zlib: report premature ends earlier

Report end-of-stream when decompressing when we detect it,
and do not wait until the writable side of a zlib stream
is closed as well.

Refs: https://github.com/nodejs/node/issues/26332

PR-URL: https://github.com/nodejs/node/pull/26363
Refs: https://github.com/nodejs/node/issues/26332
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/zlib.js b/lib/zlib.js
index b267fda4ea..5e49ba40db 100644
--- a/lib/zlib.js
+++ b/lib/zlib.js
@@ -546,6 +546,16 @@ function processCallback() {
     return;
   }
 
+  if (availInAfter > 0) {
+    // If we have more input that should be written, but we also have output
+    // space available, that means that the compression library was not
+    // interested in receiving more data, and in particular that the input
+    // stream has ended early.
+    // This applies to streams where we don't check data past the end of
+    // what was consumed; that is, everything except Gunzip/Unzip.
+    self.push(null);
+  }
+
   // finished with the chunk.
   this.buffer = null;
   this.cb();