stream: prevent stream unexpected pause when highWaterMark set to 0

jakecastelli · ronag · targos · commit 7dde37591cb4 · 2024-06-20T14:40:38.000+02:00
Co-authored-by: Robert Nagy <ronagy@icloud.com> PR-URL: #53261 Fixes: #51930 Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
diff --git 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
@@ -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']);
+  }));
+}

Original file line number	Diff line number	Diff line change
`@@ -565,7 +565,7 @@ function writeOrBuffer(stream, state, chunk, encoding, callback) {`
`565`	`565`	`state[kState] &= ~kSync;`
`566`	`566`	`}`
`567`	`567`
`568`		`- const ret = state.length < state.highWaterMark;`
	`568`	`+ const ret = state.length < state.highWaterMark \|\| state.length === 0;`
`569`	`569`
`570`	`570`	`if (!ret) {`
`571`	`571`	`state[kState] \|= kNeedDrain;`