yicheng 8b931ae09f Update meta.js (new Buffer when init)
Summary:
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> **Unless you are a React Native release maintainer and cherry-picking an *existing* commit into a current release, ensure your pull request is targeting the `master` React Native branch.**

Explain the **motivation** for making this change. What existing problem does the pull request solve?
Warning about new Buffer when init
Prefer **small pull requests**. These are much easier to review and more likely to get merged. Make sure the PR does only one thing, otherwise please split it.

**Test plan (required)**

Demonstrate the code is solid. Example: The exact commands you ran and their output, screenshots / videos if the pull request changes UI.

Make sure tests pass on both Travis and Circle CI.

**Code formatting**

Look around. Match the style of the rest of the codebase. See also the simple [style guide](https://github.com/facebook/react-native/blob/master/CONTRIBUTING.md#s
Closes https://github.com/facebook/react-native/pull/11153

Differential Revision: D4234591

fbshipit-source-id: a9373f3151de8a50c18342f45fb9684a5c7416a6
2016-11-27 02:58:29 -08:00

41 lines
1.3 KiB
JavaScript

/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
'use strict';
/* global Buffer: true */
const crypto = require('crypto');
const isUTF8 = encoding => /^utf-?8$/i.test(encoding);
const constantFor = encoding =>
/^ascii$/i.test(encoding) ? 1 :
isUTF8(encoding) ? 2 :
/^(?:utf-?16(?:le)?|ucs-?2)$/.test(encoding) ? 3 : 0;
module.exports = function(code, encoding) {
const hash = crypto.createHash('sha1');
hash.update(code, encoding);
const digest = hash.digest('binary');
const signature = Buffer.alloc ? Buffer.alloc(digest.length + 1) : new Buffer(digest.length + 1); // remove the new Buffer call when RN drops support for Node 4
signature.write(digest, 'binary');
signature.writeUInt8(
constantFor(tryAsciiPromotion(code, encoding)),
signature.length - 1);
return signature;
};
function tryAsciiPromotion(string, encoding) {
if (!isUTF8(encoding)) { return encoding; }
for (let i = 0, n = string.length; i < n; i++) {
if (string.charCodeAt(i) > 0x7f) { return encoding; }
}
return 'ascii';
}