RFR: 8317951: Refactor loading of zip library to help resolve JDK-8315220 [v3]

[David Holmes]

On Thu, 26 Oct 2023 09:58:50 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> The original code in ClassLoader does not check that the resolved method entry points through dll_lookup are found or resolved correctly. There are no null checks before using the function pointers, so a failed lookup would instantly lead to a crash. This is semantically equivalent.
>> 
>> The only difference is that ClassLoader, should it be the initializer of the library, also attempts to resolve the init_params() and compress() entry points (used by HeapDumpCompressor).
>
> Adjusted to never exit the vm if failing to resolve InitParams and Compress.

I think the original code worked on the basis that we know what a libzip is and provides and that is not likely to change, so all the expected entry points will be present.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16149#discussion_r1373046920