Re: [Qemu-devel] [PATCH v2 4/5] 9p: handle walk of ".." in the root directory

[Eric Blake <eblake@redhat.com>]

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On 08/26/2016 10:07 AM, Greg Kurz wrote:
> The 9P spec at http://man.cat-v.org/plan_9/5/intro says:
> 
> All directories must support walks to the directory .. (dot-dot) meaning
> parent directory, although by convention directories contain no explicit
> entry for .. or . (dot).  The parent of the root directory of a server's
> tree is itself.
> 
> This means that a client cannot walk further than the root directory
> exported by the server. In other words, if the client wants to walk
> "/.." or "/foo/../..", the server shoud answer like the request was

s/shoud/should/

> to walk "/".
> 
> This patch just does that:
> - we cache the QID of the root directory at attach time
> - during the walk we compare the QID of each path component with the root
>   QID to detect if we're in a "/.." situation
> - if so, we skip the current component and go to the next one
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  hw/9pfs/9p.c |   40 +++++++++++++++++++++++++++++++---------
>  hw/9pfs/9p.h |    1 +
>  2 files changed, 32 insertions(+), 9 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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