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From: Jesse Pollard <pollard@admin.navo.hpc.mil>
To: root@chaos.analogic.com, Marc-Christian Petersen <m.c.p@wolk-project.de>
Subject: Re: Symlink indirection
Date: Fri, 13 Dec 2002 10:26:00 -0600
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Cc: linux-kernel@vger.kernel.org, Andrew Walrond <andrew@walrond.org>
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On Friday 13 December 2002 09:30 am, Richard B. Johnson wrote:
> On Fri, 13 Dec 2002, Marc-Christian Petersen wrote:
> > On Friday 13 December 2002 16:06, Andrew Walrond wrote:
> >
> > Hi Andrew,
> >
> > > Is the number of allowed levels of symlink indirection (if that is the
> > > right phrase; I mean symlink -> symlink -> ... -> file) dependant on
> > > the kernel, or libc ? Where is it defined, and can it be changed?
> >
> > fs/namei.c
> >
> >  if (current->link_count >= 5)
> >
> > change to a higher value.
> >
> > So, the answer is: Kernel :)
> >
> > ciao, Marc
>
> No, that thing (whetever it is) is different.
>
> Script started on Fri Dec 13 10:26:30 2002
> # file *
> foo:        symbolic link to ../foo
> typescript: empty
> # pwd
> /root/foo
> # cd *
> # cd *
> # cd *
> # cd *
> # cd *
> # cd *
> # pwd
> /root/foo/foo/foo/foo/foo/foo/foo
> # cd *
> # cd *
> # cd *
> # pwd
> /root/foo/foo/foo/foo/foo/foo/foo/foo/foo/foo
> # cd *
> # cd *
> # cd *
> # pwd
> /root/foo/foo/foo/foo/foo/foo/foo/foo/foo/foo/foo/foo/foo
> # exit
> exit
>
> Script done on Fri Dec 13 10:27:21 2002
>
>
> You can do this until you run out of string-space. Your "link-count"
> has something to do with something else.

Example isn't the same thing:

[pollard@merlin ~/test]$ echo "test" >target
[pollard@merlin ~/test]$ ln -s target a				- 1 link
[pollard@merlin ~/test]$ ln -s a b					- 2 links
[pollard@merlin ~/test]$ ln -s b c					- 3
[pollard@merlin ~/test]$ ln -s c d					- 4
[pollard@merlin ~/test]$ cat d
test
[pollard@merlin ~/test]$ ln -s d e					-5
[pollard@merlin ~/test]$ cat e
test
[pollard@merlin ~/test]$ ln -s e f					-6
[pollard@merlin ~/test]$ cat f
cat: f: Too many levels of symbolic links

This catches problem situations like:

[pollard@merlin ~/test]$ ln -s loop loop
[pollard@merlin ~/test]$ ls -l loop
lrwxrwxrwx    1 pollard  NA0101          4 Dec 13 10:24 loop -> loop
[pollard@merlin ~/test]$ cat loop
cat: loop: Too many levels of symbolic links

-- 
-------------------------------------------------------------------------
Jesse I Pollard, II
Email: pollard@navo.hpc.mil

Any opinions expressed are solely my own.
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