Convert script to Swift Package Manager library

.gitignore

@@ -3,3 +3,4 @@
 *.swp
 *.swo
 ._*
+/.build

Makefile

@@ -2,25 +2,15 @@ VERSION = 2
 LIBRARY_PREFIX = pam_watchid
 LIBRARY_NAME = $(LIBRARY_PREFIX).so
 DESTINATION = /usr/local/lib/pam
-TARGET = apple-darwin$(shell uname -r)
+TARGET = apple-macosx10.15
 PAM_FILE_BASE = /etc/pam.d/sudo
 PAM_TEXT = auth sufficient $(LIBRARY_NAME)
 PAM_TID_TEXT = auth       sufficient     pam_tid.so
 
-# Determine if the macOS Sequoia SDK or later is available.
-DEFINES =
-# Due to the different ways in which the CLT and Xcode structure their SDK paths, one of the following will always be an empty string depending on what is configured by xcode-select. 
-CLT_SDK_MAJOR_VER = $(shell xcrun --sdk macosx --show-sdk-path | xargs readlink -f | xargs basename | sed 's/MacOSX//' | cut -d. -f1)
-XCODE_SDK_MAJOR_VER = $(shell xcrun --sdk macosx --show-sdk-path | xargs basename | sed 's/MacOSX//' | cut -d. -f1)
-SDK_REQUIRED_MAJOR_VER = 15
-ifeq "$(SDK_REQUIRED_MAJOR_VER)" "$(word 1, $(sort $(SDK_REQUIRED_MAJOR_VER) $(XCODE_SDK_MAJOR_VER) $(CLT_SDK_MAJOR_VER)))"
-	DEFINES += -DSEQUOIASDK
-endif
-
 all:
-	swiftc watchid-pam-extension.swift $(DEFINES) -o $(LIBRARY_PREFIX)_x86_64.so -target x86_64-$(TARGET) -emit-library
-	swiftc watchid-pam-extension.swift $(DEFINES) -o $(LIBRARY_PREFIX)_arm64.so -target arm64-$(TARGET) -emit-library
-	lipo -create $(LIBRARY_PREFIX)_arm64.so $(LIBRARY_PREFIX)_x86_64.so -output $(LIBRARY_NAME)
+	swift build -c release --triple x86_64-$(TARGET)
+	swift build -c release --triple arm64-$(TARGET)
+	lipo -create .build/x86_64-apple-macosx/release/libpam-watchid.dylib .build/arm64-apple-macosx/release/libpam-watchid.dylib -output $(LIBRARY_NAME)
 
 install: all
 	sudo mkdir -p $(DESTINATION)

Package.swift

@@ -0,0 +1,22 @@
+// swift-tools-version:5.1
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "pam-watchid",
+    platforms: [.macOS(.v10_15)],
+    products: [
+        // Products define the executables and libraries a package produces, making them visible to other packages.
+        .library(
+            name: "pam-watchid",
+            type: .dynamic,
+            targets: ["pam-watchid"]),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package, defining a module or a test suite.
+        // Targets can depend on other targets in this package and products from dependencies.
+        .target(
+            name: "pam-watchid"),
+    ]
+)

watchid-pam-extension.swift → Sources/pam-watchid/pam_watchid.swift

@@ -80,7 +80,7 @@ private func parseArguments(argc: Int, argv: vchar) -> [String: String] {
 
 private extension LAPolicy {
     static var deviceOwnerAuthenticationIgnoringUserID: LAPolicy {
-#if SEQUOIASDK
+#if compiler(>=6.0)
         if #available(macOS 15, *) {
             return .deviceOwnerAuthenticationWithBiometricsOrCompanion
         } else {