Lua engine: Enable checks for debug builds, kill sol::buffer. (#9419)

src/frontend/mame/luaengine.cpp

@@ -95,18 +95,6 @@ template <> struct is_container<image_interface_formats> : std::true_type { };
 template <> struct is_container<plugin_options_plugins> : std::true_type { };
 
 
-sol::buffer *sol_lua_get(sol::types<buffer *>, lua_State *L, int index, sol::stack::record &tracking)
-{
-	return new sol::buffer(stack::get<int>(L, index), L);
-}
-
-int sol_lua_push(sol::types<buffer *>, lua_State *L, buffer *value)
-{
-	delete value;
-	return 1;
-}
-
-
 template <typename T>
 struct usertype_container<lua_engine::devenum<T> > : lua_engine::immutable_collection_helper<lua_engine::devenum<T>, T>
 {
@@ -834,7 +822,15 @@ void lua_engine::initialize()
 					}
 					new (&file) emu_file(path, flags);
 				}));
-	file_type.set("read", [](emu_file &file, sol::buffer *buff) { buff->set_len(file.read(buff->get_ptr(), buff->get_len())); return buff; });
+	file_type.set("read",
+			[] (emu_file &file, sol::this_state s, size_t len)
+			{
+				buffer_helper buf(s);
+				auto space = buf.prepare(len);
+				space.add(file.read(space.get(), len));
+				buf.push();
+				return sol::stack::pop<sol::object>(s);
+			});
 	file_type.set("write", [](emu_file &file, const std::string &data) { return file.write(data.data(), data.size()); });
 	file_type.set("puts", &emu_file::puts);
 	file_type.set("open", static_cast<std::error_condition (emu_file::*)(std::string_view)>(&emu_file::open));
@@ -1001,16 +997,18 @@ void lua_engine::initialize()
 			}
 			return sol::make_object(sol(), ret);
 		});
-	item_type.set("read_block", [](save_item &item, int offset, sol::buffer *buff) {
-			if(!item.base || ((offset + buff->get_len()) > (item.size * item.count)))
+	item_type.set("read_block", [](save_item &item, sol::this_state s, int offset, size_t len) {
+			buffer_helper buf(s);
+			auto space = buf.prepare(len);
+			if(!item.base || ((offset + len) > (item.size * item.count)))
 			{
-				buff->set_len(0);
+				space.add(0);
 			}
 			else
 			{
 				const uint32_t blocksize = item.size * item.valcount;
-				uint32_t remaining = buff->get_len();
-				uint8_t *dest = reinterpret_cast<uint8_t *>(buff->get_ptr());
+				size_t remaining = len;
+				uint8_t *dest = reinterpret_cast<uint8_t *>(space.get());
 				while(remaining)
 				{
 					const uint32_t blockno = offset / blocksize;
@@ -1022,8 +1020,10 @@ void lua_engine::initialize()
 					remaining -= chunk;
 					dest += chunk;
 				}
+				space.add(len);
 			}
-			return buff;
+			buf.push();
+			return sol::stack::pop<sol::object>(s);
 		});
 	item_type.set("write", [](save_item &item, int offset, uint64_t value) {
 			if(!item.base || (offset >= item.count))

src/frontend/mame/luaengine.h

@@ -21,7 +21,11 @@
 #include <tuple>
 #include <vector>
 
+#ifdef MAME_DEBUG
+#define SOL_ALL_SAFETIES_ON 1
+#else
 #define SOL_SAFE_USERTYPE 1
+#endif
 #include "sol/sol.hpp"
 
 struct lua_State;
@@ -30,6 +34,7 @@ class lua_engine
 {
 public:
 	// helper structures
+	class buffer_helper;
 	template <typename T> struct devenum;
 	template <typename T> struct simple_list_wrapper;
 	template <typename T> struct tag_object_ptr_map;

src/frontend/mame/luaengine.ipp

@@ -16,10 +16,100 @@
 
 #include <lua.hpp>
 
+#include <cassert>
 #include <system_error>
 
 
 
