The suggested resolution of LWG 3083 is to make invalid indices
undefined, but we can fairly easily check for them and treat them as
errors in the same way as allocation failure. This avoids a segfault or
worse, setting an error flag on the stream instead.
PR libstdc++/68197
* include/bits/ios_base.h (ios_base::iword, ios_base::pword): Cast
indices to unsigned.
* src/c++11/ios.cc (ios_base::_M_grow_words): Treat negative indices
as failure. Refactor error handling.
* testsuite/27_io/ios_base/storage/68197.cc: New.
Tested x86_64-linux, committed to trunk.
commit 96341ebb5bca2cc79857e26335ed504a348fbddd
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Sat Mar 17 15:25:16 2018 +0000
PR libstdc++/68197 fail on negative iword/pword indices
The suggested resolution of LWG 3083 is to make invalid indices
undefined, but we can fairly easily check for them and treat them as
errors in the same way as allocation failure. This avoids a segfault or
worse, setting an error flag on the stream instead.
PR libstdc++/68197
* include/bits/ios_base.h (ios_base::iword, ios_base::pword): Cast
indices to unsigned.
* src/c++11/ios.cc (ios_base::_M_grow_words): Treat negative indices
as failure. Refactor error handling.
* testsuite/27_io/ios_base/storage/68197.cc: New.
diff --git a/libstdc++-v3/include/bits/ios_base.h
b/libstdc++-v3/include/bits/ios_base.h
index d296be4eb30..c0c4e3b2abe 100644
--- a/libstdc++-v3/include/bits/ios_base.h
+++ b/libstdc++-v3/include/bits/ios_base.h
@@ -810,7 +810,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
long&
iword(int __ix)
{
- _Words& __word = (__ix < _M_word_size)
+ _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
? _M_word[__ix] : _M_grow_words(__ix, true);
return __word._M_iword;
}
@@ -831,7 +831,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
void*&
pword(int __ix)
{
- _Words& __word = (__ix < _M_word_size)
+ _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
? _M_word[__ix] : _M_grow_words(__ix, false);
return __word._M_pword;
}
diff --git a/libstdc++-v3/src/c++11/ios.cc b/libstdc++-v3/src/c++11/ios.cc
index 82063e4b2f5..f5351777f90 100644
--- a/libstdc++-v3/src/c++11/ios.cc
+++ b/libstdc++-v3/src/c++11/ios.cc
@@ -109,37 +109,30 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
ios_base::register_callback(event_callback __fn, int __index)
{ _M_callbacks = new _Callback_list(__fn, __index, _M_callbacks); }
- // 27.4.2.5 iword/pword storage
+ // 27.4.2.5 [ios.base.storage] iword/pword storage
ios_base::_Words&
ios_base::_M_grow_words(int __ix, bool __iword)
{
// Precondition: _M_word_size <= __ix
int __newsize = _S_local_word_size;
_Words* __words = _M_local_word;
- if (__ix > _S_local_word_size - 1)
+ const char* __error = nullptr;
+ if ((unsigned)__ix >= (unsigned)numeric_limits<int>::max())
+ __error = __N("ios_base::_M_grow_words is not valid");
+ else if (__ix > _S_local_word_size - 1)
{
- if (__ix < numeric_limits<int>::max())
+ __newsize = __ix + 1;
+ /* We still need to catch bad_alloc even though we use
+ a nothrow new, because the new-expression can throw
+ a bad_array_new_length. */
+ __try
+ { __words = new (std::nothrow) _Words[__newsize]; }
+ __catch(const std::bad_alloc&)
