Sergio Durigan Junior writes ("Bug#968635: dgit-mirror-ssh-wrapper broke
(again) due to rsync update"):
> On Tuesday, August 18 2020, Sean Whitton wrote:
> > Hmm, unlike the -I and -v options, the -u option seems like it could
> > break things. Could you explain why you think it won't, please?
>
> Thanks for looking into this.
>
> First of all, I think it's worth noting that this change comes from
> rsync. The purpose of the patch I submitted is merely to adjust
> dgit-mirror-ssh-wrapper to accept rsync's new "eFlags" markers, and not
> actually to invoke rsync with '-u'. You can see the specific upstream
> change here:
>
>
> https://git.samba.org/?p=rsync.git;a=commitdiff;h=bb16db174;hp=d6f0342a344f4718beae65a5a68d19b2751e5f6a
>
> More specifically, this part:
>
> + eFlags[x++] = 'u'; /* include name of uid 0 & gid 0 in the id map */
>
> which is what caused the change that eventually broke
> dgit-mirror-ssh-wrapper.
I think Sean has been under the impression that the meaning of the
flags that follow --server can be found by reading the manual.
Certainly I was under that impression.
> Now, it's interesting to note that the 'u' here does not reflect the
> client's '-u' option.
This is the key thing I was missing.
> I don't know how the inclusion of "uid/gid 0 in the id map" can break
> things, but maybe I'm overlooking something. However, if we indeed
> agree that things can break here, then it seems to me that a new bug
> should be filed against rsync, IMO.
Sean was probably thinking -u here meant "skip files that are newer on
the receiver". That's what I was thinking.
I think we can have two general approaches to these undocumented
command line options:
(1) UTSL to find out what each flag means, and decide if we like it.
I certainly didn't do that right at the beginning. If we do this we
should really review all the existing ones.
(2) Trust rsync upstream not to get this wrong, and assume that if
the rsync client contrives to pass these options as part of --server,
that they aren't dangerous.
I'm in favour of (2), which would imply immediately applying Sergio's
patch. Sean, what do you think ?
Regareds,
Ian.
--
Ian Jackson <ijack...@chiark.greenend.org.uk> These opinions are my own.
Pronouns: they/he. If I emailed you from @fyvzl.net or @evade.org.uk,
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