scripts: apply fixes to helpers when using set -eE

[georglauterbach]

Description

For an upcoming PR, these changes are required, because the script that is using the helpers uses set -eE. This leads to situations where errors are not properly handled in our helpers (yet; I plan on changing that in the future).

Fixes issues of an upcoming PR that I do not want to include in the upcoming PR because I am a nice maintainer and I try my best to separate concerns with PRs :D 😆

The return 0 statements at the end of some functions seem superflous, but they are not, because the previos command (even when run inside an if-clause) set the return value to non-zero, which is not what we want.

Type of change

• New feature (non-breaking change which adds functionality)
• Improvement (non-breaking change that does improve existing functionality)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• If necessary I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[casperklein]

The return 0 statements at the end of some functions seem superflous, but they are not, because the previos command (even when run inside an if-clause) set the return value to non-zero, which is not what we want.

function _adjust_mtime_for_postfix_maincf
{
  if [[ $(( $(date '+%s') - $(stat -c '%Y' '/etc/postfix/main.cf') )) -lt 2 ]]
  then
    touch -d '2 seconds ago' /etc/postfix/main.cf
  fi
  return 0
}

If touch fails for some reason, why would we want to return success (0)?

[georglauterbach]

The return 0 statements at the end of some functions seem superflous, but they are not, because the previos command (even when run inside an if-clause) set the return value to non-zero, which is not what we want.

function _adjust_mtime_for_postfix_maincf
{
  if [[ $(( $(date '+%s') - $(stat -c '%Y' '/etc/postfix/main.cf') )) -lt 2 ]]
  then
    touch -d '2 seconds ago' /etc/postfix/main.cf
  fi
  return 0
}

If touch fails for some reason, why would we want to return success (0)?

It's not the touch - it's the condition in the if-clause that, when the if evaluated to false, would implicitly set the return value to false, i.e. 1, that I was worried about.

Looking at it again, you're right about the if-is-true case though. So a return ${?} after the touch should also be added.

[casperklein]

when the if evaluated to false, would implicitly set the return value to false, i.e. 1, that I was worried about.

I think you are wrong, that's not the case:

if [ 1 -eq 0 ]; then
        echo "this should never be shown"
fi
echo $? # returns 0

or

if false; then
        echo "this should never be shown"
fi
echo $? # returns 0

[georglauterbach]

You are indeed correct, there is a difference between

set -eE

function x() {
  if false && :; then :; fi
}

x
echo "this will show up"

and

set -eE

function x() {
  false && :
}

x
echo "this wont show up"

---

I will correct my error and remove unnecessary return 0 statements.