Re: [rdiff-backup-users] [PATCH] Preserve symlink permissions

[Blair Zajac]

On Nov 4, 2006, at 1:53 PM, Andrew Ferguson wrote:

> Hi,
>
> Some Unix systems (at least the *BSDs and Mac OS X) set the permission
> bits on symbolic links to "777 - umask" at link creation. This is
> different from Linux, where all symbolic links are mode 777.
>
> This patch changes rdiff-backup's umask temporarily when it creates
> symbolic links so that their exact permissions are maintained during
> backup and restore. The patch is against the current CVS  
> repository, but
> should also work for 1.1.x and 1.0.x versions.
>
> Although the permission bits seem to have no effect, I created this
> patch so that rdiff-backup comes even closer to making a perfect  
> backup
> on BSD-like systems. It has been tested on Linux, Mac OS X, and during
> network backup and restore.
>
> Cheers,
> Andrew
>
> --
> Andrew Ferguson - address@hidden
>
> diff -Nur rdiff-backup-cvs/rdiff_backup/rpath.py rdiff-backup- 
> symlink-perms/rdiff_backup/rpath.py
> --- rdiff-backup-cvs/rdiff_backup/rpath.py	2006-01-13  
> 00:29:47.000000000 -0500
> +++ rdiff-backup-symlink-perms/rdiff_backup/rpath.py	2006-11-04  
> 15:55:39.000000000 -0500
> @@ -100,7 +100,12 @@
>
>         if rpin.isreg(): return copy_reg_file(rpin, rpout, compress)
>         elif rpin.isdir(): rpout.mkdir()
> -       elif rpin.issym(): rpout.symlink(rpin.readlink())
> +       elif rpin.issym():
> +               # some systems support permissions for symlinks, but
> +               # only by setting at creation via the umask
> +               os.umask(0777 - rpin.getperms())
> +               rpout.symlink(rpin.readlink())
> +               os.umask(077)   # restore rdiff-backup standard umask

I think it would be clearer to do something like this saving the  
current result of the umask, so if the umask is changed anywhere  
else, it'll always be restored:

                # some systems support permissions for symlinks, but
                # only by setting at creation via the umask
                orig_umask = os.umask(0777 - rpin.getperms())
                rpout.symlink(rpin.readlink())
                os.umask(orig_umask)

Regards,
Blair

--
Blair Zajac, Ph.D.
CTO, OrcaWare Technologies
<address@hidden>
Subversion training, consulting and support
http://www.orcaware.com/svn/