On 12/03/2010 01:48 AM, Jiri Denemark wrote:
> virDrvSupportsFeature API is allowed to return -1 on error while all but
> one uses of VIR_DRV_SUPPORTS_FEATURE only check for (non)zero return
> value. Let's make this macro return zero on error, which is what
> everyone expects anyway.
> ---
> src/driver.h | 8 ++++----
> src/libvirt.c | 5 ++++-
> 2 files changed, 8 insertions(+), 5 deletions(-)
That is, if you care about the possibility of an error, call the
function directly; and if you use the macro, then you don't care about
errors and are happy treating an error the same as not present.
Seems reasonable.
>
> diff --git a/src/driver.h b/src/driver.h
> index b770e5e..e797a75 100644
> --- a/src/driver.h
> +++ b/src/driver.h
> @@ -52,12 +52,12 @@ typedef enum {
> * Note that you must check for errors.
However, this comment is no longer applicable. So you'll need a v2 that
fixes the documentation, and make it explicit that the macro ignores
errors, as well as a cross-reference to the actual function for someone
that cares about errors.
> *
> * Returns:
> - * >= 1 Feature is supported.
> + * != 0 Feature is supported.
> * 0 Feature is not supported.
> - * -1 Error.
> */
> -# define VIR_DRV_SUPPORTS_FEATURE(drv,conn,feature) \
> - ((drv)->supports_feature ? (drv)->supports_feature((conn),(feature)) : 0)
> +# define VIR_DRV_SUPPORTS_FEATURE(drv,conn,feature) \
> + ((drv)->supports_feature ? \
> + (drv)->supports_feature((conn), (feature)) > 0 : 0)
>
--
Eric Blake eblake@xxxxxxxxxx +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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