[9fans] 9p question

[9fans] 9p question

[Venkatesh Srinivas]

Hi,

How come you can't TWalk along an open Fid?

Thanks,
-- vs

Re: [9fans] 9p question

[Russ Cox]

On Thu, Jul 30, 2009 at 8:28 AM, Venkatesh Srinivas<me@acm.jhu.edu> wrote:
> How come you can't TWalk along an open Fid?

In the original 9P protocol, that didn't make sense,
because walk always updated the fid it was starting from.
If you open a fid and then walk it elsewhere,
is it still open?  Is that an implicit close?
And the operation isn't needed by the Plan 9 kernel anyway,
so out it goes.

In the current 9P protocol, I think it would be fine to
allow a walk to start at an open fid as long as newfid
was being used to create a new fid.  This would
make it easy to implement fchdir on Unix.

Russ

Re: [9fans] 9p question

[Iruata Souza]

On Thu, Jul 30, 2009 at 1:08 PM, Russ Cox<rsc@swtch.com> wrote:
> On Thu, Jul 30, 2009 at 8:28 AM, Venkatesh Srinivas<me@acm.jhu.edu> wrote:
>> How come you can't TWalk along an open Fid?
>
> In the original 9P protocol, that didn't make sense,
> because walk always updated the fid it was starting from.
> If you open a fid and then walk it elsewhere,
> is it still open?  Is that an implicit close?
> And the operation isn't needed by the Plan 9 kernel anyway,
> so out it goes.
>
> In the current 9P protocol, I think it would be fine to
> allow a walk to start at an open fid as long as newfid
> was being used to create a new fid.  This would
> make it easy to implement fchdir on Unix.
>

it would surely make it easier for unix implementations. i have had
plenty of issues with that in o9fs.

but as yourself pointed out, what would that walk mean?

iru

Re: [9fans] 9p question

[Russ Cox]

> it would surely make it easier for unix implementations. i have had
> plenty of issues with that in o9fs.
>
> but as yourself pointed out, what would that walk mean?

as i also pointed out, there's no problem if
the walk is creating a new fid.  it would be unopened.

russ

[9fans] 9p question

[Roman]

While  playing with u9fs and 9p I ask myself: Is there are any good reason that
each R-message contains fid ? I take a look at u9fs sources and have found 
that R-messages have exactly the same fid as T-messages. Is this a common
behavior and if yes, why do we need fids in R-messages at all ?

Thanks,
Roman.