[Minor] Improve error message in type check function

diff --git a/src/lua/lua_common.c b/src/lua/lua_common.c
index 183fa0503eb628085f06c5e5e2f0bb931d0b7a19..fe715f393ea5b722fb50d22c541d95c1e4bbd5a7 100644 (file)
--- a/src/lua/lua_common.c
+++ b/src/lua/lua_common.c
@@ -1198,18 +1198,10 @@ rspamd_lua_check_udata_common (lua_State *L, gint pos, const gchar *classname,
 {
        void *p = lua_touserdata (L, pos);
        GString *err_msg;
+       guint i, top = lua_gettop (L);
 
        if (p == NULL) {
-               if (fatal) {
-                       err_msg = g_string_sized_new (100);
-                       rspamd_printf_gstring (err_msg, "expected %s at %d, but got %s; trace: ",
-                                       classname, pos, lua_typename (L, lua_type (L, pos)));
-                       rspamd_lua_traceback_string (L, err_msg);
-                       msg_err ("lua typecheck error: %v", err_msg);
-                       g_string_free (err_msg, TRUE);
-               }
-
-               return NULL;
+               goto err;
        }
        else {
                /* Match class */
@@ -1217,43 +1209,65 @@ rspamd_lua_check_udata_common (lua_State *L, gint pos, const gchar *classname,
                        luaL_getmetatable (L, classname);
 
                        if (!lua_rawequal (L, -1, -2)) {
-                               p = NULL;
+                               goto err;
+                       }
+               }
+               else {
+                       goto err;
+               }
+       }
+
+       lua_settop (L, top);
+
+       return p;
+
+err:
+       if (fatal) {
+               const gchar *actual_classname = NULL;
+
+               if (lua_getmetatable (L, pos)) {
+                       lua_pushstring (L, "__index");
+                       lua_gettable (L, -3);
+                       lua_pushstring (L, "class");
+                       lua_gettable (L, -2);
+                       actual_classname = lua_tostring (L, -1);
+               }
+               else {
+                       actual_classname = lua_typename (L, lua_type (L, -1));
+               }
+
+               err_msg = g_string_sized_new (100);
+               rspamd_printf_gstring (err_msg, "expected %s at %d, but userdata has "
+                                                                               "%s metatable; trace: ",
+                               classname, pos, actual_classname);
+               rspamd_lua_traceback_string (L, err_msg);
+               rspamd_printf_gstring (err_msg, " stack(%d): ", top);
+
+               for (i = 1; i <= MIN (top, 10); i ++) {
+                       if (lua_type (L, i) == LUA_TUSERDATA) {
+                               lua_getmetatable (L, i);
                                lua_pushstring (L, "__index");
                                lua_gettable (L, -3);
                                lua_pushstring (L, "class");
                                lua_gettable (L, -2);
 
-                               if (fatal) {
-                                       err_msg = g_string_sized_new (100);
-                                       rspamd_printf_gstring (err_msg, "expected %s at %d, but userdata has "
-                                                       "classname: %s; trace: ",
-                                                       classname, pos, lua_tostring (L, -1));
-                                       rspamd_lua_traceback_string (L, err_msg);
-                                       msg_err ("lua typecheck error: %v", err_msg);
-                                       g_string_free (err_msg, TRUE);
-                               }
-
-                               lua_pop (L, 2); /* __index -> classname */
+                               rspamd_printf_gstring (err_msg, "[%d: ud=%s] ", i,
+                                               lua_tostring (L, -1));
+                               lua_pop (L, 3);
                        }
-
-                       lua_pop (L, 2);
-               }
-               else {
-                       p = NULL;
-
-                       if (fatal) {
-                               err_msg = g_string_sized_new (100);
-                               rspamd_printf_gstring (err_msg, "expected %s at %d, but userdata has "
-                                               "no metatable; trace: ",
-                                               classname, pos);
-                               rspamd_lua_traceback_string (L, err_msg);
-                               msg_err ("lua typecheck error: %v", err_msg);
-                               g_string_free (err_msg, TRUE);
+                       else {
+                               rspamd_printf_gstring (err_msg, "[%d: %s] ", i,
+                                               lua_typename (L, lua_type (L, i)));
                        }
                }
+
+               msg_err ("lua type error: %v", err_msg);
+               g_string_free (err_msg, TRUE);
        }
 
-       return p;
+       lua_settop (L, top);
+
+       return NULL;
 }
 
 void *