Prevent panic if status line is empty in mdstat

[amakutunowicz]

This change fixes a potential source of panic when the status line in
mdstat is empty and the code is trying to reference the first item in a
zero-sized slice.

@discordianfish @pgier

Signed-off-by: Artur Makutunowicz artur@makutunowicz.net

[discordianfish]

Thanks, looks reasonable! You still need to sign-off your commit though. Ignore the circleci issues, we'll fix them.

And curious, where did you see mdstat having an empty line?

[amakutunowicz]

Looks like my public email setting was incorrect - can we somehow rerun the tests here? It should pass now.

I can't really say what exactly happened (I didn't log the mdstat contents), but sporadically I was able to see panics caused by that particular line.

[SuperQ]

DCO complains with this:

Commit sha: ed8f4a3, Author: Artur Makutunowicz, Committer: Artur Makutunowicz; Expected "Artur Makutunowicz arma@linkedin.com", but got "Artur Makutunowicz artur@makutunowicz.net".

[SuperQ]

You might need to edit the email in your git commit and force push.

[pgier]

You might need to rebase to pick up the lint fixes

[amakutunowicz]

Hello, is there anything else I can do to make this change merged and release a new version, so it can be picked up by Go modules?

[SuperQ]

If you could rebase your fork and branch, that should fix up the tests.

git checkout master
git remote add upstream https://github.com/prometheus/procfs.git
git fetch --all
git fetch upstream HEAD
git rebase FETCH_HEAD
git push
git checkout statusline-empty
git rebase -i origin/master
git push -f

[amakutunowicz]

@SuperQ Thanks, that seemed to work!