From 2b2ad96ef284be7370ddf535b39fa05cf1d77fb1 Mon Sep 17 00:00:00 2001 From: Gabriel Schulhof Date: Thu, 7 Feb 2019 12:11:01 -0800 Subject: [PATCH] n-api: finalize during second-pass callback Calling into the engine from a weak callback is unsafe, however, the engine offers a way to attach a second-pass weak callback which gets called when it is safe to call into JavaScript. This moves the point at which the N-API finalize callback gets called to this latter point. Fixes: https://github.com/nodejs/node/issues/25927 PR-URL: https://github.com/nodejs/node/pull/25992 Backport-PR-URL: https://github.com/nodejs/node/pull/26060 Reviewed-By: Anna Henningsen Reviewed-By: Colin Ihrig Reviewed-By: Michael Dawson --- src/node_api.cc | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/src/node_api.cc b/src/node_api.cc index 196f5512c9cd0f..ec477e1d23c92a 100644 --- a/src/node_api.cc +++ b/src/node_api.cc @@ -448,10 +448,25 @@ class Reference : private Finalizer { } private: + // The N-API finalizer callback may make calls into the engine. V8's heap is + // not in a consistent state during the weak callback, and therefore it does + // not support calls back into it. However, it provides a mechanism for adding + // a finalizer which may make calls back into the engine by allowing us to + // attach such a second-pass finalizer from the first pass finalizer. Thus, + // we do that here to ensure that the N-API finalizer callback is free to call + // into the engine. static void FinalizeCallback(const v8::WeakCallbackInfo& data) { Reference* reference = data.GetParameter(); + + // The reference must be reset during the first pass. reference->_persistent.Reset(); + data.SetSecondPassCallback(SecondPassCallback); + } + + static void SecondPassCallback(const v8::WeakCallbackInfo& data) { + Reference* reference = data.GetParameter(); + // Check before calling the finalize callback, because the callback might // delete it. bool delete_self = reference->_delete_self;