usb printer driver and zero length transfer

[Kallol Biswas]

Hi,
     I am new to USB world and looking for clarification on usb
printer's
behavior when transferring data with size  multiple of  wMaxPacketSize.

I have been running redhat 7.1 (linux kernel 2.4.2-2) on x86 PC with a
USB 1.1 controller. There is a target mode printer driver running on the

other side.

On the host the device file is /dev/usb/lp0.
If a data packet of 64 bytes is sent with

"cat data8 > /dev/usb/lp0" , the size of data8 is 64, a zero length
packet
at the end of the transfer is not sent.

Is this a correct behavior?  How do we force the printer driver send
a zero length packet at the end of a transfer if the packet size is
a multiple of wMAxPacketSize?

Kallol