static int scsi_read_dvd_structure(SCSIDiskState *s, SCSIDiskReq *r,
                                   uint8_t *outbuf)
{
    static const int rds_caps_size[5] = {
        [0] = 2048 + 4,
        [1] = 4 + 4,
        [3] = 188 + 4,
        [4] = 2048 + 4,
    };

    uint8_t media = r->req.cmd.buf[1];
    uint8_t layer = r->req.cmd.buf[6];
    uint8_t format = r->req.cmd.buf[7];
    int size = -1;

    if (s->qdev.type != TYPE_ROM) {
        return -1;
    }
    if (media != 0) {
        scsi_check_condition(r, SENSE_CODE(INVALID_FIELD));
        return -1;
    }

    if (format != 0xff) {
        if (!blk_is_available(s->qdev.conf.blk)) {
            scsi_check_condition(r, SENSE_CODE(NO_MEDIUM));
            return -1;
        }
        if (media_is_cd(s)) {
            scsi_check_condition(r, SENSE_CODE(INCOMPATIBLE_FORMAT));
            return -1;
        }
        if (format >= ARRAY_SIZE(rds_caps_size)) {
            return -1;
        }
        size = rds_caps_size[format];
        memset(outbuf, 0, size);
    }

    switch (format) {
    case 0x00: {
        /* Physical format information */
        uint64_t nb_sectors;
        if (layer != 0) {
            goto fail;
        }
        blk_get_geometry(s->qdev.conf.blk, &nb_sectors);

        outbuf[4] = 1;   /* DVD-ROM, part version 1 */
        outbuf[5] = 0xf; /* 120mm disc, minimum rate unspecified */
        outbuf[6] = 1;   /* one layer, read-only (per MMC-2 spec) */
        outbuf[7] = 0;   /* default densities */

        stl_be_p(&outbuf[12], (nb_sectors >> 2) - 1); /* end sector */
        stl_be_p(&outbuf[16], (nb_sectors >> 2) - 1); /* l0 end sector */
        break;
    }

    case 0x01: /* DVD copyright information, all zeros */
        break;

    case 0x03: /* BCA information - invalid field for no BCA info */
        return -1;

    case 0x04: /* DVD disc manufacturing information, all zeros */
        break;

    case 0xff: { /* List capabilities */
        int i;
        size = 4;
        for (i = 0; i < ARRAY_SIZE(rds_caps_size); i++) {
            if (!rds_caps_size[i]) {
                continue;
            }
            outbuf[size] = i;
            outbuf[size + 1] = 0x40; /* Not writable, readable */
            stw_be_p(&outbuf[size + 2], rds_caps_size[i]);
            size += 4;
        }
        break;
     }

    default:
        return -1;
    }

    /* Size of buffer, not including 2 byte size field */
    stw_be_p(outbuf, size - 2);
    return size;

fail:
    return -1;
}
Unknown