modified the security helper to assist in preventing directory traversal when using sanitize_filename() for user input
diff --git a/user_guide/libraries/security.html b/user_guide/libraries/security.html
index a50d948..6d6216d 100644
--- a/user_guide/libraries/security.html
+++ b/user_guide/libraries/security.html
@@ -102,6 +102,11 @@
<code>$filename = $this->security->sanitize_filename($this->input->post('filename'));</code>
+<p>If it is acceptable for the user input to include relative paths, e.g. <kbd>file/in/some/approved/folder.txt</kbd>, you can set the second optional parameter,
+ <samp>$relative_path</samp> to TRUE.</p>
+
+<code>$filename = $this->security->sanitize_filename($this->input->post('filename'), TRUE);</code>
+
<!-- @todo write docs for CSRF methods -->
</div>