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gcc/libstdc++-v3/include/bits/fstream.tcc
Paolo Carlini dfad48c6e8 re PR libstdc++/12875 (Weird behaviour in basic_filebuf::setbuf()) 
2003-11-11  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/12875
	* include/bits/fstream.tcc (setbuf): Don't do anything
	after open(), in particular don't discard data.
	(_M_allocate_internal_buffer): Tweak to not allocate memory
	in case the buffer is provided by the user via setbuf.
	* include/ext/stdio_filebuf.h: Tweak comment.
	* testsuite/27_io/basic_filebuf/setbuf/char/12875-1.cc: New.
	* testsuite/27_io/basic_filebuf/setbuf/char/12875-2.cc: Likewise.
	* testsuite/27_io/basic_filebuf/setbuf/char/2.cc: Tweak, now
	setbuf does nothing after open().
	* testsuite/27_io/basic_filebuf/setbuf/char/3.cc: Likewise.

From-SVN: r73477
2003-11-12 01:14:34 +00:00

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// File based streams -*- C++ -*-
// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING. If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
//
// ISO C++ 14882: 27.8 File-based streams
//
#ifndef _FSTREAM_TCC
#define _FSTREAM_TCC 1
#pragma GCC system_header
namespace std
{
template<typename _CharT, typename _Traits>
void
basic_filebuf<_CharT, _Traits>::
_M_allocate_internal_buffer()
{
// Allocate internal buffer only if one doesn't already exist
// (either allocated or provided by the user via setbuf).
if (!_M_buf_allocated && !this->_M_buf)
{
this->_M_buf = new char_type[this->_M_buf_size];
_M_buf_allocated = true;
}
}
template<typename _CharT, typename _Traits>
void
basic_filebuf<_CharT, _Traits>::
_M_destroy_internal_buffer() throw()
{
if (_M_buf_allocated)
{
delete [] this->_M_buf;
this->_M_buf = NULL;
_M_buf_allocated = false;
}
delete [] _M_ext_buf;
_M_ext_buf = NULL;
_M_ext_buf_size = 0;
_M_ext_next = NULL;
_M_ext_end = NULL;
}
template<typename _CharT, typename _Traits>
basic_filebuf<_CharT, _Traits>::
basic_filebuf() : __streambuf_type(), _M_file(&_M_lock),
_M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
_M_state_last(), _M_buf(NULL), _M_buf_size(BUFSIZ),
_M_buf_allocated(false), _M_reading(false), _M_writing(false),
_M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
_M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
_M_ext_end(0)
{
if (has_facet<__codecvt_type>(this->_M_buf_locale))
_M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
}
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
basic_filebuf<_CharT, _Traits>::
open(const char* __s, ios_base::openmode __mode)
{
__filebuf_type *__ret = NULL;
if (!this->is_open())
{
_M_file.open(__s, __mode);
if (this->is_open())
{
_M_allocate_internal_buffer();
this->_M_mode = __mode;
// Setup initial buffer to 'uncommitted' mode.
_M_reading = false;
_M_writing = false;
_M_set_buffer(-1);
// Reset to initial state.
_M_state_last = _M_state_cur = _M_state_beg;
// 27.8.1.3,4
if ((__mode & ios_base::ate)
&& this->seekoff(0, ios_base::end, __mode)
== pos_type(off_type(-1)))
this->close();
else
__ret = this;
}
}
return __ret;
}
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::__filebuf_type*
basic_filebuf<_CharT, _Traits>::
close() throw()
{
__filebuf_type* __ret = NULL;
if (this->is_open())
{
bool __testfail = false;
try
{
if (!_M_terminate_output())
__testfail = true;
}
catch(...)
{
__testfail = true;
}
// NB: Do this here so that re-opened filebufs will be cool...
this->_M_mode = ios_base::openmode(0);
this->_M_pback_init = false;
_M_destroy_internal_buffer();
_M_reading = false;
_M_writing = false;
_M_set_buffer(-1);
_M_state_last = _M_state_cur = _M_state_beg;
if (!_M_file.close())
__testfail = true;
if (!__testfail)
__ret = this;
}
return __ret;
}
template<typename _CharT, typename _Traits>
streamsize
basic_filebuf<_CharT, _Traits>::
showmanyc()
{
streamsize __ret = -1;
const bool __testin = this->_M_mode & ios_base::in;
if (__testin && this->is_open())
{
// For a stateful encoding (-1) the pending sequence might be just
// shift and unshift prefixes with no actual character.
