1 // File based streams -*- C++ -*-
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
5 // Free Software Foundation, Inc.
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 2, or (at your option)
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.
18 // You should have received a copy of the GNU General Public License
19 // along with this library; see the file COPYING. If not, write to
20 // the Free Software Foundation, 51 Franklin Street, Fifth Floor,
21 // Boston, MA 02110-1301, USA.
23 // As a special exception, you may use this file as part of a free software
24 // library without restriction. Specifically, if other files instantiate
25 // templates or use macros or inline functions from this file, or you compile
26 // this file and link it with other files to produce an executable, this
27 // file does not by itself cause the resulting executable to be covered by
28 // the GNU General Public License. This exception does not however
29 // invalidate any other reasons why the executable file might be covered by
30 // the GNU General Public License.
33 * This is a Standard C++ Library header.
37 // ISO C++ 14882: 27.8 File-based streams
40 #ifndef _GLIBCXX_FSTREAM
41 #define _GLIBCXX_FSTREAM 1
43 #pragma GCC system_header
47 #include <bits/codecvt.h>
48 #include <cstdio> // For BUFSIZ
49 #include <bits/basic_file.h> // For __basic_file, __c_lock
51 _GLIBCXX_BEGIN_NAMESPACE(std)
53 // [27.8.1.1] template class basic_filebuf
55 * @brief The actual work of input and output (for files).
57 * This class associates both its input and output sequence with an
58 * external disk file, and maintains a joint file position for both
59 * sequences. Many of its semantics are described in terms of similar
60 * behavior in the Standard C Library's @c FILE streams.
62 // Requirements on traits_type, specific to this class:
63 // traits_type::pos_type must be fpos<traits_type::state_type>
64 // traits_type::off_type must be streamoff
65 // traits_type::state_type must be Assignable and DefaultConstructible,
66 // and traits_type::state_type() must be the initial state for codecvt.
67 template<typename _CharT, typename _Traits>
68 class basic_filebuf : public basic_streambuf<_CharT, _Traits>
72 typedef _CharT char_type;
73 typedef _Traits traits_type;
74 typedef typename traits_type::int_type int_type;
75 typedef typename traits_type::pos_type pos_type;
76 typedef typename traits_type::off_type off_type;
78 typedef basic_streambuf<char_type, traits_type> __streambuf_type;
79 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
80 typedef __basic_file<char> __file_type;
81 typedef typename traits_type::state_type __state_type;
82 typedef codecvt<char_type, char, __state_type> __codecvt_type;
84 friend class ios_base; // For sync_with_stdio.
88 // MT lock inherited from libio or other low-level io library.
94 /// Place to stash in || out || in | out settings for current filebuf.
95 ios_base::openmode _M_mode;
97 // Beginning state type for codecvt.
98 __state_type _M_state_beg;
100 // During output, the state that corresponds to pptr(),
101 // during input, the state that corresponds to egptr() and
103 __state_type _M_state_cur;
105 // Not used for output. During input, the state that corresponds
106 // to eback() and _M_ext_buf.
107 __state_type _M_state_last;
109 /// Pointer to the beginning of internal buffer.
113 * Actual size of internal buffer. This number is equal to the size
114 * of the put area + 1 position, reserved for the overflow char of
119 // Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.
120 bool _M_buf_allocated;
123 * _M_reading == false && _M_writing == false for 'uncommitted' mode;
124 * _M_reading == true for 'read' mode;
125 * _M_writing == true for 'write' mode;
127 * NB: _M_reading == true && _M_writing == true is unused.
134 * Necessary bits for putback buffer management.
136 * @note pbacks of over one character are not currently supported.
139 char_type* _M_pback_cur_save;
140 char_type* _M_pback_end_save;
144 // Cached codecvt facet.
145 const __codecvt_type* _M_codecvt;
148 * Buffer for external characters. Used for input when
149 * codecvt::always_noconv() == false. When valid, this corresponds
155 * Size of buffer held by _M_ext_buf.
157 streamsize _M_ext_buf_size;
160 * Pointers into the buffer held by _M_ext_buf that delimit a
161 * subsequence of bytes that have been read but not yet converted.
162 * When valid, _M_ext_next corresponds to egptr().
164 const char* _M_ext_next;
168 * Initializes pback buffers, and moves normal buffers to safety.
170 * _M_in_cur has already been moved back
177 _M_pback_cur_save = this->gptr();
178 _M_pback_end_save = this->egptr();
179 this->setg(&_M_pback, &_M_pback, &_M_pback + 1);
180 _M_pback_init = true;
185 * Deactivates pback buffer contents, and restores normal buffer.
187 * The pback buffer has only moved forward.
190 _M_destroy_pback() throw()
194 // Length _M_in_cur moved in the pback buffer.
