chore: import upstream snapshot with attribution

Sources/ContainerizationOS/Sysctl.swift

@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025-2026 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 canImport(Darwin)
+import Darwin
+#endif
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
+/// Helper type to deal with system control functionalities.
+public struct Sysctl {
+    #if os(macOS)
+    /// Simple `sysctlbyname` wrapper.
+    public static func byName(_ name: String) throws -> Int64 {
+        var num: Int64 = 0
+        var size = MemoryLayout<Int64>.size
+        if sysctlbyname(name, &num, &size, nil, 0) != 0 {
+            throw POSIXError.fromErrno()
+        }
+        return num
+    }
+    #endif
+}