Add nix derivation

src/main.rs

@@ -1,21 +1,23 @@
-use libc::{c_int, c_void, mmap, MAP_FAILED, MAP_SHARED, PROT_READ, PROT_WRITE};
+use libc::{
+    c_int, c_void, mmap, MAP_ANON, MAP_FAILED, MAP_PRIVATE, MAP_SHARED, PROT_READ, PROT_WRITE,
+};
 use std::{env, ptr};
 
 const SHARED_MEMORY_SIZE: usize = 1024;
 
 #[link(name = "agent")]
 extern "C" {
-    fn agent_start(shared_memory: *mut u8, sync_memory: *mut u8);
+    fn agent_start(shared_memory: *mut u8, sync_memory: *mut u8, private_mem: *mut u8);
 }
 
 fn main() {
     let args: Vec<String> = env::args().collect();
 
-    let shared_fd: c_int = args[1]
+    let shared_fd: c_int = args[0]
         .parse()
         .expect("Please provide a valid file descriptor as first argument");
 
-    let sync_fd: c_int = args[2]
+    let sync_fd: c_int = args[1]
         .parse()
         .expect("Please provide a valid file descriptor as first argument");
 
@@ -43,8 +45,20 @@ fn main() {
     } as *mut u8;
     assert_ne!(sync_memory, MAP_FAILED as *mut u8);
 
-    println!("Starting agent...");
+    let private_mem = unsafe {
+        mmap(
+            ptr::null_mut() as *mut c_void,
+            32 * 100,
+            PROT_READ | PROT_WRITE,
+            MAP_PRIVATE | MAP_ANON,
+            0,
+            0,
+        )
+    } as *mut u8;
+    assert_ne!(private_mem, MAP_FAILED as *mut u8);
+
+    println!("Agent: starting agent...");
     unsafe {
-        agent_start(shared_memory, sync_memory);
+        agent_start(shared_memory, sync_memory, private_mem);
     }
 }