195 _M_pback_cur_save += this->gptr() != this->eback();
196 this->setg(_M_buf, _M_pback_cur_save, _M_pback_end_save);
197 _M_pback_init = false;
202 // Constructors/destructor:
204 * @brief Does not open any files.
206 * The default constructor initializes the parent class using its
212 * @brief The destructor closes the file first.
220 * @brief Returns true if the external file is open.
223 is_open() const throw()
224 { return _M_file.is_open(); }
227 * @brief Opens an external file.
228 * @param s The name of the file.
229 * @param mode The open mode flags.
230 * @return @c this on success, NULL on failure
232 * If a file is already open, this function immediately fails.
233 * Otherwise it tries to open the file named @a s using the flags
236 * Table 92, adapted here, gives the relation between openmode
237 * combinations and the equivalent fopen() flags.
238 * (NB: lines app, in|out|app, in|app, binary|app, binary|in|out|app,
239 * and binary|in|app per DR 596)
240 * +---------------------------------------------------------+
241 * | ios_base Flag combination stdio equivalent |
242 * |binary in out trunc app |
243 * +---------------------------------------------------------+
253 * +---------------------------------------------------------+
263 * +---------------------------------------------------------+
266 open(const char* __s, ios_base::openmode __mode);
269 * @brief Closes the currently associated file.
270 * @return @c this on success, NULL on failure
272 * If no file is currently open, this function immediately fails.
274 * If a "put buffer area" exists, @c overflow(eof) is called to flush
275 * all the characters. The file is then closed.
277 * If any operations fail, this function also fails.
284 _M_allocate_internal_buffer();
287 _M_destroy_internal_buffer() throw();
289 // [27.8.1.4] overridden virtual functions
293 // Stroustrup, 1998, p. 628
294 // underflow() and uflow() functions are called to get the next
295 // character from the real input source when the buffer is empty.
296 // Buffered input uses underflow()
302 pbackfail(int_type __c = _Traits::eof());
304 // Stroustrup, 1998, p 648
305 // The overflow() function is called to transfer characters to the
306 // real output destination when the buffer is full. A call to
307 // overflow(c) outputs the contents of the buffer plus the
310 // Consume some sequence of the characters in the pending sequence.
312 overflow(int_type __c = _Traits::eof());
314 // Convert internal byte sequence to external, char-based
315 // sequence via codecvt.
317 _M_convert_to_external(char_type*, streamsize);
320 * @brief Manipulates the buffer.
321 * @param s Pointer to a buffer area.
322 * @param n Size of @a s.
325 * If no file has been opened, and both @a s and @a n are zero, then
326 * the stream becomes unbuffered. Otherwise, @c s is used as a
328 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2
331 virtual __streambuf_type*
332 setbuf(char_type* __s, streamsize __n);
335 seekoff(off_type __off, ios_base::seekdir __way,
336 ios_base::openmode __mode = ios_base::in | ios_base::out);
339 seekpos(pos_type __pos,
340 ios_base::openmode __mode = ios_base::in | ios_base::out);
342 // Common code for seekoff and seekpos
344 _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
350 imbue(const locale& __loc);
353 xsgetn(char_type* __s, streamsize __n);
356 xsputn(const char_type* __s, streamsize __n);
358 // Flushes output buffer, then writes unshift sequence.
360 _M_terminate_output();
363 * This function sets the pointers of the internal buffer, both get
364 * and put areas. Typically:
366 * __off == egptr() - eback() upon underflow/uflow ('read' mode);
367 * __off == 0 upon overflow ('write' mode);
368 * __off == -1 upon open, setbuf, seekoff/pos ('uncommitted' mode).
370 * NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size
371 * reflects the actual allocated memory and the last cell is reserved
372 * for the overflow char of a full put area.
375 _M_set_buffer(streamsize __off)
377 const bool __testin = _M_mode & ios_base::in;
378 const bool __testout = _M_mode & ios_base::out;
380 if (__testin && __off > 0)
381 this->setg(_M_buf, _M_buf, _M_buf + __off);
383 this->setg(_M_buf, _M_buf, _M_buf);
385 if (__testout && __off == 0 && _M_buf_size > 1 )
386 this->setp(_M_buf, _M_buf + _M_buf_size - 1);
388 this->setp(NULL, NULL);
392 // [27.8.1.5] Template class basic_ifstream
394 * @brief Controlling input for files.
396 * This class supports reading from named files, using the inherited
397 * functions from std::basic_istream. To control the associated
398 * sequence, an instance of std::basic_filebuf is used, which this page
399 * refers to as @c sb.
