int flb_gzip_compress(void *in_data, size_t in_len,
                      void **out_data, size_t *out_len)
{
    int flush;
    int status;
    int footer_start;
    uint8_t *pb;
    size_t out_size;
    void *out_buf;
    z_stream strm;
    mz_ulong crc;


    /*
     * GZIP relies on an algorithm with worst-case expansion
     * of 5 bytes per 32KB data. This means we need to create a variable
     * length output, that depends on the input length.
     * See RFC 1951 for details.
     */
    int max_input_expansion = ((int)(in_len / 32000) + 1) * 5;

    /*
     * Max compressed size is equal to sum of:
     *   10 byte header
     *   8 byte foot
     *   max input expansion
     *   size of input
     */
    out_size = 10 + 8 + max_input_expansion + in_len;
    out_buf = flb_malloc(out_size);

    if (!out_buf) {
        flb_errno();
        flb_error("[gzip] could not allocate outgoing buffer");
        return -1;
    }

    /* Initialize streaming buffer context */
    memset(&strm, '\0', sizeof(strm));
    strm.zalloc    = Z_NULL;
    strm.zfree     = Z_NULL;
    strm.opaque    = Z_NULL;
    strm.next_in   = in_data;
    strm.avail_in  = in_len;
    strm.total_out = 0;

    /* Deflate mode */
    deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
                 Z_DEFLATED, -Z_DEFAULT_WINDOW_BITS, 9, Z_DEFAULT_STRATEGY);

    /*
     * Miniz don't support GZip format directly, instead we will:
     *
     * - append manual GZip magic bytes
     * - deflate raw content
     * - append manual CRC32 data
     */
    gzip_header(out_buf);

    /* Header offset */
    pb = (uint8_t *) out_buf + FLB_GZIP_HEADER_OFFSET;

    flush = Z_NO_FLUSH;
    while (1) {
        strm.next_out  = pb + strm.total_out;
        strm.avail_out = out_size - (pb - (uint8_t *) out_buf);

        if (strm.avail_in == 0) {
            flush = Z_FINISH;
        }

        status = deflate(&strm, flush);
        if (status == Z_STREAM_END) {
            break;
        }
        else if (status != Z_OK) {
            deflateEnd(&strm);
            return -1;
        }
    }

    if (deflateEnd(&strm) != Z_OK) {
        flb_free(out_buf);
        return -1;
    }
    *out_len = strm.total_out;

    /* Construct the gzip checksum (CRC32 footer) */
    footer_start = FLB_GZIP_HEADER_OFFSET + *out_len;
    pb = (uint8_t *) out_buf + footer_start;

    crc = mz_crc32(MZ_CRC32_INIT, in_data, in_len);
    *pb++ = crc & 0xFF;
    *pb++ = (crc >> 8) & 0xFF;
    *pb++ = (crc >> 16) & 0xFF;
    *pb++ = (crc >> 24) & 0xFF;
    *pb++ = in_len & 0xFF;
    *pb++ = (in_len >> 8) & 0xFF;
    *pb++ = (in_len >> 16) & 0xFF;
    *pb++ = (in_len >> 24) & 0xFF;

    /* Set the real buffer size for the caller */
    *out_len += FLB_GZIP_HEADER_OFFSET + 8;
    *out_data = out_buf;

    return 0;
}
int flb_gzip_compress(void *in_data, size_t in_len,
                      void **out_data, size_t *out_len)
{
    int flush;
    int status;
    int footer_start;
    uint8_t *pb;
    size_t out_size;
    void *out_buf;
    z_stream strm;
    mz_ulong crc;


     
    int max_input_expansion = ((int)(in_len / 32000) + 1) * 5;

     
    out_size = 10 + 8 + max_input_expansion + in_len;
    out_buf = flb_malloc(out_size);

    if (!out_buf) {
        flb_errno();
        flb_error("[gzip] could not allocate outgoing buffer");
        return -1;
    }

     
    memset(&strm, '\0', sizeof(strm));
    strm.zalloc    = Z_NULL;
    strm.zfree     = Z_NULL;
    strm.opaque    = Z_NULL;
    strm.next_in   = in_data;
    strm.avail_in  = in_len;
    strm.total_out = 0;

     
    deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
                 Z_DEFLATED, -Z_DEFAULT_WINDOW_BITS, 9, Z_DEFAULT_STRATEGY);

     
    gzip_header(out_buf);

     
    pb = (uint8_t *) out_buf + FLB_GZIP_HEADER_OFFSET;

    flush = Z_NO_FLUSH;
    while (1) {
        strm.next_out  = pb + strm.total_out;
        strm.avail_out = out_size - (pb - (uint8_t *) out_buf);

        if (strm.avail_in == 0) {
            flush = Z_FINISH;
        }

        status = deflate(&strm, flush);
        if (status == Z_STREAM_END) {
            break;
        }
        else if (status != Z_OK) {
            deflateEnd(&strm);
            return -1;
        }
    }

    if (deflateEnd(&strm) != Z_OK) {
        flb_free(out_buf);
        return -1;
    }
    *out_len = strm.total_out;

     
    footer_start = FLB_GZIP_HEADER_OFFSET + *out_len;
    pb = (uint8_t *) out_buf + footer_start;

    crc = mz_crc32(MZ_CRC32_INIT, in_data, in_len);
    *pb++ = crc & 0xFF;
    *pb++ = (crc >> 8) & 0xFF;
    *pb++ = (crc >> 16) & 0xFF;
    *pb++ = (crc >> 24) & 0xFF;
    *pb++ = in_len & 0xFF;
    *pb++ = (in_len >> 8) & 0xFF;
    *pb++ = (in_len >> 16) & 0xFF;
    *pb++ = (in_len >> 24) & 0xFF;

     
    *out_len += FLB_GZIP_HEADER_OFFSET + 8;
    *out_data = out_buf;

    return 0;
}