static int vnc_update_client(VncState *vs, int has_dirty, bool sync)

{

    vs->has_dirty += has_dirty;

    if (vs->need_update && vs->ioc != NULL) {

        VncDisplay *vd = vs->vd;

        VncJob *job;

        int y;

        int height, width;

        int n = 0;



        if (vs->output.offset && !vs->audio_cap && !vs->force_update)

            /* kernel send buffers are full -> drop frames to throttle */

            return 0;



        if (!vs->has_dirty && !vs->audio_cap && !vs->force_update)

            return 0;



        /*

         * Send screen updates to the vnc client using the server

         * surface and server dirty map.  guest surface updates

         * happening in parallel don't disturb us, the next pass will

         * send them to the client.

         */

        job = vnc_job_new(vs);



        height = pixman_image_get_height(vd->server);

        width = pixman_image_get_width(vd->server);



        y = 0;

        for (;;) {

            int x, h;

            unsigned long x2;

            unsigned long offset = find_next_bit((unsigned long *) &vs->dirty,

                                                 height * VNC_DIRTY_BPL(vs),

                                                 y * VNC_DIRTY_BPL(vs));

            if (offset == height * VNC_DIRTY_BPL(vs)) {

                /* no more dirty bits */

                break;

            }

            y = offset / VNC_DIRTY_BPL(vs);

            x = offset % VNC_DIRTY_BPL(vs);

            x2 = find_next_zero_bit((unsigned long *) &vs->dirty[y],

                                    VNC_DIRTY_BPL(vs), x);

            bitmap_clear(vs->dirty[y], x, x2 - x);

            h = find_and_clear_dirty_height(vs, y, x, x2, height);

            x2 = MIN(x2, width / VNC_DIRTY_PIXELS_PER_BIT);

            if (x2 > x) {

                n += vnc_job_add_rect(job, x * VNC_DIRTY_PIXELS_PER_BIT, y,

                                      (x2 - x) * VNC_DIRTY_PIXELS_PER_BIT, h);

            }

            if (!x && x2 == width / VNC_DIRTY_PIXELS_PER_BIT) {

                y += h;

                if (y == height) {

                    break;

                }

            }

        }



        vnc_job_push(job);

        if (sync) {

            vnc_jobs_join(vs);

        }

        vs->force_update = 0;

        vs->has_dirty = 0;

        return n;

    }



    if (vs->disconnecting) {

        vnc_disconnect_finish(vs);

    } else if (sync) {

        vnc_jobs_join(vs);

    }



    return 0;

}