401 template<typename _CharT, typename _Traits>
402 class basic_ifstream : public basic_istream<_CharT, _Traits>
406 typedef _CharT char_type;
407 typedef _Traits traits_type;
408 typedef typename traits_type::int_type int_type;
409 typedef typename traits_type::pos_type pos_type;
410 typedef typename traits_type::off_type off_type;
412 // Non-standard types:
413 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
414 typedef basic_istream<char_type, traits_type> __istream_type;
417 __filebuf_type _M_filebuf;
420 // Constructors/Destructors:
422 * @brief Default constructor.
424 * Initializes @c sb using its default constructor, and passes
425 * @c &sb to the base class initializer. Does not open any files
426 * (you haven't given it a filename to open).
428 basic_ifstream() : __istream_type(), _M_filebuf()
429 { this->init(&_M_filebuf); }
432 * @brief Create an input file stream.
433 * @param s Null terminated string specifying the filename.
434 * @param mode Open file in specified mode (see std::ios_base).
436 * @c ios_base::in is automatically included in @a mode.
438 * Tip: When using std::string to hold the filename, you must use
439 * .c_str() before passing it to this constructor.
442 basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
443 : __istream_type(), _M_filebuf()
445 this->init(&_M_filebuf);
446 this->open(__s, __mode);
450 * @brief The destructor does nothing.
452 * The file is closed by the filebuf object, not the formatting
460 * @brief Accessing the underlying buffer.
461 * @return The current basic_filebuf buffer.
463 * This hides both signatures of std::basic_ios::rdbuf().
467 { return const_cast<__filebuf_type*>(&_M_filebuf); }
470 * @brief Wrapper to test for an open file.
471 * @return @c rdbuf()->is_open()
475 { return _M_filebuf.is_open(); }
477 // _GLIBCXX_RESOLVE_LIB_DEFECTS
478 // 365. Lack of const-qualification in clause 27
481 { return _M_filebuf.is_open(); }
484 * @brief Opens an external file.
485 * @param s The name of the file.
486 * @param mode The open mode flags.
488 * Calls @c std::basic_filebuf::open(s,mode|in). If that function
489 * fails, @c failbit is set in the stream's error state.
491 * Tip: When using std::string to hold the filename, you must use
492 * .c_str() before passing it to this constructor.
495 open(const char* __s, ios_base::openmode __mode = ios_base::in)
497 if (!_M_filebuf.open(__s, __mode | ios_base::in))
498 this->setstate(ios_base::failbit);
500 // _GLIBCXX_RESOLVE_LIB_DEFECTS
501 // 409. Closing an fstream should clear error state
506 * @brief Close the file.
508 * Calls @c std::basic_filebuf::close(). If that function
509 * fails, @c failbit is set in the stream's error state.
514 if (!_M_filebuf.close())
515 this->setstate(ios_base::failbit);
520 // [27.8.1.8] Template class basic_ofstream
522 * @brief Controlling output for files.
524 * This class supports reading from named files, using the inherited
525 * functions from std::basic_ostream. To control the associated
526 * sequence, an instance of std::basic_filebuf is used, which this page
527 * refers to as @c sb.
529 template<typename _CharT, typename _Traits>
530 class basic_ofstream : public basic_ostream<_CharT,_Traits>
534 typedef _CharT char_type;
535 typedef _Traits traits_type;
536 typedef typename traits_type::int_type int_type;
537 typedef typename traits_type::pos_type pos_type;
538 typedef typename traits_type::off_type off_type;
540 // Non-standard types:
541 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
542 typedef basic_ostream<char_type, traits_type> __ostream_type;
545 __filebuf_type _M_filebuf;
550 * @brief Default constructor.
552 * Initializes @c sb using its default constructor, and passes
553 * @c &sb to the base class initializer. Does not open any files
554 * (you haven't given it a filename to open).
556 basic_ofstream(): __ostream_type(), _M_filebuf()
557 { this->init(&_M_filebuf); }
560 * @brief Create an output file stream.
561 * @param s Null terminated string specifying the filename.
562 * @param mode Open file in specified mode (see std::ios_base).
564 * @c ios_base::out|ios_base::trunc is automatically included in
567 * Tip: When using std::string to hold the filename, you must use
568 * .c_str() before passing it to this constructor.
571 basic_ofstream(const char* __s,
572 ios_base::openmode __mode = ios_base::out|ios_base::trunc)
573 : __ostream_type(), _M_filebuf()
575 this->init(&_M_filebuf);
576 this->open(__s, __mode);
580 * @brief The destructor does nothing.
582 * The file is closed by the filebuf object, not the formatting
590 * @brief Accessing the underlying buffer.
591 * @return The current basic_filebuf buffer.
593 * This hides both signatures of std::basic_ios::rdbuf().
597 { return const_cast<__filebuf_type*>(&_M_filebuf); }
600 * @brief Wrapper to test for an open file.
