Defer setting an element's text if it has children to fix race condition crash, bump version to 1.2.0-rc3

src/main/main.cpp

@@ -48,7 +48,7 @@
 
 #include "../../lib/rt64/src/contrib/stb/stb_image.h"
 
-const std::string version_string = "1.2.0-rc2";
+const std::string version_string = "1.2.0-rc3";
 
 template<typename... Ts>
 void exit_error(const char* str, Ts ...args) {

src/ui/core/ui_context.cpp

@@ -36,7 +36,8 @@ namespace recompui {
         Element root_element;
         Element* autofocus_element = nullptr;
         std::vector<Element*> loose_elements;
-        std::unordered_set<ResourceId> to_update;        
+        std::unordered_set<ResourceId> to_update;
+        std::vector<std::pair<ResourceId, std::string>> to_set_text;     
         bool captures_input = true;
         bool captures_mouse = true;
         Context(Rml::ElementDocument* document) : document(document), root_element(document) {}
@@ -67,6 +68,8 @@ enum class ContextErrorType {
     AddResourceToWrongContext,
     UpdateElementWithoutContext,
     UpdateElementInWrongContext,
+    SetTextElementWithoutContext,
+    SetTextElementInWrongContext,
     GetResourceWithoutOpen,
     GetResourceFailed,
     DestroyResourceWithoutOpen,
@@ -119,6 +122,12 @@ void context_error(recompui::ContextId id, ContextErrorType type) {
         case ContextErrorType::UpdateElementInWrongContext:
             error_message = "Attempted to update a UI element in a different UI context than the one that's open";
             break;
+        case ContextErrorType::SetTextElementWithoutContext:
+            error_message = "Attempted to set the text of a UI element with no open UI context";
+            break;
+        case ContextErrorType::SetTextElementInWrongContext:
+            error_message = "Attempted to set the text of a UI element in a different UI context than the one that's open";
+            break;
         case ContextErrorType::GetResourceWithoutOpen:
             error_message = "Attempted to get a UI resource with no open UI context";
             break;
@@ -407,6 +416,22 @@ void recompui::ContextId::process_updates() {
 
         static_cast<Element*>(cur_resource->get())->handle_event(update_event);
     }
+
+    std::vector<std::pair<ResourceId, std::string>> to_set_text = std::move(opened_context->to_set_text);
+
+    // Delete the Rml elements that are pending deletion.
+    for (auto cur_text_update : to_set_text) {
+        resource_slotmap::key cur_key{ cur_text_update.first.slot_id };
+        std::unique_ptr<Style>* cur_resource = opened_context->resources.get(cur_key);
+
+        // Make sure the resource exists before setting its text, as it may have been deleted.
+        if (cur_resource == nullptr) {
+            continue;
+        }
+
+        // Perform the text update.
+        static_cast<Element*>(cur_resource->get())->base->SetInnerRML(cur_text_update.second);
+    }
 }
 
 bool recompui::ContextId::captures_input() {
@@ -514,6 +539,20 @@ void recompui::ContextId::queue_element_update(ResourceId element) {
     opened_context->to_update.emplace(element);
 }
 
+void recompui::ContextId::queue_set_text(ResourceId resource, std::string&& text) {
+    // Ensure a context is currently opened by this thread.
+    if (opened_context_id == ContextId::null()) {
+        context_error(*this, ContextErrorType::SetTextElementWithoutContext);
+    }
+
+    // Check that the context that was specified is the same one that's currently open.
+    if (*this != opened_context_id) {
+        context_error(*this, ContextErrorType::SetTextElementInWrongContext);
+    }
+
+    opened_context->to_set_text.emplace_back(std::make_pair(resource, std::move(text)));
+}
+
 recompui::Style* recompui::ContextId::create_style() {
     return add_resource_impl(std::make_unique<Style>());
 }

src/ui/core/ui_context.h

@@ -31,6 +31,7 @@ namespace recompui {
 
         void add_loose_element(Element* element);
         void queue_element_update(ResourceId element);
+        void queue_set_text(ResourceId resource, std::string&& text);
 
         Style* create_style();
 

src/ui/elements/ui_element.cpp

@@ -377,8 +377,17 @@ std::string escape_rml(std::string_view string)
 
 void Element::set_text(std::string_view text) {
     if (can_set_text) {
-        // Escape the string into Rml to prevent element injection.
-        base->SetInnerRML(escape_rml(text));
+        if (base->GetNumChildren() != 0) {
+            // Queue the text update. If it's applied immediately, it might happen
+            // while the document is being updated or rendered. This can cause a crash
+            // due to the child elements being deleted while the document is being updated.
+            // Queueing them defers it to the update thread, which prevents that issue.
+            // Escape the string into Rml to prevent element injection.
+            get_current_context().queue_set_text(resource_id, escape_rml(text));
+        }
+        else {
+            base->SetInnerRML(escape_rml(text));
+        }
     }
     else {
         assert(false && "Attempted to set text of an element that cannot have its text set.");