feat: gate semantic effects by client capability

compositor/Cargo.toml

@@ -11,6 +11,7 @@ ferese-animation = { path = "../crates/ferese-animation" }
 ferese-core = { path = "../crates/ferese-core" }
 ferese-ipc = { path = "../crates/ferese-ipc" }
 ferese-layout = { path = "../crates/ferese-layout" }
+ferese-protocols = { path = "../crates/ferese-protocols", features = ["server"] }
 libc.workspace = true
 smithay.workspace = true
 serde.workspace = true

compositor/src/backends/mod.rs

@@ -4,7 +4,7 @@ use std::ffi::OsString;
 
 use smithay::reexports::calloop::EventLoop;
 
-use crate::Ferese;
+use crate::{Ferese, private_client::ClientCapabilities};
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum BackendKind {
@@ -16,6 +16,7 @@ pub enum BackendKind {
 pub struct LaunchConfig {
     pub backend: BackendKind,
     pub client: Vec<OsString>,
+    pub client_capabilities: ClientCapabilities,
 }
 
 impl LaunchConfig {
@@ -33,6 +34,7 @@ impl LaunchConfig {
         let mut args = args.into_iter().peekable();
         let mut requested_backend = None;
         let mut client = Vec::new();
+        let mut client_capabilities = ClientCapabilities::default();
 
         while let Some(argument) = args.next() {
             if argument == "--" {
@@ -46,6 +48,10 @@ impl LaunchConfig {
                 requested_backend = Some(parse_backend(&value)?);
                 continue;
             }
+            if argument == "--grant-effects" {
+                client_capabilities.insert(ClientCapabilities::EFFECTS);
+                continue;
+            }
             if let Some(value) = argument
                 .to_str()
                 .and_then(|argument| argument.strip_prefix("--backend="))
@@ -65,7 +71,11 @@ impl LaunchConfig {
             BackendKind::Drm
         });
 
-        Ok(Self { backend, client })
+        Ok(Self {
+            backend,
+            client,
+            client_capabilities,
+        })
     }
 }
 
@@ -102,6 +112,7 @@ mod tests {
 
         assert_eq!(config.backend, BackendKind::Nested);
         assert_eq!(config.client, [OsString::from("foot")]);
+        assert!(config.client_capabilities.is_empty());
     }
 
     #[test]
@@ -110,6 +121,7 @@ mod tests {
 
         assert_eq!(config.backend, BackendKind::Drm);
         assert!(config.client.is_empty());
+        assert!(config.client_capabilities.is_empty());
     }
 
     #[test]
@@ -130,6 +142,26 @@ mod tests {
             config.client,
             [OsString::from("foot"), OsString::from("--title=Ferese")]
         );
+        assert!(config.client_capabilities.is_empty());
+    }
+
+    #[test]
+    fn explicitly_grants_effects_to_the_launched_private_client() {
+        let config = LaunchConfig::parse(
+            [
+                OsString::from("--grant-effects"),
+                OsString::from("ferese-effects-probe"),
+            ],
+            true,
+        )
+        .unwrap();
+
+        assert_eq!(config.client, [OsString::from("ferese-effects-probe")]);
+        assert!(
+            config
+                .client_capabilities
+                .contains(ClientCapabilities::EFFECTS)
+        );
     }
 
     #[test]

