RFR: 8251438: Issues with our POSIX set_signal_handler()

[Gerard Ziemski]

On Fri, 11 Dec 2020 06:26:21 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> This is a fix for a potential issue involving "The storage occupied by sa_handler and sa_sigaction may overlap, and a conforming application shall not use both simultaneously." https://pubs.opengroup.org/onlinepubs/009695399/functions/sigaction.html, when we in fact do assume different storages.
>
> src/hotspot/os/posix/signals_posix.cpp line 743:
> 
>> 741: // Implementation may use the same storage for both the sa_sigaction field and the sa_handler field,
>> 742: // so check for "sigAct.sa_flags == SA_SIGINFO"
>> 743: static address get_signal_handler(struct sigaction action) {
> 
> This copies the structure by value. While the compiler will probably optimize this out, I'd still not do it. Please use 
> static address get_signal_handler(const struct sigaction*) 
>  
> instead.

Thank you Thomas for the review.

How about:

`static address get_signal_handler(struct sigaction &action)`

?

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PR: https://git.openjdk.java.net/jdk/pull/1680