lua event.*: better safety

... when called with bad parameters, and restructure the code a bit.
Note: uv_timer_start() is documented to be OK on active timers.

diff --git a/daemon/bindings/event.c b/daemon/bindings/event.c
index 32723a1186c249754cc67489ad248aa678008d1f..a964683bdeb7441dede27f1187a60fef1b6e190b 100644 (file)
--- a/daemon/bindings/event.c
+++ b/daemon/bindings/event.c
@@ -125,18 +125,20 @@ static int event_cancel(lua_State *L)
 
        /* Fetch event if it exists */
        lua_rawgeti(L, LUA_REGISTRYINDEX, lua_tointeger(L, 1));
-       if (!lua_istable(L, -1)) {
-               lua_pushboolean(L, false);
-               return 1;
-       }
+       bool ok = lua_istable(L, -1);
 
        /* Close the timer */
-       lua_rawgeti(L, -1, 2);
-       uv_handle_t *timer = *(uv_handle_t **)lua_touserdata(L, -1);
-       if (!uv_is_closing(timer)) {
-               uv_close(timer, (uv_close_cb) event_free);
+       uv_handle_t **timer_pp = NULL;
+       if (ok) {
+               lua_rawgeti(L, -1, 2);
+               timer_pp = lua_touserdata(L, -1);
+               ok = timer_pp && *timer_pp;
+               /* That have been sufficient safety checks, hopefully. */
+       }
+       if (ok && !uv_is_closing(*timer_pp)) {
+               uv_close(*timer_pp, (uv_close_cb)event_free);
        }
-       lua_pushboolean(L, true);
+       lua_pushboolean(L, ok);
        return 1;
 }
 
@@ -148,26 +150,25 @@ static int event_reschedule(lua_State *L)
 
        /* Fetch event if it exists */
        lua_rawgeti(L, LUA_REGISTRYINDEX, lua_tointeger(L, 1));
-       if (!lua_istable(L, -1)) {
-               lua_pushboolean(L, false);
-               return 1;
-       }
+       bool ok = lua_istable(L, -1);
 
        /* Reschedule the timer */
-       lua_rawgeti(L, -1, 2);
-       uv_handle_t *timer = *(uv_handle_t **)lua_touserdata(L, -1);
-       if (!uv_is_closing(timer)) {
-               if (uv_is_active(timer)) {
-                       uv_timer_stop((uv_timer_t *)timer);
-               }
-               int ret = uv_timer_start((uv_timer_t *)timer, event_callback, lua_tointeger(L, 2), 0);
+       uv_handle_t **timer_pp = NULL;
+       if (ok) {
+               lua_rawgeti(L, -1, 2);
+               timer_pp = lua_touserdata(L, -1);
+               ok = timer_pp && *timer_pp;
+               /* That have been sufficient safety checks, hopefully. */
+       }
+       if (ok && !uv_is_closing(*timer_pp)) {
+               int ret = uv_timer_start((uv_timer_t *)*timer_pp,
+                               event_callback, lua_tointeger(L, 2), 0);
                if (ret != 0) {
-                       event_cancel(L);
-                       lua_pushboolean(L, false);
-                       return 1;
+                       uv_close(*timer_pp, (uv_close_cb)event_free);
+                       ok = false;
                }
        }
-       lua_pushboolean(L, true);
+       lua_pushboolean(L, ok);
        return 1;
 }