RFR: 8347334: JimageDiffGenerator code clean-ups [v2]

[Severin Gehwolf]

On Thu, 9 Jan 2025 17:44:05 GMT, Archie Cobbs <acobbs at openjdk.org> wrote:

>> Severin Gehwolf has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Review feedback
>
> src/jdk.jlink/share/classes/jdk/tools/jlink/internal/runtimelink/JimageDiffGenerator.java line 131:
> 
>> 129:         int bytesRead1, bytesRead2;
>> 130:         try (is1; is2) {
>> 131:             while ((bytesRead1 = is1.readNBytes(buf1, 0, buf1.length)) != 0) {
> 
> If `in1` is exactly 1024 bytes, and `in2` is those same bytes plus one extra byte (1025 bytes), this method will return a false positive.
> 
> Probably just want `while (true)` here, then read both `in1` and `in2`, then check results.

Good catch! Added a test for this case and fixed the code.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23014#discussion_r1909262927