Kill native processes on LinuxContainer.kill

Native processes should be managed the same as init process as they are
direct children of vminitd process. Thus, they should receive a signal
as well when container receives a signal.

Additional update:
- Update comments for `LinuxContainer.exec`

Author: JaewonHur

Sources/Containerization/LinuxContainer.swift

@@ -849,6 +849,11 @@ extension LinuxContainer {
     public func kill(_ signal: Signal) async throws {
         try await self.state.withLock {
             let state = try $0.startedState("kill")
+
+            for process in state.vendedProcesses.values where process.native {
+                try await process.kill(signal)
+            }
+
             try await state.process.kill(signal)
         }
     }
@@ -915,7 +920,7 @@ extension LinuxContainer {
     }
 
     /// Execute a new process in the container. The process is not started after this call, and must be manually started
-    /// via the `start` method.
+    /// via the `start` method. When `native` is true, the process is created outside of container, running in the root of VM.
     public func exec(_ id: String, configuration: LinuxProcessConfiguration, native: Bool = false) async throws -> LinuxProcess {
         try await self.state.withLock {
             var state = try $0.startedState("exec")

Sources/Containerization/LinuxProcess.swift

@@ -94,7 +94,7 @@ public final class LinuxProcess: Sendable {
 
     private let state: Mutex<State>
     private let ioSetup: Stdio
-    private let native: Bool
+    let native: Bool
     private let agent: any VirtualMachineAgent
     private let vm: any VirtualMachineInstance
     private let ociRuntimePath: String?