From 3273d0e9514da750405cc2e3662d72dcbb489380 Mon Sep 17 00:00:00 2001
From: cjihrig <cjihrig@gmail.com>
Date: Sat, 17 Aug 2019 14:56:13 -0400
Subject: [PATCH 1/2] fs: add writev() promises version

https://github.com/nodejs/node/pull/25925 added fs.writev()
and fs.writevSync(), but did not include a Promises based
equivalent. This commit adds the missing method.

Refs: https://github.com/nodejs/node/pull/25925
PR-URL: https://github.com/nodejs/node/pull/29186
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 doc/api/fs.md                            | 26 ++++++++++++
 lib/internal/fs/promises.js              | 17 ++++++++
 lib/internal/fs/utils.js                 | 14 +++++++
 test/parallel/test-fs-writev-promises.js | 51 ++++++++++++++++++++++++
 4 files changed, 108 insertions(+)
 create mode 100644 test/parallel/test-fs-writev-promises.js

diff --git a/doc/api/fs.md b/doc/api/fs.md
index d71f8afd82b878..58b17c3b21902a 100644
--- a/doc/api/fs.md
+++ b/doc/api/fs.md
@@ -4274,6 +4274,32 @@ If one or more `filehandle.write()` calls are made on a file handle and then a
 current position till the end of the file. It doesn't always write from the
 beginning of the file.
 
+#### filehandle.writev(buffers[, position])
+<!-- YAML
+added: REPLACEME
+-->
+
+* `buffers` {ArrayBufferView[]}
+* `position` {integer}
+* Returns: {Promise}
+
+Write an array of `ArrayBufferView`s to the file.
+
+The `Promise` is resolved with an object containing a `bytesWritten` property
+identifying the number of bytes written, and a `buffers` property containing
+a reference to the `buffers` input.
+
+`position` is the offset from the beginning of the file where this data
+should be written. If `typeof position !== 'number'`, the data will be written
+at the current position.
+
+It is unsafe to call `writev()` multiple times on the same file without waiting
+for the previous operation to complete.
+
+On Linux, positional writes don't work when the file is opened in append mode.
+The kernel ignores the position argument and always appends the data to
+the end of the file.
+
 ### fsPromises.access(path[, mode])
 <!-- YAML
 added: v10.0.0
diff --git a/lib/internal/fs/promises.js b/lib/internal/fs/promises.js
index e796520b26b205..7e6fae9273084f 100644
--- a/lib/internal/fs/promises.js
+++ b/lib/internal/fs/promises.js
@@ -29,6 +29,7 @@ const {
   stringToFlags,
   stringToSymlinkType,
   toUnixTimestamp,
+  validateBufferArray,
   validateOffsetLengthRead,
   validateOffsetLengthWrite,
   warnOnNonPortableTemplate
@@ -104,6 +105,10 @@ class FileHandle {
     return write(this, buffer, offset, length, position);
   }
 
+  writev(buffers, position) {
+    return writev(this, buffers, position);
+  }
+
   writeFile(data, options) {
     return writeFile(this, data, options);
   }
@@ -263,6 +268,18 @@ async function write(handle, buffer, offset, length, position) {
   return { bytesWritten, buffer };
 }
 
+async function writev(handle, buffers, position) {
+  validateFileHandle(handle);
+  validateBufferArray(buffers);
+
+  if (typeof position !== 'number')
+    position = null;
+
+  const bytesWritten = (await binding.writeBuffers(handle.fd, buffers, position,
+                                                   kUsePromises)) || 0;
+  return { bytesWritten, buffers };
+}
+
 async function rename(oldPath, newPath) {
   oldPath = getValidatedPath(oldPath, 'oldPath');
   newPath = getValidatedPath(newPath, 'newPath');
diff --git a/lib/internal/fs/utils.js b/lib/internal/fs/utils.js
index 2924f7582e7663..600d118db3c298 100644
--- a/lib/internal/fs/utils.js
+++ b/lib/internal/fs/utils.js
@@ -15,6 +15,7 @@ const {
   hideStackFrames
 } = require('internal/errors');
 const {
+  isArrayBufferView,
   isUint8Array,
   isDate,
   isBigUint64Array
@@ -500,6 +501,18 @@ const getValidatedPath = hideStackFrames((fileURLOrPath, propName = 'path') => {
   return path;
 });
 
