786 _M_buf_size = __n; 787 } 788 } 789 return this; 790 } 791 792 793 // According to 27.8.1.4 p11 - 13, seekoff should ignore the last 794 // argument (of type openmode). 795 template<typename _CharT, typename _Traits> 796 typename basic_filebuf<_CharT, _Traits>::pos_type 797 basic_filebuf<_CharT, _Traits>:: 798 seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode) 799 { 800 int __width = 0; 801 if (_M_codecvt) 802 __width = _M_codecvt->encoding(); 803 if (__width < 0) 804 __width = 0; 805 806 pos_type __ret = pos_type(off_type(-1)); 807 const bool __testfail = __off != 0 && __width <= 0; 808 if (this->is_open() && !__testfail) 809 { 810 // tellg and tellp queries do not affect any state, unless 811 // ! always_noconv and the put sequence is not empty. 812 // In that case, determining the position requires converting the 813 // put sequence. That doesn't use ext_buf, so requires a flush. 814 bool __no_movement = __way == ios_base::cur && __off == 0 815 && (!_M_writing || _M_codecvt->always_noconv()); 816 817 // Ditch any pback buffers to avoid confusion. 818 if (!__no_movement) 819 _M_destroy_pback(); 820 821 // Correct state at destination. Note that this is the correct 822 // state for the current position during output, because 823 // codecvt::unshift() returns the state to the initial state. 824 // This is also the correct state at the end of the file because 825 // an unshift sequence should have been written at the end. 826 __state_type __state = _M_state_beg; 827 off_type __computed_off = __off * __width; 828 if (_M_reading && __way == ios_base::cur) 829 { 830 __state = _M_state_last; 831 __computed_off += _M_get_ext_pos(__state); 832 } 833 if (!__no_movement) 834 __ret = _M_seek(__computed_off, __way, __state); 835 else 836 { 837 if (_M_writing) 838 __computed_off = this->pptr() - this->pbase(); 839 840 off_type __file_off = _M_file.seekoff(0, ios_base::cur); 841 if (__file_off != off_type(-1)) 842 { 843 __ret = __file_off + __computed_off; 844 __ret.state(__state); 845 } 846 } 847 } 848 return __ret; 849 } 850 851 // _GLIBCXX_RESOLVE_LIB_DEFECTS 852 // 171. Strange seekpos() semantics due to joint position 853 // According to the resolution of DR 171, seekpos should ignore the last 854 // argument (of type openmode). 855 template<typename _CharT, typename _Traits> 856 typename basic_filebuf<_CharT, _Traits>::pos_type 857 basic_filebuf<_CharT, _Traits>:: 858 seekpos(pos_type __pos, ios_base::openmode) 859 { 860 pos_type __ret = pos_type(off_type(-1)); 861 if (this->is_open()) 862 { 863 // Ditch any pback buffers to avoid confusion. 864 _M_destroy_pback(); 865 __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state()); 866 } 867 return __ret; 868 } 869 870 template<typename _CharT, typename _Traits> 871 typename basic_filebuf<_CharT, _Traits>::pos_type 872 basic_filebuf<_CharT, _Traits>:: 873 _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state) 874 { 875 pos_type __ret = pos_type(off_type(-1)); 876 if (_M_terminate_output()) 877 { 878 off_type __file_off = _M_file.seekoff(__off, __way); 879 if (__file_off != off_type(-1)) 880 { 881 _M_reading = false; 882 _M_writing = false; 883 _M_ext_next = _M_ext_end = _M_ext_buf; 884 _M_set_buffer(-1); 885 _M_state_cur = __state; 886 __ret = __file_off; 887 __ret.state(_M_state_cur); 888 } 889 } 890 return __ret; 891 } 892 893 // Returns the distance from the end of the ext buffer to the point 894 // corresponding to gptr(). This is a negative value. Updates __state 895 // from eback() correspondence to gptr(). 896 template<typename _CharT, typename _Traits> 897 int basic_filebuf<_CharT, _Traits>:: 898 _M_get_ext_pos(__state_type& __state) 899 { 900 if (_M_codecvt->always_noconv()) 901 return this->gptr() - this->egptr(); 902 else 903 { 904 // Calculate offset from _M_ext_buf that corresponds to 905 // gptr(). Precondition: __state == _M_state_last, which 906 // corresponds to eback(). 907 const int __gptr_off = 908 _M_codecvt->length(__state, _M_ext_buf, _M_ext_next, 909 this->gptr() - this->eback()); 910 return _M_ext_buf + __gptr_off - _M_ext_end; 911 } 912 } 913 914 template<typename _CharT, typename _Traits> 915 bool 916 basic_filebuf<_CharT, _Traits>:: 917 _M_terminate_output() 918 { 919 // Part one: update the output sequence. 