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Re: conffile purging and maintainer scripts



Roger Leigh <rleigh@whinlatter.ukfsn.org> writes:

> Thomas Hood <jdthood@yahoo.co.uk> writes:
>
>> Roger Leigh wrote:
>>> Until last month, dpkg "forgot" about conffiles which were removed or
>>> moved on package upgrade.  As a consequence, maintainers had to
>>> remember to purge these conffiles "by hand" in the package postrm
>>> script.
>>
>> I just want to highlight the word "these" above in order to reduce the
>> possibility of confusion.
>>
>> Postrms should not delete files that are currently conffiles of the package.
>> dpkg takes care of deleting such files at the right time.
>>
>> If a file /etc/foo was formerly a conffile of the package but no
>> longer is so then /etc/foo should be dealt with in the preinst or
>> postinst.  ("Dealing with it" has to take into account both the old
>> and the new behavior of dpkg with respect to disappearing conffiles.
>> I speak vaguely here because I haven't looked into the new
>> behavior.)  If it isn't dealt with there then it might be
>> appropriate to delete it in the postrm, but not if there is reason
>> to suspect that some other package is now using /etc/foo.
>
> How about this as a start?
>
> This should be "safe" in that it won't remove a conffile if another
> package (or itself) takes ownership of it.  It also handles removal of
> the dpkg cruft, but I'm not sure that's always appropriate, since dpkg
> should handle it, at least for the new dpkg behaviour; this only
> caters for the old.
>
> Call in a postrm like this:
> rm_conffile("/etc/my/conffile")

This updated version should cater for both the old and new behaviour.
Any comments?

# Remove a conffile which has been forgotten by dpkg
# If the file does not exist, or is owned by any package, do not remove it.
rm_conffile() {
    CONFFILE="$1"

    if [ -f "$CONFFILE" ]; then
	local delete="false"
	local fpkg=""
	local pkg=""
	if fpkg=$(dpkg -S "$CONFFILE" 2>/dev/null); then
	    # Don't delete, but check which package it came from.
	    pkg=$(echo $fpkg | sed -e  's/\(^[[:print:]][[:print:]]*\): .*$/\1/')
	    if [ "$pkg" = "$PACKAGE" ]; then
		delete="true"
	    fi
	else
	    rm -f "$CONFFILE"
	    delete="true"
	fi

	# Remove dpkg cruft
	if [ "$delete" = "true" ]; then
	    rm -f "${CONFFILE}.dpkg-old"
	    rm -f "${CONFFILE}.dpkg-new"
	    rm -f "${CONFFILE}.dpkg-dist"
	fi
    fi
}


-- 
Roger Leigh
                Printing on GNU/Linux?  http://gutenprint.sourceforge.net/
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