Fix missing Linux AppImage and launcher icons

packaging/BetterMail.desktop

@@ -4,6 +4,7 @@ Name=BetterMail
 Comment=Fast local-first Microsoft 365 mail
 Exec=BetterMail %u
 Icon=BetterMail
+StartupWMClass=BetterMail
 Categories=Network;Email;
 MimeType=x-scheme-handler/mailto;x-scheme-handler/bettermail;
 Terminal=false

scripts/package-linux-appimage.sh

@@ -21,4 +21,5 @@ install -m 644 "$icon" "$appdir/BetterMail.svg"
 install -m 644 "$icon" "$appdir/usr/share/icons/hicolor/scalable/apps/BetterMail.svg"
 
 linuxdeploy --appdir "$appdir" --desktop-file "$appdir/BetterMail.desktop" --icon-file "$appdir/BetterMail.svg"
+install -m 644 "$root/asset-pack/04-desktop/linux/hicolor/256x256/apps/bettermail.png" "$appdir/.DirIcon"
 ARCH=x86_64 appimagetool "$appdir" "$root/artifacts/BetterMail-x86_64.AppImage"

scripts/package-release.ps1

@@ -65,6 +65,10 @@ if ($Runtime -eq "linux-x64") {
     Copy-Item -LiteralPath (Join-Path $repositoryRoot "scripts/AppRun") -Destination (Join-Path $appDir "AppRun")
     Copy-Item -LiteralPath (Join-Path $repositoryRoot "packaging/BetterMail.desktop") -Destination (Join-Path $appDir "BetterMail.desktop")
     Copy-Item -LiteralPath $icon -Destination (Join-Path $appDir "BetterMail.png")
+    Copy-Item -LiteralPath $icon -Destination (Join-Path $appDir ".DirIcon")
+    $iconDirectory = Join-Path $appDir "usr/share/icons/hicolor/512x512/apps"
+    New-Item -ItemType Directory -Force $iconDirectory | Out-Null
+    Copy-Item -LiteralPath $icon -Destination (Join-Path $iconDirectory "BetterMail.png")
     chmod +x (Join-Path $appDir "AppRun")
     $packDirectory = $appDir
 }

src/BetterMail.App/BetterMail.App.csproj

@@ -24,6 +24,8 @@
     <ProjectReference Include="../BetterMail.Microsoft365/BetterMail.Microsoft365.csproj" />
   </ItemGroup>
   <ItemGroup>
+    <EmbeddedResource Include="../../asset-pack/04-desktop/linux/hicolor/512x512/apps/bettermail.png"
+                      LogicalName="BetterMail.LinuxIcon.png" />
     <AvaloniaResource Include="Assets\**" />
     <AvaloniaResource Include="..\..\asset-pack\06-banners\website-header-1500x500.png"
                       Link="Assets\BetterMailSettingsBanner.png" />

src/BetterMail.App/LinuxDesktopIntegration.cs

@@ -0,0 +1,64 @@
+using System.Diagnostics;
+
+namespace BetterMail.App;
+
+internal static class LinuxDesktopIntegration
+{
+    internal static string DataDirectory =>
+        Environment.GetEnvironmentVariable("XDG_DATA_HOME") is { Length: > 0 } directory && Path.IsPathFullyQualified(directory)
+            ? directory
+            : Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".local", "share");
+
+    public static void Register()
+    {
+        if (!OperatingSystem.IsLinux() || Environment.GetEnvironmentVariable("APPIMAGE") is not { Length: > 0 } appImage)
+            return;
+        try { Install(appImage, DataDirectory); }
+        catch (Exception exception) when (exception is IOException or UnauthorizedAccessException or ArgumentException)
+        {
+            // Read-only home directories must not prevent opening mail.
+            Trace.TraceWarning("Could not register Linux launcher: {0}", exception.GetType().Name);
+        }
+    }
+
+    internal static void Install(string appImage, string dataDirectory)
+    {
+        if (!Path.IsPathFullyQualified(appImage) || appImage.IndexOfAny(['\r', '\n', '\0']) >= 0)
+            throw new ArgumentException("The AppImage path must be an absolute single-line path.", nameof(appImage));
+
+        var iconPath = Path.Combine(dataDirectory, "icons", "hicolor", "512x512", "apps", "BetterMail.png");
+        Directory.CreateDirectory(Path.GetDirectoryName(iconPath)!);
+        using (var icon = typeof(LinuxDesktopIntegration).Assembly.GetManifestResourceStream("BetterMail.LinuxIcon.png")!)
+        using (var output = File.Create(iconPath))
+            icon.CopyTo(output);
+
+        var applications = Path.Combine(dataDirectory, "applications");
+        Directory.CreateDirectory(applications);
+        // Use a persistent icon, not the temporary AppImage mount. Registering the launcher
+        // does not change the user's default mail application.
+        // env also avoids GLib checking the executable path before decoding literal %%.
+        var desktop = $"""
+            [Desktop Entry]
+            Type=Application
+            Name=BetterMail
+            Comment=Fast local-first Microsoft 365 mail
+            Exec=env -- {QuoteExecutable(appImage)} %u
+            Icon={EscapeValue(iconPath)}
+            StartupWMClass=BetterMail
+            Categories=Network;Email;
+            MimeType=x-scheme-handler/mailto;x-scheme-handler/bettermail;
+            Terminal=false
+
+            """;
+        File.WriteAllText(Path.Combine(applications, "bettermail.desktop"), desktop);
+    }
+
+    private static string EscapeValue(string value) => value.Replace("\\", "\\\\").Replace("\n", "\\n").Replace("\r", "\\r").Replace("\t", "\\t");
+
+    private static string QuoteExecutable(string value)
+    {
+        // Exec quoting is decoded after desktop-entry string escaping.
+        var quoted = value.Replace("\\", "\\\\").Replace("\"", "\\\"").Replace("`", "\\`").Replace("$", "\\$").Replace("%", "%%");
+        return "\"" + EscapeValue(quoted) + "\"";
+    }
+}

