lua: allow methods with no arguments

In C it is possible to have methods without arguments (UBUS_METHOD_NOARG).
Enable support for the same calls in Lua too.

This commit also fixes segfault which can be caused by passing non-table type
where table is expected. The lua_gettablelen() function is called after we have
made sure we are dealing with a table in the first place.

Signed-off-by: Luka Perkov <luka@openwrt.org>

diff --git a/lua/ubus.c b/lua/ubus.c
index 45ea3bb20c07d7b47cd1aca624d2343b61668abd..6da935d39a1976b157fd103168c197e6eb26d0bb 100644 (file)
--- a/lua/ubus.c
+++ b/lua/ubus.c
@@ -349,12 +349,11 @@ static int ubus_lua_load_methods(lua_State *L, struct ubus_method *m)
        /* get the policy table */
        lua_pushinteger(L, 2);
        lua_gettable(L, -3);
-       plen = lua_gettablelen(L, -1);
 
        /* check if the method table is valid */
        if ((lua_type(L, -2) != LUA_TFUNCTION) ||
                        (lua_type(L, -1) != LUA_TTABLE) ||
-                       lua_objlen(L, -1) || !plen) {
+                       lua_objlen(L, -1)) {
                lua_pop(L, 2);
                return 1;
        }
@@ -363,6 +362,17 @@ static int ubus_lua_load_methods(lua_State *L, struct ubus_method *m)
        lua_pushvalue(L, -2);
        lua_setfield(L, -6, lua_tostring(L, -5));
 
+       m->name = lua_tostring(L, -4);
+       m->handler = ubus_method_handler;
+
+       plen = lua_gettablelen(L, -1);
+
+       /* exit if policy table is empty */
+       if (!plen) {
+               lua_pop(L, 2);
+               return 0;
+       }
+
        /* setup the policy pointers */
        p = malloc(sizeof(struct blobmsg_policy) * plen);
        memset(p, 0, sizeof(struct blobmsg_policy) * plen);
@@ -386,8 +396,6 @@ static int ubus_lua_load_methods(lua_State *L, struct ubus_method *m)
        }
 
        m->n_policy = pidx;
-       m->name = lua_tostring(L, -4);
-       m->handler = ubus_method_handler;
        lua_pop(L, 2);
 
        return 0;