kc3-lang/brotli/java/integration/BundleChecker.java

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• Hash : 5025365d
  Author :
  Date : 2016-10-17T14:04:59
  

  Add Java port of Brotli decoder.
  

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• java/integration/BundleChecker.java

• /* Copyright 2016 Google Inc. All Rights Reserved.
  
     Distributed under MIT license.
     See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
  */
  
  package org.brotli.integration;
  
  import org.brotli.dec.BrotliInputStream;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.FilterInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.math.BigInteger;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.zip.ZipEntry;
  import java.util.zip.ZipInputStream;
  
  /**
   * Decompress files and checks thier checksums.
   *
   * <p> File are read from ZIP archive passed as an array of bytes. Multiple checkers negotiate about
   * task distribution via shared AtomicInteger counter.
   * <p> All entries are expected to be valid brotli compressed streams and output CRC64 checksum
   * is expected to match the checksum hex-encoded in the first part of entry name.
   */
  public class BundleChecker implements Runnable {
    final AtomicInteger nextJob;
    final InputStream input;
  
    public BundleChecker(InputStream input, AtomicInteger nextJob) {
      this.input = input;
      this.nextJob = nextJob;
    }
  
    /** ECMA CRC64 polynomial. */
    static final long CRC_64_POLY = new BigInteger("C96C5795D7870F42", 16).longValue();
  
    /**
     * Rolls CRC64 calculation.
     *
     * <p> {@code CRC64(data) = -1 ^ updateCrc64((... updateCrc64(-1, firstBlock), ...), lastBlock);}
     * <p> This simple and reliable checksum is chosen to make is easy to calculate the same value
     * across the variety of languages (C++, Java, Go, ...).
     */
    private static long updateCrc64(long crc, byte[] data, int offset, int length) {
      for (int i = offset; i < offset + length; ++i) {
        long c = (crc ^ (long) (data[i] & 0xFF)) & 0xFF;
        for (int k = 0; k < 8; k++) {
          c = ((c & 1) == 1) ? CRC_64_POLY ^ (c >>> 1) : c >>> 1;
        }
        crc = c ^ (crc >>> 8);
      }
      return crc;
    }
  
    private long decompressAndCalculateCrc(ZipInputStream input) throws IOException {
      /* Do not allow entry readers to close the whole ZipInputStream. */
      FilterInputStream entryStream = new FilterInputStream(input) {
        @Override
        public void close() {}
      };
  
      long crc = -1;
      byte[] buffer = new byte[65536];
      BrotliInputStream decompressedStream = new BrotliInputStream(entryStream);
      while (true) {
        int len = decompressedStream.read(buffer);
        if (len <= 0) {
          break;
        }
        crc = updateCrc64(crc, buffer, 0, len);
      }
      decompressedStream.close();
      return crc ^ -1;
    }
  
    @Override
    public void run() {
      String entryName = "";
      ZipInputStream zis = new ZipInputStream(input);
      try {
        int entryIndex = 0;
        ZipEntry entry = null;
        int jobIndex = nextJob.getAndIncrement();
        while ((entry = zis.getNextEntry()) != null) {
          if (entry.isDirectory()) {
            continue;
          }
          if (entryIndex++ != jobIndex) {
            zis.closeEntry();
            continue;
          }
          entryName = entry.getName();
          String entryCrcString = entryName.substring(0, entryName.indexOf('.'));
          long entryCrc = new BigInteger(entryCrcString, 16).longValue();
          if (entryCrc != decompressAndCalculateCrc(zis)) {
            throw new RuntimeException("CRC mismatch");
          }
          zis.closeEntry();
          entryName = "";
          jobIndex = nextJob.getAndIncrement();
        }
        zis.close();
        input.close();
      } catch (Throwable ex) {
        throw new RuntimeException(entryName, ex);
      }
    }
  
    public static void main(String[] args) throws FileNotFoundException {
      if (args.length == 0) {
        throw new RuntimeException("Usage: BundleChecker <fileX.zip> ...");
      }
      for (int i = 0; i < args.length; ++i) {
        new BundleChecker(new FileInputStream(args[i]), new AtomicInteger(0)).run();
      }
    }
  }
  

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