🦾 Check for Apple Silicon

Package.swift

@@ -42,7 +42,11 @@ let package = Package(
         ),
         .target(
             name: "MasKit",
-            dependencies: ["Commandant", "PromiseKit", "Version"],
+            dependencies: [
+                "Commandant",
+                "PromiseKit",
+                "Version",
+            ],
             swiftSettings: [
                 .unsafeFlags([
                     "-I", "Sources/PrivateFrameworks/CommerceKit",

Sources/MasKit/ExternalCommands/ExternalCommand.swift

@@ -14,6 +14,7 @@ protocol ExternalCommand {
 
     var process: Process { get }
 
+    var stdout: String { get }
     var stderr: String { get }
     var stdoutPipe: Pipe { get }
     var stderrPipe: Pipe { get }
@@ -28,6 +29,11 @@ protocol ExternalCommand {
 
 /// Common implementation
 extension ExternalCommand {
+    var stdout: String {
+        let data = stdoutPipe.fileHandleForReading.readDataToEndOfFile()
+        return String(data: data, encoding: .utf8) ?? ""
+    }
+
     var stderr: String {
         let data = stderrPipe.fileHandleForReading.readDataToEndOfFile()
         return String(data: data, encoding: .utf8) ?? ""

Sources/MasKit/ExternalCommands/SysCtlSystemCommand.swift

@@ -0,0 +1,40 @@
+//
+//  SysCtlSystemCommand.swift
+//  MasKit
+//
+//  Created by Chris Araman on 6/3/21.
+//  Copyright © 2021 mas-cli. All rights reserved.
+//
+
+import Foundation
+
+/// Wrapper for the external sysctl system command.
+/// https://ss64.com/osx/sysctl.html
+struct SysCtlSystemCommand: ExternalCommand {
+    var binaryPath: String
+
+    let process = Process()
+
+    let stdoutPipe = Pipe()
+    let stderrPipe = Pipe()
+
+    init(binaryPath: String = "/usr/sbin/sysctl") {
+        self.binaryPath = binaryPath
+    }
+
+    static var isAppleSilicon: Bool = {
+        let sysctl = SysCtlSystemCommand()
+        do {
+            // Returns 1 on Apple Silicon even when run in an Intel context in Rosetta.
+            try sysctl.run(arguments: "-in", "hw.optional.arm64")
+        } catch {
+            fatalError("sysctl failed")
+        }
+
+        guard sysctl.succeeded else {
+            fatalError("sysctl failed")
+        }
+
+        return sysctl.stdout.trimmingCharacters(in: .newlines) == "1"
+    }()
+}