display using unix-domain socket (was Re: fd passing for X)

[Michal Suchanek]

On 6 October 2012 12:02, Antoine Martin <antoine at nagafix.co.uk> wrote:
> On 10/06/2012 04:56 PM, Michal Suchanek wrote:
>> Hello,
>>
>> What's the advantage of that patch?
> 1) You can use a socket path you create in advance, so you know for
> certain that it is free when you call the server.
> You then know for certain that this is what will be used by the server,
> not some free port you have no way of guessing correctly.

There is an option for the X server to print the display name from
which it should be possible to infer the display port.

If the user is choosing a port or file path the user then needs to go
through the dances of determining which port or path is still
available for starting a new X server. This is just moved from the X
server to user.

>
> 2) That socket path can be totally private, using a file path with very
> restrictive permissions if you wish to do so.

That's definitely an advantage.

>
>> As far as I understand the patch shifts the burden of finding a free
>> port (or socket path) from the X server to the user.
> Yes, it does. If by burden you mean freedom.

You have to somehow determine if the path you picked is free or in use
by earlier X server or another program.
Think about two scripts trying to start an X server at the same time, etc.

For display ports the X server does this for you and outputs the port
number when allocated if asked to.

Thanks

Michal