krata: fix exit status when guest exit happens during attach

crates/krataguest/Cargo.toml

@@ -10,6 +10,7 @@ env_logger = { workspace = true }
 futures = { workspace = true }
 ipnetwork = { workspace = true }
 krata = { path = "../krata" }
+libc = { workspace = true }
 log = { workspace = true }
 nix = { workspace = true, features = ["process"] }
 oci-spec = { workspace = true }

crates/krataguest/src/background.rs

@@ -6,14 +6,14 @@ use nix::{libc::c_int, unistd::Pid};
 use tokio::{select, time::sleep};
 use xenstore::{XsdClient, XsdInterface};
 
-pub struct ContainerBackground {
+pub struct GuestBackground {
     child: Pid,
     wait: ChildWait,
 }
 
-impl ContainerBackground {
-    pub async fn new(child: Pid) -> Result<ContainerBackground> {
-        Ok(ContainerBackground {
+impl GuestBackground {
+    pub async fn new(child: Pid) -> Result<GuestBackground> {
+        Ok(GuestBackground {
             child,
             wait: ChildWait::new()?,
         })

crates/krataguest/src/childwait.rs

@@ -8,11 +8,9 @@ use std::{
 };
 
 use anyhow::Result;
+use libc::{c_int, waitpid, WEXITSTATUS, WIFEXITED};
 use log::warn;
-use nix::{
-    libc::{c_int, wait},
-    unistd::Pid,
-};
+use nix::unistd::Pid;
 use tokio::sync::mpsc::{channel, Receiver, Sender};
 
 const CHILD_WAIT_QUEUE_LEN: usize = 10;
@@ -63,15 +61,18 @@ impl ChildWaitTask {
     fn process(&mut self) -> Result<()> {
         loop {
             let mut status: c_int = 0;
-            let pid = unsafe { wait(addr_of_mut!(status)) };
-            let event = ChildEvent {
-                pid: Pid::from_raw(pid),
-                status,
-            };
-            let _ = self.sender.try_send(event);
+            let pid = unsafe { waitpid(-1, addr_of_mut!(status), 0) };
 
-            if self.signal.load(Ordering::Acquire) {
-                return Ok(());
+            if WIFEXITED(status) {
+                let event = ChildEvent {
+                    pid: Pid::from_raw(pid),
+                    status: WEXITSTATUS(status),
+                };
+                let _ = self.sender.try_send(event);
+
+                if self.signal.load(Ordering::Acquire) {
+                    return Ok(());
+                }
             }
         }
     }

crates/krataguest/src/init.rs

@@ -22,7 +22,7 @@ use std::{fs, io};
 use sys_mount::{FilesystemType, Mount, MountFlags};
 use walkdir::WalkDir;
 
-use crate::background::ContainerBackground;
+use crate::background::GuestBackground;
 
 const IMAGE_BLOCK_DEVICE_PATH: &str = "/dev/xvda";
 const CONFIG_BLOCK_DEVICE_PATH: &str = "/dev/xvdb";
@@ -516,7 +516,7 @@ impl GuestInit {
     }
 
     async fn background(&mut self, executed: Pid) -> Result<()> {
-        let mut background = ContainerBackground::new(executed).await?;
+        let mut background = GuestBackground::new(executed).await?;
         background.run().await?;
         Ok(())
     }