macOS support for swiftly

.gitignore

@@ -6,3 +6,4 @@ xcuserdata/
 DerivedData/
 .swiftpm/
 .vscode/
+**/*.swp

.swift-version

@@ -1 +1 @@
-5.7
+5.10

DESIGN.md

@@ -54,30 +54,25 @@ This is all very similar to how rustup does things, but I figure there's no need
 ## macOS
 ### Installation of swiftly
 
-Similar to Linux, the bootstrapping script for macOS will create a `~/.swiftly/bin` directory and drop the swiftly executable in it. A similar `~/.swiftly/env` file will be created and a message will be printed suggesting users add source `~/.swiftly/env` to their `.bash_profile` or `.zshrc`.
+Similar to Linux, the bootstrapping script for macOS will create a `~/.local/bin` directory and drop the swiftly executable in it. A `~/.local/share/swiftly/env` file will be created and a message will be printed suggesting users add source `~/.local/share/swiftly/env` to their `.bash_profile` or `.zshrc`.
 
 The bootstrapping script will detect if xcode is installed and prompt the user to install it if it isn’t. We could also ask the user if they’d like us to install the xcode command line tools for them via `xcode-select --install`.
 
 ### Installation of a Swift toolchain
 
-The contents of `~/.swiftly` would look like this:
+The contents of `~/Library/Application Support/swiftly` would look like this:
 
 ```
-~/.swiftly
-
-   |
-   -- bin/
-   |
-   -- active-toolchain/
+~/Library/Application Support/swiftly
    |
    -- config.json
    |
    – env
 ```
 
-Instead of downloading tarballs containing the toolchains and storing them directly in `~/.swiftly/toolchains`, we instead install Swift toolchains to `~/Library/Developer/Toolchains` via the `.pkg` files provided for download at swift.org. (Side note: we’ll need to request that other versions than the latest be made available). To select a toolchain for use, we update the symlink at `~/.swiftly/active-toolchain` to point to the desired toolchain in `~/Library/Developer/Toolchains`. In the env file, we’ll contain a line that looks like `export PATH=”$HOME/.swiftly/active-toolchain/usr/bin:$PATH`, so the version of swift being used will automatically always be from the active toolchain. `config.json` will contain version information about the selected toolchain as well as its actual location on disk.
+Instead of downloading tarballs containing the toolchains and storing them directly in `~/.local/share/swiftly/toolchains`, we instead install Swift toolchains to `~/Library/Developer/Toolchains` via the `.pkg` files provided for download at swift.org. To select a toolchain for use, we update the symlinks at `~/Library/Application Support/swiftly/bin` to point to the desired toolchain in `~/Library/Developer/Toolchains`. In the env file, we’ll contain a line that looks like `export PATH="$HOME/Library/Application Support/swiftly:$PATH"`, so the version of swift being used will automatically always be from the active toolchain. `config.json` will contain version information about the selected toolchain as well as its actual location on disk.
 
-This scheme works for ensuring the version of Swift used on the command line can be controlled, but it doesn’t affect the active toolchain used by Xcode. From what I can tell, there doesn’t seem to be a way to tell Xcode which toolchain to use except through the GUI, which won’t work for us. A possible solution would be to have the active-toolchain symlink live with the rest of the toolchains, and then the user could select it from the GUI (we could name it something like “swiftly Active Toolchain” or something to indicate that it’s managed by swiftly). Alternatively, we could figure out how Xcode selects toolchains and do what it does in swiftly manually.
+This scheme works for ensuring the version of Swift used on the command line can be controlled, but it doesn’t affect the active toolchain used by Xcode, which uses its own mechanisms for that. Xcode, if it is installed, can find the toolchains installed by swiftly.
 
