!7

p-exp {

  byte[] data = loadBinaryFile(userDir(".mozilla/firefox/peppermint.default/sessionstore-backups/recovery.jsonlz4"));

  print("Have data: " + l(data));

  if (empty(data)) ret;

  print(bytesToHex(subByteArray(data, 0, 16)));

  int lDecompressed = intFromBytes_littleEndian(data, 8);

  print("lDecompressed=" + lDecompressed);

  // see http://fastcompression.blogspot.com/2011/05/lz4-explained.html

  int i = 12, n = l(data), iOut = 0;

  byte[] out = new byte[lDecompressed];

  while (i < n) {

    int lLiteral = (data[i] >> 4) & 0x0F;

    int lMatches = (data[i] & 0x0F)+4;

    i++;

    print("lLiteral=" + lLiteral + ", lMatches=" + lMatches);

    if (lLiteral == 15) {

      int more;

      do {

        more = data[i++] & 0xFF;

        lLiteral += more;

        print("lLiteral >> " + lLiteral);

      } while (more == 255);

    }

    print("Have literal: " + quote(fromUtf8_subArray(data, i, lLiteral)));

    arraycopy(data, i, out, iOut, lLiteral);

    iOut += lLiteral;

    i += lLiteral;

    if (i >= n) break;

    int offset = data[i] & 0xFF | (data[i+1] & 0xFF) << 8;

    print("offset=" + offset);

    i += 2;

    if (offset == 0) break with print("bad offset");

    if (lMatches == 19) {

      int more;

      do {

        more = data[i++] & 0xFF;

        lMatches += more;

        print("lMatches >> " + lLiteral);

      } while (more == 255);

    }

    int j = lMatches;

    while (j-- > 0) {

      out[iOut] = out[iOut-offset];

      iOut++;

    }

    print("Got match: " + quote(fromUtf8_subArray(out, iOut-lMatches, lMatches)));

    //break;

  }

  saveProgramTextFile("uncompressed.json", fromUtf8(out));

}