fix crashes when signalling a event thats not created yet.

this caused a crash after installing a game if the games menu wasn't init.
the same would happen if the games menu signalled the save menu.

sphaira/source/ui/menus/filebrowser.cpp

@@ -73,7 +73,7 @@ private:
     SidebarEntryFilePicker* m_icon{};
 };
 
-constinit UEvent g_change_uevent;
+std::atomic_bool g_change_signalled{};
 
 constexpr FsEntry FS_ENTRY_DEFAULT{
     "microSD card", "/", FsType::Sd, FsEntryFlag_Assoc | FsEntryFlag_IsSd,
@@ -418,7 +418,7 @@ auto IsExtension(std::string_view ext, std::span<const std::string_view> list) -
 }
 
 void SignalChange() {
-    ueventSignal(&g_change_uevent);
+    g_change_signalled = true;
 }
 
 FsView::FsView(Base* menu, const std::shared_ptr<fs::Fs>& fs, const fs::FsPath& path, const FsEntry& entry, ViewSide side) : m_menu{menu}, m_side{side} {
@@ -1026,6 +1026,7 @@ auto FsView::Scan(fs::FsPath new_path, bool is_walk_up) -> Result {
         m_previous_highlighted_file.emplace_back(f);
     }
 
+    g_change_signalled = false;
     m_path = new_path;
     m_entries.clear();
     m_entries_index.clear();
@@ -1937,7 +1938,8 @@ Base::Base(const std::shared_ptr<fs::Fs>& fs, const FsEntry& fs_entry, const fs:
 }
 
 void Base::Update(Controller* controller, TouchInfo* touch) {
-    if (R_SUCCEEDED(waitSingle(waiterForUEvent(&g_change_uevent), 0))) {
+    if (g_change_signalled.exchange(false)) {
+
         if (IsSplitScreen()) {
             view_left->SortAndFindLastFile(true);
             view_right->SortAndFindLastFile(true);
@@ -2278,7 +2280,6 @@ void Base::Init(const std::shared_ptr<fs::Fs>& fs, const FsEntry& fs_entry, cons
 
     view_left = std::make_unique<FsView>(this, fs, path, fs_entry, ViewSide::Left);
     view = view_left.get();
-    ueventCreate(&g_change_uevent, true);
 }
 
 void MountFsHelper(const std::shared_ptr<fs::Fs>& fs, const fs::FsPath& name) {

sphaira/source/ui/menus/game_menu.cpp

@@ -36,7 +36,7 @@
 namespace sphaira::ui::menu::game {
 namespace {
 
-constinit UEvent g_change_uevent;
+std::atomic_bool g_change_signalled{};
 
 struct NspSource final : dump::BaseSource {
     NspSource(const std::vector<NspEntry>& entries) : m_entries{entries} {
@@ -273,7 +273,7 @@ Result NspEntry::Read(void* buf, s64 off, s64 size, u64* bytes_read) {
 }
 
 void SignalChange() {
-    ueventSignal(&g_change_uevent);
+    g_change_signalled = true;
 }
 
 Menu::Menu(u32 flags) : grid::Menu{"Games"_i18n, flags} {
@@ -461,7 +461,6 @@ Menu::Menu(u32 flags) : grid::Menu{"Games"_i18n, flags} {
 
     fsOpenGameCardDetectionEventNotifier(std::addressof(m_gc_event_notifier));
     fsEventNotifierGetEventHandle(std::addressof(m_gc_event_notifier), std::addressof(m_gc_event), true);
-    ueventCreate(&g_change_uevent, true);
 }
 
 Menu::~Menu() {
@@ -476,8 +475,11 @@ Menu::~Menu() {
 }
 
 void Menu::Update(Controller* controller, TouchInfo* touch) {
-    s32 wait_dummy_idx;
+    if (g_change_signalled.exchange(false)) {
-    if (R_SUCCEEDED(waitMulti(&wait_dummy_idx, 0, waiterForEvent(&m_gc_event), waiterForUEvent(&g_change_uevent)))) {
+        m_dirty = true;
+    }
+
+    if (R_SUCCEEDED(eventWait(&m_gc_event, 0))) {
         m_dirty = true;
     }
 
