os/user: Fails to return correct user names when users defined outside /etc/passwd

[tzugen]

Go version

1.23.3

Output of go env in your module/workspace:

N/A

What did you do?

Use lookupUserId() to retrieve the username for a given id on Fedora Silverblue.

Internally os/user looks hardcoded in /etc/passwd , which does not contain the system users in Fedora Silverblue. Instead the /etc/nsswitch.conf should be queried to retrieve places in which users are defined and then proceeded from there. This call will also not report the correct name for users defined through ldap etc.

What did you see happen?

UnknownUserIdError

What did you expect to see?

A valid username

[seankhliao]

Please fill in the issue template properly with a reproducer.
If available, os/user will call C functions, these should invoke the appropriate nss functionality. Pure go won't support nss, related #38810

[tzugen]

Ah, ok, i only looked at the user.go file.