 ## Interface
 

Package.swift

@@ -1,10 +1,12 @@
-// swift-tools-version:5.7
+// swift-tools-version:5.10
 
 import PackageDescription
 
 let package = Package(
     name: "swiftly",
-    platforms: [.macOS(.v13)],
+    platforms: [
+        .macOS(.v13),
+    ],
     products: [
         .executable(
             name: "swiftly",
@@ -24,6 +26,7 @@ let package = Package(
                 .product(name: "ArgumentParser", package: "swift-argument-parser"),
                 .target(name: "SwiftlyCore"),
                 .target(name: "LinuxPlatform", condition: .when(platforms: [.linux])),
+                .target(name: "MacOSPlatform", condition: .when(platforms: [.macOS])),
                 .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
             ]
         ),
@@ -44,6 +47,12 @@ let package = Package(
                 .linkedLibrary("z"),
             ]
         ),
+        .target(
+            name: "MacOSPlatform",
+            dependencies: [
+                "SwiftlyCore",
+            ]
+        ),
         .systemLibrary(
             name: "CLibArchive",
             pkgConfig: "libarchive",

README.md

@@ -41,7 +41,7 @@ Target: x86_64-unknown-linux-gnu
 - Linux-based platforms listed on https://swift.org/download
   - CentOS 7 will not be supported due to some dependencies of swiftly not supporting it, however.
 
-Right now, swiftly is in the very early stages of development and is only supported on Linux, but the long term plan is to also support macOS. For more detailed information about swiftly's intended features and implementation, check out the [design document](DESIGN.md).
+Right now, swiftly is in early stages of development and is supported on Linux and macOS. For more detailed information about swiftly's intended features and implementation, check out the [design document](DESIGN.md).
 
 ## Command interface overview
 

Sources/LinuxPlatform/Linux.swift

@@ -17,6 +17,18 @@ public struct Linux: Platform {
         }
     }
 
+    public var swiftlyBinDir: URL {
+        SwiftlyCore.mockedHomeDir.map { $0.appendingPathComponent("bin", isDirectory: true) }
+            ?? ProcessInfo.processInfo.environment["SWIFTLY_BIN_DIR"].map { URL(fileURLWithPath: $0) }
+            ?? FileManager.default.homeDirectoryForCurrentUser
+            .appendingPathComponent(".local", isDirectory: true)
+            .appendingPathComponent("bin", isDirectory: true)
+    }
+
+    public var swiftlyToolchainsDir: URL {
+        self.swiftlyHomeDir.appendingPathComponent("toolchains", isDirectory: true)
+    }
+
     public var toolchainFileExtension: String {
         "tar.gz"
     }
@@ -205,23 +217,5 @@ public struct Linux: Platform {
         }
     }
 
-    private func runProgram(_ args: String..., quiet: Bool = false) throws {
-        let process = Process()
-        process.executableURL = URL(fileURLWithPath: "/usr/bin/env")
-        process.arguments = args
-
-        if quiet {
-            process.standardOutput = nil
-            process.standardError = nil
-        }
-
-        try process.run()
-        process.waitUntilExit()
-
-        guard process.terminationStatus == 0 else {
-            throw Error(message: "\(args.first!) exited with non-zero status: \(process.terminationStatus)")
-        }
-    }
-
     public static let currentPlatform: any Platform = Linux()
 }

