fs: do not emit 'finish' before 'open' on write empty file

'finish' could previously be emitted before the file has been
created when ending a write stream without having written any
data.

Refs: expressjs/multer#238

PR-URL: #29930
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Jeremiah Senkpiel <[email protected]>

Author: ronag

lib/internal/fs/streams.js

@@ -284,6 +284,12 @@ Object.setPrototypeOf(WriteStream.prototype, Writable.prototype);
 Object.setPrototypeOf(WriteStream, Writable);
 
 WriteStream.prototype._final = function(callback) {
+  if (typeof this.fd !== 'number') {
+    return this.once('open', function() {
+      this._final(callback);
+    });
+  }
+
   if (this.autoClose) {
     this.destroy();
   }

test/parallel/test-fs-write-stream-end.js

@@ -44,3 +44,17 @@ tmpdir.refresh();
     assert.strictEqual(content, 'a\n');
   }));
 }
+
+{
+  const file = path.join(tmpdir.path, 'write-end-test2.txt');
+  const stream = fs.createWriteStream(file);
+  stream.end();
+
+  let calledOpen = false;
+  stream.on('open', () => {
+    calledOpen = true;
+  });
+  stream.on('finish', common.mustCall(() => {
+    assert.strictEqual(calledOpen, true);
+  }));
+}