Add lua exception handling test code

Catch some error situations when mod used without thinking about it

games/minimal/mods/errorhandler_test/init.lua

@@ -0,0 +1,106 @@
+--
+-- exception handler test module
+--
+--
+-- To avoid this from crashing the module will startup in inactive mode.
+-- to make specific errors happen you need to cause them by following
+-- chat command:
+--
+-- exceptiontest <location> <errortype>
+--
+-- location has to be one of:
+--   * mapgen:          cause in next on_generate call
+--   * entity_step:     spawn a entity and make it do error in on_step
+--   * globalstep:      do error in next globalstep
+--   * immediate:       cause right in chat handler
+--
+-- errortypes defined are:
+--   * segv:            make sigsegv happen
+--   * zerodivision:    cause a division by zero to happen
+--   * exception:       throw an exception
+
+if core.cause_error == nil or
+	type(core.cause_error) ~= "function" then
+	return
+end
+	
+
+core.log("action", "WARNING: loading exception handler test module!")
+
+local exceptiondata = {
+	tocause = "none",
+	mapgen = false,
+	entity_step = false,
+	globalstep = false,
+}
+
+local exception_entity =
+{
+	on_step = function(self, dtime)
+		if exceptiondata.entity_step then
+			core.cause_error(exceptiondata.tocause)
+		end
+	end,
+}
+local exception_entity_name = "errorhandler_test:error_entity"
+
+local function exception_chat_handler(playername, param)
+	local parameters = param:split(" ")
+	
+	if #parameters ~= 2 then
+		core.chat_send_player(playername, "Invalid argument count for exceptiontest")
+	end
+	
+	core.log("error", "Causing error at:" .. parameters[1])
+	
+	if parameters[1] == "mapgen" then
+		exceptiondata.tocause = parameters[2]
+		exceptiondata.mapgen = true
+	elseif parameters[1] == "entity_step" then
+		--spawn entity at player location
+		local player = core.get_player_by_name(playername)
+		
+		if player:is_player() then
+			local pos = player:getpos()
+			
+			core.add_entity(pos, exception_entity_name)
+		end
+		
+		exceptiondata.tocause = parameters[2]
+		exceptiondata.entity_step = true
+		
+	elseif parameters[1] == "globalstep" then
+		exceptiondata.tocause = parameters[2]
+		exceptiondata.globalstep = true
+		
+	elseif parameters[1] == "immediate" then
+		core.cause_error(parameters[2])
+		
+	else
+		core.chat_send_player(playername, "Invalid error location: " .. dump(parameters[1]))
+	end
+end
+
+core.register_chatcommand("exceptiontest",
+	{
+		params      = "<location> <errortype>",
+		description = "cause a given error to happen.\n" ..
+				" location=(mapgen,entity_step,globalstep,immediate)\n" ..
+				" errortype=(segv,zerodivision,exception)",
+		func        = exception_chat_handler,
+		privs       = { server=true }
+	})
+	
+core.register_globalstep(function(dtime)
+	if exceptiondata.globalstep then
+		core.cause_error(exceptiondata.tocause)
+	end
+end)
+
+core.register_on_generated(function(minp, maxp, blockseed)
+	if exceptiondata.mapgen then
+		core.cause_error(exceptiondata.tocause)
+	end
+end)
+
+core.register_entity(exception_entity_name, exception_entity)

src/script/lua_api/l_server.cpp

@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "server.h"
 #include "environment.h"
 #include "player.h"
+#include "log.h"
 
 // request_shutdown()
 int ModApiServer::l_request_shutdown(lua_State *L)
@@ -449,6 +450,36 @@ int ModApiServer::l_notify_authentication_modified(lua_State *L)
 	return 0;
 }
 
+#ifndef NDEBUG
+// cause_error(type_of_error)
+int ModApiServer::l_cause_error(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+	std::string type_of_error = "none";
+	if(lua_isstring(L, 1))
+		type_of_error = lua_tostring(L, 1);
+
+	errorstream << "Error handler test called, errortype=" << type_of_error << std::endl;
+
+	if(type_of_error == "segv") {
+		volatile int* some_pointer = 0;
+		errorstream << "Cause a sigsegv now: " << (*some_pointer) << std::endl;
+
+	} else if (type_of_error == "zerodivision") {
+
+		unsigned int some_number = porting::getTimeS();
+		unsigned int zerovalue = 0;
+		unsigned int result = some_number / zerovalue;
+		errorstream << "Well this shouldn't ever be shown: " << result << std::endl;
+
+	} else if (type_of_error == "exception") {
+		throw BaseException("Errorhandler test fct called");
+	}
+
+	return 0;
+}
+#endif
+
 void ModApiServer::Initialize(lua_State *L, int top)
 {
 	API_FCT(request_shutdown);
@@ -475,4 +506,8 @@ void ModApiServer::Initialize(lua_State *L, int top)
 	API_FCT(kick_player);
 	API_FCT(unban_player_or_ip);
 	API_FCT(notify_authentication_modified);
+
+#ifndef NDEBUG
+	API_FCT(cause_error);
+#endif
 }

src/script/lua_api/l_server.h

@@ -88,6 +88,11 @@ private:
 	// notify_authentication_modified(name)
 	static int l_notify_authentication_modified(lua_State *L);
 
+#ifndef NDEBUG
+	//  cause_error(type_of_error)
+	static int l_cause_error(lua_State *L);
+#endif
+
 public:
 	static void Initialize(lua_State *L, int top);