add assert

src/main.rs

@@ -21,7 +21,7 @@ fn main() {
 
     let sync_fd: c_int = args[1]
         .parse()
-        .expect("Please provide a valid file descriptor as first argument");
+        .expect("Please provide a valid file descriptor as second argument");
 
     let shared_memory = unsafe {
         mmap(
@@ -55,6 +55,7 @@ fn main() {
         .as_raw_fd()
         .try_into()
         .unwrap();
+    assert!(private_file > 2);
 
     unsafe {
         agent_start(shared_memory, sync_memory, private_file);