fix(messages)!: vim.ui_attach message callbacks are unsafe

Problem:  Lua callbacks for "msg_show" events with vim.ui_attach() are
          executed when it is not safe.
Solution: Disallow non-fast API calls for "msg_show" event callbacks.
          Automatically detach callback after excessive errors.
          Make sure fast APIs do not modify Nvim state.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 998f911392..e6ec88c5e8 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -594,10 +594,12 @@ ArrayOf(String) nvim_get_runtime_file(String name, Boolean all, Arena *arena, Er
   kvi_init(cookie.rv);
 
   int flags = DIP_DIRFILE | (all ? DIP_ALL : 0);
+  TryState tstate;
+
+  try_enter(&tstate);
+  do_in_runtimepath((name.size ? name.data : ""), flags, find_runtime_cb, &cookie);
+  vim_ignored = try_leave(&tstate, err);
 
-  TRY_WRAP(err, {
-    do_in_runtimepath((name.size ? name.data : ""), flags, find_runtime_cb, &cookie);
-  });
   return arena_take_arraybuilder(arena, &cookie.rv);
 }