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

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(+)