Add Users and Group related functions

[otavio]

This was a collaborative work between Johannes Schilling
dario@deaktualisierung.org, Fredrick Brennan copypaste@kittens.ph
and myself.

This PR is a split-off from #864 so we merge ready parts first. Next, we work on the iterators.

Signed-off-by: Otavio Salvador otavio@ossystems.com.br

[asomers]

So what's the plan? What do you expect to add in a follow up PR?

[otavio]

@asomers we did not include the iterators here and I'd like to extend it after this is merged as it is independent and allow for reducing the code to work/review.

Do you mind to go over this here so we clean any leftover and merge this one?

[otavio]

@asomers any comment on this one?

[asomers]

Looks good! I'm almost inclined to merge as-is, except for the one issue I raised inline. Also, it needs a CHANGELOG entry.

[otavio]

@asomers I made the changes. Please let me know if something else is still needed.

[asomers]

Now that you no longer Errno::clear, you need to remove some unsafe blocks, apparently.

[otavio]

Now that you no longer Errno::clear, you need to remove some unsafe blocks, apparently.

Just did; sorry for missing that.

[otavio]

@asomers fixed the unnecessary unsafe block. Should be good to go.

[asomers]

bors r+

[bors]

Build succeeded

• continuous-integration/travis-ci/push
• FreeBSD 11.2