fstream.tcc

Go to the documentation of this file.
00001 // File based streams -*- C++ -*-
00002 
00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
00004 // 2007, 2008, 2009
00005 // Free Software Foundation, Inc.
00006 //
00007 // This file is part of the GNU ISO C++ Library.  This library is free
00008 // software; you can redistribute it and/or modify it under the
00009 // terms of the GNU General Public License as published by the
00010 // Free Software Foundation; either version 3, or (at your option)
00011 // any later version.
00012 
00013 // This library is distributed in the hope that it will be useful,
00014 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00015 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016 // GNU General Public License for more details.
00017 
00018 // Under Section 7 of GPL version 3, you are granted additional
00019 // permissions described in the GCC Runtime Library Exception, version
00020 // 3.1, as published by the Free Software Foundation.
00021 
00022 // You should have received a copy of the GNU General Public License and
00023 // a copy of the GCC Runtime Library Exception along with this program;
00024 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00025 // <http://www.gnu.org/licenses/>.
00026 
00027 /** @file fstream.tcc
00028  *  This is an internal header file, included by other library headers.
00029  *  You should not attempt to use it directly.
00030  */
00031 
00032 //
00033 // ISO C++ 14882: 27.8  File-based streams
00034 //
00035 
00036 #ifndef _FSTREAM_TCC
00037 #define _FSTREAM_TCC 1
00038 
00039 #pragma GCC system_header
00040 
00041 #include <cxxabi-forced.h>
00042 
00043 _GLIBCXX_BEGIN_NAMESPACE(std)
00044 
00045   template<typename _CharT, typename _Traits>
00046     void
00047     basic_filebuf<_CharT, _Traits>::
00048     _M_allocate_internal_buffer()
00049     {
00050       // Allocate internal buffer only if one doesn't already exist
00051       // (either allocated or provided by the user via setbuf).
00052       if (!_M_buf_allocated && !_M_buf)
00053     {
00054       _M_buf = new char_type[_M_buf_size];
00055       _M_buf_allocated = true;
00056     }
00057     }
00058 
00059   template<typename _CharT, typename _Traits>
00060     void
00061     basic_filebuf<_CharT, _Traits>::
00062     _M_destroy_internal_buffer() throw()
00063     {
00064       if (_M_buf_allocated)
00065     {
00066       delete [] _M_buf;
00067       _M_buf = NULL;
00068       _M_buf_allocated = false;
00069     }
00070       delete [] _M_ext_buf;
00071       _M_ext_buf = NULL;
00072       _M_ext_buf_size = 0;
00073       _M_ext_next = NULL;
00074       _M_ext_end = NULL;
00075     }
00076 
00077   template<typename _CharT, typename _Traits>
00078     basic_filebuf<_CharT, _Traits>::
00079     basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
00080     _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
00081     _M_state_last(), _M_buf(NULL), _M_buf_size(BUFSIZ),
00082     _M_buf_allocated(false), _M_reading(false), _M_writing(false), _M_pback(), 
00083     _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
00084     _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
00085     _M_ext_end(0)
00086     {
00087       if (has_facet<__codecvt_type>(this->_M_buf_locale))
00088     _M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
00089     }
00090 
00091   template<typename _CharT, typename _Traits>
00092     typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
00093     basic_filebuf<_CharT, _Traits>::
00094     open(const char* __s, ios_base::openmode __mode)
00095     {
00096       __filebuf_type *__ret = NULL;
00097       if (!this->is_open())
00098     {
00099       _M_file.open(__s, __mode);
00100       if (this->is_open())
00101         {
00102           _M_allocate_internal_buffer();
00103           _M_mode = __mode;
00104 
00105           // Setup initial buffer to 'uncommitted' mode.
00106           _M_reading = false;
00107           _M_writing = false;
00108           _M_set_buffer(-1);
00109 
00110           // Reset to initial state.
