Add Amazon Linux platform detection

Author: drexin

Sources/TSCUtility/Platform.swift

@@ -12,44 +12,59 @@ import TSCBasic
 import Foundation
 
 /// Recognized Platform types.
-public enum Platform {
+public enum Platform: Equatable {
     case android
     case darwin
     case linux(LinuxFlavor)
 
     /// Recognized flavors of linux.
-    public enum LinuxFlavor {
+    public enum LinuxFlavor: Equatable {
         case debian
         case fedora
     }
 
     /// Lazily checked current platform.
-    public static var currentPlatform = Platform.findCurrentPlatform()
+    public static var currentPlatform = Platform._findCurrentPlatform(localFileSystem)
     /// Attempt to match `uname` with recognized platforms.
-    private static func findCurrentPlatform() -> Platform? {
+    public static func _findCurrentPlatform(_ fs: FileSystem) -> Platform? {
         guard let uname = try? Process.checkNonZeroExit(args: "uname").spm_chomp().lowercased() else { return nil }
         switch uname {
         case "darwin":
             return .darwin
         case "linux":
-            if localFileSystem.isFile(AbsolutePath("/etc/debian_version")) {
-                return .linux(.debian)
-            }
-            if localFileSystem.isFile(AbsolutePath("/system/bin/toolbox")) ||
-               localFileSystem.isFile(AbsolutePath("/system/bin/toybox")) {
-                return .android
-            }
-            if localFileSystem.isFile(AbsolutePath("/etc/redhat-release")) ||
-               localFileSystem.isFile(AbsolutePath("/etc/centos-release")) ||
-               localFileSystem.isFile(AbsolutePath("/etc/fedora-release")) {
-                return .linux(.fedora)
-            }
+            return Platform._findCurrentPlatformLinux(fs)
         default:
             return nil
         }
+    }
+
+    public static func _findCurrentPlatformLinux(_ fs: FileSystem) -> Platform? {
+        if fs.isFile(AbsolutePath("/etc/debian_version")) {
+            return .linux(.debian)
+        }
+        if fs.isFile(AbsolutePath("/system/bin/toolbox")) ||
+           fs.isFile(AbsolutePath("/system/bin/toybox")) {
+            return .android
+        }
+        if fs.isFile(AbsolutePath("/etc/redhat-release")) ||
+           fs.isFile(AbsolutePath("/etc/centos-release")) ||
+           fs.isFile(AbsolutePath("/etc/fedora-release")) ||
+           Platform.isAmazonLinux2(fs) {
+            return .linux(.fedora)
+        }
+
         return nil
     }
 
+    private static func isAmazonLinux2(_ fs: FileSystem) -> Bool {
+        do {
+            let release = try fs.readFileContents(AbsolutePath("/etc/system-release")).cString
+            return release.hasPrefix("Amazon Linux release 2")
+        } catch {
+            return false
+        }
+    }
+
     /// Returns the cache directories used in Darwin.
     public static func darwinCacheDirectories() -> [AbsolutePath] {
         if let value = Platform._darwinCacheDirectories {

Tests/TSCUtilityTests/PlatformTests.swift

@@ -0,0 +1,44 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See http://swift.org/LICENSE.txt for license information
+ See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+import XCTest
+import TSCBasic
+import TSCTestSupport
+
+import TSCUtility
+
+final class PlatformTests: XCTestCase {
+    func testFindCurrentPlatformDebian() {
+        let fs = InMemoryFileSystem(files: ["/etc/debian_version": "xxx"])
+        XCTAssertEqual(Platform.linux(.debian), Platform._findCurrentPlatformLinux(fs))
+    }
+
+    func testFindCurrentPlatformAndroid() {
+        var fs = InMemoryFileSystem(files: ["/system/bin/toolbox": "xxx"])
+        XCTAssertEqual(Platform.android, Platform._findCurrentPlatformLinux(fs))
+
+        fs = InMemoryFileSystem(files: ["/system/bin/toybox": "xxx"])
+        XCTAssertEqual(Platform.android, Platform._findCurrentPlatformLinux(fs))
+    }
+
+    func testFindCurrentPlatformFedora() {
+        var fs = InMemoryFileSystem(files: ["/etc/fedora-release": "xxx"])
+        XCTAssertEqual(Platform.linux(.fedora), Platform._findCurrentPlatformLinux(fs))
+
+        fs = InMemoryFileSystem(files: ["/etc/redhat-release": "xxx"])
+        XCTAssertEqual(Platform.linux(.fedora), Platform._findCurrentPlatformLinux(fs))
+
+        fs = InMemoryFileSystem(files: ["/etc/centos-release": "xxx"])
+        XCTAssertEqual(Platform.linux(.fedora), Platform._findCurrentPlatformLinux(fs))
+
+        fs = InMemoryFileSystem(files: ["/etc/system-release": "Amazon Linux release 2 (Karoo)"])
+        XCTAssertEqual(Platform.linux(.fedora), Platform._findCurrentPlatformLinux(fs))
+    }
+}