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Re: LS and TAR don't see any file permissions ("ls -l" shows "----------+ ...")

On 03/04/2011 11:12 AM, Peter Binney wrote:
> When running "ls -l" the permissions field shows as "----------+".

Which means that the owner has no permissions, but that there are ACLs
which allow others permissions.  Not entirely unusual, given Windows'
ability to create files with a different owner than the current user,
while allowing the current user to access the file (typically when done
to places like the desktop, and caused by inheritance ACLs present on
the directory where the problematic file is being created in the first

> Oddly, "ls -l" shows the correct permissions if the pathname uses the
> windows drive letter syntax. eg:
> $ pwd
> /cygdrive/c
> $ ls -l tmp/plb.txt
> ----------+ 1 ga2binn Domain Users 5527 Mar  3 13:54 tmp/plb.txt
> $ ls -l c:/tmp/plb.txt
> -rw-r--r-- 1 ga2binn Domain Users 5527 Mar  3 13:54 c:/tmp/plb.txt

That's because using a dos-style path disregards ACL parsing, and fakes
the permission bits instead.  The + shows that ACLs are present, and
'getfacl tmp/plb.txt' will show you the difference between the owner and
your permissions.

> Similarly, TAR images have no permissions on the files contained. eg:
> $ pwd
> /cygdrive/c/tmp
> $ tar cf - plb.txt | tar vtf -
> ---------- ga2binn/Domain Users 5527 2011-03-03 13:54 plb.txt

Here, the problem is that tar doesn't preserve ACLs by default, so the
original POSIX mode (000) is preserved while the ACLs are lost,
resulting in an truly inaccessible file (note that there is no longer a
+ in the listing).

> Even more oddly, this behaviour (both LS and TAR) occurs on a new PC
> that I am moving to.

That's another big case where the user ids on the old pc do not
correpsond to the user ids on the new pc; copying preserved the old user
id, but gave ACL access to the new user, resulting in odd permissions.

Eric Blake    +1-801-349-2682
Libvirt virtualization library

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