[Info-vax] Re; Spiralog, RMS Journaling (was Re: FREESPADRIFT)

[Johnny Billquist]

On 2016-06-24 14:52, Bob Koehler wrote:
> In article <nkhf9i$7s3$1 at Iltempo.Update.UU.SE>, Johnny Billquist <bqt at softjar.se> writes:
>>
>> Uh? Say what? Everything in TCP/IP is just a stream of bytes. There are
>> no blocks, nothing is sent in any multiple of blocks.
>> (And besides, text files in Unix do not have CF and LF in them. They
>> just have LF. Which is why I was complaining about Unix ftp
>> implementations, which often lies about file size, and sometimes cheat
>> when transferring in text mode. These protocols were not designed by
>> Unix people...)
>
>    So hwo does UNIX solve it?  By lieing about it?  Does that work
>    anyhow?  If so, then why can't VMS lie about it?  Or do both UNIX
>    and VMS have to read the file twice to get it right?

With HTTP Unix just stat() the file, and return the size as reported, 
and everything is correct.

Some ftp implementations lie, in that they do a stat() and return that 
size, and at transfer they still send more data than the size reported, 
if in text mode. Which is not a problem between Unix systems, since they 
never use text mode normally. Unix to Unix normally is done in binary 
all the time, for which the size is correct.

So it becomes a potential issue if transferring between Unix and 
non-Unix systems, at which point text transfer might work wrong. 
However, with ftp, size information is not mandatory in the first place, 
and is normally not used for the actual transfer, so you can often get 
away with lying about the size, but it does break the standard.
(ftp also usually always close the connection on transfer end, so size 
is not used to see if the full file is transferred. A side effect from 
the fact than ftp use a separate channel for data transfer compared to 
commands. http uses the same channel for both, which makes it so much 
more sensitive.)

But in reality, if Unix has to transfer a file in text mode using 
internet standards, and needs to report size, you'll have to read the 
file twice on Unix as well. But only for text transfers.

	Johnny