compositor/src/effects.rs

@@ -0,0 +1,224 @@
+use std::sync::{
+    Mutex,
+    atomic::{AtomicBool, AtomicU64, Ordering},
+};
+
+use ferese_protocols::effects::v1::server::{
+    ferese_effects_manager_v1::{self, FereseEffectsManagerV1},
+    ferese_surface_effects_v1::{self, FereseSurfaceEffectsV1},
+};
+use smithay::{
+    reexports::wayland_server::{
+        Client, DataInit, Dispatch, DisplayHandle, GlobalDispatch, New, Resource, WEnum, Weak,
+        backend::ClientId, protocol::wl_surface::WlSurface,
+    },
+    wayland::compositor::with_states,
+};
+
+use crate::{Ferese, private_client::ClientCapabilities, state::ClientState};
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub(crate) enum SemanticRole {
+    Panel,
+    PanelElevated,
+    Popover,
+    Menu,
+    Notification,
+    Hud,
+    Modal,
+}
+
+#[derive(Debug)]
+struct SurfaceEffectsState {
+    attached: AtomicBool,
+    generation: AtomicU64,
+    role: Mutex<Option<SemanticRole>>,
+}
+
+impl SurfaceEffectsState {
+    fn new() -> Self {
+        Self {
+            attached: AtomicBool::new(false),
+            generation: AtomicU64::new(0),
+            role: Mutex::new(None),
+        }
+    }
+
+    fn set_role(&self, role: Option<SemanticRole>) {
+        let mut current = self.role.lock().unwrap();
+        if *current != role {
+            *current = role;
+            self.generation.fetch_add(1, Ordering::Release);
+        }
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct SurfaceEffectsUserData(Mutex<Weak<WlSurface>>);
+
+impl SurfaceEffectsUserData {
+    fn new(surface: WlSurface) -> Self {
+        Self(Mutex::new(surface.downgrade()))
+    }
+
+    fn surface(&self) -> Option<WlSurface> {
+        self.0.lock().unwrap().upgrade().ok()
+    }
+}
+
+pub(crate) fn init_global(display: &DisplayHandle) {
+    display.create_global::<Ferese, FereseEffectsManagerV1, _>(1, ());
+}
+
+// Consumed by the material renderer in the next M7 slice.
+#[allow(dead_code)]
+pub(crate) fn surface_role(surface: &WlSurface) -> Option<(SemanticRole, u64)> {
+    with_states(surface, |states| {
+        let effects = states.data_map.get::<SurfaceEffectsState>()?;
+        let role = *effects.role.lock().unwrap();
+        role.map(|role| (role, effects.generation.load(Ordering::Acquire)))
+    })
+}
+
+impl GlobalDispatch<FereseEffectsManagerV1, ()> for Ferese {
+    fn bind(
+        _state: &mut Self,
+        _display: &DisplayHandle,
+        _client: &Client,
+        resource: New<FereseEffectsManagerV1>,
+        _global_data: &(),
+        data_init: &mut DataInit<'_, Self>,
+    ) {
+        data_init.init(resource, ());
+    }
+
+    fn can_view(client: Client, _global_data: &()) -> bool {
+        client
+            .get_data::<ClientState>()
+            .is_some_and(|state| state.capabilities.contains(ClientCapabilities::EFFECTS))
+    }
+}
+
+impl Dispatch<FereseEffectsManagerV1, ()> for Ferese {
+    fn request(
+        _state: &mut Self,
+        _client: &Client,
+        manager: &FereseEffectsManagerV1,
+        request: ferese_effects_manager_v1::Request,
+        _data: &(),
+        _display: &DisplayHandle,
+        data_init: &mut DataInit<'_, Self>,
+    ) {
+        match request {
+            ferese_effects_manager_v1::Request::GetSurfaceEffects { id, surface } => {
+                let already_attached = with_states(&surface, |states| {
+                    states
+                        .data_map
+                        .insert_if_missing_threadsafe(SurfaceEffectsState::new);
+                    states
+                        .data_map
+                        .get::<SurfaceEffectsState>()
+                        .unwrap()
+                        .attached
+                        .swap(true, Ordering::AcqRel)
+                });
+
+                if already_attached {
+                    manager.post_error(
+                        ferese_effects_manager_v1::Error::AlreadyConstructed,
+                        "wl_surface already has a Ferese effects object",
+                    );
+                } else {
+                    data_init.init(id, SurfaceEffectsUserData::new(surface));
+                }
+            }
+            ferese_effects_manager_v1::Request::Destroy => {}
+            _ => unreachable!(),
+        }
+    }
+}
+
+impl Dispatch<FereseSurfaceEffectsV1, SurfaceEffectsUserData> for Ferese {
+    fn request(
+        _state: &mut Self,
+        _client: &Client,
+        _resource: &FereseSurfaceEffectsV1,
+        request: ferese_surface_effects_v1::Request,
+        data: &SurfaceEffectsUserData,
+        _display: &DisplayHandle,
+        _data_init: &mut DataInit<'_, Self>,
+    ) {
+        let Some(surface) = data.surface() else {
+            return;
+        };
+
+        match request {
+            ferese_surface_effects_v1::Request::SetRole { role } => {
+                let role = match role {
+                    WEnum::Value(ferese_surface_effects_v1::Role::Panel) => SemanticRole::Panel,
+                    WEnum::Value(ferese_surface_effects_v1::Role::PanelElevated) => {
+                        SemanticRole::PanelElevated
+                    }
+                    WEnum::Value(ferese_surface_effects_v1::Role::Popover) => SemanticRole::Popover,
+                    WEnum::Value(ferese_surface_effects_v1::Role::Menu) => SemanticRole::Menu,
+                    WEnum::Value(ferese_surface_effects_v1::Role::Notification) => {
+                        SemanticRole::Notification
+                    }
+                    WEnum::Value(ferese_surface_effects_v1::Role::Hud) => SemanticRole::Hud,
+                    WEnum::Value(ferese_surface_effects_v1::Role::Modal) => SemanticRole::Modal,
+                    WEnum::Unknown(_) | WEnum::Value(_) => return,
+                };
+                set_surface_role(&surface, Some(role));
+            }
+            ferese_surface_effects_v1::Request::ClearRole => set_surface_role(&surface, None),
+            ferese_surface_effects_v1::Request::Destroy => detach(&surface),
+            _ => unreachable!(),
+        }
+    }
+
+    fn destroyed(
+        _state: &mut Self,
+        _client: ClientId,
+        _resource: &FereseSurfaceEffectsV1,
+        data: &SurfaceEffectsUserData,
+    ) {
+        if let Some(surface) = data.surface() {
+            detach(&surface);
+        }
+    }
+}
+
+fn set_surface_role(surface: &WlSurface, role: Option<SemanticRole>) {
+    with_states(surface, |states| {
+        if let Some(effects) = states.data_map.get::<SurfaceEffectsState>() {
+            effects.set_role(role);
+        }
+    });
+}
+
+fn detach(surface: &WlSurface) {
+    with_states(surface, |states| {
+        if let Some(effects) = states.data_map.get::<SurfaceEffectsState>() {
+            effects.set_role(None);
+            effects.attached.store(false, Ordering::Release);
+        }
+    });
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn role_changes_advance_generation_only_when_material_changes() {
+        let effects = SurfaceEffectsState::new();
+        effects.set_role(Some(SemanticRole::Panel));
+        assert_eq!(effects.generation.load(Ordering::Acquire), 1);
+
+        effects.set_role(Some(SemanticRole::Panel));
+        assert_eq!(effects.generation.load(Ordering::Acquire), 1);
+
+        effects.set_role(Some(SemanticRole::Popover));
+        assert_eq!(effects.generation.load(Ordering::Acquire), 2);
+    }
+}

