feat: make fs.read params optional

doc/api/fs.md

@@ -2760,6 +2760,29 @@ The callback is given the three arguments, `(err, bytesRead, buffer)`.
 If this method is invoked as its [`util.promisify()`][]ed version, it returns
 a `Promise` for an `Object` with `bytesRead` and `buffer` properties.
 
+## `fs.read(fd, [options,] callback)`
+<!-- YAML
+added: REPLACEME
+changes:
+ - version: REPLACEME
+ pr-url: https://github.com/nodejs/node/pull/31402
+ description: Options object can be passed in
+ to make Buffer, offset, length and position optional
+-->
+* `fd` {integer}
+* `options` {Object}
+ * `buffer` {Buffer|TypedArray|DataView} **Default:** `Buffer.alloc(16384)`
+ * `offset` {integer} **Default:** `0`
+ * `length` {integer} **Default:** `buffer.length`
+ * `position` {integer} **Default:** `null`
+* `callback` {Function}
+ * `err` {Error}
+ * `bytesRead` {integer}
+ * `buffer` {Buffer}
+
+Similar to the above `fs.read` function, this version takes an optional `options` object.
+If no `options` object is specified, it will default with the above values.
+
 ## `fs.readdir(path[, options], callback)`
 <!-- YAML
 added: v0.1.8
@@ -4342,6 +4365,17 @@ Following successful read, the `Promise` is resolved with an object with a
 `bytesRead` property specifying the number of bytes read, and a `buffer`
 property that is a reference to the passed in `buffer` argument.
 
+#### `filehandle.read(options)`
+<!-- YAML
+added: REPLACEME
+-->
+* `options` {Object}
+ * `buffer` {Buffer|Uint8Array} **Default:** `Buffer.alloc(16384)`
+ * `offset` {integer} **Default:** `0`
+ * `length` {integer} **Default:** `buffer.length`
+ * `position` {integer} **Default:** `null`
+* Returns: {Promise}
+
 #### `filehandle.readFile(options)`
 <!-- YAML
 added: v10.0.0

lib/fs.js

@@ -454,8 +454,34 @@ function openSync(path, flags, mode) {
  return result;
 }
 
+// usage:
+// fs.read(fd, buffer, offset, length, position, callback);
+// OR
+// fs.read(fd, {}, callback)
 function read(fd, buffer, offset, length, position, callback) {
  validateInt32(fd, 'fd', 0);
+
+ if (arguments.length <= 3) {
+ // Assume fs.read(fd, options, callback)
+ let options = {};
+ if (arguments.length < 3) {
+ // This is fs.read(fd, callback)
+ // buffer will be the callback
+ callback = buffer;
+ } else {
+ // This is fs.read(fd, {}, callback)
+ // buffer will be the options object
+ // offset is the callback
+ options = buffer;
+ callback = offset;
+ }
+
+ buffer = options.buffer || Buffer.alloc(16384);
+ offset = options.offset || 0;
+ length = options.length || buffer.length;
+ position = options.position;
+ }
+
  validateBuffer(buffer);
  callback = maybeCallback(callback);
 

test/parallel/test-fs-read-optional-params.js

@@ -0,0 +1,36 @@
+'use strict';
+
+const common = require('../common');
+const fixtures = require('../common/fixtures');
+const fs = require('fs');
+const assert = require('assert');
+const filepath = fixtures.path('x.txt');
+const fd = fs.openSync(filepath, 'r');
+
+const expected = Buffer.from('xyz\n');
+const defaultBufferAsync = Buffer.alloc(16384);
+const bufferAsOption = Buffer.allocUnsafe(expected.length);
+
+// Test passing in an empty options object
+fs.read(fd, { position: 0 }, common.mustCall((err, bytesRead, buffer) => {
+ assert.strictEqual(bytesRead, expected.length);
+ assert.deepStrictEqual(defaultBufferAsync.length, buffer.length);
+}));
+
+// Test not passing in any options object
+fs.read(fd, common.mustCall((err, bytesRead, buffer) => {
+ assert.strictEqual(bytesRead, expected.length);
+ assert.deepStrictEqual(defaultBufferAsync.length, buffer.length);
+}));
+
+// Test passing in options
+fs.read(fd, {
+ buffer: bufferAsOption,
+ offset: 0,
+ lenght: bufferAsOption.length,
+ position: 0
+},
+ common.mustCall((err, bytesRead, buffer) => {
+ assert.strictEqual(bytesRead, expected.length);
+ assert.deepStrictEqual(bufferAsOption.length, buffer.length);
+ }));

test/parallel/test-fs-read-promises-optional-params.js

@@ -0,0 +1,19 @@
+'use strict';
+
+const common = require('../common');
+const fixtures = require('../common/fixtures');
+const fs = require('fs');
+const read = require('util').promisify(fs.read);
+const assert = require('assert');
+const filepath = fixtures.path('x.txt');
+const fd = fs.openSync(filepath, 'r');
+
+const expected = Buffer.from('xyz\n');
+const defaultBufferAsync = Buffer.alloc(16384);
+
+read(fd, {})
+ .then(function({ bytesRead, buffer }) {
+ assert.strictEqual(bytesRead, expected.length);
+ assert.deepStrictEqual(defaultBufferAsync.length, buffer.length);
+ })
+ .then(common.mustCall());