Fix xpath_node_set assignment to provide strong exception guarantee

Since the type of the set was updated before assignment, assigning in
out-of-memory condition could change the type to not match the content.

3 files changed, 16 insertions, 10 deletions

diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 1c1b539..fbe13f6 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -11025,7 +11025,7 @@ namespace pugi
 	}
 #endif
 
-	PUGI__FN void xpath_node_set::_assign(const_iterator begin_, const_iterator end_)
+	PUGI__FN void xpath_node_set::_assign(const_iterator begin_, const_iterator end_, type_t type_)
 	{
 		assert(begin_ <= end_);
 
@@ -11041,6 +11041,7 @@ namespace pugi
 
 			_begin = &_storage;
 			_end = &_storage + size_;
+			_type = type_;
 		}
 		else
 		{
@@ -11064,6 +11065,7 @@ namespace pugi
 			// finalize
 			_begin = storage;
 			_end = storage + size_;
+			_type = type_;
 		}
 	}
 
@@ -11071,9 +11073,9 @@ namespace pugi
 	{
 	}
 
-	PUGI__FN xpath_node_set::xpath_node_set(const_iterator begin_, const_iterator end_, type_t type_): _type(type_), _begin(&_storage), _end(&_storage)
+	PUGI__FN xpath_node_set::xpath_node_set(const_iterator begin_, const_iterator end_, type_t type_): _type(type_unsorted), _begin(&_storage), _end(&_storage)
 	{
-		_assign(begin_, end_);
+		_assign(begin_, end_, type_);
 	}
 
 	PUGI__FN xpath_node_set::~xpath_node_set()
@@ -11081,17 +11083,16 @@ namespace pugi
 		if (_begin != &_storage) impl::xml_memory::deallocate(_begin);
 	}
 		
-	PUGI__FN xpath_node_set::xpath_node_set(const xpath_node_set& ns): _type(ns._type), _begin(&_storage), _end(&_storage)
+	PUGI__FN xpath_node_set::xpath_node_set(const xpath_node_set& ns): _type(type_unsorted), _begin(&_storage), _end(&_storage)
 	{
-		_assign(ns._begin, ns._end);
+		_assign(ns._begin, ns._end, ns._type);
 	}
 	
 	PUGI__FN xpath_node_set& xpath_node_set::operator=(const xpath_node_set& ns)
 	{
 		if (this == &ns) return *this;
-		
-		_type = ns._type;
-		_assign(ns._begin, ns._end);
+
+		_assign(ns._begin, ns._end, ns._type);
 
 		return *this;
 	}
diff --git a/src/pugixml.hpp b/src/pugixml.hpp
index 02ca86b..b56f66a 100644
--- a/src/pugixml.hpp
+++ b/src/pugixml.hpp
@@ -1286,7 +1286,7 @@ namespace pugi
 		xpath_node* _begin;
 		xpath_node* _end;
 
-		void _assign(const_iterator begin, const_iterator end);
+		void _assign(const_iterator begin, const_iterator end, type_t type);
 	};
 #endif
 
diff --git a/tests/test_xpath_api.cpp b/tests/test_xpath_api.cpp
index df078a0..4fc5be3 100644
--- a/tests/test_xpath_api.cpp
+++ b/tests/test_xpath_api.cpp
@@ -381,15 +381,20 @@ TEST_XML(xpath_api_node_set_assign_out_of_memory_preserve, "<node><a/><b/></node
 {
 	xpath_node_set ns = doc.select_nodes(STR("node/*"));
 	CHECK(ns.size() == 2);
+	CHECK(ns.type() == xpath_node_set::type_sorted);
 
 	xpath_node_set nsall = doc.select_nodes(STR("//*"));
+	nsall.sort(true);
 	CHECK(nsall.size() == 3);
+	CHECK(nsall.type() == xpath_node_set::type_sorted_reverse);
 
 	test_runner::_memory_fail_threshold = 1;
 
 	CHECK_ALLOC_FAIL(ns = nsall);
 
-	CHECK(ns.size() == 2 && ns[0] == doc.child(STR("node")).child(STR("a")) && ns[1] == doc.child(STR("node")).child(STR("b")));
+	CHECK(ns.size() == 2);
+	CHECK(ns.type() == xpath_node_set::type_sorted);
+	CHECK(ns[0] == doc.child(STR("node")).child(STR("a")) && ns[1] == doc.child(STR("node")).child(STR("b")));
 }
 
 TEST_XML(xpath_api_deprecated_select_single_node, "<node><head/><foo id='1'/><foo/><tail/></node>")