chore: import upstream snapshot with attribution

Sources/Containerization/UnixSocketRelayManager.swift

@@ -0,0 +1,73 @@
+//===----------------------------------------------------------------------===//
+// 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.
+//===----------------------------------------------------------------------===//
+
+import ContainerizationError
+import Foundation
+import Logging
+
+package actor UnixSocketRelayManager {
+    private let vm: any VirtualMachineInstance
+    private var relays: [String: UnixSocketRelay]
+    private let log: Logger?
+
+    init(vm: any VirtualMachineInstance, log: Logger? = nil) {
+        self.vm = vm
+        self.relays = [:]
+        self.log = log
+    }
+}
+
+extension UnixSocketRelayManager {
+    func start(port: UInt32, socket: UnixSocketConfiguration) async throws {
+        guard relays[socket.id] == nil else {
+            throw ContainerizationError(
+                .invalidState,
+                message: "socket relay \(socket.id) already started"
+            )
+        }
+
+        let relay = try UnixSocketRelay(
+            port: port,
+            socket: socket,
+            vm: vm,
+            log: log
+        )
+
+        do {
+            relays[socket.id] = relay
+            try await relay.start()
+        } catch {
+            relays.removeValue(forKey: socket.id)
+            throw error
+        }
+    }
+
+    func stop(socket: UnixSocketConfiguration) async throws {
+        guard let storedRelay = relays.removeValue(forKey: socket.id) else {
+            throw ContainerizationError(
+                .notFound,
+                message: "failed to stop socket relay"
+            )
+        }
+        try storedRelay.stop()
+    }
+
+    func stopAll() async throws {
+        for (_, relay) in relays {
+            try relay.stop()
+        }
+    }
+}