zlib api usage

zlib_example.cpp

// The maximum size needed for the compressed output.  
int GetMaxCompressedLen(int souceLen)
{
    // round up any fraction of a block
    int n16kBlocks = (souceLen + 16383) / 16384;
    return ( souceLen + 6 + (n16kBlocks * 5) );

}

int ZlibCompress(const BYTE* input, int inlen, BYTE* output, int outlen)
{
    assert(input && output);

    /* allocate deflate state */
    z_stream strm;
    strm.total_in = strm.avail_in = inlen;
    strm.total_out = strm.avail_out = outlen;
    strm.next_in = (Bytef*)input;
    strm.next_out = (Bytef*)output;
    strm.zalloc = Z_NULL;
    strm.zfree  = Z_NULL;
    strm.opaque = Z_NULL;

    int ret = -1;
    int err = deflateInit(&strm, Z_DEFAULT_COMPRESSION);
    if (err == Z_OK)
    {
        err = deflate(&strm, Z_FINISH);
        if (err == Z_STREAM_END)
        {
            ret = strm.total_out;
        }
    }
    deflateEnd(&strm);
    return ret;
}

int ZlibUnCompress(const BYTE* input, int inlen, BYTE* output, int outlen)
{
    assert(input && output);
    z_stream strm;
    strm.total_in = strm.avail_in = inlen;
    strm.total_out = strm.avail_out = outlen;
    strm.next_in = (Bytef*)input;
    strm.next_out = (Bytef*)output;
    strm.zalloc = Z_NULL;
    strm.zfree  = Z_NULL;
    strm.opaque = Z_NULL;

    int ret = -1;
    int err = inflateInit(&strm);
    if (err == Z_OK)
    {
        err = inflate(&strm, Z_FINISH);
        if (err == Z_STREAM_END)
        {
            ret = strm.total_out;
        }
    }
    inflateEnd(&strm);
    return ret;
}


int _tmain(int argc, _TCHAR* argv[])
{
    FILE* fp = fopen("main.cpp", "r");
    if (fp == NULL)
    {
        return 1;
    }

    const int MAX_BUF_SIZE = 1024 * 32;
    BYTE buf[MAX_BUF_SIZE];
    int bytes = fread(buf, sizeof(char), MAX_BUF_SIZE, fp);
    if (bytes <= 0)
    {
        fclose(fp);
        return 1;
    }
    fclose(fp);

    int comp_len = GetMaxCompressedLen(bytes);
    BYTE* compbuffer = new BYTE[comp_len];
    int complen = ZlibCompress(buf, bytes, compbuffer, comp_len);
    if (complen < 0)
    {
        delete compbuffer;
        return 1;
    }

    BYTE* uncompbuf = new BYTE[bytes];
    int uncomplen = ZlibUnCompress(compbuffer, complen, uncompbuf, bytes);

    int result = memcmp(buf, uncompbuf, bytes);
    delete uncompbuf;
        if (result == 0)
    {
        printf("OK.\n");
    }
    else
    {
        printf("Failed.\n");
    }

  return 0;
}