add box enter

Cargo.toml

@@ -12,3 +12,4 @@ name = "izoli"
 path = "src/bin/izoli.rs"
 
 [dependencies]
+nix = { version = "0.29.0", features = ["sched"] }

src/izolibox.rs

@@ -1 +1,25 @@
+use nix::{
+    libc::SIGCHLD,
+    sched::{self, CloneCb, CloneFlags},
+    unistd::Pid,
+};
+
+const STACK_SIZE: usize = 8192;
+
 pub struct IzoliBox {}
+
+impl IzoliBox {
+    pub fn new() -> Self {
+        Self {}
+    }
+
+    pub fn enter(&self, callback: CloneCb<'_>) -> Result<Pid, nix::errno::Errno> {
+        let mut stack = [0u8; STACK_SIZE];
+        let flags = CloneFlags::CLONE_NEWNS
+            | CloneFlags::CLONE_NEWUTS
+            | CloneFlags::CLONE_NEWIPC
+            | CloneFlags::CLONE_NEWPID;
+
+        unsafe { sched::clone(callback, &mut stack, flags, Some(SIGCHLD)) }
+    }
+}