Bill Fisher: This patch fixes a less likely case where '\b' can back up into invalid memory, when driven by a regex_iterator (for case 1, see r185273 or http://llvm.org/bugs/show_bug.cgi?id=16240)

The attached test program also supplies a test for the case 1 fix in r185273.

llvm-svn: 186089

1 files changed, 3 insertions, 2 deletions

diff --git a/libcxx/include/regex b/libcxx/include/regex
index 36d5677072f..19e08b13aaf 100644
--- a/libcxx/include/regex
+++ b/libcxx/include/regex
@@ -5811,9 +5811,10 @@ regex_search(_BidirectionalIterator __first, _BidirectionalIterator __last,
              const basic_regex<_CharT, _Traits>& __e,
              regex_constants::match_flag_type __flags = regex_constants::match_default)
 {
-    basic_string<_CharT> __s(__first, __last);
+    int __offset = (__flags & regex_constants::match_prev_avail) ? 1 : 0;
+    basic_string<_CharT> __s(_VSTD::prev(__first, __offset), __last);
     match_results<const _CharT*> __mc;
-    bool __r = __e.__search(__s.data(), __s.data() + __s.size(), __mc, __flags);
+    bool __r = __e.__search(__s.data() + __offset, __s.data() + __s.size(), __mc, __flags);
     __m.__assign(__first, __last, __mc, __flags & regex_constants::__no_update_pos);
     return __r;
 }