Fix xml_node::offset_debug for corner cases

Computed offsets for documents with nodes that were added using append_buffer
or newly appended nodes without name/value information were invalid.

2 files changed, 41 insertions, 4 deletions

diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 973cfd6..3fe492b 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -5402,8 +5402,8 @@ namespace pugi
 
 		impl::xml_document_struct& doc = impl::get_document(_root);
 
-		const char_t* buffer = doc.buffer;
-		if (!buffer) return -1;
+		// we can determine the offset reliably only if there is exactly once parse buffer
+		if (!doc.buffer || doc.extra_buffers) return -1;
 
 		switch (type())
 		{
@@ -5413,13 +5413,13 @@ namespace pugi
 		case node_element:
 		case node_declaration:
 		case node_pi:
-			return (_root->header & impl::xml_memory_page_name_allocated_or_shared_mask) ? -1 : _root->name - buffer;
+			return _root->name && (_root->header & impl::xml_memory_page_name_allocated_or_shared_mask) == 0 ? _root->name - doc.buffer : -1;
 
 		case node_pcdata:
 		case node_cdata:
 		case node_comment:
 		case node_doctype:
-			return (_root->header & impl::xml_memory_page_value_allocated_or_shared_mask) ? -1 : _root->value - buffer;
+			return _root->value && (_root->header & impl::xml_memory_page_value_allocated_or_shared_mask) == 0 ? _root->value - doc.buffer : -1;
 
 		default:
 			return -1;
diff --git a/tests/test_dom_traverse.cpp b/tests/test_dom_traverse.cpp
index 83afec8..721a079 100644
--- a/tests/test_dom_traverse.cpp
+++ b/tests/test_dom_traverse.cpp
@@ -924,6 +924,43 @@ TEST_XML_FLAGS(dom_offset_debug, "<?xml?><!DOCTYPE><?pi?><!--comment--><node>pcd
 	CHECK((cit++)->offset_debug() == 58);
 }
 
+TEST(dom_offset_debug_encoding)
+{
+	char buf[] = { 0, '<', 0, 'n', 0, '/', 0, '>' };
+
+	xml_document doc;
+	CHECK(doc.load_buffer(buf, sizeof(buf)));
+
+	CHECK(doc.offset_debug() == 0);
+	CHECK(doc.first_child().offset_debug() == 1);
+}
+
+TEST_XML(dom_offset_debug_append, "<node/>")
+{
+	xml_node c1 = doc.first_child();
+	xml_node c2 = doc.append_child(STR("node"));
+	xml_node c3 = doc.append_child(node_pcdata);
+
+	CHECK(doc.offset_debug() == 0);
+	CHECK(c1.offset_debug() == 1);
+	CHECK(c2.offset_debug() == -1);
+	CHECK(c3.offset_debug() == -1);
+
+	c1.set_name(STR("nodenode"));
+	CHECK(c1.offset_debug() == -1);
+}
+
+TEST_XML(dom_offset_debug_append_buffer, "<node/>")
+{
+	CHECK(doc.offset_debug() == 0);
+	CHECK(doc.first_child().offset_debug() == 1);
+
+	CHECK(doc.append_buffer("<node/>", 7));
+	CHECK(doc.offset_debug() == -1);
+	CHECK(doc.first_child().offset_debug() == -1);
+	CHECK(doc.last_child().offset_debug() == -1);
+}
+
 TEST_XML(dom_internal_object, "<node attr='value'>value</node>")
 {
 	xml_node node = doc.child(STR("node"));