#2522 fix issue that could cause a crash

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Config *global setting* `split_type` is now categorized as a *space setting* instead [#2479](https://github.com/koekeishiya/yabai/issues/2479)
 - Additional options `x-axis` and `y-axis` can now be used with `config auto_balance` command [#190](https://github.com/koekeishiya/yabai/issues/190)
 - Minor adjustment to screen-padding and window-gap [#2502](https://github.com/koekeishiya/yabai/issues/2502)
+- Fix issue that could cause a crash when a newly launched application terminates rapidly during/after launch [#2522](https://github.com/koekeishiya/yabai/issues/2522)
 
 ## [7.1.5] - 2024-11-01
 ### Changed

src/process_manager.c

@@ -103,6 +103,7 @@ static PROCESS_EVENT_HANDLER(process_handler)
 
         __atomic_store_n(&process->terminated, true, __ATOMIC_RELEASE);
         process_manager_remove_process(pm, &psn);
+        workspace_application_unobserve(g_workspace_context, process);
         __asm__ __volatile__ ("" ::: "memory");
 
         event_loop_post(&g_event_loop, APPLICATION_TERMINATED, process, 0);

src/workspace.h

@@ -25,6 +25,7 @@ static inline bool workspace_is_macos_##name(void) \
 struct process;
 void *workspace_application_create_running_ns_application(struct process *process);
 void workspace_application_destroy_running_ns_application(void *context, struct process *process);
+void workspace_application_unobserve(void *context, struct process *process);
 bool workspace_application_is_observable(struct process *process);
 bool workspace_application_is_finished_launching(struct process *process);
 void workspace_application_observe_finished_launching(void *context, struct process *process);

src/workspace.m

@@ -86,6 +86,20 @@ void workspace_application_observe_activation_policy(void *context, struct proce
     }
 }
 
+void workspace_application_unobserve(void *ws_context, struct process *process)
+{
+    NSRunningApplication *application = __atomic_load_n(&process->ns_application, __ATOMIC_RELAXED);
+    if (application) {
+        @try {
+            [application removeObserver:ws_context forKeyPath:@"activationPolicy" context:process];
+        } @catch (NSException * __unused exception) {}
+
+        @try {
+            [application removeObserver:ws_context forKeyPath:@"finishedLaunching" context:process];
+        } @catch (NSException * __unused exception) {}
+    }
+}
+
 bool workspace_application_is_observable(struct process *process)
 {
     NSRunningApplication *application = __atomic_load_n(&process->ns_application, __ATOMIC_RELAXED);
@@ -196,7 +210,7 @@ - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(N
 {
     if ([keyPath isEqualToString:@"activationPolicy"]) {
         struct process *process = context;
-        assert(!process->terminated);
+        if (process->terminated) return;
 
         id result = [change objectForKey:NSKeyValueChangeNewKey];
         if ([result intValue] != process->policy) {
@@ -221,7 +235,7 @@ - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(N
 
     if ([keyPath isEqualToString:@"finishedLaunching"]) {
         struct process *process = context;
-        assert(!process->terminated);
+        if (process->terminated) return;
 
         id result = [change objectForKey:NSKeyValueChangeNewKey];
         if ([result intValue] == 1) {