On Dec 9 09:50, Mark Paulus wrote: > So, does that mean that if process 1 opens a semaphore, > process 2 also grabs it, then process 1 unlinks it, and then > "reconnects" to it, that process 1 and process 2 do not have > and cannot have the same semaphore anymore, even though > they are using the same IPC_KEY? > > (Or am I way confused/off base here)?
Only partially. IPC_KEYs have nothing to do with it since we're talking about *POSIX* semaphores, not *SYSV* semaphores. Otherwise you're right. After some process has called sem_unlink(), any subsequent call to sem_open with the same sempahore name connects to a new semaphore. Corinna > > On Thu, 09 Dec 2004 17:44:42 +0100, Corinna Vinschen wrote: > > >[Catching up on some older mails] > > >> ----- Forwarded message from "Gerrit P. Haase" ----- > >> From: "Gerrit P. Haase" > >> To: cygwin ML > >> Subject: sem_* functions in cygwin > >> Date: Sun, 21 Nov 2004 22:48:20 +0100 > >> > >> Hi, > >> > >> nearly all sem_* functions are available, but sem_unlock is missing, > >> was there a problem implementing sem_unlock() or was it just missed > >> by accident? > >> > >> > >> Gerrit > >> ----- End forwarded message ----- > > >I guess you're asking about sem_unlink(). It's not implemented so far > >since named POSIX semaphores are implemented using named Windows semaphores. > >The SUSv3 description contains a pretty unfortunate implementation detail: > > > Calls to sem_open() to recreate or reconnect to the semaphore refer > > to a new semaphore after sem_unlink() is called. > > >There's no way I know of, which allows to implement this using named > >Windows semaphores. At least not without adding a lot of annoying > >bookkeeping overhead, possibly involving cygserver. > > > >Corinna > > >-- > >Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple > >Problem reports: http://cygwin.com/problems.html > >Documentation: http://cygwin.com/docs.html > >FAQ: http://cygwin.com/faq/ > > > > > > -- > Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple > Problem reports: http://cygwin.com/problems.html > Documentation: http://cygwin.com/docs.html > FAQ: http://cygwin.com/faq/ -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader mailto:[EMAIL PROTECTED] Red Hat, Inc. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
