Function fuse_setup 

pub unsafe extern "C" fn fuse_setup(
    argc: c_int,
    argv: *mut *mut c_char,
    op: *const fuse_operations,
    op_size: size_t,
    mountpoint: *mut *mut c_char,
    multithreaded: *mut c_int,
    user_data: *mut c_void,
) -> *mut fuse

This is the part of fuse_main() before the event loop