Exemplo n.º 1
0
  /*
   * gets an (uncompressed) stream representing the chunk data returns null if
   * the chunk is not found or an error occurs
   */
  public synchronized DataInputStream getChunkDataInputStream(int x, int z) {
    if (outOfBounds(x, z)) {
      debugln("READ", x, z, "out of bounds");
      return null;
    }

    try {
      int offset = getOffset(x, z);
      if (offset == 0) {
        // debugln("READ", x, z, "miss");
        return null;
      }

      int sectorNumber = offset >> 8;
      int numSectors = offset & 0xFF;

      if (sectorNumber + numSectors > sectorFree.size()) {
        debugln("READ", x, z, "invalid sector");
        return null;
      }

      file.seek(sectorNumber * SECTOR_BYTES);
      int length = file.readInt();

      if (length > SECTOR_BYTES * numSectors) {
        debugln("READ", x, z, "invalid length: " + length + " > 4096 * " + numSectors);
        return null;
      }

      byte version = file.readByte();
      if (version == VERSION_GZIP) {
        byte[] data = new byte[length - 1];
        file.read(data);
        DataInputStream ret =
            new DataInputStream(
                new BufferedInputStream(new GZIPInputStream(new ByteArrayInputStream(data))));
        // debug("READ", x, z, " = found");
        return ret;
      } else if (version == VERSION_DEFLATE) {
        byte[] data = new byte[length - 1];
        file.read(data);
        DataInputStream ret =
            new DataInputStream(
                new BufferedInputStream(new InflaterInputStream(new ByteArrayInputStream(data))));
        // debug("READ", x, z, " = found");
        return ret;
      }

      debugln("READ", x, z, "unknown version " + version);
      return null;
    } catch (IOException e) {
      debugln("READ", x, z, "exception");
      return null;
    }
  }
Exemplo n.º 2
0
  /**
   * Read block from file.
   *
   * @param file - File to read.
   * @param off - Marker position in file to start read from if {@code -1} read last blockSz bytes.
   * @param blockSz - Maximum number of chars to read.
   * @param lastModified - File last modification time.
   * @return Read file block.
   * @throws IOException In case of error.
   */
  public static VisorFileBlock readBlock(File file, long off, int blockSz, long lastModified)
      throws IOException {
    RandomAccessFile raf = null;

    try {
      long fSz = file.length();
      long fLastModified = file.lastModified();

      long pos = off >= 0 ? off : Math.max(fSz - blockSz, 0);

      // Try read more that file length.
      if (fLastModified == lastModified && fSz != 0 && pos >= fSz)
        throw new IOException(
            "Trying to read file block with wrong offset: " + pos + " while file size: " + fSz);

      if (fSz == 0)
        return new VisorFileBlock(file.getPath(), pos, fLastModified, 0, false, EMPTY_FILE_BUF);
      else {
        int toRead = Math.min(blockSz, (int) (fSz - pos));

        byte[] buf = new byte[toRead];

        raf = new RandomAccessFile(file, "r");

        raf.seek(pos);

        int cntRead = raf.read(buf, 0, toRead);

        if (cntRead != toRead)
          throw new IOException(
              "Count of requested and actually read bytes does not match [cntRead="
                  + cntRead
                  + ", toRead="
                  + toRead
                  + ']');

        boolean zipped = buf.length > 512;

        return new VisorFileBlock(
            file.getPath(), pos, fSz, fLastModified, zipped, zipped ? zipBytes(buf) : buf);
      }
    } finally {
      U.close(raf, null);
    }
  }