[9fans] u9fs CD installation

[Digby Tarvin digbyt@acm.org]

>
>Anyhow, despite the documentation, both kfs and the file server
>allow chown via wstat if in you've done 'kfscmd allow' or by booting
>the file server in insecure mode, respectively.  (For normal operation,
>the documentation is correct.)
>
>That's how the install procedure sets up the owners correctly initially.
>
>As for u9fs, it looks like it should work but obviously doesn't.
>
Aha!, got it.

Thanks - that pointer regarding chowning after the initial create
got me looking in the right place.

The rwstat() routine in u9fs silently ignores any attempt to change 
the file owner under all circumstances.

I had to implement am 'allow' option in u9fs to allow the CD installation
procedure to create my file system properly. This option has to enable
the setting of file ownership, and also disable all other permission
checking so that the changed files remain accessible to the install
program.

I am running u9fs in a chrooted environment, so this is probably not
too dangerous.

Presumably I could make this am attach specifier like the 'device'
access enabling one, but for now it is a command line option for
two reasons:
1.	The install program would need to know to use it
2.	It is probably more secure to only be able to enable this
    by being super user on the file server.

I guess, given that this problem hasn't been found before, that this
mode of installation isn't attempted very often. But if anyone
else is interested, I will tidy it up and make it available.

Regards,
DigbyT
-- 
Digby R. S. Tarvin                                              digbyt@acm.org
http://www.cthulhu.dircon.co.uk