[libvirt] [PATCH v2 3/8] util: Generate a common internal only error print

[John Ferlan]

On 06/05/2017 03:39 AM, Peter Krempa wrote:
> On Fri, Jun 02, 2017 at 06:17:17 -0400, John Ferlan wrote:
>> If virObjectIsClass fails "internally" to virobject.c, create a macro to
>> generate the VIR_WARN describing what the problem is. Also improve the
>> checks and message a bit to indicate which was the failure - whether the
>> obj was NULL or just not the right class
>>
>> Signed-off-by: John Ferlan <jferlan at redhat.com>
>> ---
>>  src/util/virobject.c | 16 +++++++++++-----
>>  1 file changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/util/virobject.c b/src/util/virobject.c
>> index 34805d3..9f5f187 100644
>> --- a/src/util/virobject.c
>> +++ b/src/util/virobject.c
>> @@ -47,6 +47,16 @@ struct _virClass {
>>      virObjectDisposeCallback dispose;
>>  };
>>  
>> +#define VIR_OBJECT_USAGE_PRINT_WARNING(anyobj, objclass)                    \
>> +    do {                                                                    \
>> +        virObjectPtr obj = anyobj;                                          \
>> +        if (!obj)                                                           \
>> +            VIR_WARN("Object %p is not a virObject class instance", anyobj);\
> 
> Is this really helpful?
> 
> Object (nil) is not a virObject class instance.
> 
> %p does not make sense since it's always NULL, and also obviously a
> null pointer is not a class instance ...
> 

True; however, if you had snipped more context:

-    VIR_WARN("Object %p (%s) is not a virObjectLockable instance",
-              anyobj, obj ? obj->klass->name : "(unknown)");

the old context used the "? ... :" and would also have said "Object
(nil) (unknown) is not... " - I just went more direct and removed the
assumption that it's a virObjectLockable instance.  I can change the
message if that's all you object to though.

The goal here was the second half of the message to be more explicit.

John