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Re: [libvirt] [PATCH] esx: Fix dynamic dispatch for CastFromAnyType functions



On Mon, Apr 25, 2011 at 01:32:43PM +0200, Matthias Bolte wrote:
> 2011/4/25 Matthias Bolte <matthias bolte googlemail com>:
> > This was broken by the refactoring in ac1e6586ec75. It resulted in a
> > segfault for 'virsh vol-dumpxml' and related volume functions.
> >
> 
> Actually that patch doesn't fix the problem correctly. It just turns
> the segfault into an error message.
> 
> Here's v2 that really fixes the problem. Note the important difference
> between anyType->_type and anyType->type :)
> 
> Matthias

> From a17245fb92c88439ffbb84e34bebf1afb6903885 Mon Sep 17 00:00:00 2001
> From: Matthias Bolte <matthias bolte googlemail com>
> Date: Mon, 25 Apr 2011 12:38:17 +0200
> Subject: [PATCH] esx: Fix dynamic dispatch for CastFromAnyType functions
> 
> This was broken by the refactoring in ac1e6586ec75. It resulted in a
> segfault for 'virsh vol-dumpxml' and related volume functions.
> 
> Before the refactoring all users of the ESX_VI__TEMPLATE__DISPATCH
> macro dispatched on the item type, as the item is the input to all those
> functions.
> 
> Commit ac1e6586ec75 made the dynamically dispatched CastFromAnyType
> functions use this macro too, but this functions dispatched on the
> actual type of the AnyType object. The item is the output of the
> CastFromAnyType functions.
> 
> This difference was missed in the refactoring, making CastFromAnyType
> functions dereferencing the item pointer that is NULL at the time of
> the dispatch.
> ---
>  src/esx/esx_vi_types.c |   14 ++++++++------
>  1 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/src/esx/esx_vi_types.c b/src/esx/esx_vi_types.c
> index dd83954..3c81021 100644
> --- a/src/esx/esx_vi_types.c
> +++ b/src/esx/esx_vi_types.c
> @@ -533,8 +533,9 @@
>   * Macros to implement dynamic dispatched functions
>   */
>  
> -#define ESX_VI__TEMPLATE__DISPATCH(__type, _dispatch, _error_return)          \
> -    switch (item->_type) {                                                    \
> +#define ESX_VI__TEMPLATE__DISPATCH(_actual_type, __type, _dispatch,           \
> +                                   _error_return)                             \
> +    switch (_actual_type) {                                                   \
>        _dispatch                                                               \
>                                                                                \
>        case esxVI_Type_##__type:                                               \
> @@ -543,7 +544,7 @@
>        default:                                                                \
>          ESX_VI_ERROR(VIR_ERR_INTERNAL_ERROR,                                  \
>                       _("Call to %s for unexpected type '%s'"), __FUNCTION__,  \
> -                     esxVI_Type_ToString(item->_type));                       \
> +                     esxVI_Type_ToString(_actual_type));                      \
>          return _error_return;                                                 \
>      }
>  
> @@ -585,7 +586,8 @@
>  
>  #define ESX_VI__TEMPLATE__DYNAMIC_FREE(__type, _dispatch, _body)              \
>      ESX_VI__TEMPLATE__FREE(__type,                                            \
> -      ESX_VI__TEMPLATE__DISPATCH(__type, _dispatch, /* nothing */)            \
> +      ESX_VI__TEMPLATE__DISPATCH(item->_type, __type, _dispatch,              \
> +                                 /* nothing */)                               \
>        _body)
>  
>  
> @@ -618,14 +620,14 @@
>  
>  #define ESX_VI__TEMPLATE__DYNAMIC_CAST_FROM_ANY_TYPE(__type, _dispatch)       \
>      ESX_VI__TEMPLATE__CAST_FROM_ANY_TYPE_EXTRA(__type, esxVI_##__type,        \
> -      ESX_VI__TEMPLATE__DISPATCH(__type, _dispatch, -1),                      \
> +      ESX_VI__TEMPLATE__DISPATCH(anyType->type, __type, _dispatch, -1),       \
>        /* nothing */)
>  
>  
>  
>  #define ESX_VI__TEMPLATE__DYNAMIC_SERIALIZE(__type, _dispatch, _serialize)    \
>      ESX_VI__TEMPLATE__SERIALIZE_EXTRA(__type,                                 \
> -      ESX_VI__TEMPLATE__DISPATCH(__type, _dispatch, -1),                      \
> +      ESX_VI__TEMPLATE__DISPATCH(item->_type, __type, _dispatch, -1),         \
>        _serialize)
>  

  Not sure I fully understand but looks regular and okay, ACK :-)

Daniel


-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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