Re: Delayed ldconfig execution in postinst step

[Eduard Bloch <edi@gmx.de>]

#include <hallo.h>
* Goswin von Brederlow [Sun, Mar 12 2006, 03:35:42PM]:

> I think it would be a good idea to have a general dpkg hook to
> register a command to be run at the end of dpkg. The syntax would be
> something like this:
> 
> dpkg-hook /usr/lib/man/update-manpages  - run only once in total
> dpkg-hook --on-depends foobar ldconfig  - run once before depends of foobar

What is a depends? Do you mean dependency or dependents?
Further, I would not depend on package installation operations but
instead invent something like "dpkg-hook --execute ldconfig" to run
outstanding tasks noted under the name "ldconfig".

> dpkg-hook --add-option add-font -- path - add argument 'path' to a
>                                           previous add-font hook
> dpkg-hook --no-wait foobar              - run foobar in the background
> 
> When dpkg is invoked it woul run those hook between depends of
> packages or before terminating. When apt is run it could pass an
> option to dpkg (except on the last run) to not run the hooks on exit
> and they would be gathered for the full apt run.
> 
> 
> Your option has the benefit of working NOW while mine would be more
> general and work for manpages, fonts, menus, .... But one could
> combine the two, make /usr/lib/dpkg/ldconfig into a script that calls
> 'dpkg-hook --on-depends foobar /sbin/ldconfig'. The --on-depends might
> not be needed as you said, one would have to try that.

Still not fully undestanding what you mean with --on-depends... I guess
we merge the both ideas to have something now. I have following vision:

 - a script called "dpkg-postponer" or so which may act different
   depending on argv[0]
 - a directory like /usr/lib/ccache with symlinks to dpkg-postponer, say
   /usr/lib/dpkg/hooks
 - a bunch of links to dpkg-postponer in that directory
 - dpkg-diverts on dpkg executable to have a link to dpkg-postponer and
   original dpkg

So, when postponer is executed as "dpkg", it forks a daemon creating a
Unix Domain socket and then runs original dpkg (note: this functionality
can be moved to dpkg itself later). Before doing that it also prepends
our symlink directory to $PATH. When executed as "dpkg-hook", it will do
things you describe above - send the command and options trough the
socket to the daemon, which calls the command on dpkg's exit.
When executed as eg. "ldconfig" it will act like "dpkg-hook ldconfig".
When dpkg terminates, the wrapper sends the daemon the "--execute"
command and a "--terminate" command, then exits with dpkg's return code.

That's all. IMO a matter of few hours to implement and test (in Perl).

Eduard.

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