From 571eb6dc742b383579964cefb025477e3ab8a2d4 Mon Sep 17 00:00:00 2001
From: Benjamin Gruenbaum <benjamingr@gmail.com>
Date: Fri, 11 Feb 2022 12:32:10 +0200
Subject: [PATCH] fs: fix cb/sync writev empty array behavior

PR-URL: https://github.com/nodejs/node/pull/41932
Refs: https://github.com/nodejs/node/issues/41910
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/fs.js                            |  9 +++++++++
 test/parallel/test-fs-writev-sync.js | 12 +++++++++++-
 test/parallel/test-fs-writev.js      | 21 ++++++++++++++++++++-
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/lib/fs.js b/lib/fs.js
index 9c0173ec27c1c0..75349f5b1f6f0e 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -907,6 +907,11 @@ function writev(fd, buffers, position, callback) {
   validateBufferArray(buffers);
   callback = maybeCallback(callback || position);
 
+  if (buffers.length === 0) {
+    process.nextTick(callback, null, 0, buffers);
+    return;
+  }
+
   const req = new FSReqCallback();
   req.oncomplete = wrapper;
 
@@ -933,6 +938,10 @@ function writevSync(fd, buffers, position) {
   fd = getValidatedFd(fd);
   validateBufferArray(buffers);
 
+  if (buffers.length === 0) {
+    return 0;
+  }
+
   const ctx = {};
 
   if (typeof position !== 'number')
diff --git a/test/parallel/test-fs-writev-sync.js b/test/parallel/test-fs-writev-sync.js
index 33b76c7af25d9f..1db437972ed29d 100644
--- a/test/parallel/test-fs-writev-sync.js
+++ b/test/parallel/test-fs-writev-sync.js
@@ -56,11 +56,21 @@ const getFileName = (i) => path.join(tmpdir.path, `writev_sync_${i}.txt`);
   assert(Buffer.concat(bufferArr).equals(fs.readFileSync(filename)));
 }
 
+// fs.writevSync with empty array of buffers
+{
+  const filename = getFileName(3);
+  const fd = fs.openSync(filename, 'w');
+  const written = fs.writevSync(fd, []);
+  assert.strictEqual(written, 0);
+  fs.closeSync(fd);
+
+}
+
 /**
  * Testing with wrong input types
  */
 {
-  const filename = getFileName(3);
+  const filename = getFileName(4);
   const fd = fs.openSync(filename, 'w');
 
   [false, 'test', {}, [{}], ['sdf'], null, undefined].forEach((i) => {
diff --git a/test/parallel/test-fs-writev.js b/test/parallel/test-fs-writev.js
index a516f9c328f1b2..7ea52ef77ac4ee 100644
--- a/test/parallel/test-fs-writev.js
+++ b/test/parallel/test-fs-writev.js
@@ -57,11 +57,30 @@ const getFileName = (i) => path.join(tmpdir.path, `writev_${i}.txt`);
   fs.writev(fd, bufferArr, done);
 }
 
+
+// fs.writev with empty array of buffers
+{
+  const filename = getFileName(3);
+  const fd = fs.openSync(filename, 'w');
+  const bufferArr = [];
+  let afterSyncCall = false;
+
+  const done = common.mustSucceed((written, buffers) => {
+    assert.strictEqual(buffers.length, 0);
+    assert.strictEqual(written, 0);
+    assert(afterSyncCall);
+    fs.closeSync(fd);
+  });
+
+  fs.writev(fd, bufferArr, done);
+  afterSyncCall = true;
+}
+
 /**
  * Testing with wrong input types
  */
 {
-  const filename = getFileName(3);
+  const filename = getFileName(4);
   const fd = fs.openSync(filename, 'w');
 
   [false, 'test', {}, [{}], ['sdf'], null, undefined].forEach((i) => {