From 02c4869beec52d2664c747d520dfe078d2b3c714 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Tue, 21 Jul 2020 07:45:11 +0200
Subject: [PATCH] stream: fix Duplex._construct race

Ensures that _construct has finished before invoking
_destroy.

The 'constructed' property was not properly set to false
for both writable and readable state.

Fixes: https://github.com/nodejs/node/issues/34448

PR-URL: https://github.com/nodejs/node/pull/34456
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
---
 lib/internal/streams/destroy.js        | 14 +++++++-------
 test/parallel/test-stream-construct.js | 26 ++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/lib/internal/streams/destroy.js b/lib/internal/streams/destroy.js
index a2a91245ca46ea..3bccd46b7e65da 100644
--- a/lib/internal/streams/destroy.js
+++ b/lib/internal/streams/destroy.js
@@ -203,13 +203,6 @@ function construct(stream, cb) {
     return;
   }
 
-  stream.once(kConstruct, cb);
-
-  if (stream.listenerCount(kConstruct) > 1) {
-    // Duplex
-    return;
-  }
-
   const r = stream._readableState;
   const w = stream._writableState;
 
@@ -220,6 +213,13 @@ function construct(stream, cb) {
     w.constructed = false;
   }
 
+  stream.once(kConstruct, cb);
+
+  if (stream.listenerCount(kConstruct) > 1) {
+    // Duplex
+    return;
+  }
+
   process.nextTick(constructNT, stream);
 }
 
diff --git a/test/parallel/test-stream-construct.js b/test/parallel/test-stream-construct.js
index a3e2b4d2e3e8bd..9b38f30a01f8c2 100644
--- a/test/parallel/test-stream-construct.js
+++ b/test/parallel/test-stream-construct.js
@@ -242,3 +242,29 @@ testDestroy((opts) => new Writable({
     construct: common.mustCall()
   });
 }
+
+{
+  // https://github.com/nodejs/node/issues/34448
+
+  let constructed = false;
+  const d = new Duplex({
+    readable: false,
+    construct: common.mustCall((callback) => {
+      setImmediate(common.mustCall(() => {
+        constructed = true;
+        callback();
+      }));
+    }),
+    write(chunk, encoding, callback) {
+      callback();
+    },
+    read() {
+      this.push(null);
+    }
+  });
+  d.resume();
+  d.end('foo');
+  d.on('close', common.mustCall(() => {
+    assert.strictEqual(constructed, true);
+  }));
+}