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Date:      Sun, 7 Nov 1999 11:24:58 +0000
From:      David Malone <dwmalone@maths.tcd.ie>
To:        Jonathan Lemon <jlemon@americantv.com>
Cc:        current@freebsd.org, Ollivier Robert <roberto@keltia.freenix.fr>
Subject:   Re: Serious locking problem in CURRENT
Message-ID:  <19991107112458.A14670@walton.maths.tcd.ie>
In-Reply-To: <199911061929.NAA26145@free.pcs>
References:  <local.mail.freebsd-current/19991105225916.A14961@keltia.freenix.fr> <local.mail.freebsd-current/19991106005016.A865@keltia.freenix.fr> <local.mail.freebsd-current/19991106134548.A2921@walton.maths.tcd.ie> <199911061929.NAA26145@free.pcs>

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On Sat, Nov 06, 1999 at 01:29:16PM -0600, Jonathan Lemon wrote:

> From the manual page for flock:
> 
> NOTES
>      Locks are on files, not file descriptors.  That is, file descriptors du-
>      plicated through dup(2) or fork(2) do not result in multiple instances of
>      a lock, but rather multiple references to a single lock.  If a process
>      holding a lock on a file forks and the child explicitly unlocks the file,
>      the parent will lose its lock.

Doesn't this make it impossible to hold a lock on a file when you
want to fork a child to do some task 'cos the lock will be dropped
when the child closes its copy of the file discriptor on exit?
Either it's a posix goof or the lock shouldn't be let go until
either explicitly released or the last instance of the file discriptor
is closed?

	David.


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