fix(boot): make the graphical menu mouse opt-in

Add menu-styles.graphical.enable-mouse, which is off by default. Without it, or without a pointing device, the cursor is not drawn and the hint only mentions the keyboard.

README.md

@@ -130,7 +130,7 @@ $ sprout.efi --boot="Boot Xen"
 $ sprout.efi --autoconfigure
 # Use the basic boot menu instead of the simple one.
 $ sprout.efi --menu-style=basic
-# Use the graphical boot menu, which can be used with the mouse.
+# Use the graphical boot menu.
 $ sprout.efi --menu-style=graphical
 # Show the boot menu for 10 seconds before booting the default entry.
 $ sprout.efi --menu-timeout=10
@@ -142,6 +142,16 @@ $ sprout.efi --retain-boot-console
 $ sprout.efi --bls-strict-mode
 ```
 
+### Graphical Menu
+
+The graphical menu selects entries with the keyboard. The mouse is off by default. To use it, enable it in
+`sprout.toml`. The cursor is only shown when the mouse is enabled and the firmware has a pointing device.
+
+```toml
+[menu-styles.graphical]
+enable-mouse = true
+```
+
 ### Boot Linux from ESP
 
 ```toml

crates/boot/src/main.rs

@@ -630,6 +630,9 @@ fn run(reboot_on_error: &mut bool) -> Result<()> {
             .menu_style
             .unwrap_or(config.options.menu_style);
 
+        // The graphical menu only uses the mouse when it is enabled in the configuration.
+        let graphical_mouse = config.menu_styles.graphical.enable_mouse;
+
         // Find the forced boot entry, unless the boot menu is forced.
         // The oneshot entry from the bootloader interface is forced by id, and it is used instead of
         // --boot. If the forced boot entry can't be found, such as when it was removed,
@@ -664,8 +667,15 @@ fn run(reboot_on_error: &mut bool) -> Result<()> {
         let entry = match forced_entry {
             Some(entry) => entry,
             // Delegate to the menu to select an entry to boot.
-            None => menu::select(&timer, menu_timeout, menu_disabled, menu_style, &entries)
+            None => menu::select(
-                .context("unable to select entry via boot menu")?,
+                &timer,
+                menu_timeout,
+                menu_disabled,
+                menu_style,
+                graphical_mouse,
+                &entries,
+            )
+            .context("unable to select entry via boot menu")?,
         };
 
         // Tell the bootloader interface what the selected entry is.

crates/boot/src/menu.rs

@@ -22,7 +22,7 @@ pub mod basic;
 /// font: The bitmap font that the graphical menu draws text with.
 mod font;
 
-/// graphical: A menu drawn on the graphics output that is used with the keyboard or the mouse.
+/// graphical: A menu drawn on the graphics output that is used with the keyboard, or the mouse if enabled.
 pub mod graphical;
 
 /// logo: The Sprout logo that the graphical menu draws in a corner.
@@ -177,6 +177,7 @@ pub fn select<'live>(
     timeout: Option<Duration>,
     menu_disabled: bool,
     style: MenuStyle,
+    graphical_mouse: bool,
     entries: &'live [BootableEntry],
 ) -> Result<&'live BootableEntry> {
     // A hidden menu gives the user a moment to ask for the menu with a key press.
@@ -208,7 +209,11 @@ pub fn select<'live>(
 
         // The graphical menu needs a graphics output, which not every machine has.
         // If it fails, the simple menu is used instead, which falls back to the basic menu.
-        MenuStyle::Graphical => GraphicalMenu.select(timeout, entries).or_else(|error| {
+        MenuStyle::Graphical => GraphicalMenu {
+            enable_mouse: graphical_mouse,
+        }
+        .select(timeout, entries)
+        .or_else(|error| {
             warn!(
                 "unable to show the graphical boot menu, using the simple menu: {:#}",
                 error

crates/boot/src/menu/graphical.rs

@@ -29,7 +29,10 @@ const PIXELS_PER_MILLIMETER: i64 = 8;
 const TITLE: &str = "sprout";
 
 /// The hint shown once the countdown has been stopped.
-const HINT: &str = "Pick an entry with the arrow keys or the mouse.";
+const HINT: &str = "Pick an entry with the arrow keys.";
+
+/// The hint shown instead of [HINT] when the mouse is in use.
+const HINT_MOUSE: &str = "Pick an entry with the arrow keys or the mouse.";
 
