obs-source: Check for early source destruction

This should prevent problems where the source is destroyed but a pointer is still around to it.

source/obs-source.cpp

@@ -19,9 +19,21 @@
 
 #include "obs-source.hpp"
 
+void obs::source::handle_destroy(void* p, calldata_t* calldata){
+	obs::source* self = reinterpret_cast<obs::source*>(p);
+	obs_source_t* source;
+	if (calldata_get_ptr(calldata, "source", &source)) {
+		if (self->self == source) {
+			self->self = nullptr;
+		}
+	}
+}
+
 obs::source::~source()
 {
-	if (this->track_ownership) {
+	auto sh = obs_source_get_signal_handler(this->self);
+	signal_handler_disconnect(sh, "destroy", obs::source::handle_destroy, this);
+	if (this->track_ownership && this->self) {
 		obs_source_release(this->self);
 	}
 	this->self = nullptr;
@@ -34,6 +46,8 @@ obs::source::source(std::string name, bool track_ownership, bool add_reference)
 	if (!add_reference) {
 		obs_source_release(this->self);
 	}
+	auto sh = obs_source_get_signal_handler(this->self);
+	signal_handler_connect(sh, "destroy", obs::source::handle_destroy, this);
 }
 
 obs::source::source(obs_source_t* source, bool track_ownership, bool add_reference)
@@ -43,17 +57,24 @@ obs::source::source(obs_source_t* source, bool track_ownership, bool add_referen
 	if (add_reference) {
 		obs_source_addref(this->self);
 	}
+	auto sh = obs_source_get_signal_handler(this->self);
+	signal_handler_connect(sh, "destroy", obs::source::handle_destroy, this);
 }
 
 obs::source& obs::source::operator=(const source& ref)
 {
 	if (this != &ref) {
 		if (self) {
+			if (track_ownership) {
 				obs_source_release(self);
 			}
+		}
 		self = ref.self;
+		track_ownership = ref.track_ownership;
+		if (track_ownership) {
 			obs_source_addref(self);
 		}
+	}
 	return *this;
 }
 
@@ -68,24 +89,41 @@ obs::source& obs::source::operator=(source&& ref) noexcept
 
 obs_source_type obs::source::type()
 {
+	if (!self) {
+		return (obs_source_type)-1;
+	}
 	return obs_source_get_type(self);
 }
 
 void* obs::source::type_data()
 {
+	if (!self) {
+		return nullptr;
+	}
 	return obs_source_get_type_data(self);
 }
 
 uint32_t obs::source::width()
 {
+	if (!self) {
+		return 0;
+	}
 	return obs_source_get_width(self);
 }
 
 uint32_t obs::source::height()
 {
+	if (!self) {
+		return 0;
+	}
 	return obs_source_get_height(self);
 }
 
+bool obs::source::destroyed()
+{
+	return self == nullptr;
+}
+
 void obs::source::clear()
 {
 	self = nullptr;

source/obs-source.hpp

@@ -33,6 +33,8 @@ namespace obs {
 		obs_source_t* self;
 		bool          track_ownership = false;
 
+		static void handle_destroy(void* p, calldata_t* calldata);
+
 		public:
 		virtual ~source();
 
@@ -51,6 +53,8 @@ namespace obs {
 		uint32_t width();
 		uint32_t height();
 
+		bool destroyed();
+
 		public: // Unsafe Methods
 		void clear();