00111           _M_state_last = _M_state_cur = _M_state_beg;
00112 
00113           // 27.8.1.3,4
00114           if ((__mode & ios_base::ate)
00115           && this->seekoff(0, ios_base::end, __mode)
00116           == pos_type(off_type(-1)))
00117         this->close();
00118           else
00119         __ret = this;
00120         }
00121     }
00122       return __ret;
00123     }
00124 
00125   template<typename _CharT, typename _Traits>
00126     typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
00127     basic_filebuf<_CharT, _Traits>::
00128     close()
00129     {
00130       if (!this->is_open())
00131     return NULL;
00132 
00133       bool __testfail = false;
00134       {
00135     // NB: Do this here so that re-opened filebufs will be cool...
00136     struct __close_sentry
00137     {
00138       basic_filebuf *__fb;
00139       __close_sentry (basic_filebuf *__fbi): __fb(__fbi) { }
00140       ~__close_sentry ()
00141       {
00142         __fb->_M_mode = ios_base::openmode(0);
00143         __fb->_M_pback_init = false;
00144         __fb->_M_destroy_internal_buffer();
00145         __fb->_M_reading = false;
00146         __fb->_M_writing = false;
00147         __fb->_M_set_buffer(-1);
00148         __fb->_M_state_last = __fb->_M_state_cur = __fb->_M_state_beg;
00149       }
00150     } __cs (this);
00151 
00152     __try
00153       {
00154         if (!_M_terminate_output())
00155           __testfail = true;
00156       }
00157     __catch(__cxxabiv1::__forced_unwind&)
00158       {
00159         _M_file.close();
00160         __throw_exception_again;
00161       }
00162     __catch(...)
00163       { __testfail = true; }
00164       }
00165 
00166       if (!_M_file.close())
00167     __testfail = true;
00168 
00169       if (__testfail)
00170     return NULL;
00171       else
00172     return this;
00173     }
00174 
00175   template<typename _CharT, typename _Traits>
00176     streamsize
00177     basic_filebuf<_CharT, _Traits>::
00178     showmanyc()
00179     {
00180       streamsize __ret = -1;
00181       const bool __testin = _M_mode & ios_base::in;
00182       if (__testin && this->is_open())
00183     {
00184       // For a stateful encoding (-1) the pending sequence might be just
00185       // shift and unshift prefixes with no actual character.
00186       __ret = this->egptr() - this->gptr();
00187 
00188 #if _GLIBCXX_HAVE_DOS_BASED_FILESYSTEM
00189       // About this workaround, see libstdc++/20806.
00190       const bool __testbinary = _M_mode & ios_base::binary;
00191       if (__check_facet(_M_codecvt).encoding() >= 0
00192           && __testbinary)
00193 #else
00194       if (__check_facet(_M_codecvt).encoding() >= 0)
00195 #endif
00196         __ret += _M_file.showmanyc() / _M_codecvt->max_length();
00197     }
00198       return __ret;
00199     }
00200 
00201   template<typename _CharT, typename _Traits>
00202     typename basic_filebuf<_CharT, _Traits>::int_type
00203     basic_filebuf<_CharT, _Traits>::
00204     underflow()
00205     {
00206       int_type __ret = traits_type::eof();
00207       const bool __testin = _M_mode & ios_base::in;
00208       if (__testin && !_M_writing)
00209     {
00210       // Check for pback madness, and if so switch back to the
00211       // normal buffers and jet outta here before expensive
00212       // fileops happen...
00213       _M_destroy_pback();
00214 
00215       if (this->gptr() < this->egptr())
00216         return traits_type::to_int_type(*this->gptr());
00217 
00218       // Get and convert input sequence.
00219       const size_t __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
00220 
00221       // Will be set to true if ::read() returns 0 indicating EOF.
00222       bool __got_eof = false;
00223       // Number of internal characters produced.
00224       streamsize __ilen = 0;
00225       codecvt_base::result __r = codecvt_base::ok;
00226       if (__check_facet(_M_codecvt).always_noconv())
00227         {
00228           __ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
00229                       __buflen);
00230           if (__ilen == 0)
00231         __got_eof = true;
00232         }
00233       else
00234         {
00235               // Worst-case number of external bytes.
00236           // XXX Not done encoding() == -1.
00237           const int __enc = _M_codecvt->encoding();
00238           streamsize __blen; // Minimum buffer size.
