Scripting engine now only loads selected libraries, using code originally contributed by @loopole.

src/scripting.c

@@ -265,9 +265,28 @@ void luaMaskCountHook(lua_State *lua, lua_Debug *ar) {
     }
 }
 
+void luaLoadLib(lua_State *lua, const char *libname, lua_CFunction luafunc) {
+  lua_pushcfunction(lua, luafunc);
+  lua_pushstring(lua, libname);
+  lua_call(lua, 1, 0);
+}
+
+void luaLoadLibraries(lua_State *lua) {
+    luaLoadLib(lua, "", luaopen_base);
+    luaLoadLib(lua, LUA_TABLIBNAME, luaopen_table);
+    luaLoadLib(lua, LUA_STRLIBNAME, luaopen_string);
+    luaLoadLib(lua, LUA_MATHLIBNAME, luaopen_math);
+    luaLoadLib(lua, LUA_DBLIBNAME, luaopen_debug); 
+
+#if 0 /* Stuff that we don't load currently, for sandboxing concerns. */
+    luaLoadLib(lua, LUA_LOADLIBNAME, luaopen_package);
+    luaLoadLib(lua, LUA_OSLIBNAME, luaopen_os);
+#endif
+}
+
 void scriptingInit(void) {
     lua_State *lua = lua_open();
-    luaL_openlibs(lua);
+    luaLoadLibraries(lua);
 
     /* Initialize a dictionary we use to map SHAs to scripts.
      * This is useful for replication, as we need to replicate EVALSHA