Add support for legacy ISOs on Apple Silicon

Mist/Helpers/Codesigner.swift

@@ -25,4 +25,19 @@ struct Codesigner {
             throw MistError.invalidTerminationStatus(status: response.terminationStatus, output: response.standardOutput, error: response.standardError)
         }
     }
+
+    /// Ad-hoc sign all files within a directory (or app bundle).
+    ///
+    /// - Parameters:
+    ///   - url: The URL of the directory to ad-hoc sign.
+    ///
+    /// - Throws: A `MistError` if the command failed to execute.
+    static func adhocSign(_ url: URL) async throws {
+        let arguments: [String] = ["find", url.path, "-type", "f", "-exec", "codesign", "--sign", "-", "--force", "{}", ";"]
+        let response: HelperToolCommandResponse = try ShellExecutor.shared.execute(arguments)
+
+        guard response.terminationStatus == 0 else {
+            throw MistError.invalidTerminationStatus(status: response.terminationStatus, output: response.standardOutput, error: response.standardError)
+        }
+    }
 }

Mist/Helpers/TaskManager.swift

@@ -426,6 +426,7 @@ class TaskManager: ObservableObject {
         return tasks
     }
 
+    // swiftlint:disable:next function_body_length
     private static func isoTasks(for installer: Installer, filename: String, destination destinationURL: URL, temporaryDirectory temporaryDirectoryURL: URL) -> [MistTask] {
 
         let temporaryImageURL: URL = temporaryDirectoryURL.appendingPathComponent("\(installer.id).dmg")
@@ -443,6 +444,12 @@ class TaskManager: ObservableObject {
                 },
                 MistTask(type: .create, description: "macOS Installer in temporary Disk Image") {
 
+                    // Workaround to make OS X Yosemite 10.10 to macOS Catalina 10.15 createinstallmedia work on Apple Silicon
+                    if let architecture: Architecture = Hardware.architecture,
+                        architecture == .appleSilicon && !installer.bigSurOrNewer {
+                        try await Codesigner.adhocSign(installer.temporaryInstallerURL)
+                    }
+
                     // Workaround to make macOS Sierra 10.12 createinstallmedia work
                     if installer.version.hasPrefix("10.12") {
                         let infoPlistURL: URL = installer.temporaryInstallerURL.appendingPathComponent("Contents/Info.plist")
@@ -533,6 +540,12 @@ class TaskManager: ObservableObject {
         let tasks: [MistTask] = [
             MistTask(type: .create, description: "Bootable Installer") {
 
+                // Workaround to make OS X Yosemite 10.10 to macOS Catalina 10.15 createinstallmedia work on Apple Silicon
+                if let architecture: Architecture = Hardware.architecture,
+                    architecture == .appleSilicon && !installer.bigSurOrNewer {
+                    try await Codesigner.adhocSign(installer.temporaryInstallerURL)
+                }
+
                 // Workaround to make macOS Sierra 10.12 createinstallmedia work
                 if installer.version.hasPrefix("10.12") {
                     let infoPlistURL: URL = installer.temporaryInstallerURL.appendingPathComponent("Contents/Info.plist")

Mist/Views/List/InstallerExportView.swift

@@ -18,16 +18,6 @@ struct InstallerExportView: View {
     private var exportPackage: Bool = false
     var installer: Installer
     @Binding var exports: [InstallerExportType]
-    private var isoCompatible: Bool {
-        guard let architecture: Architecture = Hardware.architecture else {
-            return false
-        }
-
-        return architecture == .intel || (architecture == .appleSilicon && installer.bigSurOrNewer)
-    }
-    private var compatibilityMessage: String {
-        "**Note:** ISOs are unavailable for building **macOS Catalina 10.15 and older** on [Apple Silicon Macs](https://support.apple.com/en-us/HT211814)."
-    }
 
     var body: some View {
         VStack {
@@ -40,16 +30,11 @@ struct InstallerExportView: View {
                 InstallerExportViewItem(exportType: .diskImage, selected: $exportDiskImage)
                     .disabled(exports.count == 1 && exportDiskImage)
                 InstallerExportViewItem(exportType: .iso, selected: $exportISO)
-                    .disabled(isoCompatible ? exports.count == 1 && exportISO : true)
-                    .opacity(isoCompatible ? 1 : 0.5)
+                    .disabled(exports.count == 1 && exportISO)
                 InstallerExportViewItem(exportType: .package, selected: $exportPackage)
                     .disabled(exports.count == 1 && exportPackage)
                 Spacer()
             }
-            if !isoCompatible {
-                Text(.init(compatibilityMessage))
-                    .padding(.top)
-            }
         }
         .padding()
         .onChange(of: exportApplication) { _ in
@@ -73,10 +58,6 @@ struct InstallerExportView: View {
 
         var exports: [InstallerExportType] = []
 
-        if !isoCompatible && exportISO {
-            exportISO = false
-        }
-
         if !exportApplication && !exportDiskImage && !exportISO && !exportPackage {
             exportApplication = true
         }

Mist/Views/List/ListRowInstaller.swift

@@ -91,8 +91,7 @@ struct ListRowInstaller: View {
                 }
                 .help("Download and export macOS Installer")
                 .buttonStyle(.mistAction)
-                if let architecture: Architecture = Hardware.architecture,
-                    (architecture == .appleSilicon && installer.bigSurOrNewer) || (architecture == .intel && installer.mavericksOrNewer) {
+                if installer.mavericksOrNewer {
                     Button {
                         pressButton(.volumeSelection)
                     } label: {

Mist/Views/Settings/SettingsISOsView.swift

@@ -13,7 +13,7 @@ struct SettingsISOsView: View {
     private let imageName: String = "ISO"
     private let title: String = "ISOs"
     // swiftlint:disable:next line_length
-    private let description: String = "ISOs are Bootable macOS Installer Disk Images that can be restored on external USB drives, or used with virtualization software (ie. [Parallels Desktop](https://www.parallels.com/au/products/desktop/), [UTM](https://mac.getutm.app), [VMware Fusion](https://www.vmware.com/au/products/fusion.html), [VirtualBox](https://www.virtualbox.org)).\n\n**Note:** ISOs are unavailable for building **macOS Catalina 10.15 and older** on [Apple Silicon Macs](https://support.apple.com/en-us/HT211814)."
+    private let description: String = "ISOs are Bootable macOS Installer Disk Images that can be restored on external USB drives, or used with virtualization software (ie. [Parallels Desktop](https://www.parallels.com/au/products/desktop/), [UTM](https://mac.getutm.app), [VMware Fusion](https://www.vmware.com/au/products/fusion.html), [VirtualBox](https://www.virtualbox.org))."
 
     var body: some View {
         VStack(alignment: .leading) {