On Tue, 11 Oct 2022 08:11:02 GMT, Aleksey Shipilev <sh...@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.
For POSIX we expect the handler argument for os::signal to be a sigaction
handler (taking 3 arguments). For Windows we expect os::signal to take a 1
argument handler, since Windows seemingly doesn't support the sigaction stuff.
How is that a portability layer?
So all of the calls are going to need their handler functions examined. In at
least one use (in os_windows), the UserHandler function takes 3 arguments
though only uses one, and is called with only one.
Looking at where os::signal is called, it's not clear it needs to be in os, and
given the inconsistent expectations it probably shouldn't be. All calls are in
posix-specific or windows-specific files. I'd suggest removing os::signal
entirely, and having windows code use ::signal and posix code use ::sigaction.
Maybe with some convenience wrappers around each, but those wrappers are
windows-specific or posix-specific and never the twain shall meet.
That all seems to me like it would be better to separate from this change,
keeping this one nice and simple.
-------------
PR: https://git.openjdk.org/jdk/pull/10494
