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Message-ID: <3D455EA0.6050207@ra.anl.gov>
Date: Mon, 29 Jul 2002 10:26:24 -0500
From: "Sukru Tikves" <stikves AT ra DOT anl DOT gov>
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To: cygwin AT cygwin DOT com
Subject: Interprocess friendly Semaphores
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Hello All,

I have a UNIX application that utilizes fork() and semaphores.

Unfortunately the current Cygwin behaiour is to terminate the child 
process immediately, because it does not understand PROCESS_SHARED 
semaphores.

[ thread.cc ]
 > pthread_cond::fixup_after_fork ()
 > {
 >  debug_printf ("cond %x in fixup_after_fork", this);
 >   if (shared != PTHREAD_PROCESS_PRIVATE)
 >     api_fatal ("doesn't understand PROCESS_SHARED condition
 > variables");

I know that windows supports sharing semaphores between processes. The 
following MSDN node describes it:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/synchro_1a2g.asp

Changing the above code piece and the following will probably fix 
something. But I do not know the fork() behaviour and I'm sure that more 
work will be necessary.

Also I do not know how to recompile Cygwin [ ./configure script says:
configure: error: can not find install-sh or install.sh in . ./.. ./../.. ]

Can you help me?

[ thread.cc ]
 >  /*attr checked in the C call */
 >  if (attr && attr->pshared == PTHREAD_PROCESS_SHARED)
 >    {
 >      // fail
 >      magic = 0;
 >      return;
 >    }
 >  if (wincap.has_try_enter_critical_section ())
 >    InitializeCriticalSection (&criticalsection);
 >  else
 >    {
 >      this->win32_obj_id = ::CreateMutex (&sec_none_nih, false, NULL);
 >      if (!win32_obj_id)
 >        magic = 0;
 >    }
 >      if (!win32_obj_id)
 >        magic = 0;
 >    }

PS: I have checked out sources via CVS.


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