 /// The color of the top of the background, which fades into [BACKGROUND_BOTTOM].
 const BACKGROUND_TOP: (u8, u8, u8) = (0x3a, 0x1c, 0x4e);
@@ -87,8 +90,11 @@ const CURSOR: [&str; 16] = [
     "     XXXX  ",
 ];
 
-/// A graphical boot menu that selects entries with the keyboard or the mouse.
+/// A graphical boot menu that selects entries with the keyboard, or the mouse if enabled.
-pub struct GraphicalMenu;
+pub struct GraphicalMenu {
+    /// Whether the mouse is used when the firmware has a pointing device.
+    pub enable_mouse: bool,
+}
 
 /// The pointing devices of the firmware.
 /// Firmware commonly has both kinds of protocol, even if one has no device behind it.
@@ -258,7 +264,7 @@ impl Layout {
             .map(|entry| entry.title().chars().count())
             .max()
             .unwrap_or(0);
-        let status = HINT.len().max(STATUS_WIDEST.len());
+        let status = HINT.len().max(HINT_MOUSE.len()).max(STATUS_WIDEST.len());
         let panel_width = ((longest + 4) * cell + padding * 2)
             .max(40 * cell)
             .max((status + 8) * cell)
@@ -806,6 +812,7 @@ fn run(
     loop {
         scene.status = match remaining {
             Some(remaining) => format!("Boot in {} s.", remaining.as_millis().div_ceil(1000)),
+            None if mouse.is_some() => String::from(HINT_MOUSE),
             None => String::from(HINT),
         };
         for screen in screens.iter_mut() {
@@ -901,7 +908,7 @@ impl BootMenu for GraphicalMenu {
         }
 
         let mut screens = Screen::open_all(entries)?;
-        let mut mouse = Mouse::open();
+        let mut mouse = self.enable_mouse.then(Mouse::open).flatten();
 
         let result = uefi::system::with_stdin(|input| {
             run(input, mouse.take(), &mut screens, timeout, entries, default)

crates/config/src/lib.rs

@@ -38,6 +38,9 @@ pub struct RootConfiguration {
     /// Default options for Sprout.
     #[serde(default)]
     pub options: OptionsConfiguration,
+    /// Settings for each style of boot menu.
+    #[serde(rename = "menu-styles", default)]
+    pub menu_styles: MenuStylesConfiguration,
     /// Values to be inserted into the root sprout context.
     #[serde(default)]
     pub values: BTreeMap<String, String>,
@@ -99,12 +102,30 @@ pub struct OptionsConfiguration {
     pub bls_strict_mode: bool,
 }
 
+/// Settings for each style of boot menu.
+#[derive(Serialize, Deserialize, Debug, Default, Clone)]
+pub struct MenuStylesConfiguration {
+    /// Settings for the graphical boot menu.
+    #[serde(default)]
+    pub graphical: GraphicalMenuConfiguration,
+}
+
+/// Settings for the graphical boot menu.
+#[derive(Serialize, Deserialize, Debug, Default, Clone)]
+pub struct GraphicalMenuConfiguration {
+    /// Enables selecting entries with the mouse, and shows the cursor. When disabled, or when
+    /// the firmware has no pointing device, entries are selected with the keyboard only.
+    #[serde(rename = "enable-mouse", default)]
+    pub enable_mouse: bool,
+}
+
 /// The default configuration, which matches an empty configuration file.
 impl Default for RootConfiguration {
     fn default() -> Self {
         Self {
             version: latest_version(),
             options: Default::default(),
+            menu_styles: Default::default(),
             values: Default::default(),
             drivers: Default::default(),
             extractors: Default::default(),
@@ -171,6 +192,17 @@ mod tests {
         assert_eq!(default.options.autoconfigure, empty.options.autoconfigure);
     }
 
+    #[test]
+    fn graphical_mouse_is_off_by_default() {
+        assert!(
+            !RootConfiguration::default()
+                .menu_styles
+                .graphical
+                .enable_mouse
+        );
+        assert!(!empty().menu_styles.graphical.enable_mouse);
+    }
+
     #[test]
     fn bls_strict_mode_is_off_by_default() {
         assert!(!RootConfiguration::default().options.bls_strict_mode);