How can i get a filepath of current(opened) dxf file?

Hello, i'm developing a small plugin for LibreCAD, i can't find the filepath of current dxf file. Does LibreCAD have a method/variable that can solve my trouble? Thanks much.

The plugin interface does not have and need this information.
It is intended to modify the document representation in memory.
Modifying an open DXF file from outside LibreCAD, on file level,  is a bad idea generally.
There is no mechanism in LibreCAD which can handle this correct.