00239           streamsize __rlen; // Number of chars to read.
00240           if (__enc > 0)
00241         __blen = __rlen = __buflen * __enc;
00242           else
00243         {
00244           __blen = __buflen + _M_codecvt->max_length() - 1;
00245           __rlen = __buflen;
00246         }
00247           const streamsize __remainder = _M_ext_end - _M_ext_next;
00248           __rlen = __rlen > __remainder ? __rlen - __remainder : 0;
00249 
00250           // An imbue in 'read' mode implies first converting the external
00251           // chars already present.
00252           if (_M_reading && this->egptr() == this->eback() && __remainder)
00253         __rlen = 0;
00254 
00255           // Allocate buffer if necessary and move unconverted
00256           // bytes to front.
00257           if (_M_ext_buf_size < __blen)
00258         {
00259           char* __buf = new char[__blen];
00260           if (__remainder)
00261             __builtin_memcpy(__buf, _M_ext_next, __remainder);
00262 
00263           delete [] _M_ext_buf;
00264           _M_ext_buf = __buf;
00265           _M_ext_buf_size = __blen;
00266         }
00267           else if (__remainder)
00268         __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
00269 
00270           _M_ext_next = _M_ext_buf;
00271           _M_ext_end = _M_ext_buf + __remainder;
00272           _M_state_last = _M_state_cur;
00273 
00274           do
00275         {
00276           if (__rlen > 0)
00277             {
00278               // Sanity check!
00279               // This may fail if the return value of
00280               // codecvt::max_length() is bogus.
00281               if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
00282             {
00283               __throw_ios_failure(__N("basic_filebuf::underflow "
00284                           "codecvt::max_length() "
00285                           "is not valid"));
00286             }
00287               streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
00288               if (__elen == 0)
00289             __got_eof = true;
00290               else if (__elen == -1)
00291             break;
00292               _M_ext_end += __elen;
00293             }
00294 
00295           char_type* __iend = this->eback();
00296           if (_M_ext_next < _M_ext_end)
00297             __r = _M_codecvt->in(_M_state_cur, _M_ext_next,
00298                      _M_ext_end, _M_ext_next,
00299                      this->eback(),
00300                      this->eback() + __buflen, __iend);
00301           if (__r == codecvt_base::noconv)
00302             {
00303               size_t __avail = _M_ext_end - _M_ext_buf;
00304               __ilen = std::min(__avail, __buflen);
00305               traits_type::copy(this->eback(),
00306                     reinterpret_cast<char_type*>
00307                     (_M_ext_buf), __ilen);
00308               _M_ext_next = _M_ext_buf + __ilen;
00309             }
00310           else
00311             __ilen = __iend - this->eback();
00312 
00313           // _M_codecvt->in may return error while __ilen > 0: this is
00314           // ok, and actually occurs in case of mixed encodings (e.g.,
00315           // XML files).
00316           if (__r == codecvt_base::error)
00317             break;
00318 
00319           __rlen = 1;
00320         }
00321           while (__ilen == 0 && !__got_eof);
00322         }
00323 
00324       if (__ilen > 0)
00325         {
00326           _M_set_buffer(__ilen);
00327           _M_reading = true;
00328           __ret = traits_type::to_int_type(*this->gptr());
00329         }
00330       else if (__got_eof)
00331         {
00332           // If the actual end of file is reached, set 'uncommitted'
00333           // mode, thus allowing an immediate write without an
00334           // intervening seek.
00335           _M_set_buffer(-1);
00336           _M_reading = false;
00337           // However, reaching it while looping on partial means that
00338           // the file has got an incomplete character.
00339           if (__r == codecvt_base::partial)
00340         __throw_ios_failure(__N("basic_filebuf::underflow "
00341                     "incomplete character in file"));
00342         }
00343       else if (__r == codecvt_base::error)
00344         __throw_ios_failure(__N("basic_filebuf::underflow "
00345                 "invalid byte sequence in file"));
00346       else
00347         __throw_ios_failure(__N("basic_filebuf::underflow "
00348                 "error reading the file"));
00349     }
00350       return __ret;
00351     }
00352 
00353   template<typename _CharT, typename _Traits>
00354     typename basic_filebuf<_CharT, _Traits>::int_type
00355     basic_filebuf<_CharT, _Traits>::
00356     pbackfail(int_type __i)
00357     {
00358       int_type __ret = traits_type::eof();
00359       const bool __testin = _M_mode & ios_base::in;
00360       if (__testin && !_M_writing)
00361     {
00362       // Remember whether the pback buffer is active, otherwise below
00363       // we may try to store in it a second char (libstdc++/9761).
