[Bug 1940008] Re: systemd lsb-base integration script leaking shell variable changes which can break consumers

[Ryan]

I'm not a bash script architect, but I bodged together this workaround
and the ipmiutil_wdt service starts correctly with it applied to my
system:

https://gist.github.com/TheWug/1a7f509e040f10c05039acc06fe29d9e

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Title:
  systemd lsb-base integration script leaking shell variable changes
  which can break consumers

Status in systemd package in Ubuntu:
  New

Bug description:
  I am using systemd version 248.3-1ubuntu3 from the impish repository.

  It was compiled and built in the following manner:
  # add impish deb-src repository to apt sources
  apt build-dep systemd/impish
  apt source -b systemd/impish

  Once built, it was installed over the top of systemd 245.4-4ubuntu3.

  I am running ubuntu 20.04.2.

  The source tarball of systemd includes a file
  (./debian/systemd/lib/lsb/init-functions.d/40-systemd) which is
  intended to be installed into the drop-in script directory provided by
  the lsb-base package (/lib/lsb/init-functions.d).

  The problem that I am having is that this file (which is sourced by
  any script which sources /lib/lsb/init-functions) is setting
  variables, and in doing so, accidentally overwriting variables which
  are configured by the calling script.

  https://gist.github.com/TheWug/e120145f08e994d89e235e077a82ea75#file-40-systemd-L19

  I noticed this when investigating why ipmiutil_wdt.service (provided
  by package ipmiutil) was failing to start. The problem is that the
  ipmiutil_wdt script, which makes use of init-functions, was statically
  setting some variables for later use, including one called $prog.
  $prog is then inadvertently overwritten by 40-systemd when
  ipmiutil_wdt sources /lib/lsb/init-functions.

  I think this is systemd's bug because systemd's lsb-base drop-in is
  not being a "good neighbor" to the scripts with which it shares a
  controlling shell. Even if ipmiutil were to rewrite its ipmiutil-wdt
  script, any other such script provided by another package which tries
  to use a variable called $prog (or $executable, or $argument, or
  $service, or $state, or any of a handful of others) will find its feet
  being stepped on by systemd's drop-in.

  I propose that the drop-in be modified to encapsulate all of this
  behavior where variables are assigned to within a function or subshell
  or something, so they can't accidentally contaminate the outside
  world.

  Other related package versions:
  lsb-base: 11.1.0ubuntu2
  ipmiutil: 3.1.5-1

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