+ { __words = nullptr; }
+ if (!__words)
+ __error = __N("ios_base::_M_grow_words allocation failed");
+ else
{
- __newsize = __ix + 1;
- /* We still need to catch bad_alloc even though we use
- a nothrow new, because the new-expression can throw
- a bad_array_new_length. */
- __try
- { __words = new (std::nothrow) _Words[__newsize]; }
- __catch(const std::bad_alloc&)
- { __words = nullptr; }
- if (!__words)
- {
- _M_streambuf_state |= badbit;
- if (_M_streambuf_state & _M_exception)
- __throw_ios_failure(__N("ios_base::_M_grow_words "
- "allocation failed"));
- if (__iword)
- _M_word_zero._M_iword = 0;
- else
- _M_word_zero._M_pword = 0;
- return _M_word_zero;
- }
for (int __i = 0; __i < _M_word_size; __i++)
__words[__i] = _M_word[__i];
if (_M_word && _M_word != _M_local_word)
@@ -148,17 +141,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_word = 0;
}
}
+ }
+ if (__error)
+ {
+ _M_streambuf_state |= badbit;
+ if (_M_streambuf_state & _M_exception)
+ __throw_ios_failure(__error);
+ if (__iword)
+ _M_word_zero._M_iword = 0;
else
- {
- _M_streambuf_state |= badbit;
- if (_M_streambuf_state & _M_exception)
- __throw_ios_failure(__N("ios_base::_M_grow_words is not valid"));
- if (__iword)
- _M_word_zero._M_iword = 0;
- else
- _M_word_zero._M_pword = 0;
- return _M_word_zero;
- }
+ _M_word_zero._M_pword = 0;
+ return _M_word_zero;
}
_M_word = __words;
_M_word_size = __newsize;
diff --git a/libstdc++-v3/testsuite/27_io/ios_base/storage/68197.cc
b/libstdc++-v3/testsuite/27_io/ios_base/storage/68197.cc
new file mode 100644
index 00000000000..1004e8127c2
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/ios_base/storage/68197.cc
@@ -0,0 +1,95 @@
+// Copyright (C) 2018 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 3, 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 COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do run { target c++11 } }
+
+#include <ios>
+#include <climits>
+#include <testsuite_hooks.h>
+
+// PR libstdc++/68197
+
+struct sbuf : std::streambuf { } sb;
+
+void
+test01()
+{
+ std::ios ios(&sb);
+ long& i1 = ios.iword(-1);
+ VERIFY( i1 == 0 );
+ VERIFY( ios.bad() );
+ ios.clear();
+ i1 = 1;
+ VERIFY( ios.iword(-1) == 0 );
+ VERIFY( ios.bad() );
+ ios.clear();
+ long& i2 = ios.iword(INT_MIN);
+ VERIFY( i2 == 0 );
+ VERIFY( ios.bad() );
+ ios.clear();
+ i2 = 2;
+ VERIFY( ios.iword(INT_MIN) == 0 );
+ VERIFY( ios.bad() );
+ ios.clear();
+
+ bool caught = false;
+ ios.exceptions(std::ios::badbit);
+ try {
+ ios.iword(-1);
+ } catch (const std::exception&) {
+ caught = true;
+ }
+ VERIFY( caught );
+}
+
+void
+test02()
+{
+ std::ios ios(&sb);
+ void*& p1 = ios.pword(-1);
+ VERIFY( p1 == nullptr );
+ VERIFY( ios.bad() );
+ ios.clear();
+ p1 = &p1;
+ VERIFY( ios.pword(-1) == nullptr );
+ VERIFY( ios.bad() );
+ ios.clear();
+ void*& p2 = ios.pword(INT_MIN);
+ VERIFY( p2 == nullptr );
+ VERIFY( ios.bad() );
+ ios.clear();
+ p2 = &p2;
+ VERIFY( ios.pword(INT_MIN) == nullptr );
+ VERIFY( ios.bad() );
+ ios.clear();
+
+ bool caught = false;
+ ios.exceptions(std::ios::badbit);
+ try {
+ ios.pword(-1);
+ } catch (const std::exception&) {
+ caught = true;
+ }
+ VERIFY( caught );
+}
+
+int
+main()
+{
+ test01();
+ test02();
+}
