On 22/05/17 11:08 +0100, Jonathan Wakely wrote:
On 20/05/17 15:10 +0800, Xi Ruoyao wrote:
On 2017-05-19 15:38 +0100, Jonathan Wakely wrote:
On 18/05/17 19:10 +0800, Xi Ruoyao wrote:
This UB has been hiding so long...
Indeed! Thanks for the patch.
2017-03-11 Xi Ruoyao <r...@stu.xidian.edu.cn>
PR libstdc++/67214
* include/bits/locale_facets.tcc (_M_extract_int):
Add explicit conversion to avoid signed overflow.
---
libstdc++-v3/include/bits/locale_facets.tcc | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/bits/locale_facets.tcc
b/libstdc++-v3/include/bits/locale_facets.tcc
index 351190c..5f85d15 100644
--- a/libstdc++-v3/include/bits/locale_facets.tcc
+++ b/libstdc++-v3/include/bits/locale_facets.tcc
@@ -470,7 +470,8 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
bool __testoverflow = false;
const __unsigned_type __max =
(__negative && __gnu_cxx::__numeric_traits<_ValueT>::__is_signed)
- ? -__gnu_cxx::__numeric_traits<_ValueT>::__min
+ ? -static_cast<__unsigned_type>(__gnu_cxx::
+ __numeric_traits<_ValueT>::__min)
Do we need to keep the negation, or can we just cast to
__unsigned_type?
For 2's complement we can just cast to __unsigned_type. But for
clarity and other strange architectures I think we should keep
the negation.
https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html
"GCC only supports two's complement integer types"
I doubt that's ever going to change, but keeping the negation also
doesn't do any harm. I'll test and commit this, thanks.
Here's what I committed, which also adds a typedef for the
__numeric_traits type, to make everything more readable.
Tested powerpc64le-linux. Committed to trunk.
commit effe4603accc56b08eda6453eb1abf752cfaafba
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue May 23 11:11:41 2017 +0100
PR libstdc++/67214 Avoid signed overflow in num_get::_M_extract_int
2017-05-23 Xi Ruoyao <r...@stu.xidian.edu.cn>
PR libstdc++/67214
* include/bits/locale_facets.tcc (num_get::_M_extract_int): Add
explicit conversion to avoid signed overflow.
diff --git a/libstdc++-v3/include/bits/locale_facets.tcc b/libstdc++-v3/include/bits/locale_facets.tcc
index 351190c..d7710e6 100644
--- a/libstdc++-v3/include/bits/locale_facets.tcc
+++ b/libstdc++-v3/include/bits/locale_facets.tcc
@@ -375,10 +375,10 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
_M_extract_int(_InIter __beg, _InIter __end, ios_base& __io,
ios_base::iostate& __err, _ValueT& __v) const
{
- typedef char_traits<_CharT> __traits_type;
+ typedef char_traits<_CharT> __traits_type;
using __gnu_cxx::__add_unsigned;
- typedef typename __add_unsigned<_ValueT>::__type __unsigned_type;
- typedef __numpunct_cache<_CharT> __cache_type;
+ typedef typename __add_unsigned<_ValueT>::__type __unsigned_type;
+ typedef __numpunct_cache<_CharT> __cache_type;
__use_cache<__cache_type> __uc;
const locale& __loc = __io._M_getloc();
const __cache_type* __lc = __uc(__loc);
@@ -463,15 +463,16 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
- __num_base::_S_izero : __base);
// Extract.
+ typedef __gnu_cxx::__numeric_traits<_ValueT> __num_traits;
string __found_grouping;
if (__lc->_M_use_grouping)
__found_grouping.reserve(32);
bool __testfail = false;
bool __testoverflow = false;
const __unsigned_type __max =
- (__negative && __gnu_cxx::__numeric_traits<_ValueT>::__is_signed)
- ? -__gnu_cxx::__numeric_traits<_ValueT>::__min
- : __gnu_cxx::__numeric_traits<_ValueT>::__max;
+ (__negative && __num_traits::__is_signed)
+ ? -static_cast<__unsigned_type>(__num_traits::__min)
+ : __num_traits::__max;
const __unsigned_type __smax = __max / __base;
__unsigned_type __result = 0;
int __digit = 0;
@@ -572,11 +573,10 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
}
else if (__testoverflow)
{
- if (__negative
- && __gnu_cxx::__numeric_traits<_ValueT>::__is_signed)
- __v = __gnu_cxx::__numeric_traits<_ValueT>::__min;
+ if (__negative && __num_traits::__is_signed)
+ __v = __num_traits::__min;
else
- __v = __gnu_cxx::__numeric_traits<_ValueT>::__max;
+ __v = __num_traits::__max;
__err = ios_base::failbit;
}
else
