light position relative to object coordinate system?

I’m trying to do a shadow casting demo, but at a certain moment in my program i need to know where a light is relative to my object coordinate system. I tryed it with glGetLightfv(GL_LIGHT0, GL_POSITION, etc.) but it returns the position relative to the world coordinate system. Is there a function that returns what i want it to return, or i’ll have to use an inversed matrix? I tryed it also with an inversed matrix, but it doesn’t work. Anyone can help me?