Signal Handling in JNI side

[Aniket Kulkarni]

Hello All,

Greeting.

I am Aniket. I am new to this community, hoping to get solution here.

I have created a dll file from c program.
There is a crash(SIGSEGV) in that dll for which signal handler in c is implementead
If I use the dll in another c language code, the signal handler is getting call program is exiting gracefully.
But If I tried to run the same dll function through java code, java program is crashing, why???

I am totally new JAVA, please guide me to solve this

doing all this x64 windows machine with visual studio 2019 IDE to create DLL and Eclipse for JAVA code
But want to creatr cross platform code, which can run on windows as well as linux

P.S. - I know I am rereferring NULL pointer in Addition(), that is just to trigger SIGSEGV fault, so signal_handler can get call...But currently that is not happening, instead JVM is handling that signal

[Matthias Bläsing]

Hi Aniket,

Am Montag, dem 08.05.2023 um 05:12 -0700 schrieb Aniket Kulkarni:
> I have created a dll file from c program.
> There is a crash(SIGSEGV) in that dll for which signal handler in c
> is implementead
> If I use the dll in another c language code, the signal handler is
> getting call program is exiting gracefully.
> But If I tried to run the same dll function through java code, java
> program is crashing, why???

The HotspotVM uses signal handlers internally and thus will normally
not allow "normal" code to use them.

More information can be found here:

https://docs.oracle.com/en/java/javase/17/troubleshoot/handle-signals-and-exceptions.html#GUID-CB49A2A7-2A9F-4C18-948F-6D4A96FF688D

> doing all this x64 windows machine with visual studio 2019 IDE to
> create DLL and Eclipse for JAVA code
> But want to creatr cross platform code, which can run on windows as
> well as linux

If this is your library: Don't use signals to communicate programming
errors. If I remember correctly you have no guarantee, where a signal
handler is invoked and thus you might get lucky, but you can fail hard.

HTH

Matthias

[Aniket Kulkarni]

Hello Matthias,

Thanks for your guidance.

just a question - Is there any way to modify HotspotVM's signal handler, so alongside VM's message. I can at least print my statements alongside it.

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Regards,

Aniket Kulkarni Software Engineer Fortytwo Labs 7558579044 Aniket....@fortytwo42.in https://www.fortytwolabs.com/ 202, Siddh Icon, Baner, Pune, India

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[Matthias Bläsing]

Hi Aniket,

Am Dienstag, dem 09.05.2023 um 11:26 +0530 schrieb Aniket Kulkarni:
>
> Thanks for your guidance.
> just a question - Is there any way to modify HotspotVM's signal
> handler, so alongside VM's message. I can at least print my
> statements alongside it.
>

Sorry, I can't tell you more, than the documentation about the signal
chaining mechanism already referenced.

Greetings

Matthias

[Neil C Smith]

On Tue, 9 May 2023 at 06:56, Aniket Kulkarni
<aniket....@fortytwo42.in> wrote:
> just a question - Is there any way to modify HotspotVM's signal handler, so alongside VM's message. I can at least print my statements alongside it.

In theory you can attach signal handlers on the Java side, but whether
they can handle or do anything useful with this case is another
matter!

There are sun.misc.Signal(Handler) classes in the jdk.unsupported module.

You could look at (or borrow) the code from JLine 3 that uses these
via reflection -
https://github.com/jline/jline3/blob/master/terminal/src/main/java/org/jline/utils/Signals.java

Best wishes,

Neil

--
Neil C Smith
Codelerity Ltd.
www.codelerity.com

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