Date: Mon, 20 Sep 1999 23:28:11 -0700 (PDT) From: Julian Elischer <julian@whistle.com> To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: Brian Beattie <beattie@aracnet.com>, "Matthew N. Dodd" <winter@jurai.net>, Chuck Robey <chuckr@mat.net>, Wayne Cuddy <wayne@crb-web.com>, FreeBSD Hackers List <freebsd-hackers@FreeBSD.ORG> Subject: Re: what is devfs? Message-ID: <Pine.BSF.4.05.9909202321540.22714-100000@home.elischer.org> In-Reply-To: <19990920231629.26284@hydrogen.fircrest.net>
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On Mon, 20 Sep 1999, John-Mark Gurney wrote: > Julian Elischer scribbled this message on Sep 20: > > > what happens in this case: > > > mount /devfs > > > cd /devfs > > > mv ttyd1 da0c # sure you don't normally do this but you CAN! > > > > da0c is now the name of the vissible alias of ttyd1 > > > > > cd / > > > umount /devfs > > > mount /devfs > > > > ttyd1 is now the name of the visible alias of the device. > > > > > > > > sorry, that doesn't cut it as you loose your "dynamic" links from the > > > umount to mount, and we are back to the major/minor number to keep > > > track of which device node belongs to which device... > > > > no the "original" name is tracked. > > > > I don't see your problem > > > > the device reverts to it;s original name as it should.... > > > > it remembers any permissions it was given under either name... > > > > I think this is good. > > you may think it's bad. why? > > POLA! if we have persisten permissions and ownership, and we allow > renaming, then renaming should also be persistant... after the mount > again, da0c either no longer exists, or is no longer ttyd1... which > neither is an acceptable solution... I think at this stage you've gone overboard.. part of the definition of devfs is that a device shows up on mount with it's canonical name.. On each new mount every time, even if you've mounted it in 10 different places. this is as designed. it is easy to document and easy to understand. this is as 'L' as it gets in POLA in this case.. (L != 0) The only way you could do more would be to make the backing nodes be symlinks, and store the renamed name in the symlink field. I don't think it's worth the extra work. I can provide permssion persistance on a "BY CANONICAL NAME" basis. after that he complexity of the problem goes balistic. julian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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