601 * @return @c rdbuf()->is_open()
605 { return _M_filebuf.is_open(); }
607 // _GLIBCXX_RESOLVE_LIB_DEFECTS
608 // 365. Lack of const-qualification in clause 27
611 { return _M_filebuf.is_open(); }
614 * @brief Opens an external file.
615 * @param s The name of the file.
616 * @param mode The open mode flags.
618 * Calls @c std::basic_filebuf::open(s,mode|out|trunc). If that
619 * function fails, @c failbit is set in the stream's error state.
621 * Tip: When using std::string to hold the filename, you must use
622 * .c_str() before passing it to this constructor.
625 open(const char* __s,
626 ios_base::openmode __mode = ios_base::out | ios_base::trunc)
628 if (!_M_filebuf.open(__s, __mode | ios_base::out))
629 this->setstate(ios_base::failbit);
631 // _GLIBCXX_RESOLVE_LIB_DEFECTS
632 // 409. Closing an fstream should clear error state
637 * @brief Close the file.
639 * Calls @c std::basic_filebuf::close(). If that function
640 * fails, @c failbit is set in the stream's error state.
645 if (!_M_filebuf.close())
646 this->setstate(ios_base::failbit);
651 // [27.8.1.11] Template class basic_fstream
653 * @brief Controlling input and output for files.
655 * This class supports reading from and writing to named files, using
656 * the inherited functions from std::basic_iostream. To control the
657 * associated sequence, an instance of std::basic_filebuf is used, which
658 * this page refers to as @c sb.
660 template<typename _CharT, typename _Traits>
661 class basic_fstream : public basic_iostream<_CharT, _Traits>
665 typedef _CharT char_type;
666 typedef _Traits traits_type;
667 typedef typename traits_type::int_type int_type;
668 typedef typename traits_type::pos_type pos_type;
669 typedef typename traits_type::off_type off_type;
671 // Non-standard types:
672 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
673 typedef basic_ios<char_type, traits_type> __ios_type;
674 typedef basic_iostream<char_type, traits_type> __iostream_type;
677 __filebuf_type _M_filebuf;
680 // Constructors/destructor:
682 * @brief Default constructor.
684 * Initializes @c sb using its default constructor, and passes
685 * @c &sb to the base class initializer. Does not open any files
686 * (you haven't given it a filename to open).
689 : __iostream_type(), _M_filebuf()
690 { this->init(&_M_filebuf); }
693 * @brief Create an input/output file stream.
694 * @param s Null terminated string specifying the filename.
695 * @param mode Open file in specified mode (see std::ios_base).
697 * Tip: When using std::string to hold the filename, you must use
698 * .c_str() before passing it to this constructor.
701 basic_fstream(const char* __s,
702 ios_base::openmode __mode = ios_base::in | ios_base::out)
703 : __iostream_type(NULL), _M_filebuf()
705 this->init(&_M_filebuf);
706 this->open(__s, __mode);
710 * @brief The destructor does nothing.
712 * The file is closed by the filebuf object, not the formatting
720 * @brief Accessing the underlying buffer.
721 * @return The current basic_filebuf buffer.
723 * This hides both signatures of std::basic_ios::rdbuf().
727 { return const_cast<__filebuf_type*>(&_M_filebuf); }
730 * @brief Wrapper to test for an open file.
731 * @return @c rdbuf()->is_open()
735 { return _M_filebuf.is_open(); }
737 // _GLIBCXX_RESOLVE_LIB_DEFECTS
738 // 365. Lack of const-qualification in clause 27
741 { return _M_filebuf.is_open(); }
744 * @brief Opens an external file.
745 * @param s The name of the file.
746 * @param mode The open mode flags.
748 * Calls @c std::basic_filebuf::open(s,mode). If that
749 * function fails, @c failbit is set in the stream's error state.
751 * Tip: When using std::string to hold the filename, you must use
752 * .c_str() before passing it to this constructor.
755 open(const char* __s,
756 ios_base::openmode __mode = ios_base::in | ios_base::out)
758 if (!_M_filebuf.open(__s, __mode))
759 this->setstate(ios_base::failbit);
761 // _GLIBCXX_RESOLVE_LIB_DEFECTS
762 // 409. Closing an fstream should clear error state
767 * @brief Close the file.
769 * Calls @c std::basic_filebuf::close(). If that function
770 * fails, @c failbit is set in the stream's error state.
775 if (!_M_filebuf.close())
776 this->setstate(ios_base::failbit);
780 _GLIBCXX_END_NAMESPACE
782 #ifndef _GLIBCXX_EXPORT_TEMPLATE
783 # include <bits/fstream.tcc>
786 #endif /* _GLIBCXX_FSTREAM */