00364       const bool __testpb = _M_pback_init;
00365       const bool __testeof = traits_type::eq_int_type(__i, __ret);
00366       int_type __tmp;
00367       if (this->eback() < this->gptr())
00368         {
00369           this->gbump(-1);
00370           __tmp = traits_type::to_int_type(*this->gptr());
00371         }
00372       else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
00373         {
00374           __tmp = this->underflow();
00375           if (traits_type::eq_int_type(__tmp, __ret))
00376         return __ret;
00377         }
00378       else
00379         {
00380           // At the beginning of the buffer, need to make a
00381           // putback position available.  But the seek may fail
00382           // (f.i., at the beginning of a file, see
00383           // libstdc++/9439) and in that case we return
00384           // traits_type::eof().
00385           return __ret;
00386         }
00387 
00388       // Try to put back __i into input sequence in one of three ways.
00389       // Order these tests done in is unspecified by the standard.
00390       if (!__testeof && traits_type::eq_int_type(__i, __tmp))
00391         __ret = __i;
00392       else if (__testeof)
00393         __ret = traits_type::not_eof(__i);
00394       else if (!__testpb)
00395         {
00396           _M_create_pback();
00397           _M_reading = true;
00398           *this->gptr() = traits_type::to_char_type(__i);
00399           __ret = __i;
00400         }
00401     }
00402       return __ret;
00403     }
00404 
00405   template<typename _CharT, typename _Traits>
00406     typename basic_filebuf<_CharT, _Traits>::int_type
00407     basic_filebuf<_CharT, _Traits>::
00408     overflow(int_type __c)
00409     {
00410       int_type __ret = traits_type::eof();
00411       const bool __testeof = traits_type::eq_int_type(__c, __ret);
00412       const bool __testout = _M_mode & ios_base::out;
00413       if (__testout && !_M_reading)
00414     {
00415       if (this->pbase() < this->pptr())
00416         {
00417           // If appropriate, append the overflow char.
00418           if (!__testeof)
00419         {
00420           *this->pptr() = traits_type::to_char_type(__c);
00421           this->pbump(1);
00422         }
00423 
00424           // Convert pending sequence to external representation,
00425           // and output.
00426           if (_M_convert_to_external(this->pbase(),
00427                      this->pptr() - this->pbase()))
00428         {
00429           _M_set_buffer(0);
00430           __ret = traits_type::not_eof(__c);
00431         }
00432         }
00433       else if (_M_buf_size > 1)
00434         {
00435           // Overflow in 'uncommitted' mode: set _M_writing, set
00436           // the buffer to the initial 'write' mode, and put __c
00437           // into the buffer.
00438           _M_set_buffer(0);
00439           _M_writing = true;
00440           if (!__testeof)
00441         {
00442           *this->pptr() = traits_type::to_char_type(__c);
00443           this->pbump(1);
00444         }
00445           __ret = traits_type::not_eof(__c);
00446         }
00447       else
00448         {
00449           // Unbuffered.
00450           char_type __conv = traits_type::to_char_type(__c);
00451           if (__testeof || _M_convert_to_external(&__conv, 1))
00452         {
00453           _M_writing = true;
00454           __ret = traits_type::not_eof(__c);
00455         }
00456         }
00457     }
00458       return __ret;
00459     }
00460 
00461   template<typename _CharT, typename _Traits>
00462     bool
00463     basic_filebuf<_CharT, _Traits>::
00464     _M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
00465     {
00466       // Sizes of external and pending output.
