linux-kernel - Re: [PATCH -mm] replacement for broken kbuild-dont-put-temp-files-in-the-source-tree.patch

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Date:	Mon, 30 Oct 2006 10:22:33 -0500
From:	Valdis.Kletnieks@...edu
To:	Oleg Verych <olecom@...wer.upol.cz>
Cc:	Jan Beulich <jbeulich@...ell.com>, dsd@...too.org,
	kernel@...too.org, draconx@...il.com, jpdenheijer@...il.com,
	Andrew Morton <akpm@...l.org>, Sam Ravnborg <sam@...nborg.org>,
	Andi Kleen <ak@...e.de>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -mm] replacement for broken kbuild-dont-put-temp-files-in-the-source-tree.patch

On Mon, 30 Oct 2006 14:42:16 GMT, Oleg Verych said:

> So, how about (using your btmp directory) create symlink to /dev/null in
> the (dev) sub-directory and then set no write permission? No tmp,
> things are local to build output, old gas's happy:
> ,__
> |olecom@...wer:/tmp/_build_2.6.19-rc3/btmp
> !__$ mkdir dev
> ,__
> |olecom@...wer:/tmp/_build_2.6.19-rc3/btmp
> !__$ cd dev ; ln -s /dev/null null ; chmod u-w . ; ls -la
> total 0
> dr-xr-x--- 2 olecom root 60 2006-10-30 15:34 .
> drwxr-x--- 3 olecom root 80 2006-10-30 15:34 ..
> lrwxrwxrwx 1 olecom root  9 2006-10-30 15:34 null -> /dev/null
> ,__
> |olecom@...wer:/tmp/_build_2.6.19-rc3/btmp/dev
> !__$ cd .. ; rm dev/null
> rm: cannot remove dev/null': Permission denied

Did you try this as root, which is where the original "/dev/null dissapears"
problem shows up?

[/tmp]3 id
uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel) context=valdis:staff_r:staff_t
[/tmp]3 mkdir z9
[/tmp]3 touch z9/foo
[/tmp]3 chmod 0 z9
[/tmp]3 rm z9/foo
[/tmp]3 ln -s /dev/null z9
[/tmp]3 ls -l z9
total 0
lrwxrwxrwx 1 root root 9 Oct 30 10:20 null -> /dev/null
[/tmp]3 rm z9/null
[/tmp]3 ls -ld z9
d--------- 2 root root 40 Oct 30 10:21 z9

Hmm.. and even the 'ln' worked even when z9 was chmod 0. ;)


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