Get UID/GID for current user in write file_test.go

[jakefhyde]

This can just get merged whenever, it's just to enable these tests to run locally. I've confirmed they work both with go test ./... and make test.

[jiaqiluo]

Can we drop the build arg to allow it to run on arm64 now?

[jiaqiluo]

Hi @jakefhyde, I think this question is still valid. Please let me know if I misunderstand anything.

[jakefhyde]

Let me try and see if it works

[HarrisonWAffel]

Ah shoot, I forgot this test is shared between both platforms. On windows u.Uid is going to return a security identifier (e.g. S-1-5-21-788787744-2135942908-530990601-500) and not a simple integer, so atoi will fail. We should either do a GOOS check to conditionally pass the current uid and guid, or create platform specific test files (though they would be nearly identical).

[jakefhyde]

Ah shoot, I forgot this test is shared between both platforms. On windows u.Uid is going to return a security identifier (e.g. S-1-5-21-788787744-2135942908-530990601-500) and not a simple integer, so atoi will fail. We should either do a GOOS check to conditionally pass the current uid and guid, or create platform specific test files (though they would be nearly identical).

I'll opt for the former (for now).

[jakefhyde]

@HarrisonWAffel actually from looking at the docs, it appears it does nothing if uid and gid are -1 (means no change) so that might be a better option for the test. This will also be useful for any files the system-agent creates. Also FWIW it doesn't error when installed as a systemd service because they run as root (ID 0).