chore: import upstream snapshot with attribution

vminitd/Sources/VminitdCore/ContainerProcess.swift

@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2026 Apple Inc. and the Containerization project authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+#if os(Linux)
+
+import ContainerizationOS
+import Foundation
+
+/// Exit status information for a container process
+struct ContainerExitStatus: Sendable {
+    var exitCode: Int32
+    var exitedAt: Date
+}
+
+/// Protocol for managing container processes
+///
+/// This protocol abstracts the underlying container runtime implementation,
+/// allowing for different backends like vmexec or runc.
+protocol ContainerProcess: Sendable {
+    /// Unique identifier for the container process
+    var id: String { get }
+
+    /// Process ID of the running container (nil if not started)
+    var pid: Int32? { get }
+
+    /// Start the container process
+    /// - Returns: The process ID of the started container
+    /// - Throws: If the process fails to start
+    func start() async throws -> Int32
+
+    /// Wait for the container process to exit
+    /// - Returns: Exit status information when the process exits
+    func wait() async -> ContainerExitStatus
+
+    /// Send a signal to the container process
+    /// - Parameter signal: The signal number to send
+    /// - Throws: If the signal cannot be sent
+    func kill(_ signal: Int32) async throws
+
+    /// Resize the terminal for the container process
+    /// - Parameter size: The new terminal size
+    /// - Throws: If the terminal cannot be resized or process doesn't have a terminal
+    func resize(size: Terminal.Size) throws
+
+    /// Close stdin for the container process
+    /// - Throws: If stdin cannot be closed
+    func closeStdin() throws
+
+    /// Delete the container process and clean up resources
+    /// - Throws: If cleanup fails
+    func delete() async throws
+
+    /// Set the exit status of the process.
+    func setExit(_ status: Int32)
+}
+
+#endif