Avoid unmatched ShowCursor/HideCursor requests

locker/src/monitor.rs

@@ -1,5 +1,5 @@
 use log::{debug, warn};
-use std::cmp;
+use std::{cmp, cell::RefCell};
 use xcb::{x, randr, xfixes, Xid};
 
 use bscreensaver_util::{BSCREENSAVER_WM_CLASS, create_atom};
@@ -7,7 +7,6 @@ use bscreensaver_util::{BSCREENSAVER_WM_CLASS, create_atom};
 const BACKLIGHT_ATOM_NAME: &[u8] = b"Backlight";
 const BACKLIGHT_FALLBACK_ATOM_NAME: &[u8] = b"BACKLIGHT";
 
-#[derive(Clone, Copy)]
 struct BacklightControl {
     property: x::Atom,
     min_level: i32,
@@ -15,7 +14,6 @@ struct BacklightControl {
     step: u32,
 }
 
-#[derive(Clone, Copy)]
 pub struct Monitor {
     pub root: x::Window,
     pub black_gc: x::Gcontext,
@@ -26,6 +24,8 @@ pub struct Monitor {
     pub y: i16,
     pub width: u16,
     pub height: u16,
+    // RefCell used here to avoid requiring '&mut self' on blank/unblank
+    cursor_hidden: RefCell<u32>,
     backlight_control: Option<BacklightControl>,
 }
 
@@ -78,6 +78,7 @@ impl Monitor {
                         y: reply.y(),
                         width: reply.width(),
                         height: reply.height(),
+                        cursor_hidden: RefCell::new(0),
                         backlight_control: backlight_control.ok().flatten(),
                     });
                 }
@@ -87,6 +88,15 @@ impl Monitor {
         Ok(monitors)
     }
 
+    pub fn geometry(&self) -> x::Rectangle {
+        x::Rectangle {
+            x: self.x,
+            y: self.y,
+            width: self.width,
+            height: self.height,
+        }
+    }
+
     pub fn blank(&self, conn: &xcb::Connection) -> anyhow::Result<()> {
         let mut cookies = Vec::new();
         cookies.push(conn.send_request_checked(&x::ConfigureWindow {
@@ -186,10 +196,15 @@ impl Monitor {
     }
 
     pub fn show_cursor(&self, conn: &xcb::Connection) {
-        if let Err(err) = conn.send_and_check_request(&xfixes::ShowCursor {
+        let ok = self.cursor_hidden.try_borrow().map(|ch| *ch > 0).unwrap_or(true);
-            window: self.blanker_window,
+        if ok {
-        }) {
+            if let Err(err) = conn.send_and_check_request(&xfixes::ShowCursor {
-            warn!("Failed to show cursor: {}", err);
+                window: self.blanker_window,
+            }) {
+                warn!("Failed to show cursor: {}", err);
+            } else {
+                let _ = self.cursor_hidden.try_borrow_mut().map(|mut ch| *ch -= 1);
+            }
         }
     }
 
@@ -198,6 +213,8 @@ impl Monitor {
             window: self.blanker_window,
         }) {
             warn!("Failed to hide cursor: {}", err);
+        } else {
+            let _ = self.cursor_hidden.try_borrow_mut().map(|mut ch| *ch += 1);
         }
     }
 
@@ -210,7 +227,7 @@ impl Monitor {
     }
 
     fn brightness_change<F: FnOnce(&BacklightControl, u32) -> i32>(&self, conn: &xcb::Connection, updater: F) -> anyhow::Result<()> {
-        if let Some(backlight_control) = self.backlight_control {
+        if let Some(backlight_control) = &self.backlight_control {
             if let Ok(Some(cur_brightness)) = self.get_current_brightness(conn, &backlight_control) {
                 let new_level = updater(&backlight_control, cur_brightness);
                 let new_level = cmp::min(backlight_control.max_level, new_level);