00467       streamsize __elen;
00468       streamsize __plen;
00469       if (__check_facet(_M_codecvt).always_noconv())
00470     {
00471       __elen = _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
00472       __plen = __ilen;
00473     }
00474       else
00475     {
00476       // Worst-case number of external bytes needed.
00477       // XXX Not done encoding() == -1.
00478       streamsize __blen = __ilen * _M_codecvt->max_length();
00479       char* __buf = static_cast<char*>(__builtin_alloca(__blen));
00480 
00481       char* __bend;
00482       const char_type* __iend;
00483       codecvt_base::result __r;
00484       __r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
00485                 __iend, __buf, __buf + __blen, __bend);
00486 
00487       if (__r == codecvt_base::ok || __r == codecvt_base::partial)
00488         __blen = __bend - __buf;
00489       else if (__r == codecvt_base::noconv)
00490         {
00491           // Same as the always_noconv case above.
00492           __buf = reinterpret_cast<char*>(__ibuf);
00493           __blen = __ilen;
00494         }
00495       else
00496         __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
00497                     "conversion error"));
00498   
00499       __elen = _M_file.xsputn(__buf, __blen);
00500       __plen = __blen;
00501 
00502       // Try once more for partial conversions.
00503       if (__r == codecvt_base::partial && __elen == __plen)
00504         {
00505           const char_type* __iresume = __iend;
00506           streamsize __rlen = this->pptr() - __iend;
00507           __r = _M_codecvt->out(_M_state_cur, __iresume,
00508                     __iresume + __rlen, __iend, __buf,
00509                     __buf + __blen, __bend);
00510           if (__r != codecvt_base::error)
00511         {
00512           __rlen = __bend - __buf;
00513           __elen = _M_file.xsputn(__buf, __rlen);
00514           __plen = __rlen;
00515         }
00516           else
00517         __throw_ios_failure(__N("basic_filebuf::_M_convert_to_external "
00518                     "conversion error"));
00519         }
00520     }
00521       return __elen == __plen;
00522     }
00523 
00524    template<typename _CharT, typename _Traits>
00525      streamsize
00526      basic_filebuf<_CharT, _Traits>::
00527      xsgetn(_CharT* __s, streamsize __n)
00528      {
00529        // Clear out pback buffer before going on to the real deal...
00530        streamsize __ret = 0;
00531        if (_M_pback_init)
00532      {
00533        if (__n > 0 && this->gptr() == this->eback())
00534          {
00535            *__s++ = *this->gptr();
00536            this->gbump(1);
00537            __ret = 1;
00538            --__n;
00539          }
00540        _M_destroy_pback();
00541      }
00542        
00543        // Optimization in the always_noconv() case, to be generalized in the
00544        // future: when __n > __buflen we read directly instead of using the
00545        // buffer repeatedly.
00546        const bool __testin = _M_mode & ios_base::in;
00547        const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
00548 
00549        if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
00550        && __testin && !_M_writing)
00551      {
00552        // First, copy the chars already present in the buffer.
00553        const streamsize __avail = this->egptr() - this->gptr();
00554        if (__avail != 0)
00555          {
00556            if (__avail == 1)
00557          *__s = *this->gptr();
00558            else
00559          traits_type::copy(__s, this->gptr(), __avail);
00560            __s += __avail;
00561            this->gbump(__avail);
00562            __ret += __avail;
00563            __n -= __avail;
00564          }
00565 
00566        // Need to loop in case of short reads (relatively common
00567        // with pipes).
00568        streamsize __len;
00569        for (;;)
00570          {
00571            __len = _M_file.xsgetn(reinterpret_cast<char*>(__s),
00572                       __n);
00573            if (__len == -1)
00574          __throw_ios_failure(__N("basic_filebuf::xsgetn "
00575                      "error reading the file"));
00576            if (__len == 0)
00577          break;
00578 
00579            __n -= __len;
00580            __ret += __len;
00581            if (__n == 0)
00582          break;
00583 
00584            __s += __len;
00585          }
00586 
00587        if (__n == 0)
00588          {
00589            _M_set_buffer(0);
00590            _M_reading = true;
00591          }
00592        else if (__len == 0)
00593          {
00594            // If end of file is reached, set 'uncommitted'
00595            // mode, thus allowing an immediate write without
00596            // an intervening seek.
