motd symlink from initscripts gets moved on base-files upgrade

[Adam Conrad]

Binary package hint: base-files

On the machines we've upgraded in the Canonical DC, we have the following curious situation:

adconrad@mcmurdo:~$ ls -l /etc/motd*
-rw-r--r-- 1 root root 417 2008-04-09 23:22 /etc/motd
lrwxrwxrwx 1 root root 13 2008-04-03 19:37 /etc/motd.old -> /var/run/motd
-rw-r--r-- 1 root root 266 2008-04-03 19:37 /etc/motd.tail

This seems to be the result of the following code in base-files's postinst:

  if [ -f /etc/motd ]; then
    oldmd=`awk 'NR > 2' /etc/motd | md5sum | awk '{print $1}'`
    newmd=`awk 'NR > 2' /usr/share/base-files/motd | md5sum | awk '{print $1}'`
    if [ "$oldmd" != "$newmd" ]; then
      if grep -q "$oldmd" /usr/share/base-files/motd.md5sums; then
        awk 'NR <= 2' /etc/motd > /etc/motd.new
        awk 'NR > 2' /usr/share/base-files/motd >> /etc/motd.new
        mv /etc/motd /etc/motd.old
        mv /etc/motd.new /etc/motd
      fi
    fi
  fi

If the test was changed from "if [ -f /etc/motd ]; then" to "if [ -f /etc/motd ] && [ ! -L /etc/motd ]; then", this postinst would stop mangling symlinks and should coexist well with the New World Order. (For bonus points, adding a bit of transitional code to fix the broken situation wouldn't hurt... if motd.old is a link and motd isn't, and ugrading from << version_with_fix, assume you broke it..)

[Steve Langasek (vorlon)]

This patch looks correct to me, but it fails to fix the previous upgrade breakage. Work in progress.

[Steve Langasek (vorlon)]

whereas this patch actually works.

[Launchpad Janitor (janitor)]

This bug was fixed in the package base-files - 4.0.1ubuntu4

---------------
base-files (4.0.1ubuntu4) hardy; urgency=low

  * Update the motd upgrade handling to know about /etc/motd.tail, which
    is where the static contents of the motd are stored now with
    initscripts 2.86.ds1-7 and above; and handle fixing the broken
    upgrades introduced in 4.0.1ubuntu3. LP: #214853

 -- Steve Langasek <email address hidden> Thu, 10 Apr 2008 00:02:43 +0000