compositor/src/main.rs

@@ -3,11 +3,13 @@
 mod backends;
 mod config;
 mod cursor;
+mod effects;
 mod grabs;
 mod handlers;
 mod input;
 mod ipc;
 mod metrics;
+mod private_client;
 mod stacking;
 mod state;
 mod window_rules;
@@ -66,7 +68,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     unsafe { std::env::set_var("WAYLAND_DISPLAY", &state.socket_name) };
 
     info!(socket = ?state.socket_name, backend = ?launch.backend, "Ferese is accepting Wayland clients");
-    spawn_client(launch.client);
+    spawn_client(&mut state, launch.client, launch.client_capabilities);
     event_loop.run(None, &mut state, |_| {})?;
     Ok(())
 }
@@ -77,15 +79,34 @@ fn init_logging() {
     tracing_subscriber::fmt().with_env_filter(filter).init();
 }
 
-fn spawn_client(mut args: Vec<std::ffi::OsString>) {
+fn spawn_client(
+    state: &mut Ferese,
+    mut args: Vec<std::ffi::OsString>,
+    capabilities: private_client::ClientCapabilities,
+) {
     if args.is_empty() {
         info!("no client requested; pass one after `--`, for example `-- foot`");
         return;
     }
     let program = args.remove(0);
 
