[libvirt] [PATCH 2/4] Update modified mac address in place in virGetInterface

[Daniel P. Berrange]

On Wed, Jul 22, 2009 at 01:20:57AM -0400, Laine Stump wrote:
> If the mac address of an interface is changed, we must either create a
> new virInterface object in the cache that has the new name/mac, or
> modify the existing object in the cache. Because the cache is in a
> hash that's indexed by name only, we can't create a new entry having
> the same name without destroying the old one first (which isn't a
> possibility as someone else is already referencing the old one), so
> we're stuck modifying the existing entry. We have to do that without
> changing the pointer to the mac though, so we really can only do it if
> the length of the new mac is equal to or less than the old
> mac. Otherwise, we have to just bail.
> 
> Fixing this problem to properly handle this corner case would require
> a hash table that used both name and mac as keys, but that would be
> inefficient (using the existing hash table implementation, which only
> allows a single key), and probably unnecessary, as the length of mac
> for any given interface will never change in practice.

Yep, the odds of this error case happening are sooooo small, that
giving a fatal error here is more than good enough.

Daniel
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