__ret = this->egptr() - this->gptr();
if (__check_facet(_M_codecvt).encoding() >= 0)
__ret += _M_file.showmanyc() / _M_codecvt->max_length();
}
return __ret;
}
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::int_type
basic_filebuf<_CharT, _Traits>::
underflow()
{
int_type __ret = traits_type::eof();
const bool __testin = this->_M_mode & ios_base::in;
const bool __testout = this->_M_mode & ios_base::out;
if (__testin && !_M_writing)
{
// Check for pback madness, and if so swich back to the
// normal buffers and jet outta here before expensive
// fileops happen...
_M_destroy_pback();
if (this->gptr() < this->egptr())
return traits_type::to_int_type(*this->gptr());
// Get and convert input sequence.
const size_t __buflen = this->_M_buf_size > 1
? this->_M_buf_size - 1 : 1;
// Will be set to true if ::read() returns 0 indicating EOF.
bool __got_eof = false;
// Number of internal characters produced.
streamsize __ilen = 0;
if (__check_facet(_M_codecvt).always_noconv())
{
__ilen = _M_file.xsgetn(reinterpret_cast<char*>(this->eback()),
__buflen);
if (__ilen == 0)
__got_eof = true;
}
else
{
// Worst-case number of external bytes.
// XXX Not done encoding() == -1.
const int __enc = _M_codecvt->encoding();
streamsize __blen; // Minimum buffer size.
streamsize __rlen; // Number of chars to read.
if (__enc > 0)
__blen = __rlen = __buflen * __enc;
else
{
__blen = __buflen + _M_codecvt->max_length() - 1;
__rlen = __buflen;
}
const streamsize __remainder = _M_ext_end - _M_ext_next;
__rlen = __rlen > __remainder ? __rlen - __remainder : 0;
// Allocate buffer if necessary and move unconverted
// bytes to front.
if (_M_ext_buf_size < __blen)
{
char* __buf = new char[__blen];
if (__remainder > 0)
std::memcpy(__buf, _M_ext_next, __remainder);
delete [] _M_ext_buf;
_M_ext_buf = __buf;
_M_ext_buf_size = __blen;
}
else if (__remainder > 0)
std::memmove(_M_ext_buf, _M_ext_next, __remainder);
_M_ext_next = _M_ext_buf;
_M_ext_end = _M_ext_buf + __remainder;
_M_state_last = _M_state_cur;
do
{
if (__rlen > 0)
{
// Sanity check!
// This may fail if the return value of
// codecvt::max_length() is bogus.
if (_M_ext_end - _M_ext_buf + __rlen > _M_ext_buf_size)
{
__throw_ios_failure("codecvt::max_length() "
"is not valid");
}
streamsize __elen = _M_file.xsgetn(_M_ext_end, __rlen);
if (__elen == 0)
__got_eof = true;
_M_ext_end += __elen;
}
char_type* __iend;
codecvt_base::result __r;
__r = _M_codecvt->in(_M_state_cur, _M_ext_next,
_M_ext_end, _M_ext_next, this->eback(),
this->eback() + __buflen, __iend);
if (__r == codecvt_base::ok || __r == codecvt_base::partial)
__ilen = __iend - this->eback();
else if (__r == codecvt_base::noconv)
{
size_t __avail = _M_ext_end - _M_ext_buf;
__ilen = std::min(__avail, __buflen);
traits_type::copy(this->eback(),
reinterpret_cast<char_type*>(_M_ext_buf), __ilen);
_M_ext_next = _M_ext_buf + __ilen;
}
else
{
__ilen = 0;
break;
}
__rlen = 1;
}
while (!__got_eof && __ilen == 0);
}
if (__ilen > 0)
{
_M_set_buffer(__ilen);
_M_reading = true;
__ret = traits_type::to_int_type(*this->gptr());
}
else if (__got_eof)
{
// If the actual end of file is reached, set 'uncommitted'
// mode, thus allowing an immediate write without an
// intervening seek.
