RFR: 8295125: os::signal should be os specific

[Kim Barrett]

On Thu, 20 Oct 2022 05:59:33 GMT, David Holmes <dholmes at openjdk.org> wrote:

> This was intended as a significant cleanup RFE but it turned out things were a lot messier than initially envisaged, so the resultant cleanup is quite limited.
> 
> The OS API/namespace was simplified by removing three signal related functions that are not needed in shared code:
>  - signal
>  - user_handler
>  - raise
> The first two were reworked and placed into PosixSignals and os::win32.
> There was no need for a specific XX::raise API as os::raise simply called ::raise.
> 
> On the Posix side we had the basic signal handler installation code in two places:
> 
> 1. Inline in set_signal_handler and used by nearly all the VM signals
> 2. In os::signal which was used by three different "clients"
>   - VM error handler for updating crash handler
>   - VM for installing SIG_BREAK handler
>   - JDK via JVM_RegisterSignal
> 
> This was refactored so that we have:
> 
> 1. PosixSignals::install_sigaction_signal_handler
>   - used by the VM only
>     - set_signal_handler
>     - VM error handler for updating crash handler
>     - VM for installing SIG_BREAK handler
> 
> 2. PosixSignals::install_generic_signal_handler
>   - used by JDK via JVM_RegisterSignal
> 
> The sigaction handlers were all consistently defined as per the posix definition:
>     void func(int signo, siginfo_t *info, void *context);
>   
> 
> On the Windows side we just fixed the incorrect definition of UserHandler and made some consistency changes to use the right signal handler type where possible.
> 
> Thanks.

I'm loath to say "looks good", but looks okay for what it is.

Fixing JDK-8295702 will likely involve some refactoring of what's here. But
that's a problem for the next person who pokes at this tar baby.

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

Marked as reviewed by kbarrett (Reviewer).

PR: https://git.openjdk.org/jdk/pull/10780