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Date:      Fri, 6 Apr 2007 12:30:48 +0100
From:      David Taylor <davidt@yadt.co.uk>
To:        FreeBSD Current <current@FreeBSD.org>
Subject:   Re: Surviving /dev/null disappearance
Message-ID:  <20070406113048.GA49739@outcold.yadt.co.uk>
In-Reply-To: <461434A6.3080001@FreeBSD.org>
References:  <cb5206420704030216r44243573h7981c1e35ef7225@mail.gmail.com> <46128475.9060602@FreeBSD.org> <cb5206420704040151w3c4f32f7gfd4aa017d40a1199@mail.gmail.com> <4613D6F3.4080701@mac.com> <461434A6.3080001@FreeBSD.org>

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On Wed, 04 Apr 2007, Maxim Sobolev wrote:
> Chuck Swiger wrote:
> >Andrew Pantyukhin wrote:
> >>On 4/3/07, Maxim Sobolev <sobomax@freebsd.org> wrote:
> >>>Patch ld(1) to detect the condition and don't unlink the device node?
> >>
> >>Yes, but there has to be a generic solution, so that
> >>we don't reinvent the wheel for every one of the
> >>thousands apps that may do this.
> >>
> >>Isn't there some safety-net wrapper function that
> >>refuses to remove device nodes and maybe some other
> >>types of files?
> >
> >Why not set a filesystem flag like schg on device nodes under a devfs 
> >tree...?
> 
> Well, I suspect that it may cause ld(1) fail instead. What we want it to 
> do is to not perform unlink(2) before open(2) when -o argument is device 
> node.

I think calling ld with it's output set to a device node is basically
pilot error.  ld unlinks files rather than truncating them for good
reasons --- to avoid overwriting libraries that are in use (the unlinked
file is still around on disk until the last fd referencing it is closed).

-- 
David Taylor



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