_M_set_buffer(-1);
_M_reading = false;
}
}
return __ret;
}
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::int_type
basic_filebuf<_CharT, _Traits>::
pbackfail(int_type __i)
{
int_type __ret = traits_type::eof();
const bool __testin = this->_M_mode & ios_base::in;
if (__testin && !_M_writing)
{
// Remember whether the pback buffer is active, otherwise below
// we may try to store in it a second char (libstdc++/9761).
const bool __testpb = this->_M_pback_init;
const bool __testeof = traits_type::eq_int_type(__i, __ret);
int_type __tmp;
if (this->eback() < this->gptr())
{
this->gbump(-1);
__tmp = traits_type::to_int_type(*this->gptr());
}
else if (this->seekoff(-1, ios_base::cur) != pos_type(off_type(-1)))
{
__tmp = this->underflow();
if (traits_type::eq_int_type(__tmp, __ret))
return __ret;
}
else
{
// At the beginning of the buffer, need to make a
// putback position available. But the seek may fail
// (f.i., at the beginning of a file, see
// libstdc++/9439) and in that case we return
// traits_type::eof().
return __ret;
}
// Try to put back __i into input sequence in one of three ways.
// Order these tests done in is unspecified by the standard.
if (!__testeof && traits_type::eq_int_type(__i, __tmp))
__ret = __i;
else if (__testeof)
__ret = traits_type::not_eof(__i);
else if (!__testpb)
{
_M_create_pback();
_M_reading = true;
*this->gptr() = traits_type::to_char_type(__i);
__ret = __i;
}
}
return __ret;
}
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::int_type
basic_filebuf<_CharT, _Traits>::
overflow(int_type __c)
{
int_type __ret = traits_type::eof();
const bool __testeof = traits_type::eq_int_type(__c, __ret);
const bool __testout = this->_M_mode & ios_base::out;
if (__testout && !_M_reading)
{
if (this->pbase() < this->pptr())
{
// If appropriate, append the overflow char.
if (!__testeof)
{
*this->pptr() = traits_type::to_char_type(__c);
this->pbump(1);
}
// Convert pending sequence to external representation,
// output.
if (_M_convert_to_external(this->pbase(),
this->pptr() - this->pbase())
&& (!__testeof || (__testeof && !_M_file.sync())))
{
_M_set_buffer(0);
__ret = traits_type::not_eof(__c);
}
}
else if (this->_M_buf_size > 1)
{
// Overflow in 'uncommitted' mode: set _M_writing, set
// the buffer to the initial 'write' mode, and put __c
// into the buffer.
_M_set_buffer(0);
_M_writing = true;
if (!__testeof)
{
*this->pptr() = traits_type::to_char_type(__c);
this->pbump(1);
}
__ret = traits_type::not_eof(__c);
}
else
{
// Unbuffered.
char_type __conv = traits_type::to_char_type(__c);
if (__testeof || _M_convert_to_external(&__conv, 1))
{
_M_writing = true;
__ret = traits_type::not_eof(__c);
}
}
}
return __ret;
}
template<typename _CharT, typename _Traits>
bool
basic_filebuf<_CharT, _Traits>::
_M_convert_to_external(_CharT* __ibuf, streamsize __ilen)
{
// Sizes of external and pending output.
streamsize __elen = 0;
streamsize __plen = 0;
if (__check_facet(_M_codecvt).always_noconv())
{
__elen += _M_file.xsputn(reinterpret_cast<char*>(__ibuf), __ilen);
__plen += __ilen;
}
else
{
// Worst-case number of external bytes needed.
// XXX Not done encoding() == -1.
streamsize __blen = __ilen * _M_codecvt->max_length();
char* __buf = static_cast<char*>(__builtin_alloca(__blen));
char* __bend;
const char_type* __iend;
codecvt_base::result __r;
__r = _M_codecvt->out(_M_state_cur, __ibuf, __ibuf + __ilen,
__iend, __buf, __buf + __blen, __bend);
if (__r == codecvt_base::ok || __r == codecvt_base::partial)
__blen = __bend - __buf;
else if (__r == codecvt_base::noconv)
{
// Same as the always_noconv case above.
__buf = reinterpret_cast<char*>(__ibuf);
__blen = __ilen;
}
else
{
// Result == error.
