Use File.read over IO.read

[Bo98]

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IO.read can allow arbitrary command execution. Since we know we only want to read files, File.read is safer here for security.

The usage of IO.read in the cases here weren't particularly exploitable - they mostly required there to be JSON files in the working directory with maliciously crafted filenames. Not knowing what's in your working directory when running brew pr-upload or brew bottle --merge isn't a situation I expect anyone to ever be in and it would require some extreme levels of social engineering to trick someone into thinking a funky looking JSON file is ok. A formula file with a maliciously crafted name should also never get any further than the CI, where exploits have negligible impact due to the fact you can just run arbitrary Ruby code.

[BrewTestBot]

Review period skipped due to critical label.

[Rylan12]

Makes sense to me

[MikeMcQuaid]

IO.read can allow arbitrary command execution.

TIL. Suggestion: global rubocop to stop us using it. This change makes sense to me as-is 👍🏻

[Bo98]

Suggestion: global rubocop to stop us using it.

I'll have a look. I'm somewhat surprised Security/Open doesn't cover this already.