how can I teminate the system copying action in my program

Question

I create a folder with appointed space size. when I copy(or upload ) a file into this folder,if program find the folder space added the file which is copying will exceed the size I appointed before, then I want my program will terminate this copying action.
the step before has been realized, now the problem puzzled me is terminate the system copying action. how should I do with C#.
someone said using API, but which function should be picked? and how to get the handle for copy.