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re PR libstdc++/12875 (Weird behaviour in basic_filebuf::setbuf())

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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
This commit is contained in:
Paolo Carlini 2003-11-12 01:14:34 +00:00 committed by Paolo Carlini
parent a5966c9ef9
commit dfad48c6e8
7 changed files with 155 additions and 40 deletions
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14
libstdc++-v3/ChangeLog
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@ -1,3 +1,17 @@
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.
2003-11-11 Doug Gregor <gregod@cs.rpi.edu>
* docs/html/debug.html: Document libstdc++ debug mode.

49
libstdc++-v3/include/bits/fstream.tcc
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@ -44,15 +44,15 @@ namespace std
basic_filebuf<_CharT, _Traits>::
_M_allocate_internal_buffer()
{
if (!_M_buf_allocated && this->_M_buf_size)
// 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)
{
// Allocate internal buffer.
this->_M_buf = new char_type[this->_M_buf_size];
_M_buf_allocated = true;
}
}
// Both close and setbuf need to deallocate internal buffers, if it exists.
template<typename _CharT, typename _Traits>
void
basic_filebuf<_CharT, _Traits>::
@ -213,8 +213,8 @@ namespace std
else
{
// Worst-case number of external bytes.
// XXX Not done encoding() == -1.
const int __enc = _M_codecvt->encoding();
// 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)
@ -539,29 +539,22 @@ namespace std
basic_filebuf<_CharT, _Traits>::
setbuf(char_type* __s, streamsize __n)
{
if (!this->is_open() && __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.
// Step 1: Destroy the current internal array.
_M_destroy_internal_buffer();
// Step 2: Use the external array.
this->_M_buf = __s;
this->_M_buf_size = __n;
_M_reading = false;
_M_writing = false;
_M_set_buffer(-1);
}
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;
}

10
libstdc++-v3/include/ext/stdio_filebuf.h
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@ -66,9 +66,7 @@ namespace __gnu_cxx
* @param fd An open file descriptor.
* @param mode Same meaning as in a standard filebuf.
* @param del Whether to close the file on destruction.
* @param size Optimal or preferred size of internal buffer, in bytes.
* Note that it includes a position for the overflow char,
* therefore, can't be smaller than 2.
* @param size Optimal or preferred size of internal buffer, in chars.
*
* This constructor associates a file stream buffer with an open
* POSIX file descriptor. Iff @a del is true, then the associated
@ -80,10 +78,8 @@ namespace __gnu_cxx
/**
* @param f An open @c FILE*.
* @param mode Same meaning as in a standard filebuf.
* @param size Optimal or preferred size of internal buffer, in bytes.
* Defaults to system's @c BUFSIZ. Note that it includes
* a position for the overflow char, therefore, can't be
* smaller than 2.
* @param size Optimal or preferred size of internal buffer, in chars.
* Defaults to system's @c BUFSIZ.
*
* This constructor associates a file stream buffer with an open
* C @c FILE*. The @c FILE* will not be automatically closed when the

57
libstdc++-v3/testsuite/27_io/basic_filebuf/setbuf/char/12875-1.cc Normal file
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@ -0,0 +1,57 @@
// Copyright (C) 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.
// 27.8.1.4 Overridden virtual functions
#include <fstream>
#include <cstdio>
#include <cstring>
#include <testsuite_hooks.h>
// libstdc++/12875
void test01()
{
using namespace std;
bool test __attribute__((unused)) = true;
const char* name = "tmp_setbuf4";
static char buf[1024];
FILE* out = fopen(name, "w");
fputs("Hello, world", out);
fclose(out);
filebuf in;
in.open(name, ios_base::in);
char str[256];
streamsize r = in.sgetn(str, 6);
VERIFY( r == 6 );
VERIFY( !memcmp(str, "Hello,", 6) );
in.pubsetbuf(buf, 1024);
r = in.sgetn(str, 6);
VERIFY( r == 6 );
VERIFY( !memcmp(str, " world", 6) );
in.close();
}
// libstdc++/12875
int main()
{
test01();
return 0;
}

55
libstdc++-v3/testsuite/27_io/basic_filebuf/setbuf/char/12875-2.cc Normal file
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@ -0,0 +1,55 @@
// Copyright (C) 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.
// 27.8.1.4 Overridden virtual functions
#include <fstream>
#include <cstdio>
#include <cstring>
#include <testsuite_hooks.h>
// libstdc++/12875
void test02()
{
using namespace std;
bool test __attribute__((unused)) = true;
const char* name = "tmp_setbuf5";
static char buf[1024];
filebuf out;
out.open(name, ios_base::out);
streamsize r = out.sputn("Hello,", 6);
VERIFY( r == 6 );
out.pubsetbuf(buf, 1024);
r = out.sputn(" world", 6);
VERIFY( r == 6 );
VERIFY( out.close() );
FILE* in = fopen(name, "r");
char str[256];
fgets(str, 256, in);
VERIFY( !strcmp(str, "Hello, world") );
fclose(in);
}
int main()
{
test02();
return 0;
}

2
libstdc++-v3/testsuite/27_io/basic_filebuf/setbuf/char/2.cc
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@ -32,8 +32,8 @@ void test01()
const char* strlit = "how to tell a story and other essays: mark twain";
const size_t strlitsize = std::strlen(strlit);
filebuf fbuf;
fbuf.open("tmp_setbuf2", ios_base::out);
fbuf.pubsetbuf(buf, 512);
fbuf.open("tmp_setbuf2", ios_base::out);
fbuf.sputn(strlit, strlitsize);
VERIFY( std::strncmp(strlit, buf, strlitsize) == 0 );
}

8
libstdc++-v3/testsuite/27_io/basic_filebuf/setbuf/char/3.cc
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@ -23,7 +23,7 @@
#include <fstream>
#include <testsuite_hooks.h>
void test02()
void test03()
{
using namespace std;
@ -32,17 +32,17 @@ void test02()
const char* strlit = "how to tell a story and other essays: mark twain";
const size_t strlitsize = std::strlen(strlit);
filebuf fbuf01;
fbuf01.open("tmp", ios_base::out);
// NB: +2 otherwise sputn is optimized to a direct write,
// bypassing the buffer.
fbuf01.pubsetbuf(buf, strlitsize + 2);
fbuf01.open("tmp_setbuf3", ios_base::out);
fbuf01.sputn(strlit, strlitsize);
VERIFY( std::strncmp(strlit, buf, strlitsize) == 0 );
}
int main()
{
test02();
test03();
return 0;
}