From 0fac303d1cc2454d04da50facbc752b3ba0284bd Mon Sep 17 00:00:00 2001
From: jakecastelli <38635403+jakecastelli@users.noreply.github.com>
Date: Sat, 8 Jun 2024 11:34:40 +0930
Subject: [PATCH] stream: prevent stream unexpected pause when highWaterMark
 set to 0

Co-authored-by: Robert Nagy <ronagy@icloud.com>
PR-URL: https://github.com/nodejs/node/pull/53261
Fixes: https://github.com/nodejs/node/issues/51930
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
---
 lib/internal/streams/writable.js            |  2 +-
 test/parallel/test-streams-highwatermark.js | 24 +++++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/lib/internal/streams/writable.js b/lib/internal/streams/writable.js
index 9f6fa4936dca62..268b54b964a835 100644
--- a/lib/internal/streams/writable.js
+++ b/lib/internal/streams/writable.js
@@ -565,7 +565,7 @@ function writeOrBuffer(stream, state, chunk, encoding, callback) {
     state[kState] &= ~kSync;
   }
 
-  const ret = state.length < state.highWaterMark;
+  const ret = state.length < state.highWaterMark || state.length === 0;
 
   if (!ret) {
     state[kState] |= kNeedDrain;
diff --git a/test/parallel/test-streams-highwatermark.js b/test/parallel/test-streams-highwatermark.js
index 7018c5bf29ce08..978a53913bd52f 100644
--- a/test/parallel/test-streams-highwatermark.js
+++ b/test/parallel/test-streams-highwatermark.js
@@ -85,3 +85,27 @@ const { inspect } = require('util');
              hwm,
   }));
 }
+
+{
+  const res = [];
+  const r = new stream.Readable({
+    read() {},
+  });
+  const w = new stream.Writable({
+    highWaterMark: 0,
+    write(chunk, encoding, callback) {
+      res.push(chunk.toString());
+      callback();
+    },
+  });
+
+  r.pipe(w);
+  r.push('a');
+  r.push('b');
+  r.push('c');
+  r.push(null);
+
+  r.on('end', common.mustCall(() => {
+    assert.deepStrictEqual(res, ['a', 'b', 'c']);
+  }));
+}