Ensure UI stack access by a single thread at a time.

source/main.c

@@ -15,6 +15,8 @@ void cleanup() {
     clipboard_clear();
 
     task_quit_all();
+
+    ui_exit();
     screen_exit();
 
     socExit();
@@ -65,6 +67,7 @@ int main(int argc, const char* argv[]) {
     }
 
     screen_init();
+    ui_init();
 
     mainmenu_open();
 

source/ui/ui.c

@@ -13,34 +13,65 @@
 static ui_view* ui_stack[MAX_UI_VIEWS];
 static int ui_stack_top = -1;
 
+static Handle ui_stack_mutex = 0;
+
+void ui_init() {
+    if(ui_stack_mutex == 0) {
+        svcCreateMutex(&ui_stack_mutex, false);
+    }
+}
+
+void ui_exit() {
+    if(ui_stack_mutex != 0) {
+        svcCloseHandle(ui_stack_mutex);
+        ui_stack_mutex = 0;
+    }
+}
+
 bool ui_push(ui_view* view) {
     if(view == NULL) {
         return false;
     }
 
+    svcWaitSynchronization(ui_stack_mutex, U64_MAX);
+
     if(ui_stack_top >= MAX_UI_VIEWS - 1) {
         return false;
     }
 
     ui_stack[++ui_stack_top] = view;
+
+    svcReleaseMutex(ui_stack_mutex);
+
     return true;
 }
 
 ui_view* ui_peek() {
+    svcWaitSynchronization(ui_stack_mutex, U64_MAX);
+
     if(ui_stack_top == -1) {
         return NULL;
     }
 
-    return ui_stack[ui_stack_top];
+    ui_view* ui = ui_stack[ui_stack_top];
+
+    svcReleaseMutex(ui_stack_mutex);
+
+    return ui;
 }
 
 ui_view* ui_pop() {
+    svcWaitSynchronization(ui_stack_mutex, U64_MAX);
+
     if(ui_stack_top == -1) {
         return NULL;
     }
 
-    ui_view* view = ui_peek();
+    ui_view* view = ui_stack[ui_stack_top];
     ui_stack[ui_stack_top--] = NULL;
+
+    svcReleaseMutex(ui_stack_mutex);
+
     return view;
 }
 

source/ui/ui.h

@@ -11,6 +11,9 @@ typedef struct ui_view_s {
     void (*drawBottom)(struct ui_view_s* view, void* data, float x1, float y1, float x2, float y2);
 } ui_view;
 
+void ui_init();
+void ui_exit();
+
 bool ui_push(ui_view* view);
 ui_view* ui_peek();
 ui_view* ui_pop();