pdf.js/src/core/decrypt_stream.js

/* Copyright 2012 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/* eslint-disable no-var */

import { DecodeStream } from "./stream.js";

var DecryptStream = (function DecryptStreamClosure() {
  // eslint-disable-next-line no-shadow
  function DecryptStream(str, maybeLength, decrypt) {
    this.str = str;
    this.dict = str.dict;
    this.decrypt = decrypt;
    this.nextChunk = null;
    this.initialized = false;

    DecodeStream.call(this, maybeLength);
  }

  var chunkSize = 512;

  DecryptStream.prototype = Object.create(DecodeStream.prototype);

  DecryptStream.prototype.readBlock = function DecryptStream_readBlock() {
    var chunk;
    if (this.initialized) {
      chunk = this.nextChunk;
    } else {
      chunk = this.str.getBytes(chunkSize);
      this.initialized = true;
    }
    if (!chunk || chunk.length === 0) {
      this.eof = true;
      return;
    }
    this.nextChunk = this.str.getBytes(chunkSize);
    var hasMoreData = this.nextChunk && this.nextChunk.length > 0;

    var decrypt = this.decrypt;
    chunk = decrypt(chunk, !hasMoreData);

    var bufferLength = this.bufferLength;
    var i,
      n = chunk.length;
    var buffer = this.ensureBuffer(bufferLength + n);
    for (i = 0; i < n; i++) {
      buffer[bufferLength++] = chunk[i];
    }
    this.bufferLength = bufferLength;
  };

  return DecryptStream;
})();

export { DecryptStream };