Fix crash with bitmaps and resetting Lua VM

Kill requests depending on bitmaps and palettes going away, to avoid
having the emulator crash if there is a request using those bitmaps
and palettes in flight while Lua VM is reset.

Noticed by FatRatKnight.

include/core/framebuffer.hpp

@@ -101,5 +101,9 @@ void take_screenshot(const std::string& file) throw(std::bad_alloc, std::runtime
  * Get scale factors.
  */
 std::pair<uint32_t, uint32_t> get_scale_factors(uint32_t width, uint32_t height);
+/**
+ * Kill pending requests associated with object.
+ */
+void render_kill_request(void* obj);
 
 #endif

include/library/framebuffer.hpp

@@ -355,7 +355,10 @@ struct render_object
  * Destructor.
  */
 	virtual ~render_object() throw();
-
+/**
+ * Kill object function. If it returns true, kill the request. Default is to return false.
+ */
+	virtual bool kill_request(void* obj) throw();
 /**
  * Draw the object.
  *
@@ -537,7 +540,10 @@ struct render_queue
  * Frees all objects in the queue without applying them.
  */
 	void clear() throw();
-
+/**
+ * Call kill_request on all objects in queue.
+ */
+	void kill_request(void* obj) throw();
 /**
  * Get memory from internal allocator.
  */
@@ -561,7 +567,7 @@ struct render_queue
 	~render_queue() throw();
 private:
 	void add(struct render_object& obj) throw(std::bad_alloc);
-	struct node { struct render_object* obj; struct node* next; };
+	struct node { struct render_object* obj; struct node* next; bool killed; };
 	struct page { char content[RENDER_PAGE_SIZE]; };
 	struct node* queue_head;
 	struct node* queue_tail;

include/lua/bitmap.hpp

@@ -10,6 +10,7 @@
 struct lua_bitmap
 {
 	lua_bitmap(uint32_t w, uint32_t h);
+	~lua_bitmap();
 	size_t width;
 	size_t height;
 	std::vector<uint16_t> pixels;
@@ -18,6 +19,7 @@ struct lua_bitmap
 struct lua_dbitmap
 {
 	lua_dbitmap(uint32_t w, uint32_t h);
+	~lua_dbitmap();
 	size_t width;
 	size_t height;
 	std::vector<premultiplied_color> pixels;

src/core/framebuffer.cpp

@@ -326,3 +326,10 @@ void triplebuffer_logic::end_read() throw()
 	mutex::holder h(*mut);
 	read_active--;
 }
+
+void render_kill_request(void* obj)
+{
+	buffer1.rq.kill_request(obj);
+	buffer2.rq.kill_request(obj);
+	buffer3.rq.kill_request(obj);
+}

src/library/framebuffer.cpp

@@ -501,6 +501,7 @@ void render_queue::add(struct render_object& obj) throw(std::bad_alloc)
 	struct node* n = reinterpret_cast<struct node*>(alloc(sizeof(node)));
 	n->obj = &obj;
 	n->next = NULL;
+	n->killed = false;
 	if(queue_tail)
 		queue_tail = queue_tail->next = n;
 	else
@@ -512,7 +513,8 @@ template<bool X> void render_queue::run(struct framebuffer<X>& scr) throw()
 	struct node* tmp = queue_head;
 	while(tmp) {
 		try {
-			(*(tmp->obj))(scr);
+			if(!tmp->killed)
+				(*(tmp->obj))(scr);
 			tmp = tmp->next;
 		} catch(...) {
 		}
@@ -522,7 +524,8 @@ template<bool X> void render_queue::run(struct framebuffer<X>& scr) throw()
 void render_queue::clear() throw()
 {
 	while(queue_head) {
-		queue_head->obj->~render_object();
+		if(!queue_head->killed)
+			queue_head->obj->~render_object();
 		queue_head = queue_head->next;
 	}
 	//Release all memory for reuse.
@@ -545,6 +548,22 @@ void* render_queue::alloc(size_t block) throw(std::bad_alloc)
 	return mem;
 }
 
+void render_queue::kill_request(void* obj) throw()
+{
+	struct node* tmp = queue_head;
+	while(tmp) {
+		try {
+			if(!tmp->killed && tmp->obj->kill_request(obj)) {
+				//Kill this request.
+				tmp->killed = true;
+				tmp->obj->~render_object();
+			}
+			tmp = tmp->next;
+		} catch(...) {
+		}
+	}
+}
+
 render_queue::render_queue() throw()
 {
 	queue_head = NULL;
@@ -562,6 +581,11 @@ render_object::~render_object() throw()
 {
 }
 
+bool render_object::kill_request(void* obj) throw()
+{
+	return false;
+}
+
 bitmap_font::bitmap_font() throw(std::bad_alloc)
 {
 	bad_glyph_data[0] = 0x018001AAU;

src/lua/gui-bitmap.cpp

@@ -1,4 +1,5 @@
 #include "lua/internal.hpp"
+#include "core/framebuffer.hpp"
 #include "library/framebuffer.hpp"
 #include "lua/bitmap.hpp"
 #include <vector>
@@ -11,6 +12,11 @@ lua_bitmap::lua_bitmap(uint32_t w, uint32_t h)
 	memset(&pixels[0], 0, width * height);
 }
 
+lua_bitmap::~lua_bitmap()
+{
+	render_kill_request(this);
+}
+
 lua_dbitmap::lua_dbitmap(uint32_t w, uint32_t h)
 {
 	width = w;
@@ -18,6 +24,11 @@ lua_dbitmap::lua_dbitmap(uint32_t w, uint32_t h)
 	pixels.resize(width * height);
 }
 
+lua_dbitmap::~lua_dbitmap()
+{
+	render_kill_request(this);
+}
+
 lua_palette::lua_palette()
 {
 	palette_mutex = &mutex::aquire();
@@ -40,6 +51,7 @@ namespace
 			b = _bitmap;
 			b2 = NULL;
 			p = _palette;
+			killed = false;
 		}
 
 		render_object_bitmap(int32_t _x, int32_t _y, lua_obj_pin<lua_dbitmap>* _bitmap) throw()
@@ -49,15 +61,31 @@ namespace
 			b = NULL;
 			b2 = _bitmap;
 			p = NULL;
+			killed = false;
 		}
 
 		~render_object_bitmap() throw()
 		{
+			if(killed)
+				return;
 			delete b;
 			delete b2;
 			delete p;
 		}
 
+		bool kill_request(void* obj) throw()
+		{
+			if(!obj)
+				return false;		//Can't kill on NULL object.
+			if(p && p->object() == obj)
+				return killed = true;
+			if(b && b->object() == obj)
+				return killed = true;
+			if(b2 && b2->object() == obj)
+				return killed = true;
+			return false;
+		}
+
 		template<bool T> void composite_op(struct framebuffer<T>& scr) throw()
 		{
 			if(p)
@@ -111,6 +139,7 @@ namespace
 		lua_obj_pin<lua_bitmap>* b;
 		lua_obj_pin<lua_dbitmap>* b2;
 		lua_obj_pin<lua_palette>* p;
+		bool killed;
 	};
 
 	function_ptr_luafun gui_bitmap("gui.bitmap_draw", [](lua_State* LS, const std::string& fname) -> int {