[Fwd: [gp@familiehaase.de: sem_* functions in cygwin]]

[Gerrit P. Haase]

Gerrit P. Haase wrote:
> 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.
> 
> 
> I got an undefined reference to sem_unlock().

I don't remember now which package it was, however there is a maro
used in linux which is based on ipc_unlock():
#define sem_unlock(id)  ipc_unlock(&sem_ids,id)

http://www.iglu.org.il/lxr/ident?i=sem_unlock


Gerrit
-- 
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