call_usermodehelper_setup — prepare to call a usermode helper
struct subprocess_info * call_usermodehelper_setup
(char * path, char ** argv, char ** envp);
path to usermode executable
arg vector for process
environment for process
Returns either NULL on allocation failure, or a subprocess_info structure. This should be passed to call_usermodehelper_exec to exec the process and free the structure.