fix(logname): return error exit code when there is an error

[rodrigost23]

Fixes #9312

[sylvestre]

could you please add a test to make sure we don't regress in the future? thanks

[codspeed-hq]

CodSpeed Performance Report

Merging #9313 will not alter performance

_{Comparing rodrigost23:fix-logname-exit-code (8da2ce3) with main (2d718f2)}

Summary

✅ 127 untouched
⏩ 6 skipped¹

Footnotes

1. 6 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/overlay-headers (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)

[sylvestre]

why unshare here ?

[rodrigost23]

I've tried making getlogin return null by

1. setting stdin to /dev/null
2. using terminal_sim_stdio with stdin set to false
3. using setsid logname

On my machine, none of these caused it to return null. Running it with unshare -U logname did produce the expected error.

Do you know a more reliable way to trigger this behavior without using unshare?

[oech3]

@rodrigost23 User NS sandbox is disabled at Ubuntu by default. Would you add to CI file something like https://github.com/oech3/coreutils/blob/9cf774bed8919636f437caf0e7ee379fc701cdab/.github/workflows/GnuTests.yml#L121-L123 (with spell-checker:ignore userns)?

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/overlay-headers (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)