RFR: 8277489: Rewrite JAAS UnixLoginModule with FFM [v10]

[Martin Doerr]

On Wed, 21 Jan 2026 21:11:28 GMT, Weijun Wang <weijun at openjdk.org> wrote:

>> Do you have a suggestion? I intentionally indented based on argument nesting. `FunctionDescriptor.of(...` is the 2nd argument of `downcallHandle` so I indented one level (8 spaces) to the method. `OperatingSystem.isAix()...` is argument of `findOrThrow` and `calling_convention_requires_int_as_long...` etc are arguments of `FunctionDescriptor.of` and they are indented one level further. IntelliJ IDEA unindents the `FunctionDescriptor.of(...)` block but I think that's misleading.
>
> As for whether it's a better alternative of JNI, FFM is usually considered at least as fast as JNI. In this case, on my Mac, the FFM version is much much faster. I guess the main reason is while the C code is quite small it calls back to Java object manipulation too much.

> IntelliJ IDEA unindents the FunctionDescriptor.of(...) block but I think that's misleading.

That's what I thought.

Ok. Another advantage is that we don't need the .c file any more. If performance matters, we could still tune it by using the critical option. But I guess it's fast enough.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/28931#discussion_r2714401065