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[PATCH] libstdc++/7961
- From: Paolo Carlini <pcarlini at unitus dot it>
- To: libstdc++ at gcc dot gnu dot org
- Cc: john dot carter at tait dot co dot nz, bkoz <bkoz at redhat dot com>
- Date: Fri, 01 Nov 2002 12:50:45 +0100
- Subject: [PATCH] libstdc++/7961
Hi,
I believe John is right, even if it is difficult to create an
actually seg-faulting testcase. In the following
#include <string>
#include <cassert>
int main()
{
std::string lhs("abc");
lhs.push_back('\0');
lhs += "def";
assert( lhs != "abc" );
}
operator!= (memcmp, that is) access "abc" past its final '\0',
since lhs.size() == 7 and this value is currently used in
the memcmp() call from compare().
Indeed, John's fix makes compare(const _CharT* __s) consistent
with the current implementation of compare(size_type, size_type,
const _CharT*) in the use of traits_type::length(__s) and min().
Ok to apply?
Ciao, Paolo.
P.S. For Andreas: in v3 there are no risks of overflows in the
final computations of __r since max_size < npos/4.
///////
2002-11-01 John Carter <john.carter@tait.co.nz>
PR libstdc++/7961
* include/bits/basic_string.tcc
(compare(const _CharT* __s)): Don't access __s past its length.
diff -urN libstdc++-v3-orig/include/bits/basic_string.tcc libstdc++-v3/include/bits/basic_string.tcc
--- libstdc++-v3-orig/include/bits/basic_string.tcc 2002-10-27 08:35:06.000000000 +0100
+++ libstdc++-v3/include/bits/basic_string.tcc 2002-11-01 12:14:17.000000000 +0100
@@ -884,9 +884,11 @@
compare(const _CharT* __s) const
{
size_type __size = this->size();
- int __r = traits_type::compare(_M_data(), __s, __size);
+ size_type __osize = traits_type::length(__s);
+ size_type __len = min(__size, __osize);
+ int __r = traits_type::compare(_M_data(), __s, __len);
if (!__r)
- __r = __size - traits_type::length(__s);
+ __r = __size - __osize;
return __r;
}