From: Jeremy Maitin-Shepard <jbms@attbi.com>
To: linux-kernel@vger.kernel.org
Subject: Re: udev and devfs - The final word
Date: Sun, 04 Jan 2004 20:43:27 -0500 [thread overview]
Message-ID: <87k747w4ow.fsf@jbms.ath.cx> (raw)
In-Reply-To: <200401042335.i04NZqQZ029910@turing-police.cc.vt.edu> (Valdis Kletnieks's message of "Sun, 04 Jan 2004 18:35:51 -0500")
Valdis.Kletnieks@vt.edu writes:
> On Sun, 04 Jan 2004 23:01:04 +0100, Andries Brouwer said:
>> A common Unix idiom is testing for the identity
>> of two files by comparing st_ino and st_dev.
>> A broken idiom?
> Comparing two of these obtained at the same time is *usually* a good
> test, although racy even on current systems. (Consider the case of an
> unlink()/creat() pair between the two stat() calls - there's been more than
> one race condition resulting in a security hole based on THIS one). It's
> only safe if you actually have an open reference to both files before you
> fstat() either one. And yes, it has to be fstat(), as you can't guarantee
> that the file referenced by path in stat() is the one you did an
> open() on.
Unfortunately, programs such as tar depend on inode numbers of distinct
files being distinct even when the file is not open over a period of
several minutes/seconds. This is needed to avoid dumping hard links
more than once. Furthermore, there is no efficient way to write
programs such as tar without depending on this capability. Thus, if
st_ino cannot be used reliably for this purpose, it would be useful for
there to be a system call for retrieving a true
unique-within-the-filesystem identifier for the file.
--
Jeremy Maitin-Shepard
next prev parent reply other threads:[~2004-01-05 1:40 UTC|newest]
Thread overview: 169+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <18Cz7-7Ep-7@gated-at.bofh.it>
2003-12-31 3:05 ` udev and devfs - The final word Pascal Schmidt
2003-12-31 19:23 ` Greg KH
2003-12-31 20:19 ` Rob Love
2003-12-31 22:01 ` Nathan Conrad
2003-12-31 22:20 ` Rob Love
2003-12-31 21:45 ` Tommi Virtanen
2003-12-31 23:10 ` Rob Love
2003-12-31 21:52 ` Tommi Virtanen
2004-01-02 0:17 ` Hollis Blanchard
2004-01-02 0:36 ` viro
2004-01-03 6:04 ` Greg KH
2003-12-31 22:55 ` viro
2003-12-31 23:05 ` Rob Love
2003-12-31 23:48 ` Andreas Dilger
2004-01-07 10:15 ` Olaf Hering
2004-01-07 11:18 ` viro
2004-01-07 13:00 ` Olaf Hering
2004-01-07 13:26 ` viro
2004-01-07 13:27 ` Olaf Hering
2004-01-01 0:15 ` Andries Brouwer
2004-01-01 0:31 ` Rob Love
2004-01-01 12:34 ` Rob Landley
2004-01-01 15:22 ` Rob Love
2004-01-01 15:48 ` Andries Brouwer
2004-01-01 15:54 ` Rob Love
2004-01-02 20:42 ` Linus Torvalds
2004-01-03 3:00 ` Andries Brouwer
2004-01-03 4:46 ` Linus Torvalds
2004-01-03 13:10 ` Andries Brouwer
2004-01-03 22:27 ` Linus Torvalds
2004-01-03 23:08 ` Andries Brouwer
2004-01-04 1:16 ` Mark Mielke
