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From: Rainer Weikusat <rweikusat@mssgmbh.com>
Newsgroups: comp.os.linux.development.apps
Subject: Re: mkdir() and thread safety()
Date: Thu, 31 Mar 2011 11:17:09 +0100
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Richard Kettlewell <rjk@greenend.org.uk> writes:
> David Schwartz <davids@webmaster.com> writes:
>> Rainer Weikusat <rweiku...@mssgmbh.com> wrote:
>>> Also, the UNIX(*) standard demands that mkdir is supposed to fail
>>> with EEXIST when the named file already existed. This is not possible
>>> when mkdir is not an atomic operation.
>>
>> Yes, it is. The algorithm I specified will always fail if the named
>> file already existed before the operation started. There is no
>> requirement for atomicity. You can't just make up requirements because
>> they seem reasonable to you.
>
> I'd go further than that: even when there is a standardized requirement
> for atomicity (or any other property), you may still need to check what
> the implementation does.  NFS's failure to properly support O_EXCL is
> notorious.

You actually need to do so because Kennedy was shot, clearly proving
that all kinds of things nobody expects CAN and DO happen ...