From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Sat,  7 Feb 1998 23:09:45 -0600
From: G. David Butler gdb@dbSystems.com
Subject: [9fans] create(2)/open(2) race for file creation
Topicbox-Message-UUID: 71d8e2ac-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19980208050945.Hf14ekRK3vc6wUbQ1cWmXKXmTrd9r1Taqa25gce3FGo@z>

>From: "Rob Pike" <rob@plan9.bell-labs.com>
>Am I missing something?   If everyone does create(file, OWRITE, 000)
>only one process can succeed.   Perm==0 means no one can read or
>write the file; if you want one writer, many readers, 004 will do.

If I want to create the file, write data and close so that it can
be read/written again then I can't leave it 000 or 400, I must
leave it 600.  So, if many processes are doing:

if stat() fails {
	create()
	write()
	chmod()
	close()
}

Then it is possible for two or more processes to fail the stat
but one to create, write, chmod and close before the other others
do create.  It is a race that can't be avoided, that I can see.

>In other words, it's a create/open race, so don't run that race.

I would like to avoid it.  Your point is valid if the file is
created once and never written to again.  That is a big restriction.