-    match Command::new(&program).args(args).spawn() {
+    let mut command = Command::new(&program);
+    command.args(args);
+    let private_connection = if capabilities.is_empty() {
+        None
+    } else {
+        match private_client::prepare_command(state, &mut command, capabilities) {
+            Ok(connection) => Some(connection),
+            Err(error) => {
+                warn!(program = ?program, %error, "failed to create private Wayland connection");
+                return;
+            }
+        }
+    };
+
+    match command.spawn() {
         Ok(child) => info!(program = ?program, pid = child.id(), "spawned Wayland client"),
         Err(error) => warn!(program = ?program, %error, "failed to spawn Wayland client"),
     }
+    drop(private_connection);
 }

compositor/src/private_client.rs

@@ -0,0 +1,77 @@
+use std::{
+    io,
+    os::{
+        fd::AsRawFd,
+        unix::{net::UnixStream, process::CommandExt},
+    },
+    process::Command,
+    sync::Arc,
+};
+
+use crate::{Ferese, state::ClientState};
+
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
+pub(crate) struct ClientCapabilities(u8);
+
+impl ClientCapabilities {
+    pub(crate) const EFFECTS: Self = Self(1 << 0);
+
+    pub(crate) fn contains(self, capability: Self) -> bool {
+        self.0 & capability.0 == capability.0
+    }
+
+    pub(crate) fn insert(&mut self, capability: Self) {
+        self.0 |= capability.0;
+    }
+
+    pub(crate) fn is_empty(self) -> bool {
+        self.0 == 0
+    }
+}
+
+pub(crate) fn prepare_command(
+    state: &mut Ferese,
+    command: &mut Command,
+    capabilities: ClientCapabilities,
+) -> io::Result<UnixStream> {
+    let (server, client) = UnixStream::pair()?;
+    state.display_handle.insert_client(
+        server,
+        Arc::new(ClientState {
+            capabilities,
+            ..ClientState::default()
+        }),
+    )?;
+
+    let client_fd = client.as_raw_fd();
+    command.env_remove("WAYLAND_DISPLAY");
+    command.env("WAYLAND_SOCKET", client_fd.to_string());
+    // SAFETY: fcntl(F_SETFD) is async-signal-safe. The closure only clears
+    // CLOEXEC on the socket already owned by this Command's parent process.
+    unsafe {
+        command.pre_exec(move || {
+            if libc::fcntl(client_fd, libc::F_SETFD, 0) == -1 {
+                return Err(io::Error::last_os_error());
+            }
+            Ok(())
+        });
+    }
+
+    Ok(client)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn capabilities_are_explicit_and_independent() {
+        let mut capabilities = ClientCapabilities::default();
+        assert!(capabilities.is_empty());
+        assert!(!capabilities.contains(ClientCapabilities::EFFECTS));
+
+        capabilities.insert(ClientCapabilities::EFFECTS);
+        assert!(!capabilities.is_empty());
+        assert!(capabilities.contains(ClientCapabilities::EFFECTS));
+    }
+}

compositor/src/state.rs

@@ -355,6 +355,7 @@ impl Ferese {
     ) -> Result<Self, Box<dyn Error>> {
         let display_handle = display.handle();
         crate::handlers::screencopy::init_global(&display_handle);
+        crate::effects::init_global(&display_handle);
         let alpha_modifier_state = AlphaModifierState::new::<Self>(&display_handle);
         let compositor_state = CompositorState::new::<Self>(&display_handle);
         let cursor_shape_state = CursorShapeManagerState::new::<Self>(&display_handle);
@@ -1856,6 +1857,7 @@ fn client_size(window: &Window) -> Option<ClientSize> {
 #[derive(Default)]
 pub struct ClientState {
     pub compositor_state: CompositorClientState,
+    pub(crate) capabilities: crate::private_client::ClientCapabilities,
 }
 
 impl ClientData for ClientState {