RFR: 8341594: Use Unsafe to coalesce reads in java.util.zip.ZipUtils [v2]

[Eirik Bjørsnøs]

On Sun, 6 Oct 2024 21:49:08 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>>> How would you model unsigned long values here, though?
>> 
>> I don't think we should. `9223372036854775807 ` should be enough for everyone :-)
>> 
>> It may be worth renaming the method to `get64S` and add a `get64` variant which either clamps at `LONG.MAX_VALUE` or throws `IllegalArgumentException` for larger values. Call sites doing custom validation (like `checkZip64ExtraFieldValues`) could then call `get64S` and check for a negative long.
>> 
>> But that's food for another PR.
>
> Renaming to `get64S` is reasonable to be internally consistent. Updated. Improving validation of data in such 64-bit fields I'll leave for the future. I think a reasonable stance is to throw in the `check` methods if any such field is negative, at least for some of these fields.

> FWIW we already cap some values even lower in practice:
> 
> ```
>                             end.centot = (int)centot64; // assume total < 2g
> ```

I submitted #21384 which adds validation of end.centot and also eliminates this narrowing conversion.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21377#discussion_r1789881954