Re: [libvirt] [PATCH 3/4] qemu: Don't report false error from MigrateFinish

On Wed, Jul 08, 2015 at 15:22:51 +0200, Jiri Denemark wrote: > virDomainMigrateFinish* APIs were unfortunately designed to return the > pointer to the domain on destination and NULL on error. This looks OK in > normal cases but the same API is also called when we know migration > failed and thus we expect Finish to return NULL even if it actually did > all it was supposed to do without any error. The call is defined to > return nonnull domain pointer over RPC, which means returning NULL will > always result in an error being send. If this was not in fact an error, > the API itself wouldn't set anything to the thread local virError, which > makes the RPC layer come up with it's own "Library function returned > error but did not set virError" error. > > This is quite confusing and also hard to detect by the caller. This > patch adds a special error code which can be used to check that Finish > successfully aborted migration. > > Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; > --- > include/libvirt/virterror.h | 1 + > src/qemu/qemu_migration.c | 6 ++++++ > src/util/virerror.c | 3 +++ > 3 files changed, 10 insertions(+) I'm kind of not sure whether I like this solution or not. I understand the reasons for having it but I'm not liking it. ACK but I'd prefer another opinion on this if possible.