[Libguestfs] missing chdir before chroot in guestfsd

[Richard W.M. Jones]

On Sun, Aug 18, 2013 at 02:29:15PM +0200, Olaf Hering wrote:
> 
> daemon.c does just a chroot, without chdir. The result is that pwd does not
> work correctly (it causes fs/dcache.c:prepend_unreachable() to add the
> unreachable string). A workaround is to add "cd /" before each sh command.
> 
> ><fs> mount /dev/sda2 /
> ><fs> sh "cd / ; chroot / ; /bin/pwd"
> /
> 
> ><fs> sh "/bin/pwd"
> (unreachable)/
> 
> ><fs> sh "cd / ; /bin/pwd"
> /
> 
> This untested change may fix it.
> 
> ===================
> --- libguestfs-1.20.10.orig/daemon/guestfsd.c
> +++ libguestfs-1.20.10/daemon/guestfsd.c
> @@ -879,7 +879,11 @@ commandrvf (char **stdoutput, char **std
>        close (stdin_fd[PIPE_READ]);
>        close (stdin_fd[PIPE_WRITE]);
>  
> -      if (chroot (sysroot) == -1) {
> +      if (chdir (sysroot) == -1) {
> +        perror ("chdir");
> +        _exit (EXIT_FAILURE);
> +      }
> +      if (chroot (".") == -1) {
>          perror ("chroot");
>          _exit (EXIT_FAILURE);
>        }

If you look at the upstream code, this has been fixed, or at
least, the code is quite different.  See:

commit 2aa731e7c441581f0d72bcd06e9431b92931466a
Author: Matthew Booth <mbooth at redhat.com>
Date:   Thu Dec 13 15:22:39 2012 +0000

    daemon: Remove redundant fork in commandrvf

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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