fix(libindex): temp files on non-linux

[RTann]

O_TMPFILE does not exist on non-linux unix-based OSes, so I was unable to build ClairCore on my macOS (Darwin) machine. Similarly, I don't think it exists on Windows, but FILE_FLAG_DELETE_ON_CLOSE does, which sounds to be about the same.

The implemented solution for Darwin runs into the issue O_TMPFILE aimed to fix: ClairCore crashing can still leave files on the system. Since this was previous behavior, I don't see this as a regression, necessarily.

[codecov]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (1e1b17d) 52.11% compared to head (72cdae3) 52.04%.

Files	Patch %	Lines
libindex/tempfile_linux.go	66.66%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1140      +/-   ##
==========================================
- Coverage   52.11%   52.04%   -0.07%     
==========================================
  Files         218      219       +1     
  Lines       16724    16734      +10     
==========================================
- Hits         8715     8710       -5     
- Misses       7208     7219      +11     
- Partials      801      805       +4     

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[BradLugo]

Would it be worth adding macOS and Windows builds to CI? e.g., GOOS=darwin go build ...

[hdonnay]

It seems fine as long as they don't slow down the CI.
Might be better off as a nightly CI.
None of the server components are really supported on windows or darwin, they just need to build for Clair's cli.

[RTann]

None of the server components are really supported on windows or darwin, they just need to build for Clair's cli.

I develop on a mac and can't compile at the moment 😢

[hdonnay]

I think (*tempfile).read would be better named as Reopen or Clone. (*ref).Val should just return a *os.File instead of a *tempFile, because none of the file handles pulled out of the rc should need special handling.

[RTann]

(*ref).Val should just return a *os.File instead of a *tempFile, because none of the file handles pulled out of the rc should need special handling.

We need to make sure the file is removed on unix, so we need to call (*tempFile).Close instead of (*os.File).Close

[RTann]

(*ref).Val should just return a *os.File instead of a *tempFile, because none of the file handles pulled out of the rc should need special handling.

We need to make sure the file is removed on unix, so we need to call (*tempFile).Close instead of (*os.File).Close

Oh I see now. I'll change it

[hdonnay]

I think one last issue and it's good to go

[RTann]

rebased. will merge with CI