RFR: 8294594: Fix cast-function-type warnings in signal handling code [v2]

[Aleksey Shipilev]

On Tue, 11 Oct 2022 07:44:30 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> > Fix looks good as far as it goes (can't believe I didn't see what was going on here!) - but `os::signal` is still broken as it uses `sa_handler` instead of `sa_sigaction`.
> 
> Yikes! I think this change should proceed as is, and `os::signal` should be looked at as a new issue. That looks messy :(

There is no rush, because we are waiting for another build system change to drop. 

Why can't we do the same thing we did for `SR_handler` in `SR_initialize`?


@@ -864,7 +864,7 @@ void* os::signal(int signal_number, void* handler) {
   remove_error_signals_from_set(&(sigAct.sa_mask));
 
   sigAct.sa_flags   = SA_RESTART|SA_SIGINFO;
-  sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
+  sigAct.sa_sigaction = CAST_TO_FN_PTR(sa_sigaction_t, handler);
 
   if (sigaction(signal_number, &sigAct, &oldSigAct)) {
     // -1 means registration failed


It matches what we should do for `SIG_INFO` flag, and as Kim said, it is still likely yields the same code as `sa_handler` and `sa_sigaction` are probably the same on currently supported systems.

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PR: https://git.openjdk.org/jdk/pull/10494