2004-01-04 1:54 ` Valdis.Kletnieks
2004-01-04 18:44 ` Mark Mielke
2004-01-04 2:09 ` Linus Torvalds
2004-01-04 2:49 ` Andries Brouwer
2004-01-04 3:04 ` Linus Torvalds
2004-01-04 4:36 ` Pentium 4 HT SMP Ananda Bhattacharya
2004-01-04 5:55 ` Martin J. Bligh
2004-01-04 13:21 ` udev and devfs - The final word Andries Brouwer
2004-01-04 21:05 ` Linus Torvalds
2004-01-04 22:01 ` Andries Brouwer
2004-01-04 22:37 ` viro
2004-01-05 1:02 ` Mark Mielke
2004-01-05 2:24 ` Valdis.Kletnieks
2004-01-05 2:29 ` Andries Brouwer
2004-01-05 3:42 ` viro
2004-01-04 22:37 ` Helge Hafting
2004-01-04 23:35 ` Valdis.Kletnieks
2004-01-05 1:43 ` Jeremy Maitin-Shepard [this message]
2004-01-05 1:47 ` st_dev:st_ino (was: Re: udev and devfs - The final word) Mark Mielke
2004-01-05 2:02 ` st_dev:st_ino Jeremy Maitin-Shepard
2004-01-05 3:14 ` st_dev:st_ino viro
2004-01-05 1:58 ` udev and devfs - The final word viro
2004-01-05 2:12 ` Jeremy Maitin-Shepard
2004-01-05 2:52 ` Linus Torvalds
2004-01-05 3:06 ` David Lang
2004-01-05 3:48 ` Rob Landley
2004-01-05 4:52 ` Trond Myklebust
2004-01-05 7:03 ` [offtopic] " Rob Landley
2004-01-05 12:07 ` Trond Myklebust
2004-01-05 15:13 ` Mark Mielke
2004-01-05 16:36 ` Andreas Schwab
2004-01-05 22:18 ` Mark Mielke
2004-01-05 3:07 ` Daniel Jacobowitz
2004-01-05 3:33 ` Linus Torvalds
2004-01-05 3:50 ` viro
2004-01-05 4:02 ` Linus Torvalds
2004-01-05 4:38 ` viro
2004-01-05 4:52 ` Linus Torvalds
2004-01-05 6:11 ` viro
2004-01-05 7:47 ` Greg KH
2004-01-05 11:15 ` Vojtech Pavlik
2004-01-05 20:11 ` Theodore Ts'o
2004-01-05 21:06 ` Vojtech Pavlik
2004-01-05 22:22 ` Theodore Ts'o
2004-01-06 0:14 ` Rob Landley
2004-01-06 17:28 ` [OT] " Disconnect
2004-01-11 22:12 ` Ed L Cashin
2004-01-05 5:26 ` Eric W. Biederman
2004-01-05 7:39 ` Greg KH
2004-01-07 9:57 ` Pavel Machek
2004-01-05 12:27 ` Andries Brouwer
2004-01-05 16:13 ` Linus Torvalds
2004-01-05 17:29 ` Vojtech Pavlik
2004-01-05 17:33 ` Linus Torvalds
2004-01-05 17:52 ` Davide Libenzi
2004-01-05 18:03 ` Linus Torvalds
2004-01-05 18:09 ` Hugo Mills
2004-01-05 19:10 ` Paul Rolland
2004-01-05 19:52 ` Andries Brouwer
2004-01-05 20:38 ` Linus Torvalds
2004-01-05 22:17 ` Shawn
2004-01-05 22:25 ` Mark Mielke
2004-01-05 23:05 ` Shawn
2004-01-05 23:23 ` Shawn
2004-01-06 0:43 ` Greg KH
2004-01-06 0:53 ` Shawn
2004-01-05 23:13 ` Andries Brouwer
2004-01-05 23:32 ` Linus Torvalds
2004-01-06 0:59 ` viro
2004-01-06 1:17 ` Linus Torvalds
2004-01-06 4:28 ` viro
2004-01-06 5:07 ` Linus Torvalds
2004-01-06 1:06 ` Andries Brouwer
2004-01-06 15:00 ` Mark Mielke
2004-01-06 0:00 ` Greg KH
2004-01-06 1:41 ` Andries Brouwer
2004-01-07 17:14 ` Greg KH
2004-01-06 0:31 ` Rob Landley
2004-01-06 7:14 ` Vojtech Pavlik
2004-01-06 0:36 ` Silly udev script [was Re: udev and devfs - The final word] Greg KH
2004-01-05 7:44 ` udev and devfs - The final word James H. Cloos Jr.
