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

[Markus Grönlund]

On Thu, 26 Oct 2023 09:17:52 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Sorry I am having a hard time seeing the equivalence. The original code doesn't potentially exit after a failed dll_lookup AFAICS - only a failed dl_load does that.
>
> 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.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16149#discussion_r1372906712