From 8e080c14cf25765021bab68d332549d7166d107e Mon Sep 17 00:00:00 2001
From: Lucas Holmquist <lholmqui@redhat.com>
Date: Wed, 27 May 2020 12:55:15 -0400
Subject: [PATCH] fs: support util.promisify for fs.readv

PR-URL: https://github.com/nodejs/node/pull/33590
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
---
 doc/api/fs.md                            |  3 +++
 lib/fs.js                                |  3 +++
 test/parallel/test-fs-readv-promisify.js | 18 ++++++++++++++++++
 3 files changed, 24 insertions(+)
 create mode 100644 test/parallel/test-fs-readv-promisify.js

diff --git a/doc/api/fs.md b/doc/api/fs.md
index 21bb160313cb09..4ac95d58e20230 100644
--- a/doc/api/fs.md
+++ b/doc/api/fs.md
@@ -3209,6 +3209,9 @@ from the current position.
 The callback will be given three arguments: `err`, `bytesRead`, and
 `buffers`. `bytesRead` is how many bytes were read from the file.
 
+If this method is invoked as its [`util.promisify()`][]ed version, it returns
+a `Promise` for an `Object` with `bytesRead` and `buffers` properties.
+
 ## `fs.readvSync(fd, buffers[, position])`
 <!-- YAML
 added:
diff --git a/lib/fs.js b/lib/fs.js
index 5883a082921c90..8d2a1e044ee08f 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -597,6 +597,9 @@ function readv(fd, buffers, position, callback) {
   return binding.readBuffers(fd, buffers, position, req);
 }
 
+ObjectDefineProperty(readv, internalUtil.customPromisifyArgs,
+                     { value: ['bytesRead', 'buffers'], enumerable: false });
+
 function readvSync(fd, buffers, position) {
   validateInt32(fd, 'fd', 0);
   validateBufferArray(buffers);
diff --git a/test/parallel/test-fs-readv-promisify.js b/test/parallel/test-fs-readv-promisify.js
new file mode 100644
index 00000000000000..2af418bcc2d12b
--- /dev/null
+++ b/test/parallel/test-fs-readv-promisify.js
@@ -0,0 +1,18 @@
+'use strict';
+
+const common = require('../common');
+const fixtures = require('../common/fixtures');
+const fs = require('fs');
+const readv = require('util').promisify(fs.readv);
+const assert = require('assert');
+const filepath = fixtures.path('x.txt');
+const fd = fs.openSync(filepath, 'r');
+
+const expected = [Buffer.from('xyz\n')];
+
+readv(fd, expected)
+  .then(function({ bytesRead, buffers }) {
+    assert.deepStrictEqual(bytesRead, expected[0].length);
+    assert.deepStrictEqual(buffers, expected);
+  })
+  .then(common.mustCall());