int COMP_compress_block(COMP_CTX *ctx, unsigned char *out, int olen,
                        unsigned char *in, int ilen)
{
    int ret;
    if (ctx->meth->compress == NULL) {
        /* ZZZZZZZZZZZZZZZZZ */
        return (-1);
    }
    ret = ctx->meth->compress(ctx, out, olen, in, ilen);
    if (ret > 0) {
        ctx->compress_in += ilen;
        ctx->compress_out += ret;
    }
    return (ret);
}