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node_modules/ws/lib/buffer-util.js 1.68 KB
aaac7fed   liuqimichale   add
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  'use strict';
  
  const safeBuffer = require('safe-buffer');
  
  const Buffer = safeBuffer.Buffer;
  
  /**
   * Merges an array of buffers into a new buffer.
   *
   * @param {Buffer[]} list The array of buffers to concat
   * @param {Number} totalLength The total length of buffers in the list
   * @return {Buffer} The resulting buffer
   * @public
   */
  const concat = (list, totalLength) => {
    const target = Buffer.allocUnsafe(totalLength);
    var offset = 0;
  
    for (var i = 0; i < list.length; i++) {
      const buf = list[i];
      buf.copy(target, offset);
      offset += buf.length;
    }
  
    return target;
  };
  
  try {
    const bufferUtil = require('bufferutil');
  
    module.exports = Object.assign({ concat }, bufferUtil.BufferUtil || bufferUtil);
  } catch (e) /* istanbul ignore next */ {
    /**
     * Masks a buffer using the given mask.
     *
     * @param {Buffer} source The buffer to mask
     * @param {Buffer} mask The mask to use
     * @param {Buffer} output The buffer where to store the result
     * @param {Number} offset The offset at which to start writing
     * @param {Number} length The number of bytes to mask.
     * @public
     */
    const mask = (source, mask, output, offset, length) => {
      for (var i = 0; i < length; i++) {
        output[offset + i] = source[i] ^ mask[i & 3];
      }
    };
  
    /**
     * Unmasks a buffer using the given mask.
     *
     * @param {Buffer} buffer The buffer to unmask
     * @param {Buffer} mask The mask to use
     * @public
     */
    const unmask = (buffer, mask) => {
      // Required until https://github.com/nodejs/node/issues/9006 is resolved.
      const length = buffer.length;
      for (var i = 0; i < length; i++) {
        buffer[i] ^= mask[i & 3];
      }
    };
  
    module.exports = { concat, mask, unmask };
  }