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Date: Sun, 7 Jun 2009 12:47:37 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: fcntl (locking) bug?
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On Jun  7 11:15, Margit Schubert-While wrote:
> This is 1.5.25 but also happens on earlier versions.
> It would appear that placing a shared read lock
> on a file open for input/output is preventing the
> the process itself from writing.

Cygwin up to release 1.5.25 implements fcntl locks using Windows file
locking calls.  Windows semantics disallow write access to a shared lock
for all processes, even the one setting up the first lock.  Only an
exclusive lock allows the locking process to write.

This is supposed to be fixed in Cygwin 1.7 which will use an entire
different mechanism to implement POSIX locks.


Corinna

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

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