Implement supervised rootless network readiness

crates/lazaret-linux/tests/acquisition.rs

@@ -44,6 +44,7 @@ fn exit(result: std::io::Result<()>) -> ExitCode {
 
 fn run_all() -> std::io::Result<()> {
     successful_acquisition()?;
+    acknowledged_transition_precedes_exact_wrapper_release()?;
     lifetime_pipe_descriptor_contract()?;
     failed_stages_and_acknowledgments()?;
     production_wrapper_refuses_former_harness_path()?;
@@ -53,6 +54,47 @@ fn run_all() -> std::io::Result<()> {
     concurrent_acquisitions_serialize()
 }
 
+#[allow(clippy::disallowed_methods, clippy::disallowed_types)]
+fn acknowledged_transition_precedes_exact_wrapper_release() -> std::io::Result<()> {
+    let target_marker = marker("transition-target");
+    let parent = current_process_identity()?;
+    let staged = std::cell::Cell::new(None);
+    let acknowledged = std::cell::Cell::new(false);
+    let target = TargetCommand::new("/usr/bin/touch").argument(&target_marker);
+    let process = child_broker().acquire_with_stdio_after_ack(
+        parent,
+        context(),
+        &target,
+        ChildStandardIo::inherit(),
+        |ownership| {
+            staged.set(Some(ownership));
+            Ok(())
+        },
+        |ownership| {
+            if staged.get() != Some(ownership) {
+                return Err(std::io::Error::other("transition staged ownership changed"));
+            }
+            acknowledged.set(true);
+            Ok(ProcessOwnershipCommitAck::v1(ownership))
+        },
+        || {
+            if !acknowledged.get() || target_marker.exists() {
+                return Err(std::io::Error::other(
+                    "wrapper was released outside the acknowledged transition boundary",
+                ));
+            }
+            Ok(())
+        },
+    )?;
+    child_broker().reap(process)?;
+    if !target_marker.is_file() {
+        return Err(std::io::Error::other(
+            "acknowledged transition did not release the exact wrapper",
+        ));
+    }
+    std::fs::remove_file(target_marker)
+}
+
 #[allow(clippy::disallowed_methods, clippy::disallowed_types)]
 fn lifetime_pipe_descriptor_contract() -> std::io::Result<()> {
     let held_pipe_marker = marker("lifetime-pipe");