Xen devel - Nov 2006 - [PATCH][libxen] Fix ''contents'' field of set structures in libxen iinterface

Many of the set structures in the libxen interface contain a
''contents''
field with too many dimensions, particularly when ''contents''
stores
references.  References are defined in the various xen_*_decl.h headers 
as ''void *''.  Sets of the various classes are defined for
example as

  typedef void *xen_vm;

  typedef struct xen_vm_set
  {
     size_t size;
     xen_vm *contents[];
  } xen_vm_set;

The additional dimension on ''contents'' for sets of references
is not
required.

- Jim




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On Fri, Nov 03, 2006 at 05:41:31PM -0700, Jim Fehlig wrote:
> Many of the set structures in the libxen interface contain a
''contents''
> field with too many dimensions, particularly when
''contents'' stores
> references.  References are defined in the various xen_*_decl.h headers 
> as ''void *''.  Sets of the various classes are defined for
example as
> 
>  typedef void *xen_vm;
> 
>  typedef struct xen_vm_set
>  {
>     size_t size;
>     xen_vm *contents[];
>  } xen_vm_set;
> 
> The additional dimension on ''contents'' for sets of
references is not
> required.
> 
I meant to discuss this with you when you sent this privately a few weeks
ago -- sorry I forgot.

I can see what you''re trying to do here.  The problem is that
populating this
set becomes difficult.  The sets are read off the wire using the generic
code in xen_common.c, guided by the abstract_type that''s passed in. 
The thing
is, we have only one indicator for sets (SET) but with your patch we''ll
need
to introduce a second indicator, to distinguish between sets where the value
is put in place (like handles) and sets where the value placed is a pointer
(like sets of records).  This will have to be part of a larger patch,
unfortunately.  I''ll have a hack now and see what I can do.

Cheers,

Ewan.

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