bugtraq - Re: Changes to the filesystem while find is running

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Message-ID: <200411240531.AAA00851@Sparkle.Rodents.Montreal.QC.CA>
Date: Wed, 24 Nov 2004 00:24:57 -0500 (EST)
From: devnull@...ents.Montreal.QC.CA
To: bugtraq@...urityfocus.com, bug-findutils@....org
Subject: Re: Changes to the filesystem while find is running - comments?

(Because I'm so sick of the broken autoresponders bugtraq is full of,
I've set the From: on this mail to a black-hole address.  Please use
the address in the signature if you actually want to reach me.)

>> Before a chdir to "foo", take stock:
>> - record stat(".");  DOTFD = open("."); (get a fd to ".")

This is not possible if . is a search-only directory.  (While find will
not work very well in such a directory, care should be taken that it
not fall over just because someone happened to chmod the read bits away
from a directory just when find happens to be in it.)

More generally, I've wanted to do this - use file descriptors as
handles onto directories - and often wished for an O_NOACCESS mode to
open() in consequence.

> Of course, open(2) will follow a symlink, if the directory we
> originally stat()ed is replaced by a symlink just before we issue the
> open() call.  We of course can guard against that by issuing an
> lstat() on the fd once we have opened it.

ITYPM fstat(), not lstat(), in the last line.

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