Re: master 588a0363d9a: Improve SELinux handling in Tramp

[Po Lu]

Michael Albinus <michael.albinus@gmx.de> writes:

> Po Lu <luangruo@yahoo.com> writes:
>
> Hi,
>
>> If my understanding is correct, then with this change Tramp starts to
>> return SELinux context information from file-attributes.
>
> No. There's no visible change outside Tramp, it still returns the
> SELinux context with file-selinux-context calls only.
>
> This patch is part of Tramp optimizations I'm working on the last
> days. One observation from the traces is, that file-selinux-context
> calls almost always happen shortly after file-attributes calls. So I've
> adapted Tramp's file-attributes implementations to use also the "-Z"
> option (for ls) or "%C" option (for stat) on the remote side. From the
> result, the SELinux context is extracted and cached inside Tramp. It is
> not returned with file-attributes.
>
> When the next file-selinux-context call happens, Tramp checks first the
> cache, before it sends the respective remote command. By this, often a
> network roundtrip can be avoided.
>
>> Doesn't this mean Dired and similar should be adjusted to refrain from
>> trying to restore SELinux attributes when performing a copy from a
>> remote directory, given that different machines can have completely
>> incompatible SELinux configurations?
>
> I don't believe so. Outside Tramp, nothing has changed.
>
> Best regards, Michael.

I see.  Thank you for explaining.