zlib: do not emit event on *Sync() methods

Asynchronous functions in `zlib` should not emit the close event.

This fixes an issue where asynchronous calls in a for loop could exhaust
memory because the pending event prevents the objects from being garbage
collected.

Fixes: https://github.com/nodejs/node/issues/1668
PR-URL: https://github.com/nodejs/node/pull/5707
Reviewed-By: jasnell - James M Snell <jasnell@gmail.com>
Reviewed-By: trevnorris - Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/test/parallel/test-zlib-sync-no-event.js b/test/parallel/test-zlib-sync-no-event.js
new file mode 100644
index 0000000000..81d1ad530d
--- /dev/null
+++ b/test/parallel/test-zlib-sync-no-event.js
@@ -0,0 +1,21 @@
+'use strict';
+require('../common');
+const zlib = require('zlib');
+const assert = require('assert');
+
+const shouldNotBeCalled = () => { throw new Error('unexpected event'); };
+
+const message = 'Come on, Fhqwhgads.';
+
+const zipper = new zlib.Gzip();
+zipper.on('close', shouldNotBeCalled);
+
+const buffer = new Buffer(message);
+const zipped = zipper._processChunk(buffer, zlib.Z_FINISH);
+
+const unzipper = new zlib.Gunzip();
+unzipper.on('close', shouldNotBeCalled);
+
+const unzipped = unzipper._processChunk(zipped, zlib.Z_FINISH);
+assert.notEqual(zipped.toString(), message);
+assert.strictEqual(unzipped.toString(), message);