chore: import upstream snapshot with attribution

Sources/ContainerVersion/CommandLine+Executable.swift

@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025-2026 Apple Inc. and the container 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 Foundation
+import SystemPackage
+
+extension CommandLine {
+    /// The path of the running executable.
+    ///
+    /// Obtained via `_NSGetExecutablePath`, which returns an absolute, lexically normalized path
+    /// (no `.` or `..` components). Symlinks are not resolved, so the path is not canonical.
+    public static var executablePath: FilePath {
+        /// _NSGetExecutablePath with a zero-length buffer returns the needed buffer length
+        var bufferSize: Int32 = 0
+        var buffer = [CChar](repeating: 0, count: Int(bufferSize))
+        _ = _NSGetExecutablePath(&buffer, &bufferSize)
+
+        /// Create the buffer and get the path
+        buffer = [CChar](repeating: 0, count: Int(bufferSize))
+        guard _NSGetExecutablePath(&buffer, &bufferSize) == 0 else {
+            fatalError("unexpected: failed to get executable path")
+        }
+
+        /// Return the path with the executable file component removed the last component and
+        let executablePath = String(cString: &buffer)
+        return FilePath(executablePath)
+    }
+}