Re: [Xen-devel] [PATCH] xenstore: document xs_set_permissions

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Tue, 2015-03-31 at 11:24 +0100, Wei Liu wrote:
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

One comment/suggestion:
> ---
>  tools/xenstore/include/xenstore.h | 26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/xenstore/include/xenstore.h 
> b/tools/xenstore/include/xenstore.h
> index b4b113e..6af5978 100644
> --- a/tools/xenstore/include/xenstore.h
> +++ b/tools/xenstore/include/xenstore.h
> @@ -149,8 +149,30 @@ struct xs_permissions *xs_get_permissions(struct 
> xs_handle *h,
>                                         xs_transaction_t t,
>                                         const char *path, unsigned int *num);
>  
> -/* Set permissions of node (must be owner).
> - * Returns false on failure.
> +/* Set permissions of node (must be owner).  Returns false on failure.
> + *
> + * Domain 0 may read / write anywhere in the store, regardless of
> + * permission settings.
> + *
> + * Note:
> + * The perms array is a list of (domid, permissions) pairs. The first
> + * element in the list specifies the owner of the list, plus the flags
> + * for every domain not explicitly specified subsequently. The
> + * subsequent entries are normal capabilities.
> + *
> + * Example C code:
> + *
> + *  struct xs_permissions perms[2];
> + *
> + *  perms[0].id = dm_domid;
> + *  perms[0].perms = XS_PERM_NONE;
> + *  perms[1].id = guest_domid;
> + *  perms[1].perms = XS_PERM_READ;
> + *
> + * It means the owner of the path is domain $dm_domid,

Is it worth mentioning explicitly that the owner always gets an implicit
XS_PERM_READ|XS_PERM_WRITE?

>  all other
> + * domains (unless specified in subsequent pair) can neither read from
> + * nor write to that path. It then specifies domain $guest_domid can
> + * read from that path.
>   */
>  bool xs_set_permissions(struct xs_handle *h, xs_transaction_t t,
>                       const char *path, struct xs_permissions *perms,



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