Sources/MacOSPlatform/MacOS.swift

@@ -0,0 +1,201 @@
+import Foundation
+import SwiftlyCore
+
+public struct SwiftPkgInfo: Codable {
+    public var CFBundleIdentifier: String
+
+    public init(CFBundleIdentifier: String) {
+        self.CFBundleIdentifier = CFBundleIdentifier
+    }
+}
+
+/// `Platform` implementation for macOS systems.
+public struct MacOS: Platform {
+    public init() {}
+
+    public var appDataDirectory: URL {
+        FileManager.default.homeDirectoryForCurrentUser
+            .appendingPathComponent("Library/Application Support", isDirectory: true)
+    }
+
+    public var swiftlyBinDir: URL {
+        SwiftlyCore.mockedHomeDir.map { $0.appendingPathComponent("bin", isDirectory: true) }
+            ?? ProcessInfo.processInfo.environment["SWIFTLY_BIN_DIR"].map { URL(fileURLWithPath: $0) }
+            ?? FileManager.default.homeDirectoryForCurrentUser
+            .appendingPathComponent("Library/Application Support/swiftly/bin", isDirectory: true)
+    }
+
+    public var swiftlyToolchainsDir: URL {
+        SwiftlyCore.mockedHomeDir.map { $0.appendingPathComponent("Toolchains", isDirectory: true) }
+            // The toolchains are always installed here by the installer. We bypass the installer in the case of test mocks
+            ?? FileManager.default.homeDirectoryForCurrentUser.appendingPathComponent("Library/Developer/Toolchains", isDirectory: true)
+    }
+
+    public var toolchainFileExtension: String {
+        "pkg"
+    }
+
+    public func isSystemDependencyPresent(_: SystemDependency) -> Bool {
+        // All system dependencies on macOS should be present
+        true
+    }
+
+    public func verifySystemPrerequisitesForInstall(requireSignatureValidation _: Bool) throws {
+        // All system prerequisites should be there for macOS
+    }
+
+    public func install(from tmpFile: URL, version: ToolchainVersion) throws {
+        guard tmpFile.fileExists() else {
+            throw Error(message: "\(tmpFile) doesn't exist")
+        }
+
+        if !self.swiftlyToolchainsDir.fileExists() {
+            try FileManager.default.createDirectory(at: self.swiftlyToolchainsDir, withIntermediateDirectories: false)
+        }
+
+        if SwiftlyCore.mockedHomeDir == nil {
+            SwiftlyCore.print("Installing package in user home directory...")
+            try runProgram("installer", "-pkg", tmpFile.path, "-target", "CurrentUserHomeDirectory")
+        } else {
+            // In the case of a mock for testing purposes we won't use the installer, perferring a manual process because
+            //  the installer will not install to an arbitrary path, only a volume or user home directory.
+            let tmpDir = self.getTempFilePath()
+            let toolchainDir = self.swiftlyToolchainsDir.appendingPathComponent("\(version.identifier).xctoolchain", isDirectory: true)
+            if !toolchainDir.fileExists() {
+                try FileManager.default.createDirectory(at: toolchainDir, withIntermediateDirectories: false)
+            }
+            try runProgram("pkgutil", "--expand", tmpFile.path, tmpDir.path)
+            // There's a slight difference in the location of the special Payload file between official swift packages
+            // and the ones that are mocked here in the test framework.
+            var payload = tmpDir.appendingPathComponent("Payload")
+            if !payload.fileExists() {
+                payload = tmpDir.appendingPathComponent("\(version.identifier)-osx-package.pkg/Payload")
+            }
+            try runProgram("tar", "-C", toolchainDir.path, "-xf", payload.path)
+        }
+    }
+
+    public func uninstall(_ toolchain: ToolchainVersion) throws {
+        SwiftlyCore.print("Uninstalling package in user home directory...")
+
+        let toolchainDir = self.swiftlyToolchainsDir.appendingPathComponent("\(toolchain.identifier).xctoolchain", isDirectory: true)
+
+        let decoder = PropertyListDecoder()
+        let infoPlist = toolchainDir.appendingPathComponent("Info.plist")
+        guard let data = try? Data(contentsOf: infoPlist) else {
+            throw Error(message: "could not open \(infoPlist)")
+        }
+
+        guard let pkgInfo = try? decoder.decode(SwiftPkgInfo.self, from: data) else {
+            throw Error(message: "could not decode plist at \(infoPlist)")
+        }
+
+        try FileManager.default.removeItem(at: toolchainDir)
+
+        let homedir = ProcessInfo.processInfo.environment["HOME"]!
+        try? runProgram("pkgutil", "--volume", homedir, "--forget", pkgInfo.CFBundleIdentifier)
+    }
+
