Thanks for the good tips! Answers inline:
On Sun, Jan 22, 2017 at 8:59 PM, Andreas Beckmann <a...@debian.org> wrote:
> On 2017-01-22 19:02, Michael Stapelberg wrote:
>> After going a bit further down the road, I realized that the
>> before/after tarballs of /var/lib/dpkg/alternatives are not as useful
>> as I had assumed they would be: when installing non-trivial packages
>> (with a bunch of dependencies), they contain changes caused by a
>> number of different packages, whereas I need the changes of precisely
>> one package.
>>
>> Hence, I think using a custom script to log update-alternatives
>> command lines is actually more useful:
>>
>> $ head -50 custom-scripts/scripts-log-alternatives/*
>> ==> custom-scripts/scripts-log-alternatives/pre_install_log_alternatives <==
>> #!/bin/sh
>>
>> # Do nothing if the script already ran.
>> # The pre_install step can be run multiple times.
>> [ -e /usr/bin/update-alternatives.orig ] && exit 0
>>
>> mv /usr/bin/update-alternatives /usr/bin/update-alternatives.orig
>
> use dpkg-divert s.t. this works in upgrade scenarios, too
> (look at the existing scripts how I diverted stuff there)
Done.
>
>> cat >/usr/bin/update-alternatives <<'EOT'
>> #!/bin/sh
>> echo "LOG-ALTERNATIVES: dpkg=${DPKG_MAINTSCRIPT_PACKAGE}:
>> piuparts=${PIUPARTS_OBJECTS}: $0 $@"
>
> you probably want to output that to a logfile and dump the logfile in
> the post_remove, otherwise you'll miss
>
> update-alternatives --foo bar >/dev/null 2>&1 || true
>
> I would be surprised if no maintainer script does output redirection
Done.
>
> (you could still log in on stdout as well - gives a better timeline, but
> expect to miss some bits)
The timeline is not necessary for my use-case, so I will just use the logfile.
>
>> exec /usr/bin/update-alternatives.orig "$@"
>> EOT
>> chmod +x /usr/bin/update-alternatives
>
>> What do you think about this approach? Is that suitable for deployment
>> on piuparts.d.o?
>
> that should work quickly
>
> I can try it in my instance, do you have any "interesting" packages in
> mind for testing?
A simple package to test with is “vim”, which installs a couple of
diversions and slave alternative links.
A more interesting one is “dkms”, which depends on gcc and cpp. Only
gcc/cpp install alternatives, dkms itself doesn’t, resulting in lines
such as:
LOG-ALTERNATIVES: dpkg=gcc: piuparts=dkms:
/usr/bin/update-alternatives --quiet --install /usr/bin/c89 c89
/usr/bin/c89-gcc 20 --slave /usr/share/man/man1/c89.1.gz c89.1.gz
/usr/share/man/man1/c89-gcc.1.gz
I also tested with “fonts-ipafont-gothic”, which calls
update-alternatives from a shell function. “wesnoth” has a rather long
update-alternatives invocation. I couldn’t find/think of any other
interesting cases.
If the patch works for you, could you merge it and apply it on
piuparts.d.o please? Thank you!
--
Best regards,
Michael
From 235e7dd7007054a600bfc110b6d2b28cfbcf0953 Mon Sep 17 00:00:00 2001
From: Michael Stapelberg <stapelb...@debian.org>
Date: Sun, 22 Jan 2017 18:58:55 +0100
Subject: [PATCH] Add log-alternatives custom script
This script replaces /usr/bin/update-alternatives with a wrapper script
that logs its invocations, generating output like the following:
LOG-ALTERNATIVES: dpkg=vim: piuparts=vim: /usr/bin/update-alternatives --install /usr/bin/vi vi /usr/bin/vim.basic 30 --slave /usr/share/man/fr/man1/vi.1.gz vi.fr.1.gz /usr/share/man/fr/man1/vim.1.gz --slave /usr/share/man/it/man1/vi.1.gz vi.it.1.gz /usr/share/man/it/man1/vim.1.gz --slave /usr/share/man/pl/man1/vi.1.gz vi.pl.1.gz /usr/share/man/pl/man1/vim.1.gz --slave /usr/share/man/ru/man1/vi.1.gz vi.ru.1.gz /usr/share/man/ru/man1/vim.1.gz --slave /usr/share/man/ja/man1/vi.1.gz vi.ja.1.gz /usr/share/man/ja/man1/vim.1.gz --slave /usr/share/man/man1/vi.1.gz vi.1.gz /usr/share/man/man1/vim.1.gz
Closes: #850917
---
.../scripts-log-alternatives/post_install_log_alternatives | 7 +++++++
.../scripts-log-alternatives/pre_install_log_alternatives | 13 +++++++++++++
2 files changed, 20 insertions(+)
create mode 100755 custom-scripts/scripts-log-alternatives/post_install_log_alternatives
create mode 100755 custom-scripts/scripts-log-alternatives/pre_install_log_alternatives
diff --git a/custom-scripts/scripts-log-alternatives/post_install_log_alternatives b/custom-scripts/scripts-log-alternatives/post_install_log_alternatives
new file mode 100755
index 00000000..be99f182
--- /dev/null
+++ b/custom-scripts/scripts-log-alternatives/post_install_log_alternatives
@@ -0,0 +1,7 @@
+#!/bin/sh
+
+[ ! -e /usr/bin/update-alternatives.orig ] && exit 0
+rm /usr/bin/update-alternatives
+dpkg-divert --rename --remove /usr/bin/update-alternatives
+cat /tmp/log-alternatives.log
+rm /tmp/log-alternatives.log
diff --git a/custom-scripts/scripts-log-alternatives/pre_install_log_alternatives b/custom-scripts/scripts-log-alternatives/pre_install_log_alternatives
new file mode 100755
index 00000000..0dcf6a2e
--- /dev/null
+++ b/custom-scripts/scripts-log-alternatives/pre_install_log_alternatives
@@ -0,0 +1,13 @@
+#!/bin/sh
+
+# Do nothing if the script already ran.
+# The pre_install step can be run multiple times.
+[ -e /usr/bin/update-alternatives.orig ] && exit 0
+
+dpkg-divert --divert /usr/bin/update-alternatives.orig --rename /usr/bin/update-alternatives
+cat >/usr/bin/update-alternatives <<'EOT'
+#!/bin/sh
+echo "LOG-ALTERNATIVES: dpkg=${DPKG_MAINTSCRIPT_PACKAGE}: piuparts=${PIUPARTS_OBJECTS}: $0 $@" >>/tmp/log-alternatives.log
+exec /usr/bin/update-alternatives.orig "$@"
+EOT
+chmod +x /usr/bin/update-alternatives
--
2.11.0
