try safe handle external handle

src/handle.c

@@ -118,6 +118,14 @@ static int luv_close(lua_State* L) {
 static void luv_handle_free(uv_handle_t* handle) {
   luv_handle_t* data = (luv_handle_t*)handle->data;
   if (data) {
+    luv_ctx_t* ctx = data->ctx;
+    lua_State* L = ctx->L;
+    // release handle in ht_ref
+    lua_rawgeti(L, LUA_REGISTRYINDEX, ctx->ht_ref);
+    lua_pushnil(L);
+    lua_rawsetp(L, -2, data);
+    lua_pop(L, 1);
+
     if (data->extra_gc)
       data->extra_gc(data->extra);
     free(data);

src/lhandle.c

@@ -53,6 +53,13 @@ static luv_handle_t* luv_setup_handle(lua_State* L, luv_ctx_t* ctx) {
   data->ctx = ctx;
   data->extra = NULL;
   data->extra_gc = NULL;
+
+  // record data in ht_ref
+  lua_rawgeti(L, LUA_REGISTRYINDEX, ctx->ht_ref);
+  lua_pushboolean(L, 1);
+  lua_rawsetp(L, -2, data);
+  lua_pop(L, 1);
+
   return data;
 }
 

src/loop.c

@@ -90,9 +90,18 @@ static int luv_update_time(lua_State* L) {
 }
 
 static void luv_walk_cb(uv_handle_t* handle, void* arg) {
-  lua_State* L = (lua_State*)arg;
+  luv_ctx_t* ctx = (luv_ctx_t*)arg;
+  lua_State* L = ctx->L;
   luv_handle_t* data = (luv_handle_t*)handle->data;
 
+  // Skip foreign handles (shared event loop)
+  lua_rawgeti(L, LUA_REGISTRYINDEX, ctx->ht_ref);
+  lua_rawgetp(L, -1, data);
+  if (lua_isnil(L, -1)) {
+    lua_pop(L, 2);
+    return;
+  }
+
   // Sanity check
   // Most invalid values are large and refs are small, 0x1000000 is arbitrary.
   assert(data && data->ref < 0x1000000);
@@ -103,8 +112,9 @@ static void luv_walk_cb(uv_handle_t* handle, void* arg) {
 }
 
 static int luv_walk(lua_State* L) {
+  luv_ctx_t* ctx = luv_context(L);
   luaL_checktype(L, 1, LUA_TFUNCTION);
-  uv_walk(luv_loop(L), luv_walk_cb, L);
+  uv_walk(luv_loop(L), luv_walk_cb, ctx);
   return 0;
 }
 

src/luv.c

@@ -770,6 +770,9 @@ LUALIB_API luv_ctx_t* luv_context(lua_State* L) {
     ctx = (luv_ctx_t*)lua_newuserdata(L, sizeof(*ctx));
     memset(ctx, 0, sizeof(*ctx));
     lua_rawset(L, LUA_REGISTRYINDEX);
+    // create table to contain internal handle
+    lua_newtable(L);
+    ctx->ht_ref = luaL_ref(L, LUA_REGISTRYINDEX);
   } else {
     ctx = (luv_ctx_t*)lua_touserdata(L, -1);
   }

src/luv.h

@@ -100,6 +100,8 @@ typedef struct {
   luv_CFcpcall thrd_cpcall; /* luv thread c function in protected mode*/
 
   int          mode;        /* the mode used to run the loop (-1 if not running) */
+  int          ht_ref;      /* bookkeeping: maintain table of luv_handle_t pointers,
+                               to distinguish between internal and external handles */
 
   void* extra;              /* extra data */
 } luv_ctx_t;