@@ -569,6 +571,7 @@ void Menu::ScanHomebrew() {
 
     FreeEntries();
     m_entries.reserve(ENTRY_CHUNK_COUNT);
+    g_change_signalled = false;
 
     std::vector<NsApplicationRecord> record_list(ENTRY_CHUNK_COUNT);
     s32 offset{};

sphaira/source/ui/menus/homebrew.cpp

@@ -27,7 +27,7 @@ namespace sphaira::ui::menu::homebrew {
 namespace {
 
 Menu* g_menu{};
-constinit UEvent g_change_uevent;
+std::atomic_bool g_change_signalled{};
 
 auto GenerateStarPath(const fs::FsPath& nro_path) -> fs::FsPath {
     fs::FsPath out{};
@@ -44,7 +44,7 @@ void FreeEntry(NVGcontext* vg, NroEntry& e) {
 } // namespace
 
 void SignalChange() {
-    ueventSignal(&g_change_uevent);
+    g_change_signalled = true;
 }
 
 auto GetNroEntries() -> std::span<const NroEntry> {
@@ -68,7 +68,6 @@ Menu::Menu() : grid::Menu{"Homebrew"_i18n, MenuFlag_Tab} {
     );
 
     OnLayoutChange();
-    ueventCreate(&g_change_uevent, true);
 }
 
 Menu::~Menu() {
@@ -77,7 +76,7 @@ Menu::~Menu() {
 }
 
 void Menu::Update(Controller* controller, TouchInfo* touch) {
-    if (R_SUCCEEDED(waitSingle(waiterForUEvent(&g_change_uevent), 0))) {
+    if (g_change_signalled.exchange(false)) {
         m_dirty = true;
     }
 
@@ -198,7 +197,9 @@ void Menu::InstallHomebrew() {
 }
 
 void Menu::ScanHomebrew() {
+    g_change_signalled = false;
     FreeEntries();
+
     {
         SCOPED_TIMESTAMP("nro scan");
         nro_scan("/switch", m_entries);

sphaira/source/ui/menus/save_menu.cpp

@@ -40,7 +40,7 @@ constexpr u32 NX_SAVE_META_MAGIC = 0x4A4B5356; // JKSV
 constexpr u32 NX_SAVE_META_VERSION = 1;
 constexpr const char* NX_SAVE_META_NAME = ".nx_save_meta.bin";
 
-constinit UEvent g_change_uevent;
+std::atomic_bool g_change_signalled{};
 
 struct DumpSource final : dump::BaseSource {
     DumpSource(std::span<const std::reference_wrapper<Entry>> entries, std::span<const fs::FsPath> paths)
@@ -319,7 +319,7 @@ void FreeEntry(NVGcontext* vg, Entry& e) {
 } // namespace
 
 void SignalChange() {
-    ueventSignal(&g_change_uevent);
+    g_change_signalled = true;
 }
 
 Menu::Menu(u32 flags) : grid::Menu{"Saves"_i18n, flags} {
@@ -388,7 +388,6 @@ Menu::Menu(u32 flags) : grid::Menu{"Saves"_i18n, flags} {
     }
 
     title::Init();
-    ueventCreate(&g_change_uevent, true);
 }
 
 Menu::~Menu() {
@@ -399,7 +398,7 @@ Menu::~Menu() {
 }
 
 void Menu::Update(Controller* controller, TouchInfo* touch) {
-    if (R_SUCCEEDED(waitSingle(waiterForUEvent(&g_change_uevent), 0))) {
+    if (g_change_signalled.exchange(false)) {
         m_dirty = true;
     }
 
@@ -508,9 +507,9 @@ void Menu::ScanHomebrew() {
     constexpr auto ENTRY_CHUNK_COUNT = 1000;
     TimeStamp ts;
 
+    g_change_signalled = false;
     FreeEntries();
     ClearSelection();
-    ueventClear(&g_change_uevent);
     m_entries.reserve(ENTRY_CHUNK_COUNT);
     m_is_reversed = false;
     m_dirty = false;