+class lua_engine::buffer_helper
+{
+private:
+	class proxy
+	{
+	private:
+		buffer_helper &m_host;
+		char *m_space;
+		size_t const m_size;
+
+	public:
+		proxy(proxy const &) = delete;
+		proxy &operator=(proxy const &) = delete;
+
+		proxy(proxy &&that) : m_host(that.m_host), m_space(that.m_space), m_size(that.m_size)
+		{
+			that.m_space = nullptr;
+		}
+
+		proxy(buffer_helper &host, size_t size) : m_host(host), m_space(luaL_prepbuffsize(&host.m_buffer, size)), m_size(size)
+		{
+			m_host.m_prepared = true;
+		}
+
+		~proxy()
+		{
+			if (m_space)
+			{
+				assert(m_host.m_prepared);
+				luaL_addsize(&m_host.m_buffer, 0U);
+				m_host.m_prepared = false;
+			}
+		}
+
+		char *get()
+		{
+			return m_space;
+		}
+
+		void add(size_t size)
+		{
+			assert(m_space);
+			assert(size <= m_size);
+			assert(m_host.m_prepared);
+			m_space = nullptr;
+			luaL_addsize(&m_host.m_buffer, size);
+			m_host.m_prepared = false;
+		}
+	};
+
+	luaL_Buffer m_buffer;
+	bool m_valid;
+	bool m_prepared;
+
+public:
+	buffer_helper(buffer_helper const &) = delete;
+	buffer_helper &operator=(buffer_helper const &) = delete;
+
+	buffer_helper(lua_State *L)
+	{
+		luaL_buffinit(L, &m_buffer);
+		m_valid = true;
+		m_prepared = false;
+	}
+
+	~buffer_helper()
+	{
+		assert(!m_prepared);
+		if (m_valid)
+			luaL_pushresult(&m_buffer);
+	}
+
+	void push()
+	{
+		assert(m_valid);
+		assert(!m_prepared);
+		luaL_pushresult(&m_buffer);
+		m_valid = false;
+	}
+
+	proxy prepare(size_t size)
+	{
+		assert(m_valid);
+		assert(!m_prepared);
+		return proxy(*this, size);
+	}
+};
+
+
 template <typename T>
 struct lua_engine::simple_list_wrapper
 {
@@ -40,52 +130,9 @@ struct lua_engine::tag_object_ptr_map
 
 namespace sol {
 
-class buffer
-{
-public:
-	// sol does lua_settop(0), save userdata buffer in registry if necessary
-	buffer(int size, lua_State *L)
-	{
-		ptr = luaL_buffinitsize(L, &buff, size);
-		len = size;
-		if(buff.b != buff.initb)
-		{
-			lua_pushvalue(L, -1);
-			lua_setfield(L, LUA_REGISTRYINDEX, "sol::buffer_temp");
-		}
-	}
-	~buffer()
-	{
-		lua_State *L = buff.L;
-		if(lua_getfield(L, LUA_REGISTRYINDEX, "sol::buffer_temp") != LUA_TNIL)
-		{
-			lua_pushnil(L);
-			lua_setfield(L, LUA_REGISTRYINDEX, "sol::buffer_temp");
-		}
-		else
-			lua_pop(L, -1);
-
-		luaL_pushresultsize(&buff, len);
-	}
-
-	void set_len(int size) { len = size; }
-	int get_len() { return len; }
-	char *get_ptr() { return ptr; }
-
-private:
-	luaL_Buffer buff;
-	int len;
-	char *ptr;
-};
-
-
-// don't convert core_optons to a table directly
+// don't convert core_options to a table directly
 template <> struct is_container<core_options> : std::false_type { };
 
-// buffer customisation
-sol::buffer *sol_lua_get(sol::types<buffer *>, lua_State *L, int index, sol::stack::record &tracking);
-int sol_lua_push(sol::types<buffer *>, lua_State *L, buffer *value);
-
 
 // these things should be treated as containers
 template <typename T> struct is_container<lua_engine::devenum<T> > : std::true_type { };