RFR 8252248: __SIGRTMAX is not declared in musl libc

[Thomas Stüfe]

Hi Alexander,

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src/java.base/unix/native/libnet/net_util_md.h

why include pthread.h? SIGRTMAX is in signal.h on posix (
https://pubs.opengroup.org/onlinepubs/007908799/xsh/signal.h.html). I see
the old code included this too, pretty sure this was either incidental or
just wrong.

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Are there tests which exercise this code?

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Thanks, Thomas


On Tue, Aug 25, 2020 at 7:02 PM Alexander Scherbatiy <
alexander.scherbatiy at bell-sw.com> wrote:

>
> Hello,
>
> Could your review the fix for the issue:
>    Bug: https://bugs.openjdk.java.net/browse/JDK-8252248
>    Fix: http://cr.openjdk.java.net/~alexsch/8252248/webrev.00/
>
> Building JDK on Alpine Linux with musl libc gives the error:
> src/java.base/linux/native/libnet/linux_close.c:63:25: error:
> '__SIGRTMAX' undeclared here (not in a function); did you mean 'SIGRTMAX'?
>     63 | static int sigWakeup = (__SIGRTMAX - 2);
>
> musl libc does not contain __SIGRTMAX definition. It defines only
> SIGRTMAX as a function call [1].
>
> __SIGRTMAX is used in JDK in two files NativeThread.c and linux_close.c .
>
> The first idea of the fix was simply to substitute __SIGRTMAX to
> SIGRTMAX in NativeThread.c and use the same definition
>    #define INTERRUPT_SIGNAL (__SIGRTMAX - 2)
> in linux_close.c.
> "static int sigWakeup = (SIGRTMAX - 2)"  does not work because the
> SIGRTMAX is defined as a function and leads to "initializer element is
> not constant" error.
>
> The fix has been discussed on the portola-dev alias [2] where it was
> pointed out that the fix can be reviewed in the mainline and it was
> suggested to rename the INTERRUPT_SIGNAL and move its definition to
> net_util_md.h.
>
>
> [1] https://git.musl-libc.org/cgit/musl/tree/include/signal.h#n196
> [2]
> https://mail.openjdk.java.net/pipermail/portola-dev/2020-August/000471.html
>
> Thanks,
> Alexander.
>
>