+const validateBufferArray = hideStackFrames((buffers, propName = 'buffers') => {
+  if (!Array.isArray(buffers))
+    throw new ERR_INVALID_ARG_TYPE(propName, 'ArrayBufferView[]', buffers);
+
+  for (let i = 0; i < buffers.length; i++) {
+    if (!isArrayBufferView(buffers[i]))
+      throw new ERR_INVALID_ARG_TYPE(propName, 'ArrayBufferView[]', buffers);
+  }
+
+  return buffers;
+});
+
 let nonPortableTemplateWarn = true;
 
 function warnOnNonPortableTemplate(template) {
@@ -528,6 +541,7 @@ module.exports = {
   stringToSymlinkType,
   Stats,
   toUnixTimestamp,
+  validateBufferArray,
   validateOffsetLengthRead,
   validateOffsetLengthWrite,
   validatePath,
diff --git a/test/parallel/test-fs-writev-promises.js b/test/parallel/test-fs-writev-promises.js
new file mode 100644
index 00000000000000..ea349796cc6158
--- /dev/null
+++ b/test/parallel/test-fs-writev-promises.js
@@ -0,0 +1,51 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const path = require('path');
+const fs = require('fs').promises;
+const tmpdir = require('../common/tmpdir');
+const expected = 'ümlaut. Лорем 運務ホソモ指及 आपको करने विकास 紙読決多密所 أضف';
+let cnt = 0;
+
+function getFileName() {
+  return path.join(tmpdir.path, `writev_promises_${++cnt}.txt`);
+}
+
+tmpdir.refresh();
+
+(async () => {
+  {
+    const filename = getFileName();
+    const handle = await fs.open(filename, 'w');
+    const buffer = Buffer.from(expected);
+    const bufferArr = [buffer, buffer];
+    const expectedLength = bufferArr.length * buffer.byteLength;
+    let { bytesWritten, buffers } = await handle.writev([Buffer.from('')],
+                                                        null);
+    assert.deepStrictEqual(bytesWritten, 0);
+    assert.deepStrictEqual(buffers, [Buffer.from('')]);
+    ({ bytesWritten, buffers } = await handle.writev(bufferArr, null));
+    assert.deepStrictEqual(bytesWritten, expectedLength);
+    assert.deepStrictEqual(buffers, bufferArr);
+    assert(Buffer.concat(bufferArr).equals(await fs.readFile(filename)));
+    handle.close();
+  }
+
+  // fs.promises.writev() with an array of buffers without position.
+  {
+    const filename = getFileName();
+    const handle = await fs.open(filename, 'w');
+    const buffer = Buffer.from(expected);
+    const bufferArr = [buffer, buffer, buffer];
+    const expectedLength = bufferArr.length * buffer.byteLength;
+    let { bytesWritten, buffers } = await handle.writev([Buffer.from('')]);
+    assert.deepStrictEqual(bytesWritten, 0);
+    assert.deepStrictEqual(buffers, [Buffer.from('')]);
+    ({ bytesWritten, buffers } = await handle.writev(bufferArr));
+    assert.deepStrictEqual(bytesWritten, expectedLength);
+    assert.deepStrictEqual(buffers, bufferArr);
+    assert(Buffer.concat(bufferArr).equals(await fs.readFile(filename)));
+    handle.close();
+  }
+})();

From 8d100c21c5b7c4687b0fc7f36aeed0a517dca1f7 Mon Sep 17 00:00:00 2001
From: cjihrig <cjihrig@gmail.com>
Date: Sat, 17 Aug 2019 15:03:46 -0400
Subject: [PATCH 2/2] fs: use consistent buffer array validation

This commit updates fs.writev() and fs.writevSync() to use the
same validation method as filehandle.writev().

PR-URL: https://github.com/nodejs/node/pull/29186
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/fs.js | 27 ++++-----------------------
 1 file changed, 4 insertions(+), 23 deletions(-)

diff --git a/lib/fs.js b/lib/fs.js
index 2c10a5c8d06fc1..37d1eb7917bca1 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -72,6 +72,7 @@ const {
   stringToFlags,
   stringToSymlinkType,
   toUnixTimestamp,
+  validateBufferArray,
   validateOffsetLengthRead,
   validateOffsetLengthWrite,
   validatePath,
@@ -142,19 +143,6 @@ function maybeCallback(cb) {
   throw new ERR_INVALID_CALLBACK(cb);
 }
 
-function isBuffersArray(value) {
-  if (!Array.isArray(value))
-    return false;
-
-  for (var i = 0; i < value.length; i += 1) {
-    if (!isArrayBufferView(value[i])) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
 // Ensure that callbacks run in the global context. Only use this function
 // for callbacks that are passed to the binding layer, callbacks that are
 // invoked from JS already run in the proper scope.
@@ -626,10 +614,7 @@ function writev(fd, buffers, position, callback) {
   }
 
   validateInt32(fd, 'fd', 0);
-
-  if (!isBuffersArray(buffers)) {
-    throw new ERR_INVALID_ARG_TYPE('buffers', 'ArrayBufferView[]', buffers);
-  }
+  validateBufferArray(buffers);
 
   const req = new FSReqCallback();
   req.oncomplete = wrapper;
@@ -647,15 +632,11 @@ Object.defineProperty(writev, internalUtil.customPromisifyArgs, {
   enumerable: false
 });
 
-// fs.writevSync(fd, buffers[, position]);
 function writevSync(fd, buffers, position) {
-
   validateInt32(fd, 'fd', 0);
-  const ctx = {};
+  validateBufferArray(buffers);
 
-  if (!isBuffersArray(buffers)) {
-    throw new ERR_INVALID_ARG_TYPE('buffers', 'ArrayBufferView[]', buffers);
-  }
+  const ctx = {};
 
   if (typeof position !== 'number')
     position = null;