mlocate cron job doesn't respect its lockfile

Binary package hint: mlocate

The mlocate cron job (/etc/cron.daily/mlocate) doesn't always respect its lockfile. The cron job always removes the lockfile, even if it aborts because the lockfile already exists. The result is that every other concurrent invocation of /etc/cron.daily/mlocate will run updatedb.

The bug is pretty obvious. From /etc/cron.daily/mlocate:

-----
trap "rm -f $LOCKFILE" EXIT

if [ -e "$LOCKFILE" ]; then
    echo >&2 "Warning: $LOCKFILE present, not running updatedb."
    exit 1
else
    touch "$LOCKFILE"
fi
-----

The trap to remove the lockfile is turned on before checking for the existence of the lockfile. So even if the lockfile exists, we rm it on exit. Moving the trap inside the else block should fix it.

# lsb_release -rd
Description: Ubuntu 10.04 LTS
Release: 10.04

# apt-cache policy mlocate
mlocate:
  Installed: 0.22.2-1ubuntu1
  Candidate: 0.22.2-1ubuntu1