__blen = 0;
}
if (__blen)
{
__elen += _M_file.xsputn(__buf, __blen);
__plen += __blen;
}
// Try once more for partial conversions.
if (__r == codecvt_base::partial)
{
const char_type* __iresume = __iend;
streamsize __rlen = this->pptr() - __iend;
__r = _M_codecvt->out(_M_state_cur, __iresume,
__iresume + __rlen, __iend, __buf,
__buf + __blen, __bend);
if (__r != codecvt_base::error)
{
__rlen = __bend - __buf;
__elen += _M_file.xsputn(__buf, __rlen);
__plen += __rlen;
}
}
}
return __elen && __elen == __plen;
}
template<typename _CharT, typename _Traits>
streamsize
basic_filebuf<_CharT, _Traits>::
xsputn(const _CharT* __s, streamsize __n)
{
streamsize __ret = 0;
// Optimization in the always_noconv() case, to be generalized in the
// future: when __n is sufficiently large we write directly instead of
// using the buffer.
const bool __testout = this->_M_mode & ios_base::out;
if (__testout && !_M_reading
&& __check_facet(_M_codecvt).always_noconv())
{
// Measurement would reveal the best choice.
const streamsize __chunk = 1ul << 10;
streamsize __bufavail = this->epptr() - this->pptr();
// Don't mistake 'uncommitted' mode buffered with unbuffered.
if (!_M_writing && this->_M_buf_size > 1)
__bufavail = this->_M_buf_size - 1;
const streamsize __limit = std::min(__chunk, __bufavail);
if (__n >= __limit)
{
const streamsize __buffill = this->pptr() - this->pbase();
const char* __buf = reinterpret_cast<const char*>(this->pbase());
__ret = _M_file.xsputn_2(__buf, __buffill,
reinterpret_cast<const char*>(__s),
__n);
if (__ret == __buffill + __n)
{
_M_set_buffer(0);
_M_writing = true;
}
if (__ret > __buffill)
__ret -= __buffill;
else
__ret = 0;
}
else
__ret = __streambuf_type::xsputn(__s, __n);
}
else
__ret = __streambuf_type::xsputn(__s, __n);
return __ret;
}
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::__streambuf_type*
basic_filebuf<_CharT, _Traits>::
setbuf(char_type* __s, streamsize __n)
{
if (!this->is_open())
if (__s == 0 && __n == 0)
this->_M_buf_size = 1;
else if (__s && __n > 0)
{
// This is implementation-defined behavior, and assumes that
// an external char_type array of length __n exists and has
// been pre-allocated. If this is not the case, things will
// quickly blow up. When __n > 1, __n - 1 positions will be
// used for the get area, __n - 1 for the put area and 1
// position to host the overflow char of a full put area.
// When __n == 1, 1 position will be used for the get area
// and 0 for the put area, as in the unbuffered case above.
this->_M_buf = __s;
this->_M_buf_size = __n;
}
return this;
}
// According to 27.8.1.4 p11 - 13, seekoff should ignore the last
// argument (of type openmode).
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::pos_type
basic_filebuf<_CharT, _Traits>::
seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode)
{
pos_type __ret = pos_type(off_type(-1));
int __width = 0;
if (_M_codecvt)
__width = _M_codecvt->encoding();
if (__width < 0)
__width = 0;
const bool __testfail = __off != 0 && __width <= 0;
if (this->is_open() && !__testfail)
{
// Ditch any pback buffers to avoid confusion.
_M_destroy_pback();
// Correct state at destination. Note that this is the correct
// state for the current position during output, because
// codecvt::unshift() returns the state to the initial state.
// This is also the correct state at the end of the file because
// an unshift sequence should have been written at the end.
__state_type __state = _M_state_beg;
off_type __computed_off = __off * __width;
if (_M_reading && __way == ios_base::cur)
{
if (_M_codecvt->always_noconv())
__computed_off += this->gptr() - this->egptr();
else
{
// Calculate offset from _M_ext_buf that corresponds
// to gptr(). Note: uses _M_state_last, which
// corresponds to eback().
const int __gptr_off =
_M_codecvt->length(_M_state_last, _M_ext_buf, _M_ext_next,
this->gptr() - this->eback());
__computed_off += _M_ext_buf + __gptr_off - _M_ext_end;
// _M_state_last is modified by codecvt::length() so
// it now corresponds to gptr().
__state = _M_state_last;
}
}
__ret = _M_seek(__computed_off, __way, __state);
}
return __ret;
}
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 171. Strange seekpos() semantics due to joint position
// According to the resolution of DR 171, seekpos should ignore the last
// argument (of type openmode).
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::pos_type
basic_filebuf<_CharT, _Traits>::
seekpos(pos_type __pos, ios_base::openmode)
{
pos_type __ret = pos_type(off_type(-1));
if (this->is_open())
{
// Ditch any pback buffers to avoid confusion.
