Skip cross process mutex on OpenBSD

[sethjackson]

Contributes to #124911.

OpenBSD does not have:

• pthread_mutexattr_setrobust
• pthread_mutexattr_setpshared

https://man.openbsd.org/pthread_mutexattr.3

• pthread_mutex_consistent

https://man.openbsd.org/pthreads.3

I'm assuming that not supporting this means that trying to use this on OpenBSD will result in a PNSE?

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[jkoritzinsky]

You should also update the condition (and comment) at

runtime/src/libraries/System.Private.CoreLib/src/System/Threading/NamedMutex.Unix.cs

Line 82 in 0f01e11

private static bool UsePThreadMutexes => !OperatingSystem.IsApplePlatform() && !OperatingSystem.IsFreeBSD();

Then OpenBSD will go down the other implementation path that doesn't use any of those APIs.

[sethjackson]

You should also update the condition (and comment) at

runtime/src/libraries/System.Private.CoreLib/src/System/Threading/NamedMutex.Unix.cs

Line 82 in 0f01e11

private static bool UsePThreadMutexes => !OperatingSystem.IsApplePlatform() && !OperatingSystem.IsFreeBSD();

Then OpenBSD will go down the other implementation path that doesn't use any of those APIs.

Got it. This would require adding an IsOpenBSD method to the OperatingSystem class though right? I’m happy to do that but I believe that needs to go through API review and approval first correct? Happy to open a PR for that/follow whatever process is needed.

[jkoritzinsky]

Yes, that would require an API proposal. Though you could make the API internal initially to use it in this PR.