func: static int scsi_req_length(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf)
  
  {
  
      cmd->xfer = scsi_cdb_length(buf);
  
      switch (buf[0]) {
  
      case TEST_UNIT_READY:
  
      case REWIND:
  
      case START_STOP:
  
      case SET_CAPACITY:
  
      case WRITE_FILEMARKS:
  
      case WRITE_FILEMARKS_16:
  
      case SPACE:
  
      case RESERVE:
  
      case RELEASE:
  
      case ERASE:
  
      case ALLOW_MEDIUM_REMOVAL:
  
      case SEEK_10:
  
      case SYNCHRONIZE_CACHE:
  
      case SYNCHRONIZE_CACHE_16:
  
      case LOCATE_16:
  
      case LOCK_UNLOCK_CACHE:
  
      case SET_CD_SPEED:
  
      case SET_LIMITS:
  
      case WRITE_LONG_10:
  
      case UPDATE_BLOCK:
  
      case RESERVE_TRACK:
  
      case SET_READ_AHEAD:
  
      case PRE_FETCH:
  
      case PRE_FETCH_16:
  
      case ALLOW_OVERWRITE:
  
          cmd->xfer = 0;
  
          break;
  
      case VERIFY_10:
  
      case VERIFY_12:
  
      case VERIFY_16:
  
          if ((buf[1] & 2) == 0) {
  
              cmd->xfer = 0;
  
          } else if ((buf[1] & 4) == 1) {
  
              cmd->xfer = 1;
  
          }
  
          cmd->xfer *= dev->blocksize;
  
          break;
  
      case MODE_SENSE:
  
          break;
  
      case WRITE_SAME_10:
  
      case WRITE_SAME_16:
  
          cmd->xfer = dev->blocksize;
  
          break;
  
      case READ_CAPACITY_10:
  
          cmd->xfer = 8;
  
          break;
  
      case READ_BLOCK_LIMITS:
  
          cmd->xfer = 6;
  
          break;
  
      case SEND_VOLUME_TAG:
  
          /* GPCMD_SET_STREAMING from multimedia commands.  */
  
          if (dev->type == TYPE_ROM) {
  
              cmd->xfer = buf[10] | (buf[9] << 8);
  
          } else {
  
              cmd->xfer = buf[9] | (buf[8] << 8);
  
          }
  
          break;
  
      case WRITE_6:
  
          /* length 0 means 256 blocks */
  
          if (cmd->xfer == 0) {
  
              cmd->xfer = 256;
  
          }
  
      case WRITE_10:
  
      case WRITE_VERIFY_10:
  
      case WRITE_12:
  
      case WRITE_VERIFY_12:
  
      case WRITE_16:
  
      case WRITE_VERIFY_16:
  
          cmd->xfer *= dev->blocksize;
  
          break;
  
      case READ_6:
  
      case READ_REVERSE:
  
          /* length 0 means 256 blocks */
  
          if (cmd->xfer == 0) {
  
              cmd->xfer = 256;
  
          }
  
      case READ_10:
  
      case RECOVER_BUFFERED_DATA:
  
      case READ_12:
  
      case READ_16:
  
          cmd->xfer *= dev->blocksize;
  
          break;
  
      case FORMAT_UNIT:
  
          /* MMC mandates the parameter list to be 12-bytes long.  Parameters
  
           * for block devices are restricted to the header right now.  */
  
          if (dev->type == TYPE_ROM && (buf[1] & 16)) {
  
              cmd->xfer = 12;
  
          } else {
  
              cmd->xfer = (buf[1] & 16) == 0 ? 0 : (buf[1] & 32 ? 8 : 4);
  
          }
  
          break;
  
      case INQUIRY:
  
      case RECEIVE_DIAGNOSTIC:
  
      case SEND_DIAGNOSTIC:
  
          cmd->xfer = buf[4] | (buf[3] << 8);
  
          break;
  
      case READ_CD:
  
      case READ_BUFFER:
  
      case WRITE_BUFFER:
  
      case SEND_CUE_SHEET:
  
          cmd->xfer = buf[8] | (buf[7] << 8) | (buf[6] << 16);
  
          break;
  
      case PERSISTENT_RESERVE_OUT:
  
          cmd->xfer = ldl_be_p(&buf[5]) & 0xffffffffULL;
  
          break;
  
      case ERASE_12:
  
          if (dev->type == TYPE_ROM) {
  
              /* MMC command GET PERFORMANCE.  */
  
              cmd->xfer = scsi_get_performance_length(buf[9] | (buf[8] << 8),
  
                                                      buf[10], buf[1] & 0x1f);
  
          }
  
          break;
  
      case MECHANISM_STATUS:
  
      case READ_DVD_STRUCTURE:
  
      case SEND_DVD_STRUCTURE:
  
      case MAINTENANCE_OUT:
  
      case MAINTENANCE_IN:
  
          if (dev->type == TYPE_ROM) {
  
              /* GPCMD_REPORT_KEY and GPCMD_SEND_KEY from multi media commands */
  
              cmd->xfer = buf[9] | (buf[8] << 8);
  
          }
  
          break;
  
      case ATA_PASSTHROUGH_12:
  
          if (dev->type == TYPE_ROM) {
  
              /* BLANK command of MMC */
  
              cmd->xfer = 0;
  
          } else {
  
              cmd->xfer = ata_passthrough_12_xfer_size(dev, buf);
  
          }
  
          break;
  
      case ATA_PASSTHROUGH_16:
  
          cmd->xfer = ata_passthrough_16_xfer_size(dev, buf);
  
          break;
  
      }
  
      return 0;
  
  }
  