RFR: 8328630: Add logging when needed symbols in dll are missing. [v2]

[Robbin Ehn]

On Thu, 21 Mar 2024 10:14:06 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> So if `ret == nullptr` then we are guaranteed that `::dl_error` does not return `nullptr`, in which case we don't really need the null check, but I suppose it is conservatively more robust to have it.
>> 
>> I don't think cross-platform os::dll_last_error is really feasible given the Posix version will keep the value across unrelated syscalls while on windows it would be lost on the next syscall. But you could add the same kind of logging to Windows
>
> I had to check, actually it is possible to find a "null symbol".
> So we actually need to to clear any previous errors first with a dummy call to dlerror();

Updated posix code, I'll add windows.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18404#discussion_r1533602899