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Re: [Fwd: [email@example.com: sem_* functions in cygwin]]
- From: Mark Paulus <mark dot paulus at mci dot com>
- To: "cygwin at cygwin dot com" <cygwin at cygwin dot com>
- Date: Thu, 09 Dec 2004 09:50:35 -0700
- Subject: Re: [Fwd: [firstname.lastname@example.org: sem_* functions in cygwin]]
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)?
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
>> 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?
>> ----- 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.
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