locker/src/screensaver.rs

@@ -24,7 +24,8 @@ pub enum BlankerState {
 }
 
 struct UnlockDialog<'a> {
-    monitor: Monitor,
+    monitor_geom: x::Rectangle,
+    blanker_window: x::Window,
     embedder: Embedder<'a>,
     event_to_forward: Option<xcb::Event>,
     child: Child,
@@ -204,9 +205,9 @@ impl<'a> Screensaver<'a> {
                         },
                         xcb::Event::X(x::Event::ConfigureNotify(ev)) if ev.window() == self.embedder_window() => {
                             if let Some(unlock_dialog) = &self.unlock_dialog {
-                                let monitor = &unlock_dialog.monitor;
+                                let monitor_geom = &unlock_dialog.monitor_geom;
-                                let x = std::cmp::max(0, monitor.x as i32 + monitor.width as i32 / 2 - ev.width() as i32 / 2);
+                                let x = std::cmp::max(0, monitor_geom.x as i32 + monitor_geom.width as i32 / 2 - ev.width() as i32 / 2);
-                                let y = std::cmp::max(0, monitor.y as i32 + monitor.height as i32 / 2 - ev.height() as i32 / 2);
+                                let y = std::cmp::max(0, monitor_geom.y as i32 + monitor_geom.height as i32 / 2 - ev.height() as i32 / 2);
                                 if x != ev.x() as i32 || y != ev.y() as i32 {
                                     conn.send_and_check_request(&x::ConfigureWindow {
                                         window: unlock_dialog.embedder.embedder_window(),
@@ -274,7 +275,7 @@ impl<'a> Screensaver<'a> {
                 },
                 Some(unlock_dialog) => {
                     let mut cookies = Vec::new();
-                    for win in [unlock_dialog.monitor.blanker_window, unlock_dialog.embedder.embedder_window(), unlock_dialog.embedder.client_window()] {
+                    for win in [unlock_dialog.blanker_window, unlock_dialog.embedder.embedder_window(), unlock_dialog.embedder.client_window()] {
                         cookies.push(conn.send_request_checked(&x::ConfigureWindow {
                             window: win,
                             value_list: &[
@@ -324,7 +325,7 @@ impl<'a> Screensaver<'a> {
     }
 
     fn start_unlock_dialog(&self, conn: &'a xcb::Connection, trigger_event: Option<xcb::Event>) -> anyhow::Result<UnlockDialog<'a>> {
-        let mut pointer_monitor = None;
+        let mut monitor_data = None;
         for monitor in &self.monitors {
             let cookie = conn.send_request(&x::QueryPointer {
                 window: monitor.root,
@@ -336,13 +337,14 @@ impl<'a> Screensaver<'a> {
                 && px >= monitor.x as i32 && px < monitor.x as i32 + monitor.width as i32
                     && py >= monitor.y as i32 && py < monitor.y as i32 + monitor.height as i32
             {
-                pointer_monitor = Some(monitor);
+                monitor_data = Some((monitor.geometry(), monitor.blanker_window, monitor.unlock_window));
                 break;
             }
         }
-        let pointer_monitor = pointer_monitor.unwrap_or_else(|| {
+        let (monitor_geom, blanker_window, unlock_window) = monitor_data.unwrap_or_else(|| {
             warn!("Unable to determine which monitor pointer is on; using first one");
-            self.monitors.iter().nth(0).unwrap()
+            let monitor = self.monitors.iter().nth(0).unwrap();
+            (monitor.geometry(), monitor.blanker_window, monitor.unlock_window)
         });
 
         for monitor in &self.monitors {
@@ -391,11 +393,11 @@ impl<'a> Screensaver<'a> {
             })?;
         }
 
-        let unlock_window = pointer_monitor.unlock_window;
         let embedder = Embedder::start(conn, unlock_window, client_window)?;
 
         Ok(UnlockDialog {
-            monitor: *pointer_monitor,
+            monitor_geom,
+            blanker_window,
             embedder,
             event_to_forward: trigger_event,
             child,