[Fwd: symboilc link does not expand if followed by /..]

Corinna Vinschen vinschen@redhat.com
Wed Jul 14 11:55:00 GMT 2004


----- Forwarded message from Vinay Kumar -----
> Date: Tue, 13 Jul 2004 21:06:08 +0000 (GMT)
> From: Vinay Kumar 
> Subject: symboilc link does not expand if followed by /..
> To: cygwin-list
> 
> Hi all,
>     I found a problem with symbolic link expansion in cygwin. Symbolic
> link does not expand properly if it is followed by /.. . To see it at
> your place please do the following.
> cd /tmp
> mkdir dir1
> mkdir dir2
> touch dir1/1.c
> cd dir2
> ln -s ../dir1 symlink
> 
> if we do ls symlink it gives 1.c as expected.
> But if we do ls symlink/.. then it list contents of present directory.
> 
> @/tmp/dir2
> $ ls symlink
> 1.c
> 
> @/tmp/dir2
> $ ls symlink/..
> symlink
> 
> I think it should list contents of /tmp directory.
> Could somebody throw some light over it.
> 
> regards
> Vinay
----- End forwarded message -----

Looks like he has his point.  Under Linux it works as he describes it.
In Cygwin the following happens. 

normalize_posix_path simplifies the path first and strippes ".." by
removing the previous entry in the path.  Then path_conv::check checks
for symlinks and directories.  So, the incoming path /tmp/dir2/symlink/..
becomes /tmp/dir2 after the call to normalize_posix_path and the symlink
expansion in path_conv::check doesn't even see a symlink. 

That reflects the typical behaviour in tcsh with the setting
`set symlinks expand', but it doesn't allow any other behaviour.

It looks like a fix would require to change the order in path_conv::check.
The symlink expansion would have to be done before the path gets normalized.
Or the symlink expansion could be moved into normalize_posix_path.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Co-Project Leader          mailto:cygwin@cygwin.com
Red Hat, Inc.



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