win,fsevent: fix uv_fs_event_stop() assert

Fix a logic error where calling uv_fs_event_stop() from the event
callback tripped on a `handle->dir_handle != INVALID_HANDLE_VALUE`
assert in uv_fs_event_queue_readdirchanges().

Fixes: libuv#3258
PR-URL: libuv#3259
Reviewed-By: Jameson Nash <vtjnash@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

src/win/fs-event.c

@@ -574,10 +574,10 @@ void uv_process_fs_event_req(uv_loop_t* loop, uv_req_t* req,
     handle->cb(handle, NULL, 0, uv_translate_sys_error(err));
   }
 
-  if (!(handle->flags & UV_HANDLE_CLOSING)) {
-    uv_fs_event_queue_readdirchanges(loop, handle);
-  } else {
+  if (handle->flags & UV_HANDLE_CLOSING) {
     uv_want_endgame(loop, (uv_handle_t*)handle);
+  } else if (uv__is_active(handle)) {
+    uv_fs_event_queue_readdirchanges(loop, handle);
   }
 }
 

test/test-fs-event.c

@@ -380,7 +380,7 @@ static void timer_cb_file(uv_timer_t* handle) {
 
 static void timer_cb_touch(uv_timer_t* timer) {
   uv_close((uv_handle_t*)timer, NULL);
-  touch_file("watch_file");
+  touch_file((char*) timer->data);
   timer_cb_touch_called++;
 }
 
@@ -730,6 +730,7 @@ TEST_IMPL(fs_event_watch_file_current_dir) {
   r = uv_timer_init(loop, &timer);
   ASSERT(r == 0);
 
+  timer.data = "watch_file";
   r = uv_timer_start(&timer, timer_cb_touch, 1100, 0);
   ASSERT(r == 0);
 
@@ -1174,3 +1175,49 @@ TEST_IMPL(fs_event_watch_invalid_path) {
   MAKE_VALGRIND_HAPPY();
   return 0;
 }
+
+static int fs_event_cb_stop_calls;
+
+static void fs_event_cb_stop(uv_fs_event_t* handle, const char* path,
+                             int events, int status) {
+  uv_fs_event_stop(handle);
+  fs_event_cb_stop_calls++;
+}
+
+TEST_IMPL(fs_event_stop_in_cb) {
+  uv_fs_event_t fs;
+  uv_timer_t timer;
+  char path[] = "fs_event_stop_in_cb.txt";
+
+#if defined(NO_FS_EVENTS)
+  RETURN_SKIP(NO_FS_EVENTS);
+#endif
+
+  remove(path);
+  create_file(path);
+
+  ASSERT_EQ(0, uv_fs_event_init(uv_default_loop(), &fs));
+  ASSERT_EQ(0, uv_fs_event_start(&fs, fs_event_cb_stop, path, 0));
+
+  /* Note: timer_cb_touch() closes the handle. */
+  timer.data = path;
+  ASSERT_EQ(0, uv_timer_init(uv_default_loop(), &timer));
+  ASSERT_EQ(0, uv_timer_start(&timer, timer_cb_touch, 100, 0));
+
+  ASSERT_EQ(0, fs_event_cb_stop_calls);
+  ASSERT_EQ(0, timer_cb_touch_called);
+
+  ASSERT_EQ(0, uv_run(uv_default_loop(), UV_RUN_DEFAULT));
+
+  ASSERT_EQ(1, fs_event_cb_stop_calls);
+  ASSERT_EQ(1, timer_cb_touch_called);
+
+  uv_close((uv_handle_t*) &fs, NULL);
+  ASSERT_EQ(0, uv_run(uv_default_loop(), UV_RUN_DEFAULT));
+  ASSERT_EQ(1, fs_event_cb_stop_calls);
+
+  remove(path);
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}

test/test-list.h

@@ -391,6 +391,7 @@ TEST_DECLARE   (fs_event_close_in_callback)
 TEST_DECLARE   (fs_event_start_and_close)
 TEST_DECLARE   (fs_event_error_reporting)
 TEST_DECLARE   (fs_event_getpath)
+TEST_DECLARE   (fs_event_stop_in_cb)
 TEST_DECLARE   (fs_scandir_empty_dir)
 TEST_DECLARE   (fs_scandir_non_existent_dir)
 TEST_DECLARE   (fs_scandir_file)
@@ -1052,6 +1053,7 @@ TASK_LIST_START
   TEST_ENTRY  (fs_event_start_and_close)
   TEST_ENTRY_CUSTOM (fs_event_error_reporting, 0, 0, 60000)
   TEST_ENTRY  (fs_event_getpath)
+  TEST_ENTRY  (fs_event_stop_in_cb)
   TEST_ENTRY  (fs_scandir_empty_dir)
   TEST_ENTRY  (fs_scandir_non_existent_dir)
   TEST_ENTRY  (fs_scandir_file)