+    public func use(_ toolchain: ToolchainVersion, currentToolchain: ToolchainVersion?) throws -> Bool {
+        let toolchainBinURL = self.swiftlyToolchainsDir
+            .appendingPathComponent(toolchain.identifier + ".xctoolchain", isDirectory: true)
+            .appendingPathComponent("usr", isDirectory: true)
+            .appendingPathComponent("bin", isDirectory: true)
+
+        // Delete existing symlinks from previously in-use toolchain.
+        if let currentToolchain {
+            try self.unUse(currentToolchain: currentToolchain)
+        }
+
+        // Ensure swiftly doesn't overwrite any existing executables without getting confirmation first.
+        let swiftlyBinDirContents = try FileManager.default.contentsOfDirectory(atPath: self.swiftlyBinDir.path)
+        let toolchainBinDirContents = try FileManager.default.contentsOfDirectory(atPath: toolchainBinURL.path)
+        let willBeOverwritten = Set(toolchainBinDirContents).intersection(swiftlyBinDirContents)
+        if !willBeOverwritten.isEmpty {
+            SwiftlyCore.print("The following existing executables will be overwritten:")
+
+            for executable in willBeOverwritten {
+                SwiftlyCore.print("  \(self.swiftlyBinDir.appendingPathComponent(executable).path)")
+            }
+
+            let proceed = SwiftlyCore.readLine(prompt: "Proceed? (y/n)") ?? "n"
+
+            guard proceed == "y" else {
+                SwiftlyCore.print("Aborting use")
+                return false
+            }
+        }
+
+        for executable in toolchainBinDirContents {
+            let linkURL = self.swiftlyBinDir.appendingPathComponent(executable)
+            let executableURL = toolchainBinURL.appendingPathComponent(executable)
+
+            // Deletion confirmed with user above.
+            try linkURL.deleteIfExists()
+
+            try FileManager.default.createSymbolicLink(
+                atPath: linkURL.path,
+                withDestinationPath: executableURL.path
+            )
+        }
+
+        SwiftlyCore.print("""
+            NOTE: On macOS it is possible that the shell will pick up the system Swift on the path
+            instead of the one that swiftly has installed for you. You can run the 'hash -r'
+            command to update the shell with the latest PATHs.
+
+                hash -r
+
+            """
+        )
+
+        return true
+    }
+
+    public func unUse(currentToolchain: ToolchainVersion) throws {
+        let currentToolchainBinURL = self.swiftlyToolchainsDir
+            .appendingPathComponent(currentToolchain.identifier + ".xctoolchain", isDirectory: true)
+            .appendingPathComponent("usr", isDirectory: true)
+            .appendingPathComponent("bin", isDirectory: true)
+
+        for existingExecutable in try FileManager.default.contentsOfDirectory(atPath: currentToolchainBinURL.path) {
+            guard existingExecutable != "swiftly" else {
+                continue
+            }
+
+            let url = self.swiftlyBinDir.appendingPathComponent(existingExecutable)
+            let vals = try url.resourceValues(forKeys: [URLResourceKey.isSymbolicLinkKey])
+
+            guard let islink = vals.isSymbolicLink, islink else {
+                throw Error(message: "Found executable not managed by swiftly in SWIFTLY_BIN_DIR: \(url.path)")
+            }
+            let symlinkDest = url.resolvingSymlinksInPath()
+            guard symlinkDest.deletingLastPathComponent() == currentToolchainBinURL else {
+                throw Error(message: "Found symlink that points to non-swiftly managed executable: \(symlinkDest.path)")
+            }
+
+            try self.swiftlyBinDir.appendingPathComponent(existingExecutable).deleteIfExists()
+        }
+    }
+
+    public func listAvailableSnapshots(version _: String?) async -> [Snapshot] {
+        []
+    }
+
+    public func getExecutableName(forArch: String) -> String {
+        "swiftly-\(forArch)-macos-osx"
+    }
+
+    public func currentToolchain() throws -> ToolchainVersion? { nil }
+
+    public func getTempFilePath() -> URL {
+        FileManager.default.temporaryDirectory.appendingPathComponent("swiftly-\(UUID()).pkg")
+    }
+
+    public func verifySignature(httpClient _: SwiftlyHTTPClient, archiveDownloadURL _: URL, archive _: URL) async throws {
+        // No signature verification is required on macOS since the pkg files have their own signing
+        //  mechanism and the swift.org downloadables are trusted by stock macOS installations.
+    }
+
+    public static let currentPlatform: any Platform = MacOS()
+}