Re: [9fans] Drawterm /mnt/term permissions issue

[Ethan Grammatikidis <eekee57@fastmail.fm>]

On Thu, 4 Jun 2009 17:23:08 -0700
Russ Cox <rsc@swtch.com> wrote:

> On Thu, Jun 4, 2009 at 4:58 PM, Ethan Grammatikidis <eekee57@fastmail.fm> wrote:
> > I run a plan 9 cpu server in Qemu and use drawterm to connect from the Linux host.
> > I thought the /mnt/term mechanism would be very convenient for exchanging files
> > between host & guest, but the guest sees all user/group names as
> > unknown/unknown, preventing writing.
>
> That's surprising.  Drawterm isn't going around enforcing
> permission bits: if it can write, it writes.  What it shows
> you in ls is what it gets from stat, but it doesn't rely on
> that to make decisions about what you can open.  It just
> tries to open it.
>
> http://cvs.pdos.csail.mit.edu/cvs/drawterm/kern/devfs-posix.c?rev=1.5;content-type=text%2Fplain

Looks like a prime candidate for modification. ;) The code unconditionally sets d.uid = "unknown" immediately after stat(path, &stbuf) calls. stbuf.st_uid could be compared with the un*x UID drawterm is running as, & if matching d.uid is filled with the logged-in plan 9 username instead of "unknown". Similar for stbuf.st_gid and g.gid.

I could write a patch when I'm more awake. Rather a lot to look up when I'm falling asleep. :)

--
Ethan Grammatikidis
The lyf so short, the craft so long to lerne. -- Chaucer