00597            _M_set_buffer(-1);
00598            _M_reading = false;
00599          }
00600      }
00601        else
00602      __ret += __streambuf_type::xsgetn(__s, __n);
00603 
00604        return __ret;
00605      }
00606 
00607    template<typename _CharT, typename _Traits>
00608      streamsize
00609      basic_filebuf<_CharT, _Traits>::
00610      xsputn(const _CharT* __s, streamsize __n)
00611      {
00612        // Optimization in the always_noconv() case, to be generalized in the
00613        // future: when __n is sufficiently large we write directly instead of
00614        // using the buffer.
00615        streamsize __ret = 0;
00616        const bool __testout = _M_mode & ios_base::out;
00617        if (__check_facet(_M_codecvt).always_noconv()
00618        && __testout && !_M_reading)
00619     {
00620       // Measurement would reveal the best choice.
00621       const streamsize __chunk = 1ul << 10;
00622       streamsize __bufavail = this->epptr() - this->pptr();
00623 
00624       // Don't mistake 'uncommitted' mode buffered with unbuffered.
00625       if (!_M_writing && _M_buf_size > 1)
00626         __bufavail = _M_buf_size - 1;
00627 
00628       const streamsize __limit = std::min(__chunk, __bufavail);
00629       if (__n >= __limit)
00630         {
00631           const streamsize __buffill = this->pptr() - this->pbase();
00632           const char* __buf = reinterpret_cast<const char*>(this->pbase());
00633           __ret = _M_file.xsputn_2(__buf, __buffill,
00634                        reinterpret_cast<const char*>(__s),
00635                        __n);
00636           if (__ret == __buffill + __n)
00637         {
00638           _M_set_buffer(0);
00639           _M_writing = true;
00640         }
00641           if (__ret > __buffill)
00642         __ret -= __buffill;
00643           else
00644         __ret = 0;
00645         }
00646       else
00647         __ret = __streambuf_type::xsputn(__s, __n);
00648     }
00649        else
00650      __ret = __streambuf_type::xsputn(__s, __n);
00651        return __ret;
00652     }
00653 
00654   template<typename _CharT, typename _Traits>
00655     typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
00656     basic_filebuf<_CharT, _Traits>::
00657     setbuf(char_type* __s, streamsize __n)
00658     {
00659       if (!this->is_open())
00660     {
00661       if (__s == 0 && __n == 0)
00662         _M_buf_size = 1;
00663       else if (__s && __n > 0)
00664         {
00665           // This is implementation-defined behavior, and assumes that
00666           // an external char_type array of length __n exists and has
00667           // been pre-allocated. If this is not the case, things will
00668           // quickly blow up. When __n > 1, __n - 1 positions will be
00669           // used for the get area, __n - 1 for the put area and 1
00670           // position to host the overflow char of a full put area.
00671           // When __n == 1, 1 position will be used for the get area
00672           // and 0 for the put area, as in the unbuffered case above.
00673           _M_buf = __s;
00674           _M_buf_size = __n;
00675         }
00676     }
00677       return this;
00678     }
00679 
00680 
00681   // According to 27.8.1.4 p11 - 13, seekoff should ignore the last
00682   // argument (of type openmode).
00683   template<typename _CharT, typename _Traits>
00684     typename basic_filebuf<_CharT, _Traits>::pos_type
00685     basic_filebuf<_CharT, _Traits>::
00686     seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
00687     {
00688       int __width = 0;
00689       if (_M_codecvt)
00690     __width = _M_codecvt->encoding();
00691       if (__width < 0)
00692     __width = 0;
00693 
00694       pos_type __ret =  pos_type(off_type(-1));
00695       const bool __testfail = __off != 0 && __width <= 0;
00696       if (this->is_open() && !__testfail)
00697     {
00698       // Ditch any pback buffers to avoid confusion.
00699       _M_destroy_pback();
00700 
00701       // Correct state at destination. Note that this is the correct
00702       // state for the current position during output, because
00703       // codecvt::unshift() returns the state to the initial state.
