Sharing a Mutex Across Processes... Help?

[Mike]

I'm trying to port an application from Linux to Mac OS X that needs to
be able to share a mutex across processes. On Linux I can do this
easily by calling:

pthread_mutexattr_setpshared
(&pthreadmutexattrt,PTHREAD_PROCESS_SHARED);

Obviously, when I tried to run with the code as is it didn't work.
I've since found out that this is because OS X does not support
sharing a mutex across processes.

I'm hoping that someone out there knows a way I can do this on OS X.
It's essential for my application. So far, I've not been able to find
any Apple API that can do this (it appears they are all based on
pthreads). The next closest thing I can find would be a named
semaphore. Are they supported on all version of OS X? Or at least 10.3
and higher?

Also, if anyone has a better suggestion for how to do this I would
love to hear it.

Thanks,
Mike