watch-xdelta/lib/header.js

smart-watch xdelta script

/**
 * header头信息有关的操作
 */
'use strict';

var _regeneratorRuntime = require('babel-runtime/regenerator')['default'];

var _interopRequireDefault = require('babel-runtime/helpers/interop-require-default')['default'];

Object.defineProperty(exports, '__esModule', {
  value: true
});

var _co = require('co');

var _co2 = _interopRequireDefault(_co);

var _babelFs = require('babel-fs');

var _babelFs2 = _interopRequireDefault(_babelFs);

var DIFF_INDEX = 20;exports.DIFF_INDEX = DIFF_INDEX;
// diff文件在头信息中的起始位置

/**
 * 初始化差分文件的头信息, 具体结构可以看doc/header.docx
 * @param {Number} diffLen diff块的总大小
 * @param {Number} blk 分块的数量
 * @param {Number} blksize 分块的大小
 * @param {Number} oldFromLenB 老固件有多少个字节
 * @param {Number} newFromLenB 新固件有多少个字节
 * @return{Promise.<Buffer>} 头信息
 *
 */
var generatorHeader = _co2['default'].wrap(_regeneratorRuntime.mark(function callee$0$0(_ref) {
  var blk = _ref.blk;
  var blksize = _ref.blksize;
  var oldFromLenB = _ref.oldFromLenB;
  var newFromLenB = _ref.newFromLenB;
  var xdeltaFiles = _ref.xdeltaFiles;
  var buf;
  return _regeneratorRuntime.wrap(function callee$0$0$(context$1$0) {
    while (1) switch (context$1$0.prev = context$1$0.next) {
      case 0:
        buf = new Buffer(DIFF_INDEX + xdeltaFiles.length * 4);

        //wth1
        buf.writeUInt8(0x77, 0);
        buf.writeUInt8(0x74, 1);
        buf.writeUInt8(0x68, 2);
        buf.writeUInt8(0x31, 3);

        //block-size
        buf.writeUInt32LE(blksize, 4);

        //diffNum
        buf.writeUInt32LE(blk, 8);

        //oldFromLenB
        buf.writeUInt32LE(oldFromLenB, 12);

        //newFromLenB
        buf.writeUInt32LE(newFromLenB, 16);

        //diffLen1...diffLenN
        context$1$0.next = 11;
        return fillInDiff(buf, DIFF_INDEX, xdeltaFiles);

      case 11:
        return context$1$0.abrupt('return', buf);

      case 12:
      case 'end':
        return context$1$0.stop();
    }
  }, callee$0$0, this);
}));

exports.generatorHeader = generatorHeader;
/**
 * 填充每个diff文件的大小
 * @param {Buffer} buf 头信息
 * @param {Number} xdeltaIndex 第一个diff文件的位置
 * @param {Array} xdeltaFiles diff文件数组
 *
 */
var fillInDiff = _co2['default'].wrap(_regeneratorRuntime.mark(function callee$0$0(buf, xdeltaIndex, xdeltaFiles) {
  var i, len, file, dStat, dSize;
  return _regeneratorRuntime.wrap(function callee$0$0$(context$1$0) {
    while (1) switch (context$1$0.prev = context$1$0.next) {
      case 0:
        i = 0, len = xdeltaFiles.length;

      case 1:
        if (!(i < len)) {
          context$1$0.next = 12;
          break;
        }

        file = xdeltaFiles[i];
        context$1$0.next = 5;
        return _babelFs2['default'].stat(file);

      case 5:
        dStat = context$1$0.sent;
        dSize = dStat.size;

        buf.writeUInt32LE(dSize, xdeltaIndex);
        xdeltaIndex += 4;

      case 9:
        i++;
        context$1$0.next = 1;
        break;

      case 12:
      case 'end':
        return context$1$0.stop();
    }
  }, callee$0$0, this);
}));