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Date: Tue, 9 Oct 2007 09:59:34 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: file locking behaviour
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On Oct  8 23:37, Damjan Lango wrote:
> Hello!
> 
> I have a program that uses:
> 
> lock.l_type = F_WRLCK;
> fcntl(log->handle, F_SETLK, &lock)
> 
> the file is then locked also for reads, is that correct behaviour?
> I thought that only writing would be locked.
> on unix the file stays readable even if using the above code.

The behaviour is correct as far as mandatory locking is concerned.
Under POSIX file locking is supposed to be advisory locking which
doesn't actually enforce the lock.  The problem for us is the fact
that Windows does only implement mandatory locking and that's what
is used in Cygwin for now.  Implementing advisory file locking is
on my ToDo list for quite some time now but..., well...
http://cygwin.com/contrib.html


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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