Example

int myfilter_flush(FilterLayer *layer)
{
    MyFilterContext context = (MyFilterContext *)layer->context->data;
    if (context->buf.count) {
       int rv;
       rv = net_write(layer->lower, context->buf.data, context->buf.count);
       if (rv != context->buf.count)
           return -1; /* failed to flush data */
       context->buf.count = 0;
    }
    return net_flush(layer->lower);
}