worker: only unref port for stdin if we ref’ed it before

We set the `kStartedReading` flag from `_read()` for Worker stdio,
and then `ref()` the port.

However, the `.on('end')` handler is also attached when `._read()`
is not called, e.g. when `process.stdin` inside a Worker is prematurely
ended because stdin was not enabled by the parent thread.

In that case, we should not call `.unref()` for stdin if we did not
also call `.ref()` for it before.

Fixes: https://github.com/nodejs/node/issues/28144
PR-URL: https://github.com/nodejs/node/pull/28153
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/internal/worker/io.js b/lib/internal/worker/io.js
index 63c8a8d976..ba2150e530 100644
--- a/lib/internal/worker/io.js
+++ b/lib/internal/worker/io.js
@@ -169,8 +169,10 @@ class ReadableWorkerStdio extends Readable {
     this[kIncrementsPortRef] = true;
     this[kStartedReading] = false;
     this.on('end', () => {
-      if (this[kIncrementsPortRef] && --this[kPort][kWaitingStreams] === 0)
-        this[kPort].unref();
+      if (this[kStartedReading] && this[kIncrementsPortRef]) {
+        if (--this[kPort][kWaitingStreams] === 0)
+          this[kPort].unref();
+      }
     });
   }