In article <[EMAIL PROTECTED]>,
Jonas Bulow <[EMAIL PROTECTED]> wrote:
> Jonas Bulow wrote:
> >
> > What is the "BSD-way" of access to shared memory (mmap:ed) secure (avoid
> > race conditions, etc)? Right now I'm using posix semaphores but I would
> > like to know if there is a substitute like the way kqueue is for
> > select/poll.
>
> Hmm, I think I lost some word and deeper thought in my previous mail.
> :-)
>
> The problem is as follows:
>
> I have a couple of processes using a mmap:ed file as common data area.
> What I want to do is to make it safe for all processes to update data in
> this common memory area. I was thinking about using some part of the
> common data area for semaphores in some way. I just want a simple
> "test-and-set" operation I can use to make sure there is only one
> process writing to the common data area.
If you want the "BSD way" you should probably create a 0-length
temporary file somewhere and use the flock(2) system call on it. The
file itself isn't important; it's just something to lock.
Or you could use semop(2) on semaphores. But that's the SYSV way, not
the BSD way.
John
--
John Polstra [EMAIL PROTECTED]
John D. Polstra & Co., Inc. Seattle, Washington USA
"Disappointment is a good sign of basic intelligence." -- Chögyam Trungpa
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