zlib one hop compression

zlibOneHopCompression.cpp

int deflateArr(const char *fileData, size_t fileDataSize) {
    z_stream testStream;
    uLong crc32Res = 0;

    testStream.avail_in = (uInt)0;
    testStream.total_in = 0;
    testStream.total_out = 0;
    testStream.data_type = Z_BINARY;

    testStream.zalloc = Z_NULL;
    testStream.zfree = Z_NULL;
    testStream.opaque = Z_NULL;

    int err = deflateInit2(&testStream, Z_BEST_SPEED, Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY);
    if(Z_OK != err) {
        cerr << "Error deflateInit2:" << err << endl;
        return 1;
    }

    size_t outBufSize = deflateBound(&testStream, fileDataSize);
    vector<uint8_t> bufferedData(outBufSize); /* buffer contain compressed data to be write*/

    testStream.avail_out = (uInt)outBufSize;
    testStream.next_out = bufferedData.data();

    crc32Res = crc32(crc32Res, (const Bytef *) fileData, (uInt)fileDataSize);

    testStream.next_in = (Bytef*)fileData;
    testStream.avail_in = (uInt) fileDataSize;

    err = deflate(&testStream, Z_FINISH);
    ASSERT_X(Z_STREAM_END == err, "err:" << err);
    ASSERT_X(0 == testStream.avail_in, "testStream.avail_in:" << testStream.avail_in);
    ASSERT_X(testStream.total_out == bufferedData.size() - testStream.avail_out,
             "testStream.total_out:" << testStream.total_out << " diff:" << bufferedData.size() - testStream.avail_out);
#if 0
    size_t compressedSize = bufferedData.size() - testStream.avail_out;
    cerr << "avail_out:" << testStream.avail_out << " diff:" << compressedSize << " total_out:" << testStream.total_out << endl;
#endif
    size_t compressedSize = testStream.total_out;
    deflateEnd(&testStream);

    lock_guard<mutex> lck(mSaveToZipMutex);
    fwrite(bufferedData.data(), 1, compressedSize, mTestFile);
    fwrite(&crc32Res, 4, 1, mTestFile);

    return 0;
}