00704       // This is also the correct state at the end of the file because
00705       // an unshift sequence should have been written at the end.
00706       __state_type __state = _M_state_beg;
00707       off_type __computed_off = __off * __width;
00708       if (_M_reading && __way == ios_base::cur)
00709         {
00710           if (_M_codecvt->always_noconv())
00711         __computed_off += this->gptr() - this->egptr();
00712           else
00713         {
00714           // Calculate offset from _M_ext_buf that corresponds
00715           // to gptr(). Note: uses _M_state_last, which
00716           // corresponds to eback().
00717           const int __gptr_off =
00718             _M_codecvt->length(_M_state_last, _M_ext_buf, _M_ext_next,
00719                        this->gptr() - this->eback());
00720           __computed_off += _M_ext_buf + __gptr_off - _M_ext_end;
00721 
00722           // _M_state_last is modified by codecvt::length() so
00723           // it now corresponds to gptr().
00724           __state = _M_state_last;
00725         }
00726         }
00727       __ret = _M_seek(__computed_off, __way, __state);
00728     }
00729       return __ret;
00730     }
00731 
00732   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00733   // 171. Strange seekpos() semantics due to joint position
00734   // According to the resolution of DR 171, seekpos should ignore the last
00735   // argument (of type openmode).
00736   template<typename _CharT, typename _Traits>
00737     typename basic_filebuf<_CharT, _Traits>::pos_type
00738     basic_filebuf<_CharT, _Traits>::
00739     seekpos(pos_type __pos, ios_base::openmode)
00740     {
00741       pos_type __ret =  pos_type(off_type(-1));
00742       if (this->is_open())
00743     {
00744       // Ditch any pback buffers to avoid confusion.
00745       _M_destroy_pback();
00746       __ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
00747     }
00748       return __ret;
00749     }
00750 
00751   template<typename _CharT, typename _Traits>
00752     typename basic_filebuf<_CharT, _Traits>::pos_type
00753     basic_filebuf<_CharT, _Traits>::
00754     _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
00755     {
00756       pos_type __ret = pos_type(off_type(-1));
00757       if (_M_terminate_output())
00758     {
00759       // Returns pos_type(off_type(-1)) in case of failure.
00760       __ret = pos_type(_M_file.seekoff(__off, __way));
00761       if (__ret != pos_type(off_type(-1)))
00762         {
00763           _M_reading = false;
00764           _M_writing = false;
00765           _M_ext_next = _M_ext_end = _M_ext_buf;
00766           _M_set_buffer(-1);
00767           _M_state_cur = __state;
00768           __ret.state(_M_state_cur);
00769         }
00770     }
00771       return __ret;
00772     }
00773 
00774   template<typename _CharT, typename _Traits>
00775     bool
00776     basic_filebuf<_CharT, _Traits>::
00777     _M_terminate_output()
00778     {
00779       // Part one: update the output sequence.
00780       bool __testvalid = true;
00781       if (this->pbase() < this->pptr())
00782     {
00783       const int_type __tmp = this->overflow();
00784       if (traits_type::eq_int_type(__tmp, traits_type::eof()))
00785         __testvalid = false;
00786     }
00787 
00788       // Part two: output unshift sequence.
00789       if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
00790       && __testvalid)
00791     {
00792       // Note: this value is arbitrary, since there is no way to
00793       // get the length of the unshift sequence from codecvt,
00794       // without calling unshift.
00795       const size_t __blen = 128;
00796       char __buf[__blen];
00797       codecvt_base::result __r;
00798       streamsize __ilen = 0;
00799 
00800       do
00801         {
00802           char* __next;
00803           __r = _M_codecvt->unshift(_M_state_cur, __buf,
00804                     __buf + __blen, __next);
00805           if (__r == codecvt_base::error)
00806         __testvalid = false;
00807           else if (__r == codecvt_base::ok ||
00808                __r == codecvt_base::partial)
00809         {
00810           __ilen = __next - __buf;
00811           if (__ilen > 0)
00812             {
00813               const streamsize __elen = _M_file.xsputn(__buf, __ilen);
00814               if (__elen != __ilen)
00815             __testvalid = false;
00816             }
00817         }
00818         }
00819       while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
00820 
00821       if (__testvalid)
00822         {
00823           // This second call to overflow() is required by the standard,
00824           // but it's not clear why it's needed, since the output buffer
00825           // should be empty by this point (it should have been emptied
00826           // in the first call to overflow()).
