Re: [9fans] fd and /srv filesystem

[Chris McGee <newton688@gmail.com>]

Thanks all for the explanations. I think I understand better now.

Chris

> On Oct 4, 2023, at 12:06 PM, ori@eigenstate.org wrote:
> 
> Quoth Chris McGee <newton688@gmail.com>:
>> Hi All,
>> 
>> I was thinking about file descriptors in the context of Plan 9. On Unix an
>> fd is generally only usable by the current process, and child ones through
>> a fork with some special incantation if one wants to communicate one over a
>> domain socket. This is possibly for security reasons, avoiding other users'
>> processes from trying to guess the fd of a critical file.
>> 
>> It's common practice in Plan 9 to post an fd (sometimes via a pipe) from
>> one process to the /srv filesystem so that others can discover it and open
>> a comms channel. Does the kernel transform the fd into something when
>> posted to /srv so that it can be consumed by any other process in the
>> system?
>> 
>> Thanks,
>> Chris
>> 
> 
> it's all just Chans in the kernel; devsrv just provides
> a way of giving an open chan a name in the namespace.
> 

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