Please check the following patch, which attempts to clarify how dpkg
diversions should be handled. Once I started digging into this, the cases
looked more complex than I had expected. I tried to add more language to
explain the whole situation on the grounds that if I found it confusing,
other people almost certainly also do.
diff --git a/policy.sgml b/policy.sgml
index 24c9072..0cd241a 100644
--- a/policy.sgml
+++ b/policy.sgml
@@ -10564,26 +10564,37 @@ install-info --quiet --remove
/usr/share/info/foobar.info
supposing that a <prgn>smailwrapper</prgn> package wishes to
install a wrapper around <file>/usr/sbin/smail</file>:
<example>
- if [ install = "$1" ]; then
- dpkg-divert --package smailwrapper --add --rename \
- --divert /usr/sbin/smail.real /usr/sbin/smail
- fi
- </example> Testing <tt>$1</tt> is necessary so that the script
- doesn't try to add the diversion again when
- <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
- smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
- copy of <file>/usr/sbin/smail</file> can bypass the diversion and
- get installed as the true version.
+ dpkg-divert --package smailwrapper --add --rename \
+ --divert /usr/sbin/smail.real /usr/sbin/smail
+ </example> The <tt>--package smailwrapper</tt> ensures that
+ <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
+ can bypass the diversion and get installed as the true version.
+ It's safe to add the diversion unconditionally on upgrades since
+ it will be left unchanged if it already exists, but
+ <prgn>dpkg-divert</prgn> will display a message. To suppress that
+ message, make the command conditional on the version from which
+ the package is being upgraded:
+ <example>
+ if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
+ dpkg-divert --package smailwrapper --add --rename \
+ --divert /usr/sbin/smail.real /usr/sbin/smail
+ fi
+ </example> where <tt>1.0-2</tt> is the version at which the
+ diversion was first added to the package. Running the command
+ during abort-upgrade is pointless but harmless.
</p>
<p>
The postrm has to do the reverse:
<example>
- if [ remove = "$1" ]; then
+ if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
dpkg-divert --package smailwrapper --remove --rename \
--divert /usr/sbin/smail.real /usr/sbin/smail
fi
- </example>
+ </example> The postrm should not remove the diversion on upgrades
+ both because there's no reason to remove the diversion only to
+ immediately re-add it and since the postrm of the old package is
+ run after unpacking so the removal of the diversion will fail.
</p>
<p>
--
Russ Allbery ([EMAIL PROTECTED]) <http://www.eyrie.org/~eagle/>
--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
