are partial read responses legal

[Steve French]

Is it legal or common for a server to return less on an SMBReadX than
the client asked when there is more data and the read falls within the
negotiated buffer size?

The SNIA spec notes that if read is larger than negotiated buffer size
the server "may arbitrarily decide" to return fewer than MaxCount bytes,
perhaps implying that I would be ok in changing my current read code
from something like

	while(bytes_to_reads && (rc == 0)) {
		SMBRead(bytes_to_read)
		decrease bytes_to_read by bytes read
	}

to something that checks whether the bytes read was less than negotiated
size before deciding to retry again on a read that is going to return 0
bytes.  This also could be in combination with a check to ensure that
the bytes read matches what we expect is the end of file.