2004-01-05 7:45 ` Nigel Cunningham
2004-01-05 11:01 ` Robin Rosenberg
2004-01-05 12:39 ` Nigel Cunningham
2004-01-05 14:31 ` IRQ disabled on linux 2.6.1-rc1-mm1 Mainak Mandal _00007001_
2004-01-07 13:39 ` udev and devfs - The final word Robin Rosenberg
2004-01-07 17:16 ` Nigel Cunningham
2004-01-05 9:06 ` Valdis.Kletnieks
2004-01-05 4:15 ` Peter Chubb
2004-01-05 4:42 ` Linus Torvalds
2004-01-03 18:34 ` Wrapping jiffies [was Re: udev and devfs - The final word] Pavel Machek
2004-01-01 19:43 ` udev and devfs - The final word Kai Henningsen
2004-01-02 7:26 ` Rob Landley
2004-01-04 8:57 ` Greg KH
2004-01-04 9:43 ` Rob Landley
2004-01-02 0:17 ` Maciej Zenczykowski
[not found] ` <20040102103104.GA28168@mark.mielke.cc>
2004-01-03 6:07 ` Greg KH
2004-01-03 6:51 ` Valdis.Kletnieks
2004-01-03 11:57 ` Ian Kent
2004-01-03 22:08 ` Greg KH
2004-01-07 10:23 ` Olaf Hering
2004-01-01 23:14 ` Rob
2004-01-02 3:53 ` Tyler Hall
2004-01-01 16:17 ` Pascal Schmidt
2004-01-01 20:03 ` Greg KH
2004-01-08 13:53 "Andrey Borzenkov"
2004-01-08 15:40 ` Ian Kent
2004-01-08 17:26 ` Diego Calleja
2004-01-08 19:25 ` Andrey Borzenkov
2004-01-08 22:40 ` Alex Goddard
2004-01-09 7:03 ` "Andrey Borzenkov"
2004-01-08 18:14 ` Alex Goddard
2004-01-08 18:35 ` Alex Goddard
2004-01-08 19:22 ` Andrey Borzenkov
2004-01-09 8:51 ` Helge Hafting
-- strict thread matches above, loose matches on Subject: below --
2004-01-08 13:05 "Andrey Borzenkov"
2004-01-06 1:20 Paul Zimmerman
[not found] <fa.flhsork.uka2hg@ifi.uio.no>
[not found] ` <fa.hv9hpq7.1l1q9p3@ifi.uio.no>
2004-01-01 19:53 ` walt
2004-01-01 21:53 ` Martin Schlemmer
2004-01-01 16:59 Shaheed
[not found] <fa.af64864.ugabhg@ifi.uio.no>
[not found] ` <fa.de7jae9.1jk0pjt@ifi.uio.no>
2003-12-31 22:17 ` walt
2004-01-01 2:03 ` Martin Schlemmer
2004-01-01 2:05 ` Martin Schlemmer
2003-12-31 0:29 Greg KH
2003-12-31 0:53 ` Prakash K. Cheemplavam
2003-12-31 19:17 ` Greg KH
2004-01-02 16:45 ` Shawn
2003-12-31 12:43 ` Paulo Marques
2004-01-01 1:18 ` Helge Hafting
2004-01-03 5:59 ` Greg KH
2004-01-03 15:22 ` Helge Hafting
2004-01-03 21:18 ` viro
2004-01-03 22:11 ` Greg KH
[not found] ` <20040103140140.3b848e9f.witukind@nsbm.kicks-ass.org>
2004-01-03 22:16 ` Greg KH
2004-01-03 22:33 ` Christoph Hellwig
2004-01-02 17:54 ` Andreas Jellinghaus
2004-01-02 18:19 ` Shawn
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