commit bf0460e0a0045dcf418fc065d5bf0875f77f3bbf
author Marshall Clow <mclow.lists@gmail.com> Sun May 31 03:13:31 2015 +0000
committer Marshall Clow <mclow.lists@gmail.com> Sun May 31 03:13:31 2015 +0000
tree 16a2fd49b854a834f91a60895a4a83e7d5ee26f8
parent 0620fc865b076da2abf24884e34393b337e7ee47

Don't try to memcpy zero bytes; sometimes the source pointer is NULL, and that's UB. Thanks to Nuno Lopes for the catch.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@238666 91177308-0d34-0410-b5e6-96231b3b80d8

include/memory

diff --git a/include/memory b/include/memory
index a0e7a8b..a004c89 100644
--- a/include/memory
+++ b/include/memory
@@ -621,6 +621,8 @@
 #pragma GCC system_header
 #endif
 
+extern "C" int printf(const char * __restrict, ...);
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // addressof moved to <__functional_base>
@@ -1521,7 +1523,8 @@
         __construct_forward(allocator_type& __a, _Tp* __begin1, _Tp* __end1, _Tp*& __begin2)
         {
             ptrdiff_t _Np = __end1 - __begin1;
-            _VSTD::memcpy(__begin2, __begin1, _Np * sizeof(_Tp));
+            if (_Np > 0)
+                _VSTD::memcpy(__begin2, __begin1, _Np * sizeof(_Tp));
             __begin2 += _Np;
         }
 
@@ -1549,7 +1552,8 @@
         {
             typedef typename remove_const<_Tp>::type _Vp;
             ptrdiff_t _Np = __end1 - __begin1;
-            _VSTD::memcpy(const_cast<_Vp*>(__begin2), __begin1, _Np * sizeof(_Tp));
+            if (_Np > 0)
+                _VSTD::memcpy(const_cast<_Vp*>(__begin2), __begin1, _Np * sizeof(_Tp));
             __begin2 += _Np;
         }
 
@@ -1580,7 +1584,8 @@
         {
             ptrdiff_t _Np = __end1 - __begin1;
             __end2 -= _Np;
-            _VSTD::memcpy(__end2, __begin1, _Np * sizeof(_Tp));
+            if (_Np > 0)
+                _VSTD::memcpy(__end2, __begin1, _Np * sizeof(_Tp));
         }
 
 private: