Re: Bug#582109: debian-policy: document triggers where appropriate
Le Wed, Jul 17, 2013 at 09:27:19AM +0200, Raphael Hertzog a écrit :
>
> Julien is referring to this bug:
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=671711
>
> It might be fixed for jessie, at least I hope so, but he seems to doubt
> it.
>
> > Also, if you think that triggers will give us problems for the Jessie release,
> > may I suggest that you give it a broad audience on debian-devel ? As a
> > maintainer of a package that has triggers, I am definitely interested to learn
> > if there is something I should give particular attention there.
>
> One of the main things to do is to switch as many packages as possible to
> use the interest-noawait directive when possible.
Hi all,
regarding “noawait” triggers, the patch already contains the following, which
is new and improved compared to the existing documentation.
The <tt>*-noawait</tt> directives should be used unless the
packages awaiting triggers can not satisfy <tt>Depends</tt>
relationships until the triggers have been processed.
After reading #671711 and /usr/share/doc/dpkg-dev/triggers.txt.gz, my
impression is that a package can not become "Unpacked" and keep a list of
pending triggers, because of the following statements in triggers.txt:
1) Pending triggers are marked "never" for "Unpacked" packages in the overview
table.
2) The section "Details - triggered package" mentions that "packages in
‘config-failed’ or worse are never considered to have lists of pending
triggers". (Where config-failed means Half-Installed). In my understanding of
Dpkg states, Unpacked is "worse" than Half-Installed.
There are two consequences to this:
- "postinst configure" should do at least everything needed by
"postinst triggers", since in the situations where triggers are dropped,
the package is in a state that ensures that "postinst configure" will be run.
- we could write in section 6.5 of the Policy that for "postinst triggers"
the requirements are the same as for "postinst abort-*":
"The files contained in the package will be unpacked. All package
dependencies will at least be "Half-Installed" and will have previously been
configured and not removed. However, dependencies may not be configured or even
fully unpacked in some error situations."
I understand that changes in dpkg can enchance the mechanism to use triggers,
thus reducing the risk of having bugs, but I think that in #671711, dpkg is
following the specification, unless it failed to clear the list of pending
triggers when monodoc-browser became unpacked when it was upgraded.
Is that correct ? If yes, then I propose to go ahead and apply an improved
patch to the policy that mentions the restrictions and requirements on
"postinst triggers", because it represents an enhancement to the existing
documentation.
Have a nice day,
--
Charles Plessy
Tsurumi, Kanagawa, Japan
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