00827           const int_type __tmp = this->overflow();
00828           if (traits_type::eq_int_type(__tmp, traits_type::eof()))
00829         __testvalid = false;
00830         }
00831     }
00832       return __testvalid;
00833     }
00834 
00835   template<typename _CharT, typename _Traits>
00836     int
00837     basic_filebuf<_CharT, _Traits>::
00838     sync()
00839     {
00840       // Make sure that the internal buffer resyncs its idea of
00841       // the file position with the external file.
00842       int __ret = 0;
00843       if (this->pbase() < this->pptr())
00844     {
00845       const int_type __tmp = this->overflow();
00846       if (traits_type::eq_int_type(__tmp, traits_type::eof()))
00847         __ret = -1;
00848     }
00849       return __ret;
00850     }
00851 
00852   template<typename _CharT, typename _Traits>
00853     void
00854     basic_filebuf<_CharT, _Traits>::
00855     imbue(const locale& __loc)
00856     {
00857       bool __testvalid = true;
00858 
00859       const __codecvt_type* _M_codecvt_tmp = 0;
00860       if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
00861     _M_codecvt_tmp = &use_facet<__codecvt_type>(__loc);
00862 
00863       if (this->is_open())
00864     {
00865       // encoding() == -1 is ok only at the beginning.
00866       if ((_M_reading || _M_writing)
00867           && __check_facet(_M_codecvt).encoding() == -1)
00868         __testvalid = false;
00869       else
00870         {
00871           if (_M_reading)
00872         {
00873           if (__check_facet(_M_codecvt).always_noconv())
00874             {
00875               if (_M_codecvt_tmp
00876               && !__check_facet(_M_codecvt_tmp).always_noconv())
00877             __testvalid = this->seekoff(0, ios_base::cur, _M_mode)
00878                           != pos_type(off_type(-1));
00879             }
00880           else
00881             {
00882               // External position corresponding to gptr().
00883               _M_ext_next = _M_ext_buf
00884             + _M_codecvt->length(_M_state_last, _M_ext_buf, _M_ext_next,
00885                          this->gptr() - this->eback());
00886               const streamsize __remainder = _M_ext_end - _M_ext_next;
00887               if (__remainder)
00888             __builtin_memmove(_M_ext_buf, _M_ext_next, __remainder);
00889 
00890               _M_ext_next = _M_ext_buf;
00891               _M_ext_end = _M_ext_buf + __remainder;
00892               _M_set_buffer(-1);
00893               _M_state_last = _M_state_cur = _M_state_beg;
00894             }
00895         }
00896           else if (_M_writing && (__testvalid = _M_terminate_output()))
00897         _M_set_buffer(-1);
00898         }
00899     }
00900 
00901       if (__testvalid)
00902     _M_codecvt = _M_codecvt_tmp;
00903       else
00904     _M_codecvt = 0;
00905     }
00906 
00907   // Inhibit implicit instantiations for required instantiations,
00908   // which are defined via explicit instantiations elsewhere.
00909   // NB:  This syntax is a GNU extension.
00910 #if _GLIBCXX_EXTERN_TEMPLATE
00911   extern template class basic_filebuf<char>;
00912   extern template class basic_ifstream<char>;
00913   extern template class basic_ofstream<char>;
00914   extern template class basic_fstream<char>;
00915 
00916 #ifdef _GLIBCXX_USE_WCHAR_T
00917   extern template class basic_filebuf<wchar_t>;
00918   extern template class basic_ifstream<wchar_t>;
00919   extern template class basic_ofstream<wchar_t>;
00920   extern template class basic_fstream<wchar_t>;
00921 #endif
00922 #endif
00923 
00924 _GLIBCXX_END_NAMESPACE
00925 
00926 #endif

Generated on Thu Jul 23 21:16:06 2009 for libstdc++ by  doxygen 1.5.8