use XML::LibXML;
$s = "<foo name=bobby><name>robert
";
print "before: $s.\n";
$dom = XML::LibXML->load_xml(string => "");
$dom->findnodes("/root")->[0]->appendText($s);
print $dom->serialize;
$s2 = $dom->findnodes("//text()")->[0]->data;
print "after: $s2.\n";