src/BetterMail.App/MailtoActivation.cs

@@ -275,31 +275,7 @@ public static async Task ChooseAsync()
         {
             throw new InvalidOperationException("Install the BetterMail AppImage before choosing it as the default mail app.");
         }
-        if (appImage.Contains((char)34))
-        {
-            throw new InvalidOperationException("The AppImage path contains an unsupported quote character.");
-        }
-
-        var applications = Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.UserProfile),
-            ".local", "share", "applications");
-        Directory.CreateDirectory(applications);
-        var desktopPath = Path.Combine(applications, "bettermail.desktop");
-        var desktop = """
-            [Desktop Entry]
-            Type=Application
-            Name=BetterMail
-            Comment=Fast local-first Microsoft 365 mail
-            Exec=__APPIMAGE__ %u
-            Icon=BetterMail
-            Categories=Network;Email;
-            MimeType=x-scheme-handler/mailto;x-scheme-handler/bettermail;
-            Terminal=false
-
-            """;
-        desktop = desktop.Replace(
-            "__APPIMAGE__", string.Concat((char)34, appImage, (char)34), StringComparison.Ordinal);
-        await File.WriteAllTextAsync(desktopPath, desktop);
+        LinuxDesktopIntegration.Install(appImage, LinuxDesktopIntegration.DataDirectory);
         using var process = Process.Start(new ProcessStartInfo(
             "xdg-mime", "default bettermail.desktop x-scheme-handler/mailto x-scheme-handler/bettermail")
         {

src/BetterMail.App/Program.cs

@@ -16,6 +16,7 @@ public static void Main(string[] args)
         }
         velopack.Run();
         DefaultMailApp.Register();
+        LinuxDesktopIntegration.Register();
 
         var activation = args.FirstOrDefault(argument =>
             argument.StartsWith("mailto:", StringComparison.OrdinalIgnoreCase) ||
@@ -42,6 +43,7 @@ public static void Main(string[] args)
     public static AppBuilder BuildAvaloniaApp() => AppBuilder
         .Configure<App>()
         .UsePlatformDetect()
+        .With(new X11PlatformOptions { WmClass = "BetterMail" })
         .WithInterFont()
         .LogToTrace();
 }

tests/BetterMail.Tests/LinuxDesktopIntegrationTests.cs

@@ -0,0 +1,53 @@
+using BetterMail.App;
+
+namespace BetterMail.Tests;
+
+public sealed class LinuxDesktopIntegrationTests
+{
+    [Fact]
+    public void LauncherKeepsItsIconAndTracksMovedAppImage()
+    {
+        var directory = Path.Combine(Path.GetTempPath(), "bettermail-launcher-" + Guid.NewGuid());
+        try
+        {
+            var appImage = Path.Combine(directory, "Original Mail.AppImage");
+            LinuxDesktopIntegration.Install(appImage, directory);
+            var desktopPath = Path.Combine(directory, "applications", "bettermail.desktop");
+            var iconPath = Path.Combine(directory, "icons", "hicolor", "512x512", "apps", "BetterMail.png");
+            Assert.Equal(new byte[] { 137, 80, 78, 71, 13, 10, 26, 10 }, File.ReadAllBytes(iconPath)[..8]);
+            Assert.Contains("StartupWMClass=BetterMail", File.ReadAllText(desktopPath));
+            Assert.Contains("MimeType=x-scheme-handler/mailto;x-scheme-handler/bettermail;", File.ReadAllText(desktopPath));
+            Assert.Contains("Icon=" + iconPath.Replace("\\", "\\\\"), File.ReadAllText(desktopPath));
+
+            var moved = Path.Combine(directory, "Moved Mail.AppImage");
+            LinuxDesktopIntegration.Install(moved, directory);
+            var desktop = File.ReadAllText(desktopPath);
+            Assert.DoesNotContain("Original Mail.AppImage", desktop);
+            Assert.Contains("Moved Mail.AppImage\" %u", desktop);
+            Assert.Single(Directory.GetFiles(Path.GetDirectoryName(desktopPath)!));
+            Assert.False(File.Exists(Path.Combine(directory, "applications", "mimeapps.list")));
+        }
+        finally { Directory.Delete(directory, true); }
+    }
+
+    [Fact]
+    public void DesktopExecEscapesSpecialCharacters()
+    {
+        var directory = Path.Combine(Path.GetTempPath(), "bettermail-launcher-" + Guid.NewGuid());
+        try
+        {
+            LinuxDesktopIntegration.Install(Path.Combine(directory, "Mail $`\"%\\.AppImage"), directory);
+            var desktop = File.ReadAllText(Path.Combine(directory, "applications", "bettermail.desktop"));
+            Assert.Contains("Mail \\\\$\\\\`\\\\\"%%\\\\\\\\.AppImage\" %u", desktop);
+        }
+        finally { Directory.Delete(directory, true); }
+    }
+
+    [Theory]
+    [InlineData("relative.AppImage")]
+    [InlineData("/mail\nExec=other")]
+    public void InvalidExecutableDoesNotWriteLauncher(string executable)
+    {
+        Assert.Throws<ArgumentException>(() => LinuxDesktopIntegration.Install(executable, Path.GetTempPath()));
+    }
+}