stream: avoid destroying writable source

ronag · ronag · commit a0f3d2b71880 · 2020-03-11T19:57:10.000+01:00
User might still want to be able to use the writable side of src. This is in the case where e.g. the Duplex input is not directly connected to its output. Such a case could happen when the Duplex is reading from a socket and then echos the data back on the same socket. Fixes: 4d93e10#commitcomment-37751035 Backport-PR-URL: #32211
diff --git a/lib/internal/streams/pipeline.js b/lib/internal/streams/pipeline.js
@@ -37,6 +37,11 @@ function destroyer(stream, reading, writing, final, callback) {
   eos(stream, { readable: reading, writable: writing }, (err) => {
     if (destroyed) return;
     destroyed = true;
+
+    if (!err && reading && !writing && stream.writable) {
+      return callback();
+    }
+
     const readable = stream.readable || isRequest(stream);
     if (err || !final || !readable) {
       destroyImpl.destroyer(stream, err);
diff --git a/test/parallel/test-stream-pipeline.js b/test/parallel/test-stream-pipeline.js
@@ -995,3 +995,19 @@ const { promisify } = require('util');
     assert.strictEqual(res, '');
   }));
 }
+
+{
+  // Might still want to be able to use the writable side
+  // of src. This is in the case where e.g. the Duplex input
+  // is not directly connected to its output. Such a case could
+  // happen when the Duplex is reading from a socket and then echos
+  // the data back on the same socket.
+  const src = new PassThrough();
+  assert.strictEqual(src.writable, true);
+  const dst = new PassThrough();
+  pipeline(src, dst, common.mustCall((err) => {
+    assert.strictEqual(src.writable, true);
+    assert.strictEqual(src.destroyed, false);
+  }));
+  src.push(null);
+}
