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authorDavid Krauss <potswa@mac.com>2010-09-22 19:40:43 +0000
committerPaolo Carlini <paolo@gcc.gnu.org>2010-09-22 19:40:43 +0000
commit3531cf5ef365860700c5e89483f3a86ac969c6a4 (patch)
treea04325d2591098556af14addef9debb056684968 /libstdc++-v3/include
parent5d64ee190c8875dec5f15c0287a425a1e62041a9 (diff)
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re PR libstdc++/45628 (std::fstream::tellg invalidates I/O buffer)
2010-09-22 David Krauss <potswa@mac.com> PR libstdc++/45628 * include/bits/fstream.tcc (basic_filebuf::underflow): Add state transition to avoid modality requiring seekoff(0,ios::cur). (basic_filebuf::pbackfail): Likewise. (basic_filebuf::overflow): Likewise. (basic_filebuf::_M_seek): Avoid minor unnecessary conversion. (basic_filebuf::seekoff): Remove code to _M_get_ext_pos; make (0, ios::cur) a special case preserving buffer contents. (basic_filebuf::_M_get_ext_pos): New function to obtain status about codecvt extern_t buffer for overflow and seekoff. * include/std/fstream (basic_filebuf::_M_get_ext_pos): Likewise. * config/abi/pre/gnu.ver: Export new symbols. * testsuite/27_io/basic_filebuf/seekoff/char/45628-1.cc: New, verifies that seekoff(0, ios::cur) preserves buffers. * testsuite/27_io/basic_filebuf/seekoff/char/45628-2.cc: Likewise. for codecvt case. More lenient as it may still flush put area. * testsuite/27_io/basic_filebuf/seekoff/char/4.cc: Modify to check that seekoff is not required between read and write. * testsuite/27_io/basic_filebuf/seekoff/wchar_t/4.cc: Likewise. * testsuite/27_io/basic_filebuf/sync/wchar_t/1.cc: Remove. * testsuite/27_io/basic_filebuf/sync/wchar_t/1.cc: Likewise. * testsuite/util/testsuite_character.h (codecvt::do_length): Comply with 22.2.1.5.2/10 "Returns ... the LARGEST value in the range..." From-SVN: r164529
Diffstat (limited to 'libstdc++-v3/include')
-rw-r--r--libstdc++-v3/include/bits/fstream.tcc100
-rw-r--r--libstdc++-v3/include/std/fstream5
2 files changed, 80 insertions, 25 deletions
diff --git a/libstdc++-v3/include/bits/fstream.tcc b/libstdc++-v3/include/bits/fstream.tcc
index c498f48..2f661eb 100644
--- a/libstdc++-v3/include/bits/fstream.tcc
+++ b/libstdc++-v3/include/bits/fstream.tcc
@@ -1,7 +1,7 @@
// File based streams -*- C++ -*-
// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
-// 2007, 2008, 2009
+// 2007, 2008, 2009, 2010
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
@@ -205,8 +205,16 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
{
int_type __ret = traits_type::eof();
const bool __testin = _M_mode & ios_base::in;
- if (__testin && !_M_writing)
+ if (__testin)
{
+ if (_M_writing)
+ {
+ __ret = overflow();
+ if (__ret == traits_type::eof())
+ return __ret;
+ _M_set_buffer(-1);
+ _M_writing = false;
+ }
// Check for pback madness, and if so switch back to the
// normal buffers and jet outta here before expensive
// fileops happen...
@@ -357,8 +365,16 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
{
int_type __ret = traits_type::eof();
const bool __testin = _M_mode & ios_base::in;
- if (__testin && !_M_writing)
+ if (__testin)
{
+ if (_M_writing)
+ {
+ __ret = overflow();
+ if (__ret == traits_type::eof())
+ return __ret;
+ _M_set_buffer(-1);
+ _M_writing = false;
+ }
// Remember whether the pback buffer is active, otherwise below
// we may try to store in it a second char (libstdc++/9761).
const bool __testpb = _M_pback_init;
@@ -410,8 +426,16 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
int_type __ret = traits_type::eof();
const bool __testeof = traits_type::eq_int_type(__c, __ret);
const bool __testout = _M_mode & ios_base::out;
- if (__testout && !_M_reading)
+ if (__testout)
{
+ if (_M_reading)
+ {
+ _M_destroy_pback();
+ const int __gptr_off = _M_get_ext_pos(_M_state_last);
+ if (_M_seek(__gptr_off, ios_base::cur, _M_state_last)
+ == pos_type(off_type(-1)))
+ return __ret;
+ }
if (this->pbase() < this->pptr())
{
// If appropriate, append the overflow char.