920 bool __testvalid = true; 921 if (this->pbase() < this->pptr()) 922 { 923 const int_type __tmp = this->overflow(); 924 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 925 __testvalid = false; 926 } 927 928 // Part two: output unshift sequence. 929 if (_M_writing && !__check_facet(_M_codecvt).always_noconv() 930 && __testvalid) 931 { 932 // Note: this value is arbitrary, since there is no way to 933 // get the length of the unshift sequence from codecvt, 934 // without calling unshift. 935 const size_t __blen = 128; 936 char __buf[__blen]; 937 codecvt_base::result __r; 938 streamsize __ilen = 0; 939 940 do 941 { 942 char* __next; 943 __r = _M_codecvt->unshift(_M_state_cur, __buf, 944 __buf + __blen, __next); 945 if (__r == codecvt_base::error) 946 __testvalid = false; 947 else if (__r == codecvt_base::ok || 948 __r == codecvt_base::partial) 949 { 950 __ilen = __next - __buf; 951 if (__ilen > 0) 952 { 953 const streamsize __elen = _M_file.xsputn(__buf, __ilen); 954 if (__elen != __ilen) 955 __testvalid = false; 956 } 957 } 958 } 959 while (__r == codecvt_base::partial && __ilen > 0 && __testvalid); 960 961 if (__testvalid) 962 { 963 // This second call to overflow() is required by the standard, 964 // but it's not clear why it's needed, since the output buffer 965 // should be empty by this point (it should have been emptied 966 // in the first call to overflow()). 967 const int_type __tmp = this->overflow(); 968 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 969 __testvalid = false; 970 } 971 } 972 return __testvalid; 973 } 974 975 template<typename _CharT, typename _Traits> 976 int 977 basic_filebuf<_CharT, _Traits>:: 978 sync() 979 { 980 // Make sure that the internal buffer resyncs its idea of 981 // the file position with the external file. 982 int __ret = 0; 983 if (this->pbase() < this->pptr()) 984 { 985 const int_type __tmp = this->overflow(); 986 if (traits_type::eq_int_type(__tmp, traits_type::eof())) 987 __ret = -1; 988 } 989 return __ret; 990 } 991 992 template<typename _CharT, typename _Traits> 993 void 994 basic_filebuf<_CharT, _Traits>:: 995 imbue(const locale& __loc) 996 { 997 bool __testvalid = true; 998 999 const __codecvt_type* _M_codecvt_tmp = 0; 1000 if (__builtin_expect(has_facet<__codecvt_type>(__loc), true)) 1001 _M_codecvt_tmp = &use_facet<__codecvt_type>(__loc); 1002 1003 if (this->is_open()) 1004 { 1005 // encoding() == -1 is ok only at the beginning. 1006 if ((_M_reading || _M_writing) 1007 && __check_facet(_M_codecvt).encoding() == -1) 1008 __testvalid = false; 1009 else 1010 { 1011 if (_M_reading) 1012 { 1013 if (__check_facet(_M_codecvt).always_noconv()) 1014 { 1015 if (_M_codecvt_tmp 1016 && !__check_facet(_M_codecvt_tmp).always_noconv()) 1017 __testvalid = this->seekoff(0, ios_base::cur, _M_mode) 1018 != pos_type(off_type(-1)); 1019 } 1020 else 1021 { 1022 // External position corresponding to gptr(). 1023 _M_ext_next = _M_ext_buf 1024 + _M_codecvt->length(_M_state_last, _M_ext_buf, 1025 _M_ext_next, 1026 this->gptr() - this->eback()); 1027 const streamsize __remainder = _M_ext_end - _M_ext_next; 1028 if (__remainder) 1029 __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder); 1030 1031 _M_ext_next = _M_ext_buf; 1032 _M_ext_end = _M_ext_buf + __remainder; 1033 _M_set_buffer(-1); 1034 _M_state_last = _M_state_cur = _M_state_beg; 1035 } 1036 } 1037 else if (_M_writing && (__testvalid = _M_terminate_output())) 1038 _M_set_buffer(-1); 1039 } 1040 } 1041 1042 if (__testvalid) 1043 _M_codecvt = _M_codecvt_tmp; 1044 else 1045 _M_codecvt = 0; 1046 } 1047 1048 // Inhibit implicit instantiations for required instantiations, 1049 // which are defined via explicit instantiations elsewhere. 1050 #if _GLIBCXX_EXTERN_TEMPLATE 1051 extern template class basic_filebuf<char>; 1052 extern template class basic_ifstream<char>; 1053 extern template class basic_ofstream<char>; 1054 extern template class basic_fstream<char>; 1055 1056 #ifdef _GLIBCXX_USE_WCHAR_T 1057 extern template class basic_filebuf<wchar_t>; 1058 extern template class basic_ifstream<wchar_t>; 1059 extern template class basic_ofstream<wchar_t>; 1060 extern template class basic_fstream<wchar_t>; 1061 #endif 1062 #endif 1063 1064 _GLIBCXX_END_NAMESPACE_VERSION 1065 } // namespace std 1066 1067 #endif 1068
Indexes created Sun Mar 01 05:31:48 UTC 2026