From be71e70a91a3c857652a8b037dac7adf9d0fcdd1 Mon Sep 17 00:00:00 2001
From: SmallJoker <SmallJoker@users.noreply.github.com>
Date: Mon, 27 Apr 2020 07:02:39 +0200
Subject: Script: Enforce type checks if not nil (#9748)

* Script: Enforce type checks if not nil
---
 src/script/common/c_converter.cpp | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

(limited to 'src/script/common/c_converter.cpp')

diff --git a/src/script/common/c_converter.cpp b/src/script/common/c_converter.cpp
index 334af61c3..279d8b1a5 100644
--- a/src/script/common/c_converter.cpp
+++ b/src/script/common/c_converter.cpp
@@ -33,10 +33,9 @@ extern "C" {
 #define CHECK_TYPE(index, name, type) { \
 		int t = lua_type(L, (index)); \
 		if (t != (type)) { \
-			std::string traceback = script_get_backtrace(L); \
 			throw LuaError(std::string("Invalid ") + (name) + \
 				" (expected " + lua_typename(L, (type)) + \
-				" got " + lua_typename(L, t) + ").\n" + traceback); \
+				" got " + lua_typename(L, t) + ")."); \
 		} \
 	}
 #define CHECK_POS_COORD(name) CHECK_TYPE(-1, "position coordinate '" name "'", LUA_TNUMBER)
@@ -457,12 +456,22 @@ size_t read_stringlist(lua_State *L, int index, std::vector<std::string> *result
 	Table field getters
 */
 
+bool check_field_or_nil(lua_State *L, int index, int type, const char *fieldname)
+{
+	if (lua_isnil(L, index))
+		return false;
+
+	CHECK_TYPE(index, std::string("field \"") + fieldname + '"', type);
+	return true;
+}
+
 bool getstringfield(lua_State *L, int table,
 		const char *fieldname, std::string &result)
 {
 	lua_getfield(L, table, fieldname);
 	bool got = false;
-	if(lua_isstring(L, -1)){
+
+	if (check_field_or_nil(L, -1, LUA_TSTRING, fieldname)) {
 		size_t len = 0;
 		const char *ptr = lua_tolstring(L, -1, &len);
 		if (ptr) {
@@ -479,7 +488,8 @@ bool getfloatfield(lua_State *L, int table,
 {
 	lua_getfield(L, table, fieldname);
 	bool got = false;
-	if(lua_isnumber(L, -1)){
+
+	if (check_field_or_nil(L, -1, LUA_TNUMBER, fieldname)) {
 		result = lua_tonumber(L, -1);
 		got = true;
 	}
@@ -492,7 +502,8 @@ bool getboolfield(lua_State *L, int table,
 {
 	lua_getfield(L, table, fieldname);
 	bool got = false;
-	if(lua_isboolean(L, -1)){
+
+	if (check_field_or_nil(L, -1, LUA_TBOOLEAN, fieldname)){
 		result = lua_toboolean(L, -1);
 		got = true;
 	}
@@ -511,17 +522,6 @@ size_t getstringlistfield(lua_State *L, int table, const char *fieldname,
 	return num_strings_read;
 }
 
-std::string checkstringfield(lua_State *L, int table,
-		const char *fieldname)
-{
-	lua_getfield(L, table, fieldname);
-	CHECK_TYPE(-1, std::string("field \"") + fieldname + '"', LUA_TSTRING);
-	size_t len;
-	const char *s = lua_tolstring(L, -1, &len);
-	lua_pop(L, 1);
-	return std::string(s, len);
-}
-
 std::string getstringfield_default(lua_State *L, int table,
 		const char *fieldname, const std::string &default_)
 {
-- 
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