@@ -691,12 +715,20 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
if (__width < 0)
__width = 0;
- pos_type __ret = pos_type(off_type(-1));
+ pos_type __ret = pos_type(off_type(-1));
const bool __testfail = __off != 0 && __width <= 0;
if (this->is_open() && !__testfail)
{
+ // tellg and tellp queries do not affect any state, unless
+ // ! always_noconv and the put sequence is not empty.
+ // In that case, determining the position requires converting the
+ // put sequence. That doesn't use ext_buf, so requires a flush.
+ bool __no_movement = __way == ios_base::cur && __off == 0
+ && (!_M_writing || _M_codecvt->always_noconv());
+
// Ditch any pback buffers to avoid confusion.
- _M_destroy_pback();
+ if (!__no_movement)
+ _M_destroy_pback();
// Correct state at destination. Note that this is the correct
// state for the current position during output, because
@@ -707,24 +739,23 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
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
+ __state = _M_state_last;
+ __computed_off += _M_get_ext_pos(__state);
+ }
+ if (!__no_movement)
+ __ret = _M_seek(__computed_off, __way, __state);
+ else
+ {
+ if (_M_writing)
+ __computed_off = this->pptr() - this->pbase();
+
+ off_type __file_off = _M_file.seekoff(0, ios_base::cur);
+ if (__file_off != off_type(-1))
{
- // 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 = __file_off + __computed_off;
+ __ret.state(__state);
}
}
- __ret = _M_seek(__computed_off, __way, __state);
}
return __ret;
}
@@ -756,21 +787,42 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
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));
- if (__ret != pos_type(off_type(-1)))
+ off_type __file_off = _M_file.seekoff(__off, __way);
+ if (__file_off != off_type(-1))
{
_M_reading = false;
_M_writing = false;
_M_ext_next = _M_ext_end = _M_ext_buf;
_M_set_buffer(-1);
_M_state_cur = __state;
+ __ret = __file_off;
__ret.state(_M_state_cur);
}
}
return __ret;
}
+ // Returns the distance from the end of the ext buffer to the point
+ // corresponding to gptr(). This is a negative value. Updates __state
+ // from eback() correspondence to gptr().
+ template<typename _CharT, typename _Traits>
+ int basic_filebuf<_CharT, _Traits>::
+ _M_get_ext_pos(__state_type& __state)
+ {
+ if (_M_codecvt->always_noconv())
+ return this->gptr() - this->egptr();
+ else
+ {
+ // Calculate offset from _M_ext_buf that corresponds to
+ // gptr(). Precondition: __state == _M_state_last, which
+ // corresponds to eback().
+ const int __gptr_off =
+ _M_codecvt->length(__state, _M_ext_buf, _M_ext_next,
+ this->gptr() - this->eback());
+ return _M_ext_buf + __gptr_off - _M_ext_end;
+ }
+ }
+
template<typename _CharT, typename _Traits>
bool
basic_filebuf<_CharT, _Traits>::
diff --git a/libstdc++-v3/include/std/fstream b/libstdc++-v3/include/std/fstream
index 00690be..0ffd33d 100644
--- a/libstdc++-v3/include/std/fstream
+++ b/libstdc++-v3/include/std/fstream
@@ -351,9 +351,12 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
seekpos(pos_type __pos,
ios_base::openmode __mode = ios_base::in | ios_base::out);
- // Common code for seekoff and seekpos
+ // Common code for seekoff, seekpos, and overflow
pos_type
_M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
+
+ int
+ _M_get_ext_pos(__state_type &__state);
virtual int
sync();
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