_M_destroy_pback();
__ret = _M_seek(off_type(__pos), ios_base::beg, __pos.state());
}
return __ret;
}
template<typename _CharT, typename _Traits>
typename basic_filebuf<_CharT, _Traits>::pos_type
basic_filebuf<_CharT, _Traits>::
_M_seek(off_type __off, ios_base::seekdir __way, __state_type __state)
{
pos_type __ret = pos_type(off_type(-1));
if (_M_terminate_output())
{
// Returns pos_type(off_type(-1)) in case of failure.
__ret = pos_type(_M_file.seekoff(__off, __way));
_M_reading = false;
_M_writing = false;
_M_ext_next = _M_ext_end = _M_ext_buf;
_M_set_buffer(-1);
_M_state_cur = __state;
__ret.state(_M_state_cur);
}
return __ret;
}
template<typename _CharT, typename _Traits>
bool
basic_filebuf<_CharT, _Traits>::
_M_terminate_output()
{
bool __testvalid = true;
// Part one: update the output sequence.
if (this->pbase() < this->pptr())
{
const int_type __tmp = this->overflow();
if (traits_type::eq_int_type(__tmp, traits_type::eof()))
__testvalid = false;
}
// Part two: output unshift sequence.
if (_M_writing && !__check_facet(_M_codecvt).always_noconv()
&& __testvalid)
{
// Note: this value is arbitrary, since there is no way to
// get the length of the unshift sequence from codecvt,
// without calling unshift.
const size_t __blen = 128;
char __buf[__blen];
codecvt_base::result __r;
streamsize __ilen = 0;
do
{
char* __next;
__r = _M_codecvt->unshift(_M_state_cur, __buf,
__buf + __blen, __next);
if (__r == codecvt_base::error)
__testvalid = false;
else if (__r == codecvt_base::ok ||
__r == codecvt_base::partial)
{
__ilen = __next - __buf;
if (__ilen > 0)
{
const streamsize __elen = _M_file.xsputn(__buf, __ilen);
if (__elen != __ilen)
__testvalid = false;
}
}
}
while (__r == codecvt_base::partial && __ilen > 0 && __testvalid);
if (__testvalid)
{
// This second call to overflow() is required by the standard,
// but it's not clear why it's needed, since the output buffer
// should be empty by this point (it should have been emptied
// in the first call to overflow()).
const int_type __tmp = this->overflow();
if (traits_type::eq_int_type(__tmp, traits_type::eof()))
__testvalid = false;
}
}
return __testvalid;
}
template<typename _CharT, typename _Traits>
int
basic_filebuf<_CharT, _Traits>::
sync()
{
int __ret = 0;
// Make sure that the internal buffer resyncs its idea of
// the file position with the external file.
// NB: _M_file.sync() will be called within.
if (this->pbase() < this->pptr())
{
const int_type __tmp = this->overflow();
if (traits_type::eq_int_type(__tmp, traits_type::eof()))
__ret = -1;
}
return __ret;
}
template<typename _CharT, typename _Traits>
void
basic_filebuf<_CharT, _Traits>::
imbue(const locale& __loc)
{
if (this->_M_buf_locale != __loc)
{
bool __testfail = false;
if (this->is_open())
{
const bool __testbeg =
this->seekoff(0, ios_base::cur, this->_M_mode) ==
pos_type(off_type(0));
const bool __teststate =
__check_facet(_M_codecvt).encoding() == -1;
__testfail = !__testbeg || __teststate;
}
if (!__testfail)
{
this->_M_buf_locale = __loc;
if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
_M_codecvt = &use_facet<__codecvt_type>(__loc);
else
_M_codecvt = 0;
// NB This may require the reconversion of previously
// converted chars. This in turn may cause the
// reconstruction of the original file. YIKES!! This
// implementation interprets this requirement as requiring
// the file position be at the beginning, and a stateless
// encoding, or that the filebuf be closed. Opinions may differ.
}
}
}
// Inhibit implicit instantiations for required instantiations,
// which are defined via explicit instantiations elsewhere.
// NB: This syntax is a GNU extension.
#if _GLIBCXX_EXTERN_TEMPLATE
extern template class basic_filebuf<char>;
extern template class basic_ifstream<char>;
extern template class basic_ofstream<char>;
extern template class basic_fstream<char>;
#ifdef _GLIBCXX_USE_WCHAR_T
extern template class basic_filebuf<wchar_t>;
extern template class basic_ifstream<wchar_t>;
extern template class basic_ofstream<wchar_t>;
extern template class basic_fstream<wchar_t>;
#endif
#endif
} // namespace std
#endif
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