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Date:	Thu, 09 Dec 2004 09:50:35 -0700
From:	Mark Paulus <mark DOT paulus AT mci DOT com>
Subject:	Re: [Fwd: [gp AT familiehaase DOT de: sem_* functions in cygwin]]
In-reply-to:	<20041209164442.GA25246@cygbert.vinschen.de>
To:	"cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Message-id:	<0I8G00F7VS4BRS@